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Smithsonian Contributions to Knowledge. 192
CRETACEOUS REPTILES
UNITED SLATES.
BY
JOSEPH LBEIDY, M.D.,
PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA, CURATOR OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA, -
Wa ave Ey LNG TOON <C in yi: PUBLISHED BY THE SMITHSONIAN INSTITUTION, MAY, 1865.
NEW YORK: D. APPLETON & CO.
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C52 HEG65 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. Vert. Fat. <n
192
PReraACkhOUs REPTILES
UNITED STATES.
e BY
JOSEPH LEIDY, M.D., PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA, CURATOR OF THE AC
[ ACCEPTED FOR PUBLICATION DRCEMBER, 1864.]
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Joseru Tlenry, Secrelary 8. 1.
COLLINS, PRINTER, "| PHILADELPHIA.
PREFACE.
Tue following Memoir was commenced seven years ago, and, although various circumstances have interfered with its completion until now, the delay has not been unattended with some advantages. During the lapse of time nearly as much new material has been discovered as was originally at the command of the author, and thus our acquaintance has been greatly extended with the subjects of the memoir. In consequence the latter has been repeatedly altered, and portions have been intercalated, which may serve to explain any apparent want of continuity in the work.
The author takes the opportunity of acknowledging his obligations to Prof. George H. Cook, of Rutgers College, New Brunswick, New Jersey, who has given constant and important aid in procuring specimens for examination dur- ing his geological explorations of the State. Acknowledgments are also due to W. Parker Foulke, of Philadelphia, through whose especial exertions we are indebted for the discovery of the huge Reptile, Hadrosaurus, which forms one of the most interesting and important subjects of description in the suc- ceeding pages. Valuable assistance has also been rendered by others in ob- taining specimens for investigation, but more especially by Dr. J. H. Slack, of Philadelphia. The basis of the work has been mainly founded on the rich collee-
tion of the Academy of Natural Sciences of Philadelphia.
( iii )
CONTENTS.
Preface ‘ : : ; : - : : ‘ 3 ; Memoir on the Extinct Reptiles of the Cretaceous Formations of the United States Introduction
Sanria
Thoracosaurus heocesariensis
Bottosaurus Harlani
Undetermined Species of Crocodiles . Hyposaurus Rogersii
Discosaurus vetustus
Cimoliasaurus magnus
Piratosaurus plicatus
Mosasaurus
Macrosaurus levis
Polygonodon vetus .
Hadrosaurus Foulkii F ; Undetermined Reptiles allied to Hadrosaurus Astrodon Johnstoni
Tomodon horrificus .
Pliogonodon priscus
Chelonia
Chelone sopita
Chelone ornata
Emys firmus
Emys beatus
Emys prayus
Platemys sulcatus
Bothremys Cookii
Trionyx priscus
A Synopsis, in which an attempt is made to define more closely the Genera and Species whose
remains are described in the preceding pages Index ; ; References to the Plates .
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MEMOIR
ON THE
EXTINCT REPTILES OF THE CRETACEOUS FORMATIONS OF THE UNITED STATES.
INTRODUCTION.
THE present memoir consists of descriptions of remains of Reptiles discovered in the Cretaceous Formations of the United States. It was the author’s intention to include an account of the fossil Fishes, of which he had the opportunity of examining numerous specimens, so as to form a monograph of the extinct Vertebrata of the Cretaceous period. These specimens are, however, in so many instances mingled with others derived from Tertiary deposits that he has been led to defer an account of them until he has the opportunity of ascertaining and separating those which belong to the different formations. Other Vertebrata, Bird or Mammal, have not been detected in the Cretaceous deposits of any part of America.’
* I formerly attributed two species of Cetaceans to the Green-sand of the Cretaceous era of New Jersey, which I now believe to be erroneous, and regret the more as I have been quoted in the excellent works of Lyell (Princip. Geol. 9th ed. 145; Man. Elem. Geol. 5th ed. 254) and Dana (Man. Geol. 473, 478) in proof of the existence of such animals during the Cretaceous epoch.
Dr. Harlan described a vertebra (Journ. Acad. Nat. Sci. Phila. VI, 232, Plate xiv, Fig. 1; Med. and Phys. Researches, 282, Fig. 1), from Mullica Hill, N. J., which he considered to belong to a species of Plesiosaurus. Having accidentally noticed the specimen in the museum of the Academy, I recognized its cetacean character and referred it to a species with the name of Priscodelphinus Harlani (Proc. Acad. Nat. Sci. V, 327). As the formation at Mullica Hill belongs to the Cretaceous epoch, it thus appeared as if evidence was obtained proving the existence of a Cetacean at that age. Several other vertebre, from the Marl of New Jersey, were at the same time referred to Priscodel- phinus grandaevus (Ibidem). The latter specimens have since been ascertained to have been derived from a Miocene Tertiary deposit of Shiloh, Cumberland County.
TI have since had the opportunity of examining many Cetacean remains from the Miocene deposits of New Jersey, and have been led to the conclusion that the vertebra of Priscodelphinus Harlan is a Miocene fossil which had become an accidental occupant of the Green-sand in which it was found.
Not only have Miocene fossils occasionally found their way into the Green-sand of New Jersey, but also the remains of more recent animals. The museum of the Academy contains remains of Mastodon, Beaver, Reindeer, Deer, and Muskrat, from the Green-sand of Burlington and Camden Counties.
The tooth of a Seal, reputed to have been found in the Green-sand near Burlington, New Jersey,
1 February, 1865, ( 1 )
9 INTRODUCTION.
Most of the fossil remains which form the subject of the memoir were obtained in New Jersey, and are contained in the museum of the Academy of Natural _ Sciences of Philadelphia. Very many of them were found in the Green-sand, which, under the name of Marl, is largely excavated for agricultural purposes; others were obtained from limestone. Many specimens have been derived from Maryland, Delaware, North Carolina, Georgia, Alabama, Mississippi, and Nebraska.
The Cretaceous formations compose a large tract extending through the States of New Jersey, Maryland, and Delaware. They also appear in isolated patches in North and South Carolina, and Georgia. More extensively developed in the western portion of the latter State, they curve in a wide crescentoid tract through Alabama, Mississippi, and Tennessee to the mouth of the Ohio River. Thence passing in a narrow band through Arkansas, they afterwards expand to an enormous extent and occupy a great portion of the region between the Mississippi River and the Rocky Mountains, reaching north into the British possessions, and south into Mexico.
When we consider the great development of the Cretaceous formations in the western and southern portions of the United States in comparison with those on the eastern border, from which nearly all our fossils have been obtained, we may antici- pate many additions. These will not only increase the number of species and genera, but will serve to clear up many of the obscurities concerning those already in our possession.
According to Messrs. Meck and Hayden,’ the Cretaceous formations in the region of the Upper Missouri, in section, present the following constitution :—
EARLIER CRETACEOUS—
No. 1. Yellowish, reddish, and whitish sandstones and clays, with lignite and fossil angiospermous leaves, 400 feet in thickness. Located near Dakota, and reaching southward into northeastern Kansas.
No. 2. Gray laminated clays, with some limestone, 800 feet in thickness. Located near Fort Benton, on the Upper Missouri, also below the Great Bend. Characteristic fossils of this division are Inoceramus problematicus, I. tenuirostris, I. fragilis, Ostrea congesta, Venilia Mortoni, Phaladomya papyracea, Ammonites Mullani, A. vespertinus, Sca- phites Warreni, &e.
No. 3. Grayish calcareous marl, 200 feet in thickness. Location: Bluffs on the Missouri, below the Great Bend. Characteristic fossils consist of Inoceramus problematicus, I. pseudo- mytiloides, I. aviculoides, Ostrea congesta, &c. p
LATER CRETACEOUS— No. 4. Plastic clays, 700 feet in thickness: the middle portion barren of fossils. Located on the Missouri near Great Bend, about Fort Pierre, extending to the Bad Lands, on Sage Creek, Cheyenne River, and White River above the Bad Lands. Characteristic fossils are Nautilus Dekayi, Ammonites placenta, A. complexus, Baculites ovatus, B. com-
and referred to Stenorhynchus vetus (Proc. Acad. Nat. Sci. VI, 377), I also believe to be a Miocene fossil.
Dr. Harlan described the fragment of the femur of a Snipe (Scolopaa), from the Marl of New Jersey (Med. and Phys. Res., 282), which has been accepted by authors as an ornithic fossil of the Cretaceous period. The specimen, preserved in the museum of the Academy, is of recent origin.
1 Dana, Manual of Geology, 1863, 469; Proc. Acad. Nat. Sci. 1861, 419.
INTRODUCTION. 3 pressus, Scaphites nodosus, Helicoceras Mortoni, H. tortum, H. umbilicatum, Ptycho- ceras Mortoni, Fusus vinculum, Anisomyon borealis, Amauropsis paludiniformis, Dentalium gracile, Crassatella Evansi, Cucullea Nebrascensis, Inoceramus sublxvus, I. tenuilineatus, I. Nebrascensis, I. Vanuxemi, bones of Mosasaurus, &e.
No. 5. Gray ferruginous and yellowish sandstones and arenaceous clays, 500 feet in thickness. Location: Fox Hills near Moreau River, above Fort Pierre near Long Lake, and along the base of Big Horn Mountains. Characteristic fossils are Belemnitella bulbosa, Nautilus Dekayi, Ammonites placenta, A. lobatus, Scaphites Conradi, S. Nicolleti, Baculites grandis, Busycon Bairdii, Fusus Culbertsoni, bones of Mosasaurus, &c.
A section of the New Jersey Cretaceous deposits, according to Messrs. Meek and Hayden,‘ as compiled from the observations of Prof. Geo. H. Cook, exhibits the fallowing structure :—
EARLIER CRETACEOUS—
No. 1. Dark blue, ash colored and whitish clays and micaceous sand, with thin seams of lignite. Great quantities of sulphuret of iron. Fossil wood in some of the layers in large quantities, and angiospermous leaves. 130 feet or more in thickness.
LATER CRETACEOUS—
No. 4. Dark clays, with occasional streaks and spots of Greef-sand, containing Ammonites Dela- warensis, A. placenta, Baculites ovatus, etc. 130 feet in thickness.
First or lower bed of Green-sand, containing Nautilus Dekayi, Baculites ovatus, Belemni- tella mucronata, Terebratula Sayi, Ostrea larva, Exogyra costata, Gryphea vesicu- laris, ete. 50 feet in thickness.
Quartzose sand, highly ferruginous ; argillaceous in its upper part, containing Belemnitella mucronata, Ostrea larva, Exogyra costata, Neithea Mortoni, ete. From 65 to 70 feet in thickness.
No. 5. Second bed of Green-sand. This includes the yellow limestone of Timber Creek, containins Montivaltia Atlantica, Nucleolites crucifer, Ananchytes cinctus, ete. Also a bed of neatly unchanged shells, among which are Terebratula Harlani, Gryphea lateralis, G. convexa, ete. Lastly, Green-sand, ete., containing Scaphites Conradi, Baculites ovatus, Ammonites placenta, Cucullexa vulgaris, ete. From 45 to 50 feet in thickness.
TERTIARY—
Quartzose sand resembling ordinary beach sand, and destitute of fossils. From 45 to 50 feet in thickness. Third, or upper bed of Green-sand. 60 feet in thickness.
In Alabama, according to Prof. Winchell, as communicated by Messrs. Meek and Hayden,’ the Cretaceous formations are as follows :—
EARLIER CRETACEOUS— No. 1. Dark blue and mottled shales or clay, with vegetable remains. 300 feet or more in thickness.
LATER CRETACEOUS— No. 4. Grayish and yellowish sand, with fossil wood and Teredo tibialis; 15 feet. Gray sand with Ammonites placenta, A. Delawarensis, Gryphxa vesicularis, Exoqyra costata, Inoceramus biformis, Pecten quinquecostatus, ete.; 6 feet. Soft white limestone (“ Rotten limestone”), with Nautilus Dekayi, Ammonites Delawarensis, Baculites ovatus, ete.; 150 feet or more. Loose white sand, with Ostrea larva, Pecten quinquecostatus, Gryphxa vomer, etc. ; 45 feet.
1 Proc. Acad. Nat. Sci. 1857, 127; 1861, 426. 2 Thidem 1857, 126.
4
No. 5.
INTRODUCTION.
Soft white limestone, with Nautilus Dekayi, Baculites ovatus, Scaphites Conradi, Gryphxa vesicularis, Exogyra costata, etc.; 6 feet. Dark limestone, with obscure casts of shells; 4 feet.
In Texas the formations consist mainly of compact limestone. Dr. Shumard’ gives the following section :—
Novel:
EARLIER CRETACEOUS— Marly clay, with Ammonites Swallovii, A. Meekianus, Ancyloceras annulatus, Scaphites vermiculus, Baculites gracilis, Inoceramus capulus, etc.; 150 feet in thickness. Arenaceous beds, with Ostrea bellarugosa, remains of fishes, etc.; 80 feet.
. Caprotina limestone, with Orbitolina Texana, ete. ; 55 feet.
Blue marl, with Inoceramus problematicus, etc. ; 50 feet.
. Washita limestone, with Gryphea Pitcheri, Inoceramus problematicus, Hamites Fremonti,
etc.; 100 to 120 feet. Indurated blue marl, with Hxogyra arietina, etc. ; 60 feet.
LATER CRETACEOUS—
. Austin limestone, with Gryphea vesicularis, Exogyra costata, Nautilus Dekayt, Baculites
anceps, remains of fishes, etc.; 100 to 120 feet. Comanche Peak Group, with Exogyra Texana, Gryphzxa Pitcheri, Cardium multistriatum, Ammonites Pedernalis, Heleraster Texanus, Diadema Texana, ete. ; 300 to 400 feet. Caprina limestone, with undetermined species of shells; 60 feet.
Other localities? of Cretaceous formations of the different subdivisions are as follows :—
No.
1. At different points in New Mexico. (Newberry.$ No. 2.
On the north branch of the Saskatchewan, west of Fort 4 la Corne, lat. 54° N., in New Mexico. (Meek.)
3. Over the region from Kansas through Arkansas to Texas; Pyramid Mountain, N. Mexico. . In British America, on the Saskatchewan and Assiniboine ; on Vancouver Island; Sucia
Islands, in the Gulf of Georgia.
. At Deer Creek, on the North Platte, and not identified south of this. (Meek and Hayden.)
1 Transac. Acad. of Sciences of St. Louis, I, 583. 2 Dana, Manual of Geology, 470.
THORACOSAURUS. 5
SAURIA.
THORACOSAURUS.
Thoracosaurus neocesariensis.
New Jersey Gavial, Dz Kay, Ann. Lyc. Nat. Hist. N. Y. III, 1833, 156, pl. iii, figs. 7-10.
Gavialis neocesariensis, Dz Kay, Zool. New York, 1842, part III, 28, pl. 22, fig. 59.
Crocodilus s. Gavialis clavirostris, Morton, Proc. Acad. Nat. Sci. Phila. III, 1844, 82.—Gresen, Fauna d. Vorwelt, 1847, 122.
Crocodilus basifissus, OwEN, Jour. Geol. Soc. Lond. V, 1849, 381, pl. x, figs. 1, 2; Paleontology, 1860, 277.—Picrer, Traité de Palwont. I, 1853, 482.
Sphenosaurus, Acassiz, Proc. Acad. Nat. Sci. Phila. IV, 1849, 169.
Thoracosaurus grandis, Lewy, Proc. Acad. Nat. Sci. Phila. VI, 1852, 35.
The most characteristic of the Crocodilian remains, obtained from the strata of the Cretaceous period in the United States, consists of a nearly entire skull, which was discovered in limestone, overlying the ferruginous Marl, on the farm of Gen. William Irick, near Vincenttown, Burlington County, N. J. The specimen was presented by that gentleman, and Mr. Wm. Whitman, of this city, to the Academy of Natural Sciences, in the cabinet of which it is now contained. ‘This finely pre- served fossil consists of the skull, without the lower jaw. It has lost the anterior extremity of the muzzle, estimated to have been equal to half its original length. The teeth are also broken away, but sockets with the remains of fangs for fourteen of the back teeth exist on each side of the fossil. 'The zygomatic arches, as formed by the squamosals, are broken away, as is also the case with the articular ends of -the tympanics and the lower or outer conjoined extremities of the ecto- and ento- pterygoids.
The matrix, in which the fossil was imbedded, for the most part has been chiselled away. Portions still adherent and occupying one orbit and palatine orifice, besides the interior of the cranium and nasal passages, consist of a moderately hard, gray arenaceous limestone. The bones of the fossil are brown and friable.
In general shape and construction the fossil skull exhibits more resemblance to that of the existing Gavial of the Ganges (Gavialis Gangeticus) than of any other of the living crocodilian Reptiles, though from the non-eversion of the orbits and the more gradual prolongation of the muzzle it also presents a relationship to the genus Mecistops, of Western Africa. Of all known forms, however, it bears most resem- blance to the skull of the extinct Gavialis macrorhynchus, of the Cretaceous forma- tions of Europe.
In consequence of the anterior extremity of the muzzle being lost in the New Jersey specimen, we have no positive means of ascertaining the length-of the skull. Supposing it, however, to have held the same relation of length to breadth as in the recent Gavial, in its perfect condition it would have measured about three and three-quarter feet in length and one and a-half feet in breadth. The relation of length to breadth in the Gavialis macrorhynchus, with which the New Jersey species appears to be most closely allied, is rather less, and would have made our
6 THORACOSAURUS.
fossil head about three and a-half feet in length. If we allow as many vertebre to the New Jersey Gavial as are possessed by the existing species, or the same pro- portionate length of body to the head, the former animal in its entire condition would measure twenty feet in, length.
The upper view of the fossil skull, represented in Fig. 1, Plate I, bears a strong resemblance to that of the living Gavial, except that the boundaries of ‘the orbits are not conspicuously everted as in the latter, and the muzzle is not so abruptly narrowed forward. In the characters just mentioned the fossil appears intermediate to the Gavial and Mecistops, and resembles the Teleosauri of the Liassic formations of Europe, but most closely the Cretaceous Gavialis macrorhynchus. The posterior and lateral outlines of the cranium are the same in both the New Jersey and living Gavials, as is also the form of the large temporal foramina. The space separating the latter in our fossil, formed by the symmetrical parietal, is both relatively and absolutely narrower than in the living Gavial. The forehead, as formed by the frontal and pre-frontals, has almost the same proportionate breadth as in the latter, but is only slightly concave in consequence of the non-eversion of the orbital borders. The frontal in the fossil, as is also the case in the Gavialis macrorhynchus, is prolonged considerably more posteriorly to join the parietal than in the recent Gavial or Mecistops. The orifices of the orbits, when perfect, appear to have had nearly the same proportionate size and form as in the living Gavial, but their horders in no position are everted, not even so much as in Mecistops, or the Alligator, A. Mississipiensis,
The post-frontals, separating the orbits from the temporal foramina, are propor- tionately narrower than in the recent Gavial; while the post-orbital arches, formed through conjunction of the post-frontals with the malars, are broader.
As in the extinct Gavialis macrorhynchus, the face in advance of the forehead and orbits in the New Jersey fossil slopes with a gentle curve forward to the broken, end of the muzzle. i
The malar and lachrymal are more prolonged upon the face or muzzle than in the recent Gavial. Thus in the latter, the anterior border of the malar reaches as far forward as the position of the fourth tooth, counting from behind, and the lachrymal advances as far as the sixth tooth. In the fossil the malar extends as far forward as the seventh tooth, and the lachrymal reaches beyond the position of the ninth tooth.
The posterior extremities of the nasals are angular, and extend back on a line with the anterior orbital margins. They widen forward to the anterior ends of the pre-frontals, then very gradually narrow forward a short distance beyond the lach- rymals, and finally narrow abruptly into a pair of linear prolongations extending to the broken end of the fossil. A similar condition of the nasal bones is observed to exist in the Gavialis macrorhynchus.
The surface of the cranium, as formed by the parietal, mastoids, frontals, pre- and post-frontals, is less foveated than in the full-grown Gavial of the Ganges ; and the surface of the muzzle is likewise rather less coached though perforated by as many vasculo-neural foramina.
On both sides of the face, in the fossil, there is a large hole, situated between
THORACOSAURUS. iT
the lachrymals and pre-frontals, a short distance in advance of the inner part of the orbits, which, though perhaps accidental, reminds one of the unossified spaces noticed in a somewhat similar position in the Deer among Mammals, and corre- sponding with the orifices represented as existing in the Zeleosaurus or Pelago- saurus typus,’ between the lachrymals and nasals.
The lateral view of the fossil skull, represented in Fig. 2, Plate I, is nearly re- peated by that of the corresponding portion of the skull of the recent Gavial, except that the face in the former presents a more gradual slope from the position of the orbit.
The occipital view of the fossil also bears a near resemblance to that of the recent Gavial; its upper outline, however, is more nearly horizontal, and is not prominent at the middle. The supra-occipital is much broader in relation with its height than in the recent Gavial, or the Alligator. Its upper extremity forms a square plate, with everted edges, over an inch in breadth, articulating by transverse suture on the top of the cranium with the parictal.
The exoccipitals, the occipital condyle, and the occipital foramen present nothing peculiar. The latter is an inch and a half in breadth and ten lines in height.
The inferior view of the fossil skull, represented in Fig. 1, Plate II, though pre- senting the same general outline of form and construction as in the recent Gavial, nevertheless exhibits a number of important peculiarities. The palatine foramina, as in Gavialis macrorhynchus, are much larger than in the recent Gavial. They are oyoidal, with their narrow extremity forward and their inner sides nearly parallel. ‘They extend from the ento-pterygoids as far forward as the position of the seventh tooth, counting from behind. The part of the skull corresponding with the position of the foramina and the intervening palatines rises even more than in Mecistops. ‘The anterior extremities of the palatines reach as far forward as the position of the ninth tooth from behind. In advance of the palatines the surface of the muzzle is flat.
Neither the palatines nor the ento-pterygoids present capsular osseous dilatations, such as exist in the recent Gavial.
The posterior nares are large, and, as in the Alligator and the extinct Gavialis macrorhynchus, are divided by an osseous septum of the ento-pterygoids. The lower border of this septum forms a stout ridge expanding behind upon the basi- sphenoidal. ‘The latter includes a large, transversely oval pit, communicating with a canal piercing the bone as in other Crocodilians.
The under surface of the tympanics, as observed in this view of the skull, exhibits a deep and wide gutter or concave fossa, of which only a superficial trace is present in the recent Gavial.
The remaining portions of the maxille in the fossil, on each side, contain the sockets and portions of the fangs of fourteen teeth, occupying a space sixteen and a half inches in length.
Compared with the skull of Gavialis macrorhynchus, as represented by the figures
1 See Fig. 7, Plate XXV, of the Atlas to Pictet’s Traité de Paléontologie, 2d ed.
8 THORACOSAURUS.
of De Blainville’ and Gervais,” that of the extinct Gavial of New Jersey was more than one-third larger. ‘These two Cretaceous Crocodilians present characters in common, so peculiar in comparison with other known forms, recent and extinct, that they may be considered as belonging to a distinct genus, for which the name of Thoracosaurus has already been proposed for one of the species, and may equally
apply to the other.
Measurements of the Skull of THORACOSAURUS NEOCESARIENSIS.
Estimated length of skull : : : : from 42 inches to
Breadth at condyles of tympanics or articulation of the lower jaw
Breadth of face at the last teeth .
Breadth of face at the fourteenth teeth, gear iee Ser petal
Height of cranium at the occiput :
Breadth of cranium at the posterior border of ie anit aap the parietal and mastoids
Distance from summit of the occiput to palma eorcemter of the frontal
Length of alveolar border from back end of maxilla to the fourteenth alveolus, or broken end of the fossil
Length of palatines in the median suture
Breadth of palatines together at the middle
Length of palatine foramina
Breadth of palatine foramina
Distance from occipital condyle to br Bien end of the canal, pane ante ing with the fourteenth tooth, counting from behind
Breadth of muzzle at anterior extremity of the palatine foramina
Breadth of cranium at middle of the temporal foramina -
Transverse and antero-posterior diameters of the temporal foramina
Transverse and antero-posterior diameters of the orbits
Distance apart of orbits where nearest 3 : ° é = . Distance apart of temporal fossee : c 4 - - 5 Length of frontal : . 5 F : 5 -
Breadth of frontal between post- Seeatin
Length of parietal
Breadth of parietal posteriorly
Distance between anterior ends of malars
Breadth of nasals between anterior ends of pre- Entel Breadth of nasals between anterior ends of lachrymals Diameter of posterior nares
Thickness of border of septum pemrcet ie latter
A small fragment of the lower jaw of an extinct Gavial from the ferruginous sandstone, of the Cretaceous era, of the Highlands of Navesink, New Jersey, was described by Dr. J. E. De Kay, in 1833, in the third volume of the Annals of the Lyceum of Natural History of New York, page 158. The fragment, now more mutilated than formerly, I have had the opportunity of inspecting, through the kindness of Prof. E. Emmons, of Albany. The specimen is about six inches in
%
1 Osteographie; Reptiles, Plate 6, Crocodilus macrorhynchus.
2 Zoologie et Paléontologie Francaises, Plate 59, fig. 18.
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THORACOSAURUS. 9
length and corresponds with that part of the jaw just in advance of the divergence of the rami, and consists of portions of both dentals and splenials. The right dental contains remains of four alveoli with portions of their teeth, of which one incloses the entire crown of a successional tooth.
This fossil fragment of the lower jaw I suspect to belong to the same species as the Vincenttown skull, but to a smaller or younger individual. The symphysis of the splenials, preserved at the posterior part, in the perfect condition, is estimated to have been about seven inches in length. The breadth of the jaw at the back extremity of the symphysis of the splenials is estimated to have been about four and a quarter inches; and at the fore extremity two and three-quarter inches. The oral surface of the splenials and dentals presents about the same degree of convexity as in the recent Gavial.
The cabinet of the Academy contains a fragment of the left upper maxilla, apparently belonging to the same Gavial as the fossil skull just described, which is of especial interest from its retaining several entire and well-preserved teeth. The specimen, together with some small fragments of the jaw and teeth of the same individual, were obtained by Dr. J. L. Burtt, from the Cretaceous limestone, near Blackwoodtown, Camden County, N. J. The fragment to which we especially refer, represented in Fig. 2, Plate II, is about eight inches long, and corresponds with that portion of the left maxilla in the fossil skull which contains the back six teeth with the exception of the one or two last ones. It has a portion of the malar attached, and belonged to a rather larger individual than the Vincenttown skull, for it contains one tooth less in the space occupied by seven in the latter.
The crowns of the teeth protruding from the specimen are curved conical as in the recent Gavial, but are more robust in proportion with their length. The ridges separating their outer and inner surfaces are also less prominent than in the living Gavial. The more anterior of the teeth, towards the base of the crown, internally exhibit a slightly fluted disposition. The enamel, which is jet black, is closely striated longitudinally with fine linear ridges, and also presents a feeble annular disposition towards the summits of the crowns.
The measurements of the teeth, counting them from behind forward, are as follows :—
Lines Length of crown of third tooth . 5 ; - : ; : ; : ». A Diameter of base from without inwardly . : : : : ; : . 5t Length of crown of fourth tooth ; : hes - ; : ; LO) Diameter of base from without inwardly. : : ° . ; : . 64 Diameter of base at the divisional ridges . - - - c : : ee lt Length of crown of sixth tooth ; ; 4 : . : : . 133 Diameter of base from without inwardly . : : 4 ; 5 A a Ae Diameter of base at the divisional ridges : - 2 : ’ 4 . OF Length of sixth tooth to bottom of aivedius : : : : : : > HS9 ‘Diameter of base of eighth tooth from without inwardly . é j : : 2 9% Diameter of base of eighth tooth at divisional ridges ; F : é “aL0
A detached tooth, represented in Fig. 4, Plate I, from the same individual as the fossil fragment of jaw just described, presents the same characters as those contained
in the latter. 3 2 March, 1865,
10 THORACOSAURUS:
Two isolated teeth, obtained by Dr. Burtt from the same formation as the pre; ceding specimens, exhibit identical characters with those above described.
The crowns of. two additional teeth from the Green-sand, near Blackwoodtown, Camden County, N. J., presented by Dr. Burtt to the Academy, probably belong to the same species as the foregoing. ‘They are narrower in proportion to their length than those in the fragment of jaw, but may have occupied a more anterior position in the series.
The successional tooth, alluded to in the jaw fragment described by Dr. De Kay, resembles the larger of the two just indicated.
The summits unworn of two successional teeth, seen protruding from within the fangs of broken functional teeth, in the Vincenttown skull, in the corrugated appear- ance of their enamel and in other characters, are identical with those of the teeth described.
The cabinet of the Academy also contains several small fragments of jaws, with entire teeth, from the Cretaceous limestone of Big Timber Creek, Gloucester Co., N. J., presented by Messrs. R. Haines, J. P. Smith, T. McEuen, and S. G. Morton. The teeth, of which the most perfect is represented in Fig. 6, Plate I, correspond in size, form, and proportions, with those contained in the fragment of jaw pre- sented by Dr. Burtt.
Of five specimens, consisting of crowns of teeth, and probably referable to the same species as the preceding, from the Green-sand of Burlington County, N. J., presented to the Academy by Lewis T. Germain, the more perfect are represented in Figs. 3 and 5, Plate I. One of these corresponds in its proportions with the teeth in Dr. Burtt’s fossil, and in the fragments from Big Timber Creek. The other is much longer in relation with its diameter, and probably belonged to the anterior part of the jaw.
Accompanying the teeth, presented by Mr. Germain, there is a mutilated speci- men of a posterior caudal vertebra, the body of which is a little over three inches in length, and is eleven lines in transverse diameter at its middle.
Of other fossils referable to the extinct Gavial of New Jersey, contained in the cabinet of the Academy, there is a coherent mass of much mutilated bone fragments, obtained from the Green-sand, and presented by Daniel Brinton. ‘The fragments are exceedingly friable, and are cemented together by a portion of the Green-sand matrix. One of them consists of a portion of the left maxilla, and possesses the same size and form as the corresponding portion of the jaw of the Vincenttown skull just in advance of the palatine foramen. The outer part of the alveoli is destroyed and all traces of the teeth have disappeared. The best preserved of the fragments consists of the greater part of a fourth or fifth cervical vertebra, repre- sented in Figs. 5, 6, Plate III. It is identical in character with the vertebra from the New Jersey Green-sand, described and figured by Prof. Owen, as indicating a species of Crocodile er Alligator, for which he proposed the name of Crocedilus basifissus.1 The specific term was given in consequence of the cleft condition of the process or hypapophysis beneath the fore part of the vertebral body. The cervical
t Journ. Geol. Soc. London, V, 381, pl. x, figs. 1, 2.
THORACOSAURUS. il
vertebre of the Gavialis, or, as we may call it, Thoracosaurus macrorhynchus, appear also to have possessed the same discriminating character, as represented by Fig. 22, Plate 59, of the Atlas to Gervais’ Paléontologie. -
Other fragments adherent to the mass consist of a portion of another cervical vertebra, a much mutilated posterior caudal vertebra corresponding in its proportions with the one above indicated, an uncharacteristic piece of an ulna, and a mutilated upper extremity of a humerus.
A dermal plate and part of another, presented to the Academy by Dr. S. G. Morton, and obtained from the Green-sand of Mount Holly, Burlington Co., N. J., is probably referable to the same species. The specimens are black, dense, and heavy from the infiltration of ferruginous matters. They are deeply foveated on their free surface, and are devoid of any trace of a carina, The more perfect specimen, represented in Fig. 3, Plate I, is nearly oblong square, and measures three and a half by three inches in breadth, and is half an inch in thickness along the middle. Upon these dermal plates I formerly proposed the name of Thoraco- sdurus grandis."
Since writing the preceding, I have received for examination a collection of crocodilian fossils from Prof. Cook, of Rutger’s College, New Brunswick, N. J., which are referable to the Thoracosaurus Neocesariensis. 'The fossils were obtained from the Green-sand of Monmouth County, N. J., and are black, dense, and in a good state of preservation. They consist of ten vertebra, and a fragment of a dermal plate resembling those above described, all apparently from the same indi- vidual, which had reached maturity.
Of the vertebra, one, represented in Fig. 7, Plate III, appears to be the sixth cervical, and has lost its spinous and articular processes. It agrees in size and details with the specimen of a fourth or fifth cervical vertebra above described, and with that described by Prof. Owen as characteristic of the Crocodilus basifissus, excepting that its hypapophysis exhibits a mere trace of fission; a condition, how- ever, which indicates its more posterior position in the cervical series.
Two other vertebre, preserved nearly entire, are the first and third dorsal, of which the latter is represented in Fig. 8, Plate III. The former has lost its hypa- pophysis, but otherwise both specimens resemble in the details of form the corre- sponding bones of the Mississippi Alligator.
The remaining specimens consist of the series apparently unbroken, from the eighth dorsal to the second lumbar, inclusive. . The eighth and ninth dorsals, Fig. 9, Plate III, have lost all the processes from their vertebral arches, and their bodies are coossified by a huge exostosis. The tenth dorsal, Fig. 10, retains its spinous process, and is five and three-quarter inches high posteriorly. The last pair of dorsals and the two lumbars, of which the first is represented in Fig. 11, have lost their vertebral arches. In form and proportions all the specimens agree with the corresponding bones of the Mississippi Alligator.
Measurements of the specimens are as follows :—
4 Proc, Acad. Nat. Sci. Phila. VI, 1852, 35.
12 BOTTOSAURUS.
Lines. Length of sixth cervical vertebra at the lower part of the body . 2 ; an £25 Breadth of body anteriorly . : : 2 : . : : - ey 2D Height of body anteriorly . ; A : é : e : 4 5 a 2B Height of vertebral canal anteriorly. é : : . ; : : ee Width of vertebral canal anteriorly. - - : 7 , : z 4 peal! Length of body of first dorsal laterally “ : : c : z : . 24 Breadth of body of first dorsal anteriorly . : - . 26 Height from lower part of body posteriorly to summit of sents ae : . 68 Height of vertebral canal anteriorly . ‘ ‘ . & 5 é 2 are Width of vertebral canal anteriorly . , A A : : : . =) 2 Length of body of third dorsal inferiorly. < : : < ; 2 . 226 Length of body of third dorsal “yen - : : = : 3 : . 24 Length of hypapophysis . 5 5 : : : k e a surne Width of hypapophysis at middle : 5 5 5 z ko Height from end of hypapophysis to summit of pains ae : c : oe) Height of body anteriorly ; : . : ; - c : é . 25 Width of body anteriorly . : : 9 : a oll Height anteriorly from lower edge of bodly tio auntie of spinous process 75 Length of spinous process anteriorly from edge of vertebral canal : ; 29) 43 Height of vertebral canal anteriorly. , ‘ : : : 9 Width of vertebral canal anteriorly . 5 s : 2 = z , eel Length of transverse process above. : : 5 ; . 24 Length of eoossified eighth and ninth dorsal odes eer : riled . 58 Height of body of eighth dorsal anteriorly . °. : - ; < bY Width of body of eighth dorsal anteriorly . : : : : , : 2b Height of vertebral canal anteriorly. ; : F 5 oe 3 canes: Width of vertebral canal anteriorly. : : g 5 : 2 : 5 Length of body of tenth dorsal inferiorly. : 5 > : é z Sa 8 Length of body of tenth dorsal laterally —. : : : : ° - 3 28) Height of body anteriorly . é : : : : : : 5 : . 26 Width of body anteriorly . : : : E : 5 : = 3 aii Height of vertebral canal anteriorly. é ° - - 5 : : aS Width of vertebral canal anteriorly —. < = - 4 3 5 . ett Height of spinous process anteriorly . 5 é é 2 : : 5 . 34 Width of spinous process at middle. : 2 5 - 0 : : = IS Length of body of eleventh dorsal laterally 2 : : : : : #228 Length of body of twelfth dorsal laterally . : 2 > : c : . 30 Length of bodies of first and second lumbars laterally : 3 , 5 . 32 Height of body of first lumbar anteriorly. ; : : : : : . 24 Width of body of first lumbar anteriorly . x : : : é 5D
BOTTOSAURUS.
Bottosaurus Harlani.
Extinct species of Crocodile, Hannan, Journ. Acad. Nat. Sci. Phila. IV, 1824, 15, pl. 1.
Crocodilus Harlani, MEYER, Paleologica, 1832, 108.
Crocodilus macrorhynchus, HARLAN, Med. and Phys. Researches, 1835, 369; Trans. Geolog. Soc. Penn, I, 1835, 76; Edinb. New Phil. Journ. XVIII, 1835, 28; Jahrb. f. Miner. 1836, 105.—Gresen, Fauna d. Vorwelt, 1847, 122.
Bottosaurus, AGAssiz, Proc. Acad. Nat. Sci. Phila. IV, 1849, 169.
Crocodilus basitruncatus, OwEN, Jour. Geol. Soc. Lond. V, 1849, 380; Palwontology, 1860, 277.—Picrer, Traité de Paléont. I, 1853, 482.
In the fourth volume of the Journal of the Academy of Natural Sciences, 1824, Dr. Harlan described the fragment of a lower jaw, obtained from the Green Sand, and presented to the Academy by Samuel Wetherill, of Burlington, N. J. The
BOTTOSAURUS. 13
specimen was referred to an extinct species of Crocodile, which, in 1832, was indi- cated in the Paleologica of Meyer, as Crocodilus Harlani. Subsequently, Dr. Harlan, in his Medical and Physical Researches, published in 1835, named the species Crocodilus macrorhynchus, by which name it is generally indicated by systematic writers.
The fragment consists of the greater portion of the right dental bone, and is accompanied by a portion of the corresponding angular bone, apparently from the same jaw. ‘The specimens are black and heavy, and like many other of the Green- sand fossils are infiltrated with sulphuret of iron, in consequence of the decompo- sition of which they are in a less well preserved condition than formerly.
The fragment of the dental bone, represented in Figs. 19, 20, Plate IV, is about fifteen inches in length, and in this extent contains the remains of eleven alveoli, which perhaps comprise the whole number except three or four. It corresponds nearly in form and proportions with the homologous portion of the jaw of the Crocodile or Alligator. 'The posterior portion of the symphysis is preserved; and reaching quite to italong the inner side of the bone, is the sutural surface of the splenial. The enlargements of the dental bone for the accommodation of the canine and posterior largest teeth occupy nearly the same relative position as in the ° Crocodile (C. palustris), and are separated as in the latter by a cylindroid portion of the jaw, which in the specimen measures two and a half inches in diameter transversely, and about the same extent of depth. ‘The outer surface of the bone is abundantly supplied with unusually large vasculo-neural foramina. The remains of the alveoli, so far as one can judge in their mutilated condition, appear to indi- cate a succession of teeth related to one another in size nearly as in the series of the Crocodile or Alligator.
The fragment of the angular bone, represented in Fig. 21, Plate IV, is a portion intermediate to the oval angulo-dental foramina and its posterior prolongation. Its outer surface is vertical, and foveated, and its base or under border is convex, and measures two and a quarter inches in thickness.
Of three teeth which accompanied the fragments above described two are much mutilated, one only having an entire crown. One of the mutilated specimens appears to have occupied the third alveolus, back of the canine, and was compara- tively small. The other, represented by Fig. 8, Plate 9 of Dr. Harlan’s memoir, apparently occupied the eighth or ninth alveolus back of the canine. It possessed a mammiliform crown, from which the enamel is destroyed, and has a gibbous fang. The third specimen is the penultimate or last tooth, represented in Figs. 11, 12, Plate X VIII, and closely resembles the corresponding teeth of living Crocodiles. The fang was gibbous; and the crown is laterally compressed mammiliform, with its outer and inner surfaces separated by a prominent ridge, and its enamel strongly corrugated. The crown is six lines high, eight lines and a half antero-posteriorly, and six lines transversely.
Upon the fossils above described, Prof. Agassiz infers Harlan’s Crocodile to belong to a different genus from any previously known, for which he proposes the name of Bottosaurus."
4 Proc. Acad. Nat. Sci. Phila. IV, 169.
14 UNDETERMINED CROCODILES.
IT have not had the opportunity of inspecting other fossil remains which may positively be referred to the Bottosawrus Harlani.
Among the fossils from the New Jersey Green Sand, described by Mr. Owen, in the Journal of the Geological Society, Vol. V. p. 380, before mentioned, there was a cervical vertebra of a crocodilian different from that upon which he proposed the name of Crocodilus basifissus. 'This second vertebra, from its having the inferior apophysis of the body, or the hypapophysis, short and flattened, he views as indi- cating a species, for which he has proposed the name of Crocodilus basitruncatus. The vertebra, supposed to characterize the latter, is of a size which relates to that of the individual to which the jaw fragments above described belong, and probably also appertained tq Harlan’s Crocodile.
Since writing the above there have been presented to the Academy, by Horatio C. Wood, a number of small fragments of the lower jaw of Bottosaurus Harlani, from Burlington County, N. J. The specimens, however, present nce further char- acters in relation to the species. Accompanying them there is a tooth, represented in Fig. 14, Plate X VIII, which is a reduced one of the sameform as that already described. .
I have also recently received for examination, from the Burlington Co. Lyceum of Natural History, several small fragments of a jaw, two teeth, and a large costal rib, probably belonging to the same species. |
The fragments of a jaw are uncharacteristic. One of the teeth has a quadri- lateral fang two and a half inches in circumference. The crown is quadrate mam- miliform, but has lost the greater part of its enamel. ‘The other tooth is represented in Fig. 18, Plate XVIII. It has a compressed cylindrical fang a little less in cir- cumference than the preceding. The crown is compressed mammiliform, strongly rugose, and has its inner and outer faces defined by prominent carina-like ridges. It measures cight and a half lines long, ten lines wide at base, and seven and a half lines from without inwardly.
Undetermined Species of Crocodiles.
Of other remains of Crocodiles, with vertebre constructed on the same plan as the living representatives of the family, I have seen a number of specimens from the Green-sand of New Jersey apparently indicating several species different from the preceding. Among these is a collection of bones belonging to the same indi- vidual, from Timber Creek, Gloucester County, N, J., presented to the Academy by W. P. Foulke. They consist of two cervical, a dorsal, the sacral, and two caudal vertebrie, and portions of both humeri. The vertebre indicate an adult animal, as the arches are completely united with their respective bodies, and those of the sacrum are firmly coosified. Their comparatively small size renders it improbable that they should belong to either of the species previously indicated.
The bones are black, heavy, and firm, but unfortunately the vertebrae have had most of their processes broken off since their discovery.
The least mutilated of the cervical vertebra, apparently the sixth, represented in Fig. 12; Plate III, is rather less than two inches in length, independent of the
UNDETERMINED CROCODILES. 15
articular convexity of its body. Inferiorly, the latter is divided by a median carina expanding in front into a broad flat space without a distinct hypapophysis, other- wise the specimen presents nothing remarkable by which to characterize it. ‘The other vertebra of the neck, apparently a fourth or fifth, has the inferior carina of the body almost obsolete—commencing in a small tubercle behind, and fading away as it approaches a concavity extending between the parapophyses or inferior transverse processes. The latter are more robust than in the former specimen, and appear to have been conjoined by a ridge-like hypapophysis, though this is too much broken to judge of its true character.
The dorsal vertebra, Fig. 13, Plate III, the fifth of the series, has about the same length as those of the neck, and is nearly as broad anteriorly as it is long. Its hypapophysis is a robust mammillary tubercle, but it is otherwise like the corre- sponding bone of the conmmon Alligator.
The conjoined bodies of the sacral vertebra, represented in Fig. 14, Plate III, relate in size with the preceding, and differ in no important point with the homolo- gous parts of the Alligator.
Of the caudal vertebrae, one is the first of the series, distinguished by the double articular convexity of the body, as seen in Fig. 15, Plate II]. Unlike that of the Alligator, it is broad and flattened beneath, resembling in this respect more the condition of the bodies of the sacral vertebra. The second specimen, from near the middle of the tail,is much mutilated. It measures rather more than two inches in length, and appears to have had the same form as in the Alligator.
Of the fragments of humeri, one consists of a portion of the shaft of that of the right side, and measures three inches in circumference ; the other is the proximal extremity of the left humerus, and does not differ from the corresponding part in the Alligator. Its head measures rather more than two inches in its greater diameter, and a little more than one inch in its lesser diameter.
Recently Prof. Cook has sent to me for examination a small collection of Croco- dile bones belonging to the collection of Rutger’s College. The specimens were obtained from near Barnsboro’, Gloucester County, N. J., and consist of four ver- tebrae, the shaft of a femur, and four broken dermal bones, apparently all from the same individual.
The vertebra have had their arches fully coosified with the bodies, so that they may be considered as having belonged to an animal of mature age. ‘They belonged to a smaller individual than the specimens above described, and perhaps to a different species, for several present some peculiarities of form.
Two of the vertebre, Figs. 4, 5, Plate II, belonged in the cervical series between the fourth and last, and are probably the fourth and fifth, The bodies measure an inch and three-quarters in length, independent of their posterior convexity, and correspond in general form with those of the Alligator. ‘The hypapophysis of the fourth, Fig. 4, is a thick semicircular ridge extending between and below the level of the parapophyses. In the fifth, Fig. 5, it is a longer, straighter, and less well developed ridge, slightly notched in the middle,
The other two vertebra are the first and fifth dorsal, and have their body about as long as the cervicals. The first dorsal has lost its hypapophysis, spinous process,
16 UNDETERMINED CROCODILES.
and portions of the others, but so far as it is preserved it corresponds in form with that of the Alligator. The fifth dorsal has its body more compressed laterally than in the specimen above described from Timber Creek, and the hypapophysis is abso- lutely very much more robust than in the latter, though the vertebra is smaller. In the Barnsboro’ specimen the anterior articular concavity of the body is quadrilateral, whereas it is broadly cordiform in the Timber Creek specimen. In the former the hypapophysis is excavated in front; in the latter it is plane. These differences in two characteristic vertebre are, perhaps, sufficient to indicate that they belong to two species. Comparative measurements of the two vertebra are as follows :—
Barnsporo’ Sp. TIMBER CREEK SP.
Lines. Lines. Length of body inferiorly . : . : . . ; 20 22 Length of body laterally. ; : é 0 é é 5 PAY 22 Height of body anteriorly . é 5 ¢ é . : ey 18 Width of body anteriorly . ‘ : ‘ 0 5 : . 16 22 Thickness of body at middle ‘ : : 5 : : ap 12 17 Thickness of hypapophysis . * . 5 6 , : nS) 6 Breadth of vertebral arch laterally. 3 . 5 : SS 20 Width of vertebral canal. é : : : : < a BEG 7 Height of vertebral canal . . : ' : : : apy ths 8
The specimen of the shaft of a femur is three inches and a third in circumference, and resembles the corresponding portion of the same bone in the Alligator.
The dermal bones are square, differ in size, and are coarsely foveated. Two of them form a median elevation without being carinated; the others are flat. One of the more perfect measures two inches by twenty lines; another measures two inches eight lines by two inches.
The museum of the Academy contains two mutilated bodies of posterior dorsal or of lumbar vertebre, of mature age, from Ameytown, Burlington County, N. J., presented by T. A. Conrad. The specimens, excepting in being devoid of the hypapophysis, agree with the bodies of the dorsals above described, and are like those in the living Alligator.
In the same museum there are the bodies of three vertebrae, which have lost their arches at the sutural attachment, from Jobstown, Burlington County, N. J., presented by Dr. E. Hallowell. One of the specimens, represented in Fig. 6, Plate II, apparently of the fifth cervical vertebra, is much less convex posteriorly than in the specimens above described, and has its parapophysis wider and much less robust. Its hypapophysis is a small longitudinally cleft tubercle. The body is nineteen lines long, sixteen wide anteriorly, and fifteen high. The remaining specimens are the bodies of two posterior dorsals or lumbars, twenty lines long, and resemble the corresponding bones in the living Alligator. In the same collection, and from the same locality and donor, there is another specimen consisting of the body of a posterior dorsal vertebra with the coosified abutments of its arch remaining. The body agrees in its form and proportions with those just described, and measures twenty-one lines in length.
The body of a posterior cervical vertebra, from the Green-sand of St. George’s,
UNDETERMINED CROCODILES. i7
Delaware, presented to the Academy by 'T. A. Conrad, is represented in Fig. 7, Plate I. It belonged to a young animal, and has lost its arch at the sutural con- junction. It measures fifteen lines long, and is provided with very robust para- pophyses. The hypapophysis is well developed and associates the latter processes, forming together a large crescentoid ridge, deeply notched at the middle. It proba- bly belongs to the same species as the vertebre above described from Timber Creek.
The museum of the Academy contains a fragment of a left dental bone with a tooth, of a small Crocodile, or of a young individual of a large one, presented by C. C. Abbott. It was found in Monmouth County, N. J., and is represented in Figs. 22, 23, Plate IV. The specimen resembles in form the corresponding portion of the lower jaw of Harlan’s Crocodile, of which it may be part of a quite young individual. The suture for the splenial bone, however, does not reach the symphysis as in the fragment characteristic of Bottosawrus Harlani—ceasing about one inch short of it. Besides three alveoli, there are preserved portions of five others, and the third behind the symphysis still retains a tooth. The latter has a compressed, conical crown, with its inner and outer surfaces defined by a prominent carina-like ridge. The surfaces are finely rugose longitudinally, and the carine are rugose in a divergent manner. ‘The crown measures five lines in length and width, and a line less from without inwardly. |
Another specimen belonging to the cabinet of the Academy, represented in Fig. 8, Plate II, is a fragment of a small Gavial skull from the Green-sand of Burlington County, N. J. In construction it bears a resemblance to the corresponding part of the Vincenttown skull, to which I by no means feel sure it does not belong, though it differs in some important points. The forehead, in the fragment, between the position of the post-frontals is quite flat, while it is decidedly concave in the Vincenttown skull. ‘The frontal is less prolonged to meet the parietal than in the latter. The dividing ridge formed by the parietal between the temporal fosse is even slightly greater than in the Vincenttown skull, while the distance between the orbits at the anterior broken end of the specimen is only two inches. The upper surface of the parietal and frontal is also more strikingly foveated than in the Vincenttown skull.
Four specimens of teeth, from Blackwoodtown, Camden County, N. J., pre- sented to the Academy by Dr. J. L. Burtt, may probably belong to the same species as the fragment of skull just described. The more perfect are represented in Figs. 7, 8,9, Plate I. They have the form, curvature, and proportions of the teeth of the living Gavialis Gangeticus, and are proportionately narrower than those of Thoracosaurus Neocesariensis, and are-also more finely striated.
Figs. 22, 23, Plate III, represent the mutilated crowns of two tecth of a croco- dilian reptile, supposed to have been obtained from a Green-sand deposit of North Carolina, submitted to my examination by Dr. Isaac Lea. One of the specimens, Fig. 22, is straight and conical, circular in transverse section, with an acute ridge in front and behind which defines the inner and outer surfaces. The latter at base are smooth, and apparently have been so at the apex, which is too much broken to determine the fact positively. The intermediate portion of the surfaces is nearly
regularly fluted; the ridges separating the concave grooves extending from the 3 March, 1865,
18 HYPOSAURUS.
dentinal substance. The base of the crown is excavated. The length of the specimen is fourteen lines and a half; its diameter at base, six lines.
The second specimen, Fig. 23, differs from the former in being somewhat curved, elliptical in transverse section, and in the fluting extending to the bottom of the crown. The apex is worn off, and the specimen in its present state is ten lines and a half long, by six lines and a half in diameter antero-posteriorly near the base.
The two teeth differ from those of Pliogonodon, probably also from the Green- sand of North Carolina, in which the crown is proportionately longer, and has its surfaces subdivided into narrow planes and provided with a few interrupted vertical plice. They differ also from those of Polygonodon, in which the crown of the tooth is long and narrow and its surfaces subdivided into planes without folds or strie.
Dr. Emmons, in his Report of the North Carolina Geological Survey, page 219, fig. 38, has described and figured a large Crocodilian tooth, obtained from a bed of Miocene marl, at Elizabethtown, Bladen County, N. C. The tooth, together with some bones, Dr. Emmons nevertheless thinks originally belonged to the Green-sand formation beneath. It has a conical crown, and a robust cylindrical fang ; is hollow, and moderately curved. ‘The crown is described as circular in transverse section, and without carinz, or acute ridges separating the inner and outer surfaces, the enamel of which is traversed with “irregular rugose ridges.” .The specimen is referred to the genus Polyptychodon, under the name of P. rugosus.
Another tooth, found with the preceding, described and figured in the same chapter, page 220, fig. 39, and referred by Dr. Emmons to the same animal, appears rather to have belonged to Mosasaurus.
Fig. 12, Plate VIII, represents a dermal plate, which, together with a small fragment of a jaw, and the mutilated crown of a tooth, were submitted to my examinatiom from the Burlington County Lyceum of Natural History. The dermal plate measures two inches by twenty lines, and is without a carina. The fragment of jaw, much mutilated, is two and a half inches long, straight, and contains the much curved fangs of two teeth. It indicates a small species of Gavial, or perhaps belonged to the young of T'horacosaurus Neocesariensis. The isolated crown of a tooth closely resembles that of Fig. 7, Plate I, but is rather more curved.
HYPOSAURUS.
Hyposaurus Rogersii.
Hyposaurus Rogersii, OwEN, Quart. Jour. Geol. Soc. Lond. V, 1849, 380, pl. xi, figs. 7-10.
Holcodus acutidens, GieBEs (in part), Mem. on Mosasaurus, &c., Smithsonian Contrib. II, 1850, 9, pl. iii, fig. 13
Among the fossil vertebra, from the Green-sand formation of New Jersey, de- scribed by Prof. Owen, in the Journal of the Geological Society of London, were two specimens with biconcave bodies, which are referred to a genus of the Croco- dilian family under the name of Hyposaurus Rogersii. Prof. Owen remarks that “the peculiar and distinctive character of these vertebre is shown in the large size and especially the great antero-posterior extent of the hypapophysis. Its base occupies the whole extent of the median line of the inferior surface between the prominent borders of the anterior and posterior articular ends of the centrum.”
HYPOSAURUS. 19
Remains of this genus, on several occasions, have come under my notice, but usually in a much mutilated condition.
A small collection of bone fragments, referable to this animal, were found in the Green-sand, near White Horse, Camden County, N. J., and were presented to the Academy of Natural Sciences by W. Parker Foulke. The specimens are exceed- ingly friable, and consist of portions of several vertebrae, small fragments of a skull together with portions of the supra-angular bones of the lower jaw, fragments of a humerus, portion of a cervical rib, and the crowns of five teeth, all appertaining to a single individual.
One of the vertebral specimens, of the proportions of those referred by Prof. Owen to Hyposaurus, from the anterior part of the dorsal series, consists of the fragment of a body retaining one of the sub-concave articular faces, and the remains of the large lamelliform hypapophysis projecting like a keel from the bone inferiorly.
The best of the vertebral specimens consists of the body of a cervical vertebra with one abutment of the arch remaining. Its articular faces are half oval in out- line, with the anterior one more deeply concave than the posterior, which is like- wise the case in the other vertebral specimens. The length of the body is about two inches and a half, its depth posteriorly twenty lines, and its width above seven- teen lines. Its sides are deeply impressed; its surface next the vertebral canal is nearly plane. The transverse processes are of robust proportions, and those below are united by a stout hypapophysis bounding the fore part of the body beneath. Posterior to the hypapophysis, the under surface of the body forms a deep con- cavity subdivided by a slight median carina ending in an angular apophysis poste- riorly.
The supra-angular bone is quite peculiar, and appears to have largely contributed to the articulation of the lower jaw, though this is not certain, as the condition of the specimen is such that I am not positive whether the articular surface preserved in the fragment actually belongs to the supra-angular. Internally to the articular surface there is a large vertical sutural surface, either adapted to a true articular bone, or unlike the arrangement in any other known Crocodilian, it must have joined the splenial bone as in Turtles. Exterior to and in advance of the articula- tion of the lower jaw, the supra-angular forms a strong projecting ledge which overhangs the exterior surface of the bone and gradually diminishés over the position of the oval foramen.
The fragments of the humerus mentioned are too much injured to derive any character of importance from them.
Of the five crowns of teeth belonging to the collection the two best preserved are represented in Figs. 16, 17, Plate III. The largest resembles the teeth of the Gavial, being curved conical, nearly circular in transverse section, with prominent acute ridges defining the outer and inner surfaces, which are distinctly fluted. The smaller specimen, and such also is the character of those not represented in the plate, differs from the preceding in being compressed from without inwardly, so that its transverse section exhibits an oval outline, and it is less distinctly fluted.
Recently Dr. W. W. Lamb presented to the Academy of Natural Sciences a collection of bones, referable to a single individual of J/yposaurus, from the Green-
20 HYPOSAURUS.
sand in the vicinity of Blackwoodtown, Camden County, N. J. The specimens are very friable, in consequence of which they have been much mutilated since their discovery. They consist of portions of three cervical, as many dorsal, and five caudal vertebra, a basilar bone, four crowns of teeth, the greater part of the shaft of a femur and fragments of several other long bones aa ribs, an astragalus, two phalanges, and portions of four dermal scales.
In all the vertebral specimens the articular faces of the bodies are slightly con- cave, the anterior being more deeply depressed than the posterior. The cervical vertebrae, the best preserved of which is represented in Fig. 1, Plate IV, have their body nearly two inches and three-quarters long, with the form and proportions corresponding with those of the specimen previously described. The vertebral arch and canal are like the same parts in the Alligator. The spinous process, partially preserved in one specimen, ascends from a base extending the breadth of the arch and rapidly narrows as it rises.
The dorsal vertebrae belong to the posterior division of the series. The best of the specimens, represented in Figs. 4, 5, Plate IV, has the body about two and a quarter inches long, and of slightly greater depth and less width anteriorly.
The caudal vertebrae, Figs. 8, 9, 10, Plate IV, are short in relation with their depth and breadth. Their body is sub-cuboidal, with the articular ends slightly oblique; and they are provided with strong abutments for the articulation of sub- vertebral arches or chevron bones. The body of the best preserved specimen, Figs. 9, 10, is about two inches and a quarter long, a trifle over two inches in depth: posteriorly, and less than’ two inches in width in the same position.
The isolated basilar bone has its condyle nearly two inches wide at base, and a little over an inch in depth.
The greater part of the shaft of a femur, Fig. 4, Plate IIT, is rather more than five inches in circumference at the middle, and is pervaded its entire length by a large medullary cavity.
The astragalus measures two inches and a quarter in its long diameter, twenty lines in its short diameter, and is thirteen lines thick.
A last ungual phalanx is nearly two inches in length.
The dermal plates, of which two are represented in Figs. 11, 12, Plate IV, are without carina or tubercle, gradually thin away towards the margins, and are im- pressed by a comparatively few large and deep fover.
The teeth, which accompanied the bones just described, represented in Figs. 18-21, Plate III, are curved conical, compressed from without inwardly, and have their external and internal surfaces defined by an acute ridge. They are not fluted as in the specimens previously described, and were it not for their association might readily have been supposed to belong to a different animal. They are longitudinally wrinkled, especially near the base of the crown, and more internally than externally.
The teeth described and figured by Dr. R. W. Gibbes, in the second volume of the Smithsonian Contributions to knowledge,’ supposed to be characteristic of a
+ Memoir on Mosasaurus and the allied Genera, p. 9.
HYPOSAURUS. 21
reptile allied to Mosasawrus, and named LHolcodus acutidens, in part at least, appear rather to belong to Hyposazwrus. Of the specimens, which Dr. Gibbes has submitted to my inspection, that from New Jersey, I think, undoubtedly belongs to the last mentioned genus. The other specimen, from the Cretaceous formation of Alabama, though agreeing in its form and proportions with the teeth above described, may, nevertheless have belonged to a Mosasaurus.
The collection of the Academy contains a dorsal vertebra, represented in Figs. 6, 7, Plate IV, from the Green-sand of Burlington County, N. J., which has the same form and proportions as the corresponding vertebrae above mentioned, but is smaller. ‘The specimen probably occupied a more anterior position in the series ; though it may have belonged to a smaller species of the genus. The cabinet of the Academy also contains the body of a dorsal vertebra, from the Green-sand of New- castle County, Del., which has the same form as the Burlington County specimen, but is the fourth of an inch longer.
Since writing the foregoing I have received for examination a small collection of remains of Hyposaurus, belonging to Rutger’s College, New Brunswick, N. J. The specimens were sent by Prof. Cook, who informs me that they were obtained from a marl pit, at Tinton Falls, Monmouth County, N. J. The specimens have the same friable character as those previously described, and they appear to have belonged to two different individuals: one quite young, the other of maturer age. Those of the young individual consist of several fragments of the occipitals, a cervical rib resembling those of the Mississippi Alligator, and the body of a posterior dorsal two inches long. Those of the maturer animal consist of a posterior cervical and a fourth dorsal vertebra, the bodies of three posterior dorsals, and the shaft of a femur.
The posterior cervical, represented in Fig. 2, Plate IV, corresponds in size, form, and details of structure with those previously described. The length of its body, which is slightly more concave posteriorly than anteriorly, is three inches, and the length of the specimen between the anterior and posterior articular processes is three inches and three-quarters. The hypapophysis, somewhat mutilated, appears not to have been proportionately better developed than the corresponding processes in the cervical series of the Mississippi Alligator.
The fourth dorsal vertebra, Fig. 3, Plate IV, has lost one-half of its vertebral arch with the spinous process, and the other half of the arch is separable at its suture with the body. ‘The latter is two inches and a quarter in length below and two inches and a half at its junction with the arch. The two ends are nearly equally concave, and between them there extends a broad laminar hypapophysis, as represented in the specimens upon which Prof. Owen proposed the genus, but as in these, unluckily the process is broken so that we are unable to determine its length.
The bodies of the three posterior dorsals are rather over two inches in length, and exhibit the sutures from which the vertebral arches have been detached. They are more concave anteriorly than posteriorly, in this and other characters agreeing closely with those previously described.
The shaft of a femur corresponds closely with that already described both in size and form,
99 DISCOSAURUS.
DISCOSAURUS.
Discosaurus vetustus. Discosaurus vetustus, Lerpy, Proc. Acad. Nat. Sci. Phila. 1851, 326.
The remains of a large Saurian, apparently nearly related to the Plesiosaurus of Europe, discovered in the American Cretaceous deposits, have occasionally come under my notice. Dr. Harlan has described and figured a vertebra, obtained, together with several others, from Mullica Hill, N. J., which he referred to the Plesiosaurus.' The specimens, upon which this view was founded, are preserved in the museum of the Academy of Natural Sciences, and prove to belong to a Cetacean, of the Dolphin family. Subsequently Dr. DeKay described and figured a fragment apparently of a cervical vertebra, from the Green-sand of New Jersey, evidently belonging to the Saurian to which I allude, and which he recognized as being allied to Plesiosaurus.?
The collection of the Academy of Natural Sciences contains a few remains of the Saurian indicated from four different localities, as follow :—
1. The mutilated bodies of two caudal vertebra, as I suppose them to be, from the Cretaceous deposits of Alabama, presented by Prof. Joseph Jones, of Georgia.
The specimens, represented in Figs. 4, 5, 6, Plate V, have the body in the form of a transverse section of a cylinder, compressed from above downward, with the sides and under part slightly narrowed towards the middle. The articular extremi- ties are transversely elliptical and moderately concave, but have prominently convex borders. They are constricted or defined from the rest of the body by a narrow groove, which gives them the appearance of distinct plates or disks applied to and terminating the body. From this peculiar appearance, the name of Discosaurus was proposed for the genus to which the vertebree belong. At the under part of the body, as seen in Fig. 5, the groove is inflected on each side apparently with the view of producing facets for a chevron bone. It is this apparent adaptation of the parts to the articulation of chevron bones which has led me to consider the vertebrae under consideration as caudals, otherwise from their resemblance to the cervical vertebre of Plesiosaurus pachyomus, as represented by Prof. Owen,’ I should have viewed them as belonging to the cervical series.
Between the position of the inflections to accommodate the chevron bones, the under part of the body forms a pair of feeble ridges, the intervening surface of which presents on one side a single venous foramen communicating by a branching vertical canal with the spinal canal. The latter, in both specimens under examination, is too much broken to judge of its form, and no other information is to be ascertained from the abutments of the vertebral arch other than that they were completely coosified with the body. The side of the body is produced into a large conical protuberance
* Journ. Acad. Nat. Sci. Phila. IV, 1824, 232, pl. xiv, fig. 1; Med. Phys. Res. 1835, 882. See note, page 1, of this Memoir.
® An. Lye. Nat. Hist. New York, III, 1828, 165, pl. iii, fig. 11.
’ British Fossil Reptiles, Enaliosauria, pl. 28.
DISCOSAURUS. 23
excavated to its base into a transversely elliptical costal pit, bounded by a promi- nent acute border. The pit occupies the middle portion of the body from above downward, and extends two-thirds its length, reaching nearer the anterior than the posterior articular surface. ;
Measurements, derived from the two specimens which are almost identical in size as well as form, are as follows :—
Lines. Length of body between the grooves defining the articular extremities : als) Extreme length of body between the prominent margins of the articular extremities 24 Breadth of articular extremities c : . : 6 : : ; 4 Bi Height of articular extremities . : - 5 . . - : : . 26 Estimated breadth of spinal canal : z F ; ‘ F A : ae eG} Transverse diameter of costal pits : - : x c : : : 5 eg le! Vertical diameter of costal pits . : : - é ; ° ; : 5 dil
2. A vertebra, represented in Figs. 10, 11, 12, Plate V, rather larger than the preceding, but nearly identical in form, from the lower Cretaceous of Mississippi, presented to the Academy by Prof. M. Tuomey. In this specimen the articular extremities of the body are nearly flat surfaces, being much less depressed towards the centre and much less prominent towards the periphery than in the Alabama specimens. It differs also from the latter in having the articular surfaces termi: nating in an acute margin and not defined from the rest of the body by a groove. The body beneath, Fig. 10, presents inflections apparently for the articulation of chevron bones, those posterior being large, while those anterior are but slight. The vertebral arch, partly preserved in the specimen, is coosified with the body. It presents no conspicuous mark of its original separation, and a continuous slope extends from the side of the arch upon that of the body to the upper margin of the costal pit.
The measurements of the specimen are as follows :—
Lines. Length of the body at the acute margins of the articular extremities . : « 24 Extreme length of the body at the prominent periphery of the articular extremities 26 Breadth of the articular extremities. : é : : : , : . 36 Height of the articular extremities . , a : : . : : . 29 Diameter of spinal canal. E : s 3 : ; , 6 et Transverse diameter of costal pits . : : : : : : “ 5 Vertical diameter of costal pits . ; : - 5 “ 3 é ¢ 9
3. A much mutilated body of a vertebra from Choctaw Bluff, Clarke Co., Alabama, presented by Prof. M. 'Tuomey to the Academy. The specimen has the same form as that just described, excepting that its articular faces are more concave and it is considerably larger.
Its measurements are as follows :—
Lines. Length of body . : : ° : ; ; : : ° 4 : Peis Breadth of articular extremities . 3 A F 4 . F : : . 44 Height of articular extremities . ree ‘ 3 A ; : E « 84 Width of spinal canal : : : : F : 5 C 5 : an LO Transverse diameter of costal pits . - : : 4 17
Vertical diameter of costal pits . : - ; ! y E : i1
24 DISCOSAURUS.
4. Two vertebre, a carpal and two metacarpal bones and a phalanx, apparently all from the same individual. The specimens were found, with others, in Burlington County, N. J.
Of the vertebre, the one represented in Figs. 7, 8, 9, Plate V, is almost identical in form and size with the first described specimens from Alabama. The articular surfaces of its body present intermediate characters to those of the Alabama speci- mens and the one from Mississippi. As previously stated, in the former, the articular surfaces are defined by a narrow groove from the rest of the body, of which an acute edge forms one boundary of the groove and the prominent convex periphery of the articular surface the other. In the Mississippi specimen the corresponding groove is nearly obsolete, so that the articular surfaces appear defined from the rest of the body by an acute edge. In the Jersey specimen the acute edge forms a conspicuous linear ridge, and a feeble groove defines this from the articular surfaces. The latter are less depressed towards the centre, and less prominent at the periphery than in the Alabama specimens, but in both characters are more so than in the Mississippi specimen. In the Jersey specimen the inflections for the apparent accommodation of chevron bones are deeper than in the Alabama specimens, and give the under part of the body at its extremities a remarkably festooned appearance, as repre- sented in Fig. 8. The body inferiorly, between the inflections, in front and behind, does not exhibit the ridges so prominently as in the other specimens, but is other- wise the same. .
The measurements of the vertebra are as follows :—
Lines Length of the body in the median line inferiorly between the acute edges . iP Length between the lateral inflections of the latter . ; cl : c Sede Length of the body laterally between the acute edges > 20 Extreme length of the body between the prominent margins of the ponealae ex- tremities c Q : - : : : c . . 24 Breadth of the shales Stories : : : : cE : 5 ; . 34 Height of the articular extremities . 3 ‘ : : F : : a watt Width of spinal canal : 3 : : : : c : : : Su) Tie Transverse diameter of costal pits é ; : : . : C : egls Vertical diameter of costal pits . : : : é 4 : : c 5 akW)
The other vertebra, represented in Figs. 1, 2, 3, Plate V, much larger than the former, appears to belong to the back part of the cervical series. The body is a transverse section of a cylinder flattened from above downward and moderately narrowed at the sides and underneath towards the middle. The articular extremities are nearly plane surfaces, transversely elliptical, but emarginate above, and are de- fined from the rest of the body by a‘sub-acute border. The general level of the posterior surface is slightly depressed, and its periphery is slightly convex. The anterior surface is a little more depressed, but presents a slight central prominence. The under part of the body is less depressed than the sides, and it presents three large venous foramina, The vertebral arch is coosified with its body on a level with the floor of the spinal canal, which is almost a plane surface. The spinal canal is large and ovoid in outline. A portion of the spinous process, preserved in the specimen, proves it to be a strong, broad plate. It is deeply grooved behind
CIMOLIASAURUS. 25
at its root for an elastic ligament. The greater portion of a remaining posterior articular process indicates this to be of small size, and it has its facet directed down- ward and outward.
The side of the body is extended into a large process excavated to its base into a vertical, ear-shaped, concave, costal pit, bounded by an elevated, acute margin. The vertical diameter of the pit is equal to two-thirds that of the body, and its transverse diameter equal to half the length of the latter. The upper extremity of the pit is formed by a trilateral process projecting outwardly from the root of the vertebral arch, and is separated from the rest of the pit by a deep, crescentoid, transverse fissure, remaining as part of the suture through which the arch is united with the body of the vertebra.
The measurements of this vertebra are as follows :—
Lines. Length of the body . : : ° . : : : < ° : vol Breadth of the articular extremities : . ( . ; : : - . 43 Height of the articular extremities. . . . ‘ ; 7 2 . 33 Breadth of costal pits . Z : é : ‘ 7 - : : : Sits Height of costal pits . é : ; : : ; 6 : : : PL Breadth of spinal canal. 3 : : 6 F : 5 : ¢ * Vil Height of spinal canal 2 , : ; : : : : : : = 12
The carpal bone, represented in Figs. 13, 14, Plate IV, resembles those of Plesio- saurus. It isa thick hexahedral tablet, with the broad surfaces concave and rugged. The borders are half the width of the broad surfaces, and present parallel rows of nutritious foramina. The bone measures in its greater breadth thirty lines, in its lesser twenty lines, and its thickness ranges between twelve and sixteen lines.
The metacarpal bones, represented in Figs. 15, 16, 17, likewise resemble those of Plesiosaurus. They are quadrilateral columnar bones, with the sides concave longitudinally. The extremities are quadrate in outline, and their surfaces exhibit parallel rows of nutritious foramina.
The phalanx, represented in Fig. 18, also resembles those of Plesiosaurus. It is a slightly compressed Eide column, expanding from the middle towards both extremities.
The carpal, metacarpal, and phalangeal bones indicate that they were articulated by cartilage, and together with the other bones of the extremity formed a paddle like those of Plesiosaurus.
It is not jmprobable that I may have included, in the account of Discosaurus vetustus, the remains of more than one species, but the material at command appeared to me insufficient to justify a separation.
CIMOLIASAURUS.
Cimoliasaurus magnus. Cimoliasaurus magnus, Lery, Proc. Acad. Nat. Sci. Phila. 1851, 325; 1854, 72, pl. ii, figs. 4, 5, 6.
Vertebre differing from any of those described in the preceding pages, and belonging to a huge Saurian, are frequently found in the Green-sand deposits of 4 March, 1865.
2G CIMOLIASAURUS.
~
New Jersey. The vertebrae have slightly biconcave bodies and are usually well preserved, though all the specimens I have had the opportunity of examining have had their arches and processes broken off, apparently after their discovery. Of such vertebrae thirteen specimens, from Burlington County, N. J., were presented to the Academy of Natural Sciences by Dr. 8. G. Morton. They appear to have belonged to the same individual, and consist, as I suppose them to be, of two dorsals and eleven lumbars.
The body of the dorsal vertebra, Figs. 13-16, Plate V, is the transverse section of a cylinder compressed from above downward and contracted towards the middle, resembling in form the body of the cervical vertebra referred to Discosaurus, 'The articular faces are transversely oval, slightly emarginate above, and are more concave than in the cervical vertebra of Discosaurus. They present a central prominence, are bevelled off at the border, and are defined by a subacute edge from the rest of the body. A pair of large venous foramina underneath the latter communicate with channels opening by a single large orifice in the spinal canal, which is depressed towards the middle and wide. The vertebral arch has been coosified with the body, but its loss prevents me from ascertaining anything in regard to its form. In one of the specimens, as represented in Figs. 13, 14, 15, there projects from the middle of the side of the body a short, robust, cylindroid transverse process, termi- nating in a large irregular facet for the articulation of a rib. In the other vertebra, Fig. 16, probably a more anterior one, the transverse process is broken, but its base indicates it to have been of greater vertical extent than in the former specimen, though not quite so wide, nor does it extend so low, but above appears nearly to have reached the abutment of the vertebral arch.
The size of the two specimens is nearly equal, their measurements being as follows :—
Lines. Length of the vertebral body. 5 . : ; e 3 ; : 82-33 Breadth of articular surfaces. c 5 : 5 : 5 5 : a) ey? Height : : - : 2 s P ‘ 5 > : . 42 Width of spinal canal at the middle . ; ; E : : é : Sel, Width of spinal canal at the extremities. : : 5 3 Breadth between articular facets of transverse processes. : c : Seif
The eleven lumbar vertebra, of which the largest and smallest specimens are represented in Figs. 17-19, Plate V, and 16-18, Plate VI, do not form an unbroken series, but the specimens successively diminish in size from nearly that of the dorsals just described, to a size rather less than the supposed caudals of Discosaurus. They are nearly identical in form throughout. The more anterior have the body abso- lutely somewhat longer than in the dorsals, though the other diameters are dimi- nished. ‘The articular extremities are also slightly more dished than in the dorsals, and almost devoid of the central prominence. The venous foramina on the under part of the body are nearer together, and the intervening portion of bone appears pinched into a convex ridge. ‘The more posterior specimens, which may be re- garded as caudals, have the articular extremities of their body rather more concave, and underneath they do not form so prominent a ridge between the position of the -two venous foramina.
CIMOLIASAURUS. 27
In all the lumbar vertebre the abutments of the vertebral aren are fully coossi- fied with their body, leaving no well-marked trace of the former sutural connection. The spinal canal is wide, and is depressed at the floor towards the middle, where it exhibits one or two large venous foramina. In all the specimens the transverse processes have been broken off, but in all, their remaining bases are seen projecting from the lower part of the side of the body. They spring from nearly the whole width of the body, with which they were completely coossified, though they pre- sent the appearance as if they formerly possessed a sutural attachment. They were evidently robust and strong, and were directed obliquely outward and down- ward.
The sides of the body of the vertebra form, together with the sides of the verte- bral arch and the upper part of the transverse processes, a nearly uniform slope, broken only by a slight elevation formed by the apparent sutural coossification of the transverse process with the body. The under part of the body between the transverse processes nearly forms a level surface, more or less elevated into a ridge between the venous foramina, and depressed along a line with the position of the latter.
Measurements, derived from the largest and the smallest of the series of eleven lumbars, are as follows :—
LARGEST. SMALLEST. Lines. Lines. Length of body : : : : : A ; ; : ss 24 Breadth of articular surfaces. 5 : c : : : . 44 31 Height of articular surfaces. : 3 : : : : . 386 22 Width of spinal canal , c 3 : é . : F eo 8
The vertebrae, above described, were briefly noticed a few years ago in the Pro- ceedings of the Academy of Natural Sciences, volume V, page 325, and referred to a Reptile under the name of Cimoliasaurus magnus.
Fourteen vertebre of the same Saurian as the preceding have been submitted to my inspection by Mr. O. R. Willis, through Prof. Cook. They all evidently be- longed to the same individual, and were obtained from the Green-sand, near Free- hold, Monmouth Co., N. J. Six of the specimens are dorsal, the remainder lumbar vertebrae. Of the former, three appear to have had their transverse processes at the conjunction of the vertebral arch and body; the others had them situated succes- sively lower on the sides of the body.
Two of the more anterior dorsals are represented in Figs. 1, 2, 3, 4, Plate VI. They exhibit a slight want of symmetry, which is the case also with another ante- rior dorsal, but this character is a deformity, or mere individual peculiarity. The body is a little longer and higher, in relation with the breadth, than in the dorsals above described, and hence presents a more cylindrical form. The articular extremi- ties are moderately dished, and have a somewhat prominent annular margin. They are nearly circular, but notched above, and are sharply defined by a subacute ' ridge from the rest of the body. The bottom and sides of the latter are narrowed towards the middle or are concave longitudinally, and they present a number of foramina, varying in size, which communicate with venous channels opening into
28 CIMOLIASAURUS.
the spinal canal. The broken abutments of the vertebral arch are much broader and stronger, in accordance with their being required to sustain the transverse pro- cesses, than in the more posterior dorsals. The spinal canal is large and depressed towards the middle of the floor.
The measurements of one of the anterior dorsals, which are nearly of the same size, are as follows :— F
Lines. Length of the vertebral body . é : : : : : : : . 386 Breadth of articular surfaces. , : 5 : ¢ . : ' Sih Height of articular surfaces : : : : : : 3 : : Pur) Width of spinal canal . : : : : : é : 5 ¢ : 5 i
A more posterior dorsal vertebra, represented in Fig. 5, Plate VI, differs from the preceding in the less length and depth of the body and the slightly greater breadth, but chiefly in the lower position of the transverse process, which extends from the vertebral arch to near the middle of the side of the body. The measure- ments of this specimen are as follows :—
Lines Length of the vertebral body c : ‘ : : : : : . 33 Breadth of the articular surfaces . : 2 : 5 é : : . o4 Height of the articular surfaces . : 5 ; : 5 : 4 - . 43
The remaining two posterior dorsal vertebra, represented in Figs. 6-9, Plate VI, appear to be from near the termination of the series. ‘They have the same form of body as the Burlington County specimens of posterior dorsals, above described, with which they also nearly agree in size. ‘The transverse processes are short, robust, irregularly cylindroid protuberances, projecting from the lower part of the side of the body and terminating in an articulating facet for arib. In the foremost of the two vertebrae, Fig. 7, the facets are sub-circular and irregularly convex; in the other, Fig. 9, they are transversely oval and irregularly concave. On the under surface of the body of the former, Fig. 6, there are two large foramina on each side com- municating with venous channels opening into the spinal canal; in the latter, Fig. 8, the under part of the body presents two very large venous foramina, between which the bone forms a convex ridge, not existing in the preceding vertebra.
Measurements of the two posterior dorsal vertebrae are as follows :—
Lines. Lines. Length of the body . : : ° ° . . 383 35 Breadth of the body . ; 6 - c : S B . . o6 52 Height of the body. : . : c . 2 . 5 9 40 Width of spinal canal . : : : > ° ° 5 : 3 11 Vertical diameter of facet for the rib. . A ; c ¢ LS 16 Transverse diameter of facet for the rib ‘ . 2 6 , 5 alts) 20
The eight lumbar vertebra, of which the largest and smallest specimens are represented in Figs. 10-15, Plate VI, form a nearly unbroken series, and followed close after the dorsal specimens just described. They correspond in form and con- stitution with the Burlington County specimens, except that the median part of * their body beneath, between the position of the venous foramina, forms a more prominent ridge.
PIRATOSAURUS. 29
The measurements of the largest and smallest specimens, or the first and last of the series, are as follows :—
LARGEST. SMALLEST, Lines. Lines. Length of the vertebral body. . : ( : ; d . 385 31 Breadth of articular extremities : : ; : , : . 50 41 Height of articular extremities . . - - : . - . 39 28 Width of spinal canal - E : ; ; j : : yey 8
It is probable that the vertebra, above described as lumbars, may be regarded in part as representing sacrals and caudals. Both dorsals and lumbars bear some resemblance to the corresponding vertebree of Cetaceans, except that in these the transverse processes project from the middle of the sides of the body of the lumbars instead of the lower part. The long series of vertebrae of Cimoliasaurus consisting of lumbars apparently gradually merging into caudals, perhaps indicate the absence of a true sacrum and posterior extremities, as in Cetaceans.
I cannot avoid the suspicion that the specimens referred to Cimoliasaurus mag- nus do not belong to the same great reptile as those considered as characteristic of Discosaurus vetustus. 'The supposed caudals of the latter I have suspected to be anterior cervicals notwithstanding the apparent provision for the articulation of chevron bones. If all the vertebral specimens be viewed as belonging to one animal, they represent cervicals, dorsals, and lumbars of Discosawrus, otherwise they represent a cervical and caudals of the latter, and dorsals and lumbars of Cimoli- asaurus.
The vertebrae described as caudals of Discosaurus have almost the same size and nearly the same form as the smaller lumbars or caudals attributed to Cimoliasaurus. A rib of proportionate size, coosified with the costal pit in the former, would give them a striking resemblance to the latter, except that in Cimoliasaurus the costal or transverse processes project from the lower part of the sides of the body, whereas in Discosaurus the costal pits are situated at the middle of the sides of the body. The vertebrae, however, differ in other important particulars. Besides the absence of the conspicuous inflections (supposed to have been intended to accommodate chevron bones) in the caudals of Cimoliasaurus the body beneath is nearly level between the transverse processes, while in Discosaurus it is strongly convex in the corresponding position.
No portions of the skull nor specimens of teeth have been discovered which, with any probability, could be referred either to Discosaurus or Cimoliasaurus.
PIRATOSAURUS.
Piratosaurus plicatus.
I recently received from the Smithsonian Institution, for examination, a small collection of fossils, which, in a note accompanying the specimens, are stated to have been obtained from the drift of Red River Settlement, about fifty miles south of Selkirk Settlement, and are further labelled as from the Red River of the North. The specimens consist of a peculiar Crocodilian tooth, and others agreeing in form with those referred to Otodus appendiculatus, Corax appendiculatus, and Ptychodus
30 MOSASAURUS.
Mortoni, which would indicate the fossils as appertaining to the Cretaccous era. The reptilian tooth, and several of those of the fishes, are partially imbedded in hard iron pyrites.
The Crocodilian tooth, represented in Fig. 8, Plate XIX, presents the ordinary form of the teeth of recent Crocodiles and Alligators, being curved conical. The crown, or enamelled portion of the tooth, worn away at the point, in its present state measures seventeen lines long, and the remaining portion of the somewhat gibbous fang is half an inch long. I can detect no appearance of acute ridges separating the inner and outer faces of the crown, though such may have existed. The enamel towards the apex is smooth, but at rather moye than the basal half of the crown it is thrown into well-defined, slightly tortuous, longitudinal folds or ridges, reminding one of the appearance of those in the teeth of Polyptichodon. Between the folds the surface exhibits shallow punctures. The diameter of the tooth at the base of the crown is cight lines, The interior of the tooth is hollow as in the teeth of living Crocodiles.
MOSASAURUWS.
vaurian animal, resembling the famous fossil reptile of Maestricht, MircuEtn, Observ. Geol. N. America, 1818, 384, 385, pl. viii, fig. 4.
Saurian reptile, resembling the Maestricht Monitor, Hannay, Journ. Acad. Nat. Sci. 1825, Vol. IV, 235, pl. xiv, figs. 2, 3,4; Med. and Phys. Researches, 1835, 384.
Mosasaurus, De Kay, Ann. Lye. Nat. Hist, 1828-36, Vol. III, 135, pl. iii, figs. 1, 2.—Morroy, Am. Jour. Sci. 1830, Vol. XVIII, 246; Synop. Org. Rem. 1834, 27, pl. xi, figs. 7, 9.—Haran, Trans. Geol. Soc. 1835, 81; Med. and Phys. Res. 1835, 285.—Emmons, North Carolina Geol. Survey, 1858, 217.
Geosaurus Mitchelli, Dk Kay, An. Lye. Nat. Hist. 1828-36, Vol. III, 138; Zool. New York, 1842, Part III, 28, pl. 22, figs. 55, 56.—Hanruan, Trans. Geol. Soc. 1835, 82; Med. and Phys. Res. 1835, 285; Edinb. Phil. Journ. 1834, Vol. XVIII, 32.—Picrer, Palcontologie, 1853, Vol. I, 506.
Geosaurus, Morton, Am. Jour. Sci. 1830, Vol. XVIII, 246; Syn. Org. Rem. 1834, 28.
Ichthyosaurus missouriensis, HARLAN, Trans. Am. Phil. Soc. 1834, Vol. IV, 405, pl. xx, figs. 3-8; Trans. Geol. Soc. 1835, 80; Med. and Phys. Res. 1835, 284, 348, figs. 1-6.
Mosasaurus Dekayi, Bronn, Lethea Geog. 1838, Vol. Il, 760.—Gispes, Mem. on Mosasaurus; Smithsonian Contribu- tions, 1851, Vol. II, 8, pl. i, figs. 2, 6.
Batrachtosaurus, Hannan, Lond. and Edinb. Philos. Mag. 1839, Vol. XIX, 302.
Batrachiotherium, Haxtan, Bul. Soc. Geol. 1839, Vol. X, 90.
Mosasaurus major, De Kay, Zool. New York, 1842, Pt. III, 28, pl. 22, figs. 57, 58.
Mosasaurus occidentalis, Morton, Proc. Acad. Nat. Sci. 1844, 133.
Batrachiosaurus missouriensis, MEYER, Jahrb. Min. 1845, 312.
Mosasaurus neovidii, Meyer, Jahrb. Min. 1845, 312.
Mosasaurus Maximiliani, Gotpruss, Nov. Act. Acad. K. L. C. Nat. Cur. 1845, Vol. XXI, 179, pl. vi, vii, viii, ix, figs. 1-3.—Meyenr, Jahrb. Min. 1845, 312; 1847, 122.—Owen, Jour. Geol. Soc. Lond. 1849, Vol. V, 382, pl. x, fig. 5.— Gipses, Mem. on Mosasaurus; Smithsonian Contributions, 1851, Vol. II, 6, pl. I, fig. 7.—Picrer, Paléontologie, 1853, Vol. I, 505.—Emmoys, North Carolina Geol. Surv. 1858, 217, figs. 36a, 37.
Mosasaurus Camperi, Pictrr, in part, Paléontologie, 1845, Vol. II, 64.
Mosasaurus Hofmanni, Picret, in part, ibidem.
Allantochelys Mortoni, Acassiz, Proc. Acad. Nat. Sci. 1849, 169.
Mosasaurus minor, Gispes, Mem. on Mos. ; Smithsonian Contributions, 1851, Vol. II, 7, pl. i, figs. 3, 4, 5.
Mosasaurus Couperi, Gisnes, ibidem, pl. ii, figs. 4, 5.
Mosasaurus carolinensis, GisBEs, ibidem, 8, pl. ii, figs. 1, 2, 3.
Holcodus acutidens, Gispes, in part, ibidem, 9, pl. iii, figs. 6-9.
2? Amphorosteus Brumbyi, Gisses, ibidem.
Mosasaurus Mitchelli, Lewy, Proc. Acad. Nat. Sci. 1859, 92.
Mosasaurus missouriensis, Levy, ibidem, 1857, 90; 1859, 92.
Elliptonodon compressus, Emmons, North Carolina Geol. Surv. 1858, 222, figs. 41, 42.
Drepanodon impar, Lerpy, Proc. Acad. Nat. Sci. 1856, 255.—Esmons, North Carol. Geol. Surv., 1855, 224, figs. 45, 46.
Lesticodus impar, Leiy, Proc. Amer. Philos. Soc. 1859, VII, 10.
MOSASAURUS. 31
Nearly a century has elapsed since the discovery, in the Cretaceous deposits of Europe, of the aquatic Reptile, the Mosasaurus, or Lizard of the Meuse, but even at the present time our knowledge of the skeleton is incomplete. ‘The most im- portant of the remains found in Europe consists of the greater part of an enormous skull, including the jaws, together with the teeth, obtained from the quarries of St. Peter’s Mount, near Maestricht. The specimen, to which an unusual degree of historic value is attached, is commonly known as the head of the Maestricht Monitor, and is now preserved in the museum of the Jardin des Plantes, Paris. It has been the subject of representation and description by Buchoz,? Faujas-Saint- Fond,* Cuvier,’ Buckland,’ Gervais,° Pictet,’ Bronn,® and others. Series of vertebra of the Mosasaurus, comprising most of those from different parts of the column, found in association with the head just mentioned, have also been described by Cuvier.’
In the United States remains of the genus Mosasaurus, usually consisting of isolated teeth, small fragments of jaws, and mutilated vertebrae, have been fre- quently discovered in deposits of the Cretaceous period, and have been indicated
t M. Faujas-Saint-Fond, in his Natural History of St. Peter’s Mount, gives the following account of the diseovery and subsequent destination of the fossil: ‘‘In one of the galleries or subterraneous quarries of St. Peter’s Mount at Maestricht, at the distance of about five hundred paces from the principal entrance, and at ninety feet below the surface, the quarrymen exposed part of a skull of a large animal imbedded in the stone. They stopped their labors to give notice to Dr. Hoffman, a surgeon at Maestricht, who had for some years been collecting fossils from the quarries, and who had liberally remunerated the laborers for them. Dr. Hoffman, observing the specimen to be the most important that had vet been discovered, took every precaution to secure it entire. After having suc- ceeded in removing a large block of stone containing it, and reducing the mass to a proper condition, it was transported to his home in triumph. But this great prize in natural history, which had given Dr. Hoffman so much pleasure, now became the source of chagrin. A canon of Maestricht, wha owned the ground beneath which was the quarry whence the skull was obtained, when the fame of the specimen reached him, laid claim to it under certain feudal rights and applied to law for its recovery. Dr. Hoffman resisted, and the matter becoming serious, the chapter of canons came to the support of their reverend brother, and Dr. Hoffman not only lost the specimen but was obliged to pay the costs of the law-suit. The canon, leaving all feeling of remorse to the judges for their iniquitous decision, became the happy and contented possessor of this unique example of its kind.”
M. Faujas-Saint-Fond continues, ‘‘ Justice, though slow, arrives at last. The specimen was destined again to change its place and possessor. In 1795 the troops of the French Republic, having repulsed the Austrians, laid siege to Maestricht and bombarded Fort St. Peter. The country house of the canon, in which the skull was kept, was near the fort, and the general being informed of the cireum- stance gave orders that the artillerists should avoid that house. The canon, suspecting the object of this attention, had the skull removed and concealed in a place of safety in the city. After the French took possession of the latter, Freicine, the representative of the people, promised a reward of six hundred bottles of wine for its discovery. The promise had its effect, for the next day a dozen grenadiers brought the specimen in triumph to the house of the representative, and it was subse- quently conveyed to thé museum of Paris.”
2? Dons de la Nature, Tab. 68.
Histoire Naturelle.de la Montagne de St. Pierre de Maestricht, Pl. IV.
4 Ossemens Fossiles, Ed. 4, Atlas T. 2, Pl. 246, Fig. 1. 5 Bridgewater Treatise, Pl. 20. 5 Zoologie et Paléontologie Francaises, T. III, Pl. 60, Figs. 3-5.
7 Traité de Paléontologie, Atlas, Pl. XX VI, Fig. 3. 5 Lethxa Geognostica.
§ Ossemens Fossiles, Hd. 4, T. 10, p. 151.
39 MOSASAURUS.
or described by Mitchell,’ De Kay,’ Harlan,* Morton,* Gibbes,’ and Emmons.’ The
1 Observations on the Geology of North America, by Samuel L. Mitchell, published in the American edition of the Essay on the Theory of the Earth, by Cuvier, New York, 1818. Prof. Mitchell was the first to indicate the existence of remains of Mosasauwrus in the United States. In Plate VIII, Fig. 4, he represents the tooth of a Mosasaurus from the foot of Neversink Hills, New Jersey, and refers to it, p. 384, as resembling the teeth of the famous fossil reptile of Maestricht.
2 Annals Lyceum Nat. Hist. New York, Vol. III, p. 135, Pl. I1I, Figs. 1,2. Dr. De Kay, besides describing and figuring a tooth, from Monmouth County, New Jersey, which he refers to Mosasaurus, also gives a description and representation of 4 tooth, p. 188, Pl. III, Figs. 8, 4, which he refers to Geosaurus, but which I am inclined to suspect also belongs to the former genus.
3 Journal Acad. Nat. Sciences, Philadelphia, Vol. IV, p. 235, Pl. XIV, Figs. 2-4. Dr. Harlan represents a tooth from the vicinity of Woodbury, New Jersey, which he says resembles in every respect the teeth of the Maestricht Monitor. In his Med. and Phys. Researches, p. 285, he refers the same specimen to the genus Mosasaurus.
+ Synopsis of Organic Remains, p. 27, 28, Pl. XI, Figs. 7, 9,10. In this work Dr. Morton simply refers to and reproduces the specimens described by Drs. De Kay and Harlan. In the Proc. Acad. Nat. Sci. Puiladelphia, Vol. II, p. 132, Dr. Morton refers to a collection of remains of Mosa- saurus from New Jersey, forming part of the material of the above memoir. From differences observed in comparison with the European Mosasaurus, the author refers them to a distinct species under the name of MZ. occidentalis.
5 Memoir on Mosasaurus and the allied Genera. By Robert W. Gibbes, M. D. Smithsonian Contributions, Vol. II. The author indicates, describes, and figures a number of specimens, which he refers to several distinct species of Mosasaurus. Most of the specimens were found in the Cre- taceous deposits, or are readily referred thereto, but several he mentions as having been derived from the Eocene formations of Ashley R., 8. C., and Wilmington, N. C., but neither describes nor figures them. I have as yet seen no trace of Mosasawrus remains from any of the Tertiary deposits of the United States.
A small vertebra, with an attached portion of another, from the Cretaceous formation of Alabama, together with fragments of two small teeth, from unknown localities of Alabama and Georgia, repre- sented in Pl. I, Figs. 3, 4, 5, are referred by Dr. Gibbes to a species with the name of Mosasaurus minor.
Two specimens, the summits of large teeth, represented in Pl. II, Figs. 4, 5, from the Cretaceous formation of the Chattahoochie R., Georgia, are referred to a species under the name of Mosasaurus Coupert.
An uncharacteristic fragment of a large jaw, represented in PI. II, Figs. 1, 2, 3, is referred to a species with the name of Mosasaurus carolinensis. The specimen is stated to have been found in association with Cetacean remains in the Pliocene deposit overlying the Cretaceous formation in the vicinity of Darlington, 8S. C. As observed by the author, “it was most probably derived from the atter formation ;” and he adds, ‘its appearance and the mineralization of its structure render it probable that it came originally from the Cretaceous.” The same explanation, I am inclined to believe, would apply to the vertebra which Dr. Gibbes mentions as having been found in the Hocene deposit of Wilmington, N. C.
The allied genera of the memoir are named Holcodus, Conosaurus, and Amphorosteus. The tooth, represented in Pl. III, Fig. 13, from the Cretaceous formation of New Jersey, referred to Holcodus, belongs to the Crocodilian Hyposaurus. The tooth, represented in Figs. 6-9, from the Cretaceous of Alabama, also referred to Holcodus, I suspect belongs to Mosasaurus. The teeth, represented in Pl. III, Figs. 1-5, from the Hocene deposit of the Ashley R., 8. C., referred to Cono- saurus, I have proved, through microscopic examination of the structure, to belong to a fish. The vertebra, represented in Pl. III, Figs. 10-16, from the Cretaceous deposit of Alabama, referred to Amphorosteus, may probably prove to be different from those of Mosasaurus, but at present I consider the matter doubtful.
6 Report of the North Carolina Geological Survey, by E. Emmons, p. 217, Figs. 36a, 37. The
MOSASAURUS. 33
most important remains, comprising the greater part of a skeleton, consisting of a nearly entire skull and eighty-seven vertebrae, were found, by Major O'Fallon, on the Upper Missouri, in the vicinity of Big Bend, and were presented by him to Maximilian, Prince of Wied, who was then travelling in America. Conveyed to Europe, the remains were presented by the Prince to the Museum of the Academy of Naturalists of Bonn, and were described in the Transactions of the Academy by Dr. August Goldfuss.'
Cuvier views the skull of the great Maestricht Mosasaurus as intermediate in anatomical characters to that of the existing Monitor and Iguana.? The length of the lower jaw he gives as three feet nine inches,* and estimates the skull to have been nearly four feet. On each side of the lower jaw there are fourteen teeth ;° to the upper maxillary bone eleven teeth, and as it is estimated that there may have been three additional teeth to each side of the inter-maxillary bone, the number would be the same in the upper as in the lower jaw.° ‘The pterygoids, as in the Iguana, also possess teeth, of which Cuvier states there were eight to each bone.”
The skull of the Missouri Mosasaurus is about half the length of that of the Maestricht Mosasaurus, but Dr, Goldfuss assumes too much when he says the com- plete ossification of all parts, as well as the frequently perceptible solidification of the teeth, prove that the individual had reached maturity, for the skull and teeth of Saurians exhibit the same characters of ossification and development from youth to extreme age. As remarked by Owen, “the characters of immaturity are not manifested by the cold-blooded animals in their osseous and dental systems as they are in the warm-blooded and higher organized mammalia.’”
In the jaws of the Missouri Mosasaurus there are the remains of eleven teeth above and below, and supposing three more to have existed in the anterior extremi- ties of the jaws, which were lost, the number would be equal to that of the Mae- stricht Mosasaurus. The pterygoid bones, according to Dr. Goldfuss, are each occupied with the remains of ten teeth, being two more than the number mentioned by Cuvier as existing in the Maestricht skull.
The vertebrae of Mosasaurus have their bodies concave in front and convex behind. Cuvier" estimates the number to have been about one hundred and thirty-three. These he divides as follows: The atlas and axis; eleven vertebrie of the neck and thorax distinguished by the presence of an inferior apophysis or hypapophysis together with articular and transverse processes; five similar vertebre without the
vertebra, represented in Fig. 34a, referred to Macrosaurus, the tooth, represented in Fig. 39, referred to Polyptychodon rugosus, and that represented in Figs. 45, 46, which I referred to a reptile of un- known relation with the name of Drepanodon impar, I also suspect to belong to Mosasaurus.
* Schidelbau des Mosasaurus. Nov. Act. Acad. C. L. C. Nat. Cur., Vol. XXI, p: 73.
2 Ossem. Foss., Ed. 4, T. 10, p. 150. 8 Tbid., p. 168. “Thid} ps 151:
5 Ibid., p. 139. 6 Tbid., p. 143. 7 Ibid., p. 148.
* “Die vollstindige Verknécherung aller Theile, so wie die hiufig bemerkbare Ausfiillung der Zihne beweisen, dass das Individuum seine vollstindige Ausbildung erreicht hatte.” Schidelbau des Mosasaurus, Nov. Act. Acad. C. L. C. Nat. Cur., Vol. XXI, p. 177.
® British Fossil Reptiles, p. 187. 20 Ossem. Foss., T. 10, p. 165.
5 April, 1865,
a4 MOSASAURUS.
hypapophysis; thirty-eight without articular processes, but retaining transverse processes ; twenty-six having the latter, and in addition, facets for chevron bones ; forty-four without transverse processes, and possessing coossified chevron bones ; and seven devoid of processes.
Goldfuss' estimates the number of vertebre at about one hundred and fifty-seven, which he divides as follows: atlas and axis; thirteen vertebra with a hypapophysis; twenty-six with transverse and articular processes, but no hypapophysis; thirty with transverse, but no articular processes; thirty as in the latter, but in addition, pos- sessing chevron bones; forty-four without transverse processes, but having chevron bones; and twelve without processes.
The ribs articulated by their head alone with the ends of the transverse processes.
The most remarkable character in the anatomy of the vertebral column of the Mosasaurus, is the coossification, in the hinder part of the tail, of the chevron bones with the bodies of the vertebra, a condition previously known only as a peculiarity of Fishes. The superior and inferior vertebral arches, in association with their long spinous processes, and the absence of transverse processes, indicate the tail of M/osa- saurus to have presented the laterally compressed appearance and great vertical depth seen in many Fishes.
Another remarkable character is the absence, or rather the rudimental state, of the articular processes from about the middle of the vertebral series posteriorly, a condition likewise observed in Cetaceans.
The characters just given indicate Mosasaurus to have been eminently aquatic in habit. The tail possessed great freedom of movement in a lateral direction as in Fishes. The absence of articular processes in the posterior half of the vertebral series leads to the suspicion that no vertebra were coossified so as to constitute a sacrum. Perhaps, also, there were no hinder extremities, though these may have existed, without the presence of a sacrum, adapted to swimming, as in Plesiosaurus, with which Mosasaurus exhibits other important points of resemblance, as will be seen hereafter.
Most of the remains of Mosasaurus which I have had the opportunity of exam- ining have been derived from the Cretaceous Green-sand deposits of New Jersey, in which they are frequently found by those engaged in digging the Green-sand, or Marl as it is commonly called, for agricultural purposes. With the exception of a number of well-preserved teeth, the fossils have usually been submitted to me in such a fragmentary condition that they have served little else than to indicate the genus or family to which they belonged. I have seen no considerable portion of a skull, though I have met with small fragments of many skulls. Vertebre, though common, are usually deprived of all their processes. Bones of the extremities are almost unknown.
The fossil remains of Mosasaurus, from New Jersey, are usually jet black, or iron- gray, more or less brittle, and impregnated with sulphuret of iron. Not unfre- quently the pulp cavities of teeth and hollows of bones are occupied by solid accu- mulations of the latter substance. 'The decomposition of the sulphuret of iron,
ca
1 Schidelbau, etc., Nov. Act. Acad., Vol. X-XI, p. 194.
MOSASAURUS. 35
after the fossils are exposed to the air, renders them very liable to crack to pieces. Rarely I have seen remains of Mosasawrus, from New Jersey, of an ochre color and chalky consistence. Sometimes the fossils, but especially the teeth, are remarkably well preserved, and of very firm texture. Usually the enamel of the teeth is jet black and shining ; occasionally gray, with brownish stains.
Besides the New Jersey specimens, I have seen a few others from the Cretaceous formations of the Upper Missouri, collected by Dr. F. V. Hayden, several from a deposit, of the same age, near Columbus, Mississippi, obtained by Dr. William Spillman, and one from near Marion, Alabama.
I have been unable to satisfy myself whether the specimens from the Upper Missouri, described by Dr. Goldfuss, and those submitted to my examination by Dr. Hayden, belong to the same species as the remains of the New Jersey Mosasaurus.
The specimens sent to me for inspection by Dr. Spillman consist of a basi-occipital bone, a tympanic bone, the greater portion of a pterygoid bone with teeth, a hu- merus, several vertebrae, and a few fragments of others. ‘These were imbedded in a greenish sandstone, and apparently all belonged to the same individual, which I think was a different species, if not another genus, from the New Jersey Mosasaurus.
The museum of the Academy of Natural Sciences of Philadelphia contains thirty- two specimens of vertebra of Mosasawrus from the Green-sand of New Jersey. They are chiefly from Burlington and Monmouth Counties, and were presented to the Academy by Mr. J. P. Wetherill, Dr. S. G. Morton, Dr. Charles T. Budd, Mr. T. Conrad, Dr. J. H. Slack, and Mr. L. T. Germain. The specimens belonged to a dozen or more individuals of different ages and sizes. All are much mutilated ; one only retaining the vertebral arch. They consist of the following :—
1. A large cervical or anterior dorsal vertebra, represented in Fig. 1, Plate VII, from Monmouth County, N. J. The body measures three inches and a half from the bottom of the anterior concavity to the summit of the posterior convexity. The latter is sub-rotund, nearly as wide as high, measuring about two inches and two lines in diameter. The breadth of the specimen is six inches between the ends of the transverse processes, which are robust, conoidal, and project from the fore part of the body and abutment of the vertebral arch, obliquely backward, outward, and slightly downward. The spinal canal is obcordate, and about fourteen lines high and wide. ‘The hypapophysis springs from a broad carina-like base, and is directed obliquely downward and backward. It is cylindrical, sixteen lines in transverse diameter, and truncated at the extremity, which is depressed at the centre into a conical pit.
2. A mutilated body of a cervical or anterior dorsal vertebra, from Burlington County, N. J. The body is two inches and a half long. Its posterior convexity is sub-cireular, truncated above, and measures twenty lines wide and nineteen high. The hypapophysis is cylindrical, directed downward and slightly backward, and measures nine lines in transverse diameter.
3. Two bodies of cervical or anterior dorsal vertebrae, one of which is repre- sented in Figs. 2, 3, Plate VII. The body is two inches and five lines long, but broader in relation with its height than in the preceding. The posterior convexity is reniform in outline, two inches wide and seventcen lines high. ‘The cylindrical
36 MOSASAURUS.
hypapophysis, ten lines in diameter, projects from the middle of the body directly downward.
4. The body of a dorsal vertebra, not possessing a hypapophysis. Length three inches and a quarter; posterior convexity reniform in outline, thirty-one lines wide and twenty-one high. The remaining roots of the robust transverse processes spring from the body at its conjunction with the vertebral arch.
5. A series of three dorsal bodies, without hypapophysis, and measuring two inches and a half long. ‘The roots of the transverse processes are situated at the middle of the sides of the body. The posterior convexity is reniform, thirty-two lines wide and twenty-three high.
6. A dorsal body with robust, conoidal transverse processes projecting from the forepart outward and backward. Length of body thirty lines’; posterior convexity thirty lines wide, twenty-two high. ;
7. The body of a much mutilated dorsal vertebra, with the same form as the latter but larger.
8. Two bodies of lumbar vertebra, with the remains of long, flattened transverse processes projecting outward and downward from the lower part of their sides. ‘The posterior convexity is widest at its lower third, and narrows to the emarginate border of the spinal canal. Length of body in one specimen twenty-six lines, in the other twenty-three; greatest width of posterior convexity in both specimens thirty-one lines, height twenty-four lines. ‘This form of vertebra is represented by Fig. 4, Plate 247, of the fourth edition of Cuvier’s Ossemens Fossiles. The larger of the two specimens is represented in Figs. 9, 10, 11, Plate VII.
9. Five very much mutilated specimens of the same character as the preceding, but larger. From two different individuals and localities. The largest specimen is thirty-two lines long; the smallest twenty-six lines.
10. Five small vertebrae of the same form as the preceding, from several indivi- duals and localities. The largest specimen is twenty-one lines long; the smallest eighteen lines. ‘Two are represented in Figs, 12, 18, 14, Plate VII.
11. Four large caudal vertebra with the same form of body, and with roots of transverse processes having the same form and position as in the preceding. In addition, roots of chevron bones project from the posterior inferior part of the bodies. The most perfect of the specimens has the length, width, and height equal, being thirty-nine lines in these different directions.
12. Two caudal bodies with lateral tubercles or mere rudiments of transverse processes; otherwise having the same form as the preceding, but smaller, their length being twenty-seven lines.
13. Three much mutilated caudals, relatively narrower than the former. ‘The largest is twenty-eight lines long; the smallest twenty-four lines.
14. The body of a caudal vertebra, fourteen lines long.
Since writing the foregoing I have received, for examination, from Prof. Cook the following specimens :-—
1. A dorsal vertebra, from Freehold, Monmouth County, N. J., loaned by Dr. C. Thompson, The specimen corresponds in form with a rather larger one previously described, and is represented in Fig. 8, Plate VII. It also bears considerable re-
MOSASAURUS. — 37
semblance, both in form and size, with one of the specimens figured by Dr. Gibbes as characteristic of his Amphorosteus Brumbyi.'
2. The bodies of two large cervicals or anterior dorsals. ‘The specimens, together with small fragments of a huge skull, were found in the first bed of Green-sand at Holmdale, Monmouth County, N. J. They are too much mutilated for detailed description, but are interesting on account of their size, as they measure a trifle over four inches in length. From their under part projects a robust, cylindroid hypapo- physis, which, in both specimens, is broken at the extremity.
3. A specimen consisting of a paix of large posterior dorsals or lumbars, and part of a third with the bodies coossified by means of an irregular exostosis surrounding the articular surfaces. It belongs to Rutger’s College, and though its locality is unknown, it is supposed by Prof. Cook to have been derived from the deepest layer of the Green-sand of Monmouth County, N. J. The anterior pair of vertebral bodies together measure seven inches in length; the anterior concave surface of the first body is about four inches in diameter, and the vertebral canal, retained entire, is transversely elliptical, and measures eleven lines wide and eight lines high.
From Nebraska Territory, the museum of the Academy of Natural Sciences has received a collection of remains of Mosasaurus, consisting chiefly of vertebre, which were discovered by Dr. F. V. Hayden. The specimens are as follows :—
1. Several fragments of weather-worn rock, originally from the same mass, con- taining a series of sixteen caudal vertebrae, two others of small size detached from the series, and several bones of the extremities. The specimens were obtained on the Yellowstone River, and the bones all appear to have belonged to the same individual. The rock in which the fossils are imbedded bears some resemblance to that described by Dr. Goldfuss, as containing the Mosasaurus skeleton from the vicinity of the Big Bend of the Missouri River. It is a very hard, brittle, argilla- ceous limestone, amorphous, and of a dark, dull leaden hue. On the surface it has become softened, by the action of the weather, into a yellowish-gray material. The rock adheres so tenaciously to the equally brittle bones that they have been seriously injured in the attempt to expose them. The vertebra, several of which are repre- sented in Figs. 15, 16, Plate VII, present the anatomical characters ascribed to the posterior caudals of Mosasaurus by Cuvier, Goldfuss, and others. All had coossified chevron bones; and the anterior of the series have rudimental transverse processes, which entirely disappear in the more posterior ones. ‘The body of the first of the series measures nineteen lines in length and twenty-three lines in height and width; that of the last is fourteen lines in length and twenty lines in height and width. The better preserved of the detached caudals, represented in Fig. 16, Plate VII, has its body only nine lines in length.
2. Two bodies of posterior caudals, well preserved, from Cheyenne River. They had coossified chevron bones and no trace of transverse processes. ‘They measure fourteen lines in length, eighteen high, and nineteen wide. One of the specimens is represented in Figs. 17, 18, Plate VII.
3. Two caudal bodies, of the same form as the preceding, but rather larger, from
4 Mem. on Mosasaurus, Plate III, Figs. 14, 15, 16.
38 MOSASAURUS.
Little Moreau River, near Fort Pierre. The length of the more perfect is fifteen lines, the height twenty lines, and the width twenty-one lines.
4, A caudal body and a posterior dorsal body, from the forks of Cheyenne River. The former possesses rudimental transverse processes projecting from the middle of the sides, and measures eighteen lines in length, twenty-one in height, and twenty in width. The latter belonged to a very small species, comparatively, or to a very young individual of the larger species, but presents no indication of sutural attach- ment of parts. It measures fifteen lines in length, sixteen lines high, and nineteen lines wide. .
5. A mutilated posterior dorsal body, and a mutilated anterior caudal body, from Little Moreau River, neax Fort Pierre. ‘The former had robust, transverse pro- cesses projecting from the middle of the sides of the body anteriorly. Its length is thirty-six lines, the height of its posterior convexity thirty-four lines, and its width thirty-three lines. The caudal had no chevron bones, but strong transverse processes projecting from the lower part of the sides of the body. The articular extremities in outline are triangular with strongly rounded angles. The length of the body is twenty-eight lines, the height of the posterior convexity about twenty- six lines, and the width below twenty-nine lines.
The vertebra of Mosasaurus, previously mentioned as having been received from Dr. Spillman, who discovered them near Columbus, Massie consist of two cer: vicals and the fragment of a dorsal.
The cervical vertebra, represented in Figs. 4, 5, 6, Plate VII, have their body twenty-nine lines long, with a transversely oval posterior convexity twenty lines wide and sixteen lines high. The spinous process, long, strong, and laterally flat- tened, measures about two and a half. inches along its anterior border. ‘The spinal canal is about seven lines high and six lines wide. ‘The transverse processes are of robust proportions and remarkable form. Springing from the conjunction of the vertebral arch and body, they form a rectangular protuberance, at first descending upon the side of the latter and then turning forward at a right angle to its anterior border. ‘Their upper extremity is thick; and they narrow in their descent and anterior extension. ‘Their free extremity presents an L shaped articular surface for a cervical rib. The hypapophysis is a strong process projecting downward from the back portion of the under side of the body; springing from a carina-like base it ends in an ovoid, truncated extremity, as seen in Fig. 4, Plate VII.
The fragment ‘of a dorsal vertebra, represented in Fig. 7, Plate VII, has the body thirty lines in length, and in its details resembles the cervicals just described, except that its hypapophysis is a mere rudiment, indicating the position of the vertebra to be the next succeeding those anterior dorsals which possess a more distinctly developed process of the same character.
All the vertebrae which I have described or indicated, and indeed all the speci- mens I have seen, are apparently complete in their development, that is to say, none of them exhibit marks of original separation of the composite elements. The union of these in reptiles, especially the complete coossification of the verte- bral arch and body, indicates maturity in the skeleton. Never having seen Mosa- sauroid vertebre exhibiting certain signs of immaturity I have associated this
MOSASAURUS. 39
negative evidence with the ichthye character of the tail, and suspected that per- haps as in fishes, the vertebrae of Mosasaurus were developed from single centres of ossification. If such were the case, mere differences in size of corresponding ver- tebree would not be sufficient to determine a difference of species.
From Prof. George H. Cook, of Rutger’s College, New Brunswick, N. J., I have recently received, for examination, a number of remains of the Mosasaurus, from the Green-sand of Monmouth County, N. J. Among them is a collection, consist- ing of a multitude of small fragments of a skull, from the Marl digging on the farm of Isaac Smock, of Holmdale. The best preserved of the fragments consist of the greater part of both quadrate or tympanic bones, and the anterior extremity of the face or muzzle. The tympanic bones agree in form with the corresponding parts of those of the Maestricht skull preserved in the Paris museum, They measure about six inches in height, so that they are somewhat smaller than in the latter specimen.
The anterior extremity of the face, represented in Fig. 6, Plate XIX, consists of the forepart of the right maxillary bone, and nearly the entire intermaxillary bone. The end of the snout, as formed by the latter, is a demi-cone, with the flat surface comprising the forepart of the mouth. The height, breadth, and length of the demi-cone are nearly equal, being about three inches. The intermaxillary bone is prolonged upward and backward, and ends in a narrow process contributing to the partition of the anterior nares. It contains on each side of the palatine surface the fangs of two teeth, together with cavities for successors. It would thus appear that the number of intermaxillary teeth in Mosasawrus is one less on each side than supposed by Cuvier, though his numeration applied to the Maestricht Mosasaurus, in which species the number may have been greater than in the New Jersey Monitor.
In one respect the fossil appears to differ from the corresponding portion of the Upper Missouri skull, described by Dr. Goldfuss. In his, Plate 7, Vol. X-XI, of the Nova Acta, representing a lateral view of the skull, the intermaxillary is not visible above the border of the maxillary bone, but is so in the New Jersey fossil, as seen in Fig. 6, Plate XIX of this memoir.
The forepart of the maxillary bone has lost the end which unites it with the alveolar border of the intermaxillary corresponding in extent to the position of the first maxillary tooth. Behind the latter the fossil contains the fangs of the four succeeding teeth. Accompanying the specimen are other fragments of the alveolar border, together measuring a foot in length, and occupied by the fangs of seven teeth, but not fitting from the loss of an intervening portion. About an inch above the alveolar edge there is a longitudinal row of large vasculo-neural foramina, which communicate with a canal situated along the outer part of the bottoms of the fangs of the teeth. Similar foramina form a row along the intermaxillary bone near its upper boundary. ‘The anterior extremity of the nares, seen in the fossil, corresponds in position with the interval between the fifth and sixth maxillary teeth.
The length of the fossil, from the end of the snout to the posterior broken ex- tremity, is ten and a half inches; the distance from the end of the snout to the anterior nares is ten inches.
Another collection, received from Prof. Cook, consists of fragments of the forepart
40 MOSASAURUS.
of the lower jaw, obtained by Dr. C. Thompson from the Marl of Freehold, Mon- mouth County, N. J. Restored to their proper place the specimens correspond in size, shape, and number of insertions for teeth with the portion of a jaw of the Maestricht Monitor, figured in Plate VI, of the Historie de la Montagne de St. Pierre. The fragments compose twelve inches of the right dental bone, represented in Fig. 13, Plate XI, and sixteen of the left one. The latter presents a depth of four inches gradually decreasing to the anterior end where it measures about two inches. In their length the bones are remarkably straight, and their symphysial extremity, without arching inward, is obtusely rounded. ‘The outer surface and base are convex. The former, half way between the latter and the alveolar border, exhibits a longitudinal series of large elliptical foramina directed obliquely forward and outward from the dental canal. Nearer the base approaching the symphysis, and also in the latter position, there exist a number of similar foramina. The left dental specimen has accommodated nine teeth, which are lost, except the fifth tooth and the fang of the first. The right dental specimen accommodated seven teeth, which are lost, except the fangs of the anterior three. The fangyand alveoli in the specimens are directed obliquely forward and upward with a feeble curvature. The angle of inclination of the fangs successively increases from behind forward. In the fifth tooth it is about 50°; in the first one about 30°.
The fifth tooth remaining in the left dental bone, has its crown mutilated, but a portion of the inner surface being preserved, exhibits a number of well-defined planes. The fang is about three inches in length, and exhibits a large excavation postero- internally for a successor.
In the right dental specimen the fang of the first tooth, two and a quarter inches long, presents a small concavity postero-internally, just below the alveolar border, for a successor. The fang of the second tooth is about one-third excavated, and the excavation at base impresses the front of the fang of the third tooth about its middle. Postero-internally the third fang presents a small excavation for its own successor.
Fig. 11, Plate VIII, represents a basi-sphenoid bone of Mosasaurus, from the first marl bed of Holmdale, Monmouth County, loaned to me by Prof. Cook. The specimen, a fragment of a huge skull, measures eight inches in length and six inches in breadth at the posterior diverging processes, which abut against the basi- occipital bone.
The basi-occipital bone, from Mississippi, part of the collection of Dr. Spillman, previously mentioned, is two inches long in the median line, and of ten lines greater width at the anterior diverging processes. The latter are separated by a wide con- cavity from each other and from the occipital condyle. They terminate in a reni- form convexity; in front sustain the angularly divergent processes of the basi- sphenoid bone, and posteriorly support in part the lateral occipitals. The condyle, somewhat mutilated, in its entire condition has measured about two and a quarter inches in transverse diameter, and a little over an inch vertically. The portion contributed by the lateral occipital, preserved on one side in the fossil, is about three-fourths of an inch wide and half an inch high.
The tympanic bone, accompanying the former specimen, though much fractured,
MOSASAURUS. 41
and partly imbedded in its matrix, is sufficiently well preserved to exhibit its true form. It presents considerable difference from that of the Mosasaurus of New Jersey, as it does also from that of the Maestricht skull of the Paris museum. It is of much greater breadth in proportion to its length, and is in comparison very abruptly narrowed at its lower part. Its height is three inches and a half, and its extreme breadth above is equal. The width of the mandibular articulation is one inch ten lines. The tympanic passage is proportionately larger, as is also the case with its posterior overhanging process.
The differences between this tympanic bone and that of the New Jersey, Mis- souri, or Maestricht Mosasaurus indicate the Mississippi Mosasaurus to be a distinct species,
Cuvier’ observes, that very few bones of the extremities of Mosasawrus have been found, and their rarity was such that, for a moment, he was led to doubt whether the animal possessed limbs. He states that he was soon undeceived by recognizing a bone of the pelvis which certainly belonged to Mosasaurus. ‘The bone, considered to be a pubis, resembling that of the Monitor, is figured in the Ossemens Fossiles. Cuvier further says, that among some fossils from Seichem he detected a scapula resembling that of the Monitor; and subsequently received drawings from Maestricht of a clavicle resembling that of a common Lizard, and also a coracoid bone. From the specimens and figures Cuvier supposes the shoulder of the Mosasaurus to have exhibited a close resemblance with that of the Lizards. After remarking that he had been unable to procure any long bones of the limbs of MJosasawrus, he expresses his views in regard to certain figures of bones, represented by Faujas-Saint-Fond? and Camper,’ reproduced in the Ossemens Fossiles. In regard to the figure of a portion of an ulna, Cuvier observes, that if the bone belonged to Mosasaurus, it would indicate the extremities to have been moderately elevated. But he continues, the bones of the feet, so far as they are known, appear, on the contrary, to have belonged to a sort of contracted fin, as in the Dolphins or Plesiosaurians. Of the different bones of the feet, figured in the Ossemens Fossiles, after Camper, Cuvier likens some of them to the principal carpal bones of the Crocodile, another appeared to belong to some huge Saurian, some are phalanges, and two are attributed by him to Turtles, whose remains are not less common in the deposits containing those of the Mosasaurus. In conclusion, Cuvier adds that ‘it was not without hesitation that he expressed his conjectures from mere figures, when the immediate comparison of the bones themselves would scarcely suffice, so great is their diversity and so small the precision of their forms in reptiles.”
Goldfuss* describes and figures several bone fragments from the deposits of the Cretaceous period of the Upper Missouri, which he views as the portion of a sca- pula, a coracoid bone, and an olecranon process of the Mosasaurus. In relation to the habits of the animal, he says, as it lived in the ocean the toes no doubt were
1 Ossemens Fossiles, Ed. 4, T. 10, pp. 170-173.
2 Hist. Nat. de la Mont. de St. Pierre de Maestricht. 8 Annales du Muséum, T. XTX. * Schidelbau des Mosasaurus; Noy. Act. Acad. Caes. Leop. Carol. Nat. Cur., Vol. X XI, Pars 1, p. 173.
6 April, 1865.
42 MOSASAURUS.
webbed, but the remains which have been discovered, on the contrary, do not lead to the supposition that it possessed fins like the Jchthyosaurians.'
Prof. Owen,’ after remarking that no part of the organization of Mosasaurus is so little known as that of the locomotive extremities, and substantially quoting the views of Cuvier, expressed above, enters into the description of some long bones of the extremities, “‘ showing the Lacertian type of structure,” which were obtained in the Green-sand formation of New Jersey. Professor Owen observes, “on the highly probable supposition that these bones belong to Mosasaurus, they indicate the ex- tremities of that gigantic Lizard to have been organized according to the type of the existing Lacertilia and not of the Enaliosauria or Cetacea.”
Pictet? says the humerus of Mosasaurus is thick and short, like that of Ichthyo- saurus, but gives no evidence for this assertion. He adds, we may conjecture, from the flattening of the bones of the members, that the feet were probably converted into fins like those of the Enaliosaurians.
Some remains, apparently of MJosasaurus, which I have the opportunity of ex- amining, indicate the limbs to have been fins, partaking in their structure the characters of those of the marine Turtle and the Plesiosawrus.
The humerus previously mentioned, found in association with several cervical vertebrie, a tympanic bone, and a pterygoid with teeth, submitted to my inspection by Dr. Spillman, of Mississippi, is represented in Figs. 1, 2, Plate VIII. Having every appearance of belonging to the same skeleton as its associated bones, there can be but little doubt of its appertaining to Mosasaurus or one of its allies.
The specimen is of the right side, and bears a striking resemblance to the humerus of a Turtle, with which I suppose it to have corresponded in the relative position of its parts, and shall, therefore, so describe it.
The shaft is short and rapidly expanded towards the extremities. Its middle part is cylindrical, but much compressed antero-posteriorly. The borders form a deep curve in the length, and are transversely convex, but the outer is the more obtuse. The posterior surface, Fig. 1, is transversely convex; the anterior, Fig. 2, nearly flat, and marked just above the middle by a roughness (d) for muscular attachment.
The proximal extremity expands to more than three times the breadth of the middle of the shaft. A demi-spheroidal head (a) projects forward, midway between two tuberosities, and is partially sustained in the usual manner by a gradual uprising abutment of the shaft. The tuberosities include a deep concavity back of the head, and are associated by the posterior terminal portion of the shaft, which presents a broad and slightly concave surface extending between them. The greater tuber- osity (4), situated postero-superiorly, extends a short distance proximally beyond the head so as to increase the length of the bone. It is compressed antero-posteriorly, and, in the specimen, is imperfect at the summit. The lesser tuberosity (c), situated
1 Op. cit., p. 196. Da sie sich im Meerwasser aufhielten, so waren die Zehen ihrer Fiisse ohne Zweifel mit Schwimmhiuten verbunden; die gefundenen Knochenreste lassen dagegen nicht vermuthen, _ dass die Flossenfiisse, wie die Fischeidechsen gehabt hatten.
2 British Fossil Reptiles, p. 190 8 Traité de Paléontologie, Ed. 2, T. 1, p. 505.
MOSASAURUS. 43
postero-inferiorly, is thicker than the former, and exhibits strong marks for mus- cular attachment.
The distal extremity of the bone expands to about twice the breadth of the middle of the shaft. It is almost flat in front, moderately convex behind, and terminates in a thick angular border, which, though somewhat mutilated, has the appearance as if it had formed a fixed or immovable joint with the bones of the forearm. The measurements of the specimen are as follows :—
Inches. Lines.
Extreme length of the specimen in its present state . : . SQL
Brcath of shatha@middie 4 see ek Id teh a 11 Thickness of shaft at middle 1 2 Breadth at tuberosities, estimated 6
Diameter of head 5 1 8 Breadth at distal end 3 8 Thickness at distal end 1 2
A fragment of a huge bone, from the Green-sand of Burlington County, N. J., con- tained in the cabinet of the Academy of Natural Sciences, is represented in Figs. 3, 4, 5, Plate VIII, rather less than one-third the diameter of the original. The specimen has been usually viewed as the proximal extremity of the humerus of an enormous Turtle, and even Agassiz was impressed with the same idea, for it is the fossil characteristic of his Atlantochelys Mortoni.' It bears a resemblance to the corresponding portion of the humerus just described, and probably belongs to the gigantic Mosasaurus.
The shaft, broken across near its middle, appears of exceeding narrowness in comparison with the breadth of the bone at the tuberosities, and, indeed, is much narrower in this respect, relatively, than in the humerus above described. From this character alone we have good reason to suspect that the two specimens indicate a small and a large species of Mosasaurus.
The broken end of the bone, under immediate examination, presents an ovoidal section, with the greater diameter thirty-four lines, the shorter twenty-nine lines. The shaft contains no medullary cavity, but is occupied by an interior coarser ossific structure. ‘The upper or front part of the shaft, as in the preceding specimen, exhibits a rough, tuberous surface for muscular attachment.
The head is ovoidal in outline, fifty-three lines in its antero-posterior diameter, and forty-four lines in its short diameter.
The breadth of the bone, from the summit of one tuberosity to that of the other, is eleven inches. The greater tuberosity projects three inches proximally beyond the head, increasing by so much the length of the bone. It is compressed antero- posteriorly, is convex and rough at the summit; measures four inches wide at its middle, and twenty-six lines thick. The smaller tuberosity, irregular in form and much roughened for muscular attachment, measures forty-one lines in thickness,
The length of the fragment, from the summit of the greater tuberosity to the broken end of the shaft, is eleven inches.
4 Proc. Acad. Nat. Sci. 1849, 169.
44 MOSASAURUS.
The mass of hard blue stone, previously noticed, containing a number of caudal vertebre in a row, obtained by Dr. Hayden on the Yellowstone River, also contains a broad bone, represented in Fig. 12, Plate XVII, together with several small bones, like that represented in Fig. 13, of the same Plate, all of which appear to have belonged to the same skeleton.
The broad bone is yet partially imbedded in its hard matrix, the removal of which
-would endanger the integrity of the specimen. It resembles in general form the ulna or fibula of Plesiosawrus, and from its being found with caudal vertebre might be suspected to be the latter bone. It is not, however, unlikely that it may prove to be a tarsal bone, one of which it likewise resembles in the foot of Plesiosaurus. It is about as broad as it is long, and the exposed surface exhibits a radiate ossific structure. Internally the upper part of this surface is transversely convex, but is slightly depressed below; externally it is concave. The upper border is convex in the direction of the breadth of the bone. The inner border is longitudinally con- cave, transversely convex, thick, and smooth. The outer border is thin, emarginate, and presents an irregular pitted appearance as if it had been covered with cartilage. The lower border at its inner third forms an obtuse angle, is thick, and subdivided into a pair of concave articular facets. The measurements of the bone are as follows :—
Inches. Lines. Extreme length . ; 5 : : : 5 5 c aS 2 Breadth aboye : ; : : ; " s F 3 cig ay ie 10 Breadth at the middle . : $ . : : 0 ; 3 yee 4 Breadth below 5 3 2 Thickness at the lower border 1 2 Thickness at the outer border 4
The small bones above alluded to appear to be metatarsals and phalanges; and they closely resemble the corresponding bones of the Plesiosaurus. One of the best specimens, represented in Fig. 13, Plate XVII, has a quadrate shaft strongly expanded at the extremities. The proximal end is the larger, and presents a trans- versely oval, flat articular surface. The distal articular surface is likewise oval, but is concave. ‘The measurements of the specimen are as follows :—
Lines. Length - ° : : , < : 5 4 e c : : BPA Breadth of proximal en s - é ; : 5 ° - : Ale! Thickness of proximal end . : 5 : : : : c : ; otal | Breadth of middle of shaft . ; : 4 : 6 . é : AS ri) Thickness of middle of shaft 3 2 A 5 ‘ 3 é S : ee! Breadth of distal end . : a 5 A - - - 5 s A . 12 Thickness of distal end 5 j ‘ - ‘ , 3 5 3 ‘ ae et
Two additional specimens, partially imbedded in their matrix, present very nearly the same form and size as that just described.
Other bones of the limbs, which may, with the same probability as the preceding, be referred to Mosasaurus, I have not had the opportunity of examining.
An isolated bone, somewhat crushed in appearance, belonging to the cabinet of Prof. James Hall, and obtained by Messrs. Meek and Hayden, from the Cretaceous
MOSASAURUS. 45
deposits of Nebraska, is represented in Fig. 6, Plate VIII, and may, perhaps, apper- tain to a young Mosasaurus. It resembles a radius or tibia of Plesiosawrus. It is much compressed, cylindroid in form, and expanded nearly equally towards the extremities. The articular surfaces are transversely elliptical, slightly convex, and roughened for the attachment of cartilage. The measurements of the specimen are as follows :—
Inches. Lines. Length ; : - - - - : : : - S se 8 Breadth at middle of shaft . E A : : : ; P ea | 1 Thickness at middle of shaft ‘ : 5 5 ° ; 6 Breadth at extremities . : = : . ° é j . all 8 Thickness . : ‘ : ‘ : ; P A ; : 9
An isolated bone, obtained by Dr. Spillman, from the same formation, which contained the humerus and other bones previously described, is represented in Fig. 7, Plate VIII... It resembles the preceding specimen suspected to be a radius or tibia of a young Mosasaurus, but is much less compressed, and its articular surfaces are nearly plane or slightly concave. Its measurements are as follows :—
Inches. Lines.
Length : : C : : : : c : . : . 2
Breadth at middle of shaft 3 : . 4 : : s : 9 Thickness at middle of shaft ; ; ; : 3 . 4 : 7 Breadth of proximalend . ; : ; : : 5 A 5! 6 Thickness of proximal end : ; : ; : : ee
Breadth of distal end A 2 5 : 6 ‘ : 5 el 4 Thickness of distal end i! ‘3 S : rs : 3 5 4 10
A carpal bone, represented in Fig. 8, Plate VIII, found by Dr. Hayden on the Big Cheyenne River, probably belongs to Mosasawrus. 'The specimen is hexagonal at the border, and has its broad surfaces moderately concave. Its greatest breadth is one inch, its shortest ten lines; its thickness ranges between three and five lines.
An undetermined reptile bone, accompanying the latter, is represented in Fig. 10, of the same Plate. It is a short, much flattened, cylindroid bone, constricted at the middle, where it measures one inch and a quarter wide, and three-quarters of an inch thick. The upper extremity expands into a broad, flat, circular articular surface, with a narrow oblique prolongation at one side. The surface is broken off at the opposite side, but independent of the prolongation it measures about ane inch and a quarter in diameter. The lower extremity expands into a transversely semi-circular, ellipsoidal articular surface, measuring two inches and three-quarters in its long diameter and ten lines in its short diameter. ‘The length of the bone is one inch and three-quarters.
Another undetermined reptile bone, represented in Fig. 9, Plate VIII, belonging to Prof. James Hall, was found by Messrs. Meek and Hayden, among loose frag- ments at the base of a Cretaceous bluff, five miles below Daurion’s Hill, Nebraska. The bone is a little over two inches in length, and somewhat resembles the preced- ing, but appears lengthened at the expense of the breadth. The shaft at middle is eleven lines wide and eight lines thick, and is ovate in transverse section, The upper extremity expands into a flat, nearly circular articular surface, about one inch
46 MOSASAURUS.
and a quarter in transverse diameter, and a little less in the opposite diameter. The lower end of the bone expands transversely, and ends in a long, curved ellip- soid surface, apparently subdivided to articulate with three carpal bones. The length of this surface transversely is two inches and a quarter, its breadth three- quarters of an inch.
Specimens of isolated teeth, possessing the general characters assigned to those of the Maestricht Monitor or Mosasaurus, but exhibiting considerable diversity of size and form, are frequently discovered in the deposits of the Cretaceous period of the United States. A number of such teeth are contained in the cabinet of the Academy of Natural Sciences, and others have been loaned to me for examination, but I find it difficult to decide whether they belong to one or more species of the genus or to several distinct genera. In attempting to determine the limit of varia- tion in the form of the teeth of Mosasawrus, I have greatly felt the want of a careful description in detail, accompanied by accurate figures, of the fine specimen of the jaws and teeth, upon which the genus was founded, and which is now preserved in the museum of the Jardin des Plantes, at Paris. I have had access to an excellent plaster cast of the specimen presented by the Directors of the latter institution to the American Philosophical Society, but in many respects it fails to show nice shades of character, which are, no doubt, to be observed in the original, or wnich might be the subject of description and accurate delineation. The descriptions and figures by Faujas-Saint-Fond, Cuvier, and others, though sufficiently characteristic of the genus, and mainly correct, are not given with the detail and precision that are required for comparison of the specimens I have the opportunity of examining.
‘uvier’ briefly describes the teeth of Mosasawrus in general. He observes, that they are all pyramidal and slightly curved; their external face is plane, and defined by two acute ridges from the internal face, which is round, or rather demi-conical. Subsequently? he remarks, that the ridges are entire and without denticulations. He does not refer to the existence of divisional planes upon the teeth; and an inspection of undoubted teeth of the genus leaves no question that the ridges of the crown are minutely denticulate in the unworn condition. An examination of the cast, above mentioned, also proves that there is some diversity in the shape of the teeth in different parts of the series. Goldfuss,’ in describing the teeth of Mosasaurus, says they are slightly compressed laterally, towards the apex feebly curved backwards, and are divided into a larger inner and smaller outer half by an acute linear ridge, which is transversely striated. Their surface appears polygonal; the outer surface presenting five, the inner seven pyramidal planes. Prof. Owen,' in referring to the description of Goldfuss, remarks, “the feeble indications of angles observable in some of the teeth, those of the upper jaw chiefly, of the Mosasawrus Hoffmanni, do not bear out the term ‘ polygonal,’ which he applies to the crowns of that species as well as to those of his Mosasaurus Mazximiliani ; still less can I find these angles so constant and regular as to
1 Ossemens Fossiles, Ed. 4, T. X, p. 144. a Ibid., p, 145. * Schidelbau des Mosasaurus; Nov. Act. Acad. C. L. C. Nat. Cur., Vol. 21, p. 178. + British Fossil Reptiles, p. 185.
MOSASAURUS. 47
divide the outer surface of the crown into five, and the inner surface into seven facets.”
The plaster cast, above mentioned, of the jaws of the Maestricht Monitor, shows that the front teeth are narrower than those behind. The external surface of the crown is comparatively narrow and slightly convex, while the internal surface is of considerable extent, forming in section the transverse half of an ellipsoid. In passing backward in the dental series it appears that the external surface of the crowns increases in breadth and becomes more convex, while the internal surface in a corresponding manner decreases. In the back teeth the crown appears to be laterally compressed conical, with the external surface nearly as wide and convex as the internal, so that a transverse section presents an ellipse with acute poles. Thus the front teeth of the cast correspond with those usually described as charac- teristic of Mosasaurus, while the back ones are more like those supposed by Prof. Owen to indicate a djstinct genus, which he has named Leiodon.
In most of the teeth, usually assigned to Mosasauwrus, the inner and outer surfaces of the crown are more or less distinctly subdivided into a series of narrow planes, which are most evident towards the base of the crown. ‘These planes are variable in number, and are often slightly depressed or feebly concave. They are sometimes multiplied towards the base, but become indistinct or even disappear at the summit. In the plaster cast the divisional planes of the surfaces of the crown, while suffi- ciently evident in the more anterior teeth, appear to be obsolete in those most pos- terior, though it is true that their absence in the latter may arise from defective modelling.
In the Maestricht Monitor, Cuvier’ observes that, ‘the teeth are hollow only during their development, as they are then in all other animals. They become filled throughout their length, and are most frequently found entirely solid. ‘They complete their development in becoming attached to the jaw by means of an osseous body very different in structure from that of the tooth, with which it is neverthe- less intimately associated. The successional tooth originates in a special alveolus produced at the same time, and it penetrates the osseous body of the tooth in use. In enlarging the successional tooth finally detaches the osseous body from the jaw with which it was organically united; the body by a sort of necrosis being shed and carrying with it the tooth it supported. Gradually the successional tooth, with its body, improperly called its osseous root, assumes the position from which the old one was removed.”
Subsequently, Cuvier,’ after remarking that “he had formerly committed the error of calling the osseous structure, connecting the tooth with the jaw, the root,” observes that “he had since recognized it to be the dental pulp, which, instead of remaining soft as in mammals, becomes ossified and identified with the alveolus.” Cuvier continues, “the tooth has no true root, but adheres strongly to the pulp which secreted it, and is further held in connection with it by the remains of the capsule which furnished the enamel, and which, by becoming ossified also, and
1 Ossemens Fossiles, Ed. 4, T. 10, p. 184. ® Ossemens Fossiles, 136.
48 : MOSASAURUS.
uniting itself with the maxillary bone and the ossified dental pulp, inserts and fixes the tooth with additional force.”
Again, in comparing the mode of implantation of the teeth of Mosasaurus with the living Monitor and Iguana, Cuvier' observes of the former that “the socles (pedestals) or ossified pulps, which support the teeth, are adherent in hollows or true alveoli contrived in the thickness of the border of the jaw.”
Goldfuss,’ referring to the Maestricht and the Missouri Mosasawrus, says, “in both, the crowns of the teeth, invested with shining enamel, are sustained upon the dental capsule which is transformed into an osseous socle, coossified with the alveolus, and they are in part hollow internally and in part solid.”
Owen, in his Odontography, page 258, in reference to Mosasaurus, observes that “‘the maxillary teeth combine the pleodont with the acrodont characters.” Further on he continues, “its dentition exhibits in an eminent degree the acrodont character ; the teeth being supported on expanded conical bases anchylosed to the summit of the alveolar ridge of the jaws; no existing Saurian exactly parallels this mode of attachment of the teeth, either in regard to the breadth of the alveolar border or in the relative size of the osseous cones to the teeth which they support. A shallow socket is left where the tooth and its supporting base are shed.” The same authority, in a more recent work, Paleontology, page 279, remarks that “the teeth are anchylosed to eminences along the alveolar border of the jaw according to the acrodont type.”
Pictet, in his Traité de Paléontologie, tome 1, page 504, speaks of the tecth of Mosasaurus as being deprived of true roots and anchylosed to the jaw.
Gibbes, in his Memoir on the Mosasaurus,’ follows the descriptions of Cuvier and Owen.
Gervais, in the Zoologie et Paléontologie Francaises, tome 1, page 262, in de- scribing some teeth which he refers to Letodon, observes that as in Mosasaurus they are inserted in alveoli with which their root’is identified by means of the surround- ing layer of cement. Ina note he adds the remark, “c’est a tort que l’on décrit les dents des Mosasaures comme réellement acrodont a la maniere de celles de beaucoup de Sauriens actuels.”
From the fossil specimens I have had the opportunity of examining, the history of the dentition of Mosasawrus, so far as I have been able to trace it from the im- perfect materials, appears to be as follows :—
The mature teeth of Mosasaurus have curved conical crowns with long, robust fangs inserted into sockets or alveoli, with which they were at first connected in the ordinary manner by connective tissue, but with which they subsequently became firmly coossified. They contain in the interior a large fusiform pulp cavity com-
1 Ossemens Fossiles, 143.
* Schidelban des Mosasaurus; Nov. Act. Acad. C. L. C. Nat. Cur., XXI, 178. Bei beiden sitzen die, mit einem braunen, glinzenden Schmelze tiberzogenen Zahnkronen auf der zu einen verknécherten Sockel umgewandelten, in der-Alveole angewachsenen Zahnkapsel, und wird im Innern theils hohl, theils ausgefiillt.
8 Smithsonian Contributions, Vol. II.
* Goldfuss (Nov. Act. Acad., XXI, Pl. 9) has given two figures of teeth with their fangs, which
MOSASAURUS. 49
municating through a canal with a funnel-shaped pit at the end of the fang. See Plates IX, X, XI.
The conical crowns of the teeth are curved backward with an inclination inward; the curvature being more rapid approaching the apex. ‘They are generally divided in front and behind by an acute ridge into an inner and an outer surface. In some teeth, apparently belonging to the most posterior of the dental series of the jaws, and to those of the pterygoid bones, there is only one ridge, which is situated along the back or concave border of the crown. The ridges exhibit a minutely crimped and sub-denticulated arrangement,’ which was obliterated by wearing.
The proportionate extent of the inner and outer surfaces of the crown, as defined by the two ridges above indicated, varies very much in the different specimens of fossil teeth, apparently according to the position the latter occupied in the dental series.
In those teeth, which I suspect to belong to the anterior part of the dental series, the crown has the form corresponding with the descriptions which have usually been given as characteristic in general of the teeth of Mosasaurus (Plate IX, Figs. 1, 2,3; Plate X, Figs. 1, 2,3). It is very unequally divided by the acute ridges; the inner surface occupying two-thirds or more of the extent of the crown. The con- vexity or transverse curvature of the outer surface forms a short segment of a com- paratively large circle; that of the inner surface forms one-half to two-thirds or more of a circle, whose diameter is that of the crown. The transverse section of the crown might be appropriately called shield-shaped, as represented in the wood- cut outlines, Nos. 1, 2, 3.
In those teeth which are supposed to belong to the middle of the dental series the disproportion between the outer and inner surfaces of the crown is comparatively trifling, and the transverse section is circular or nearly so (Plate IX, Figs. 5, 6; Plate X, Figs. 7-9).
Teeth attributed to the more posterior part of the dental series have their crowns compressed from within outwardly and nearly equally divided by the acute ridges, and in transverse section are elliptical with acute poles (Plate X, Fig. 10).
Finally, the last teeth of the series have compressed crowns, with a single ridge, and an ovate transverse section (Plate X, Fig. 4).
The inner and outer surfaces of the crowns in most of the fossil teeth are une- qually subdivided into narrow planes, variable in number. They slightly multiply towards the base of the crown, and become fewer and less distinct, or altogether disappear towards the apex. They vary in degree of distinctness in different teeth, and in many do not exist at all (Plates IX, X, XI).
he indicates as a maxillary and a palatal tooth of Mosasaurus Hoffmanni. The tooth represented in his figure 4 looks as if it may have belonged to near the middle of the dental series. The inner side of its fang exhibits a small lenticular excavation; part of the receptacle of a successional tooth. Fig. 5, represented as a palatal or pterygoid tooth, I suspect rather to belong to the back part of the maxillary series. The two figures are reproduced by Gibbes in Plate I, of his Memoir on the Mosasaurus.
* This arrangement appears not to have been noticed by Cuvier in the teeth of the Maestricht
Monitor. Ossemens Fossiles, I’. X, 145. 7 ~~=«~April, 1865.
50 MOSASAURUS.
The fossil teeth under examination would appear to indicate that the subdivision of the inner and outer surfaces of the crown is best marked in the anterior teeth of the series, becomes less evident in passing backward, and ceases in the last teeth. Some of the specimens would appear to show that the subdivision of the crown held some relation with the age of the animal; not existing in the young, but developed in the mature animal. Other specimens appear to indicate that the difference was due to individual peculiarity, or perhaps in some it may denote a difference of species if not of genus.
The fangs of the teeth of Mosasaurus are remarkable for their great proportionate size, being several times the bulk of the crown they support (Plate IX, Figs. 1-7; Plate X, Figs. 1, 2, 4, 7, 8, 10).
From the enamel border of the base of the crown the fang expands in the form of a cone to the entrance of its socket, where it presents its greatest diameter and is more or less defined by a shoulder or ledge (Plate LX, Figs. 1,5; Plate X, Figs. 7, 8,10; Plate XI, Figs. 1-6).
The intra-alveolar portion of the fang, from two to four times the length of the extra-alveolar portion, is straight, oblique, or slightly curved, cylindroid, and slightly narrowed towards the obtusely rounded end. Frequently it is more or less com- pressed from without inwardly; and occasionally wrinkled at bottom.
The mature fang was at first simply inserted about three-fourths or more of its length in its socket, with which it was evidently adherent in the ordinary manner by connective tissue. Subsequently, however, it became firmly coossified with the alveolus; the ledge or base of the extra-alveolar portion with the entrance of the alveolus at the border of the jaw; the intra-alveolar portion with the sides and bottom of the alveolus.
The pulp cavity (Plate IX, Fig. 6, 7; Plate XX, Fig. 3, c) of the mature teeth of Mosasaurus occupies-a large extent of space in their interior. It is fusiform, or doubly conical, one cone extending into the crown, the other into the fang. It communicates by a large canal with a funnel-shaped pit, usually more or less com- pressed, at the bottom of the fang.’ Occasionally the canal is occupied by a coarse cementum pervaded by many large vasculo-neural canals, as represented in the diagram, Fig. 3, d, Plate XX.
The crown of the teeth of Mosasaurus (Fig. 3, a, Plate XX) is composed of. compact dentine invested with a thin layer of enamel. At the base of the enamelled crown the dentine extends, in the form of an inverted cone, within the extra-alveolar portion of the fang and terminates in a thin, abrupt annular margin, encircling the pulp cavity, as represented in the diagram, Fig. 3, e, Plate XX.
The dentine, as represented in Figs. 4, 5, 6, a, Plate XX, presents the ordinary constitution of an amorphous substance, pervaded with innumerable canaliculi diverging from the pulp cavity to the periphery of the crown, dividing in their course and giving off multitudes of lateral anastomosing branches. Below the
* Owen says, “The pulp cavity generally remains open at the middle of the base of the crown of the tooth; irregular processes of the cavity extend as medullary canals into the conical base of the tooth.” Odontography, 259.
MOSASAURUS. 51
enamel border of the crown the dentine is defined from the cementum of the extra-alveolar portion of the fang by a more amorphous bond of union of the two structures, as indicated by the clear dividing line in the figures above mentioned.
The fang (Fig. 3, 6, Plate XX) is composed of cementum or bone, as represented in Fig. 4, 5, 6, 6, of the same plate. It is mainly composed of vertical osseous fibres, pervaded by numerous vascular canals pursuing the same course as the former. It is of much finer texture than the bone of the jaw with which it may be intimately coossified, and is admirably adapted to sustain the crowns of the teeth, both as regards its organic and its physical functions.!
The teeth of Mosasaurus, belonging to the functional series or those in use, were succeeded by a new set which underwent their development at the postero-internal portion of the alveoli occupied by the former. For the reception of the growing crowns of the new teeth the fangs of the functional series were gradually excavated through absorption of their structure, in a direction from within obliquely outward and forward, upward and downward. At first the inner parapet of the jaw slightly contributed to the parietes of the cavity for the new tooth, but, with this trifling exception, it was through excavation of the contiguous fang of the functional tooth that the former was accommodated. In the progress of the excavation, the pulp cavity of the functional tooth became exposed and then cut off from communica- tion with the nerves and bloodvessels which supplied its contained pulp. The fossil specimens further indicate that it was during the progress of the excavation of the fangs of the functional teeth that these became coossified with their alveoli, as if to resist a tendency to expulsion from the jaw.
The cavities for the new teeth, in the fossils, are ovoid in form, and open at the postero-internal part of the extra-alveolar portion of the base of the fangs of the functional teeth; and from the opening the apex of the new tooth is seen pro- truding.
After the development of the crown of the new tooth the fang was produced, and the increase gradually became so great at the next step as to have converted the fang of the old tooth into a large capsule, surmounted by its crown still in use. With the advance of growth of the new tooth the crown of the old one became so enfeebled in its connection with its excavated fang as readily to be broken off by external violence, or to be displaced by the continued growth of the fang and pro- trusion of the crown of the new tooth. ‘The fang of the latter continued its growth within a mere cylinder of the fang of the old tooth until its crown was made to assume a position in the functional series.
The development of the new tooth was scarcely completed before a successor commenced the same process, and thus one tooth was followed by another throughout the life of the animal, as in recent Reptiles (Plate IX, Figs. 1, 4, 5,6; Plate X, Figs. 1, 4, 7, 8, 10; Plate XI, Figs. 4, 5, 6, 8, 10).
* Owen says, ‘‘ The expanded base of the tooth,” referring to what has been mentioned above as the extra-alveolar portion of the fang, “is composed of a mere irregular mass of dentine, which, by its progressive subdivisions into vertical columnar processes, assumes a structure resembling that of
true bone.’ Odontography, 259.
52 MOSASAURUS.
Some of the fossil’ specimens show that not unfrequently, while a successional tooth occupied a cavity within the fang of its predecessor, it was accompanied by another, situated behind the former. For the accommodation of the second suc- cessor a cavity was produced, not only at the expense of the fang occupied by the first one, but partly at the expense of the alveolar partition and fore part of the fang of the functional tooth behind. Figs. 1, ¢, 10, c, Plate X, and Figs. 5, e, 6, e, Plate IX, exhibit successive stages in the production of a cavity for a contempo- raneous second successional beats The large cavity, represented in the jest figure, is evidently compounded of two.
The pulp cavity of the teeth of Mosasaurus varied in size according to the period of development and age of the teeth, but all the fossil specimens I have seen indi- cate that it was absent at no period. I have never seen a solid tooth of the Ameri- can Mosasaurus, contrary to the statement of Cuvier, in regard to the Maestricht Monitor, that the teeth are only hollow during their development, and are most frequently found entirely solid. Nor does the large size of the pulp cavity in the mature teeth warrant the term of pleodont applied to the Mosasaurus by Owen.’
In the shedding of the crowns of the teeth of Mosasaurus they appear generally to have been detached from their excavated fangs a couple of lines from the enamel border. In several fossil specimens the base of the shed crowns is excavated in a conical or lenticular manner from the periphery to the central remnant af the pulp cavity. The peripheral border varies from a thin sharp edge to a fractured one of a couple of lines in thickness. The remnant of the pulp cavity, where it communicates with the excavation, is about a third of the diameter of the crown, and from one-third to one-half its length.
The alveoli generally appear to be completely separated in the ordinary manner among most animals by thin osseous partitions. In those instances in which there were two nearly contemporaneous successors to a tooth in use, the crowding to accommodate the former appears to have been such that the alveolar partition was obliterated, and was subsequently replaced by the cylindrical remains of the fangs which were excavated for the successional teeth.
The fossil specimens I have had the opportunity of examining, illustrating the dentition of Mosasawrus, are as follows :—
1. An alveolar fragment, containing a mutilated tooth and the fang of a second, from Burlington County, New Jersey, belonging to the museum of the Academy of Natural Sciences. It indicates an individual as large as that to which belonged the great skull of the Maestricht Mosasaurus, preserved in the museum of the Jardin des Plantes of Paris; and the mutilated tooth it contains resembles in its form those in advance of the middle of the series in the plaster cast of the skull just mentioned. An inner view of the specimen is given in Fig. 1, Plate IX. The fragment is from the right side of the upper jaw, and measures about eight inches in length by three inches in thickness. The external surface is straight longitudinally and convex vertically. About half way between the alveolar edge and the broken border, a distance of about three inches, it presents a transverse row of large vasculo-neural
+ Ossemens Fossiles, Hd. 4, T. 10, p. 134 ; 2 Odontography, 258.
MOSASAURUS. 53
foramina, which communicate with a narrow canal situated just externally to the bottom of the fangs of the teeth.
The mutilated tooth of the specimen (Fig. 1, a) has a large portion of the crown destroyed, especially at its outer part, but it has been artificially restored in such a manner as sufficiently well to exhibit its original form.
This agrees with the ordinary descriptions characterizing the teeth of Mosasaurus. It is conical, curving moderately backward and inward, and in its perfect condition has measured about two inches and a half in length. The diameter at the enamelled base has been about fourteen lines, both antero-posteriorly and trans- versely. The transverse section is shield-shaped, as represented in the wood-cut outlines, Nos. 1, 2, 3, of more perfect specimens of teeth. A pair of acute, feebly denticulated, crimped ridges divide the crown irregularly into two surfaces, of which the outer is about one-half the extent of the inner. The transverse curve of the outer surface forms a short segment of a comparatively large circle, and measures at the bottom of the crown fifteen lines; the curve of the inner surface forms half an ellipse, and measures twenty-nine lines. Both surfaces have been subdi- vided into narrow planes; the outer exhibiting traces of three or four; the inner presents eight, of which the extreme ones are twice the width of those inter- mediate.
The fang (Fig. 1, 6) is three inches and three-quarters in length, and is exserted about one-fourth; the base of the extra-alveolar portion measuring an inch and three-fourths in diameter. The intra-alveolar portion is firmly coossified with its alveolus, and is about one-half excavated postero-internally for the accommodation of a successional tooth. The cavity, from which the latter has been lost, is open at the postero-internal portion of the alveolar border, as represented in Fig. 1, d, and is also exposed by the destruction of the thin bottom of the alveolus, as seen in the same figure atc. Notwithstanding the extent of the excavation of the fang, the pulp cavity of this tooth is not exposed, except through a narrow aperture remaining from the canal of communication with the bottom of the fang.
The next succeeding fang of the fossil (Fig. 1,7) is like that just described, except that the cavity for a successional tooth is comparatively small. It is seen in the figure at 4, opening at the border of the jaw postero-internally. It is oval, about sixteen lines in depth, and eight lines in breadth. The end of the fang is seen, as represented in the figure at g, through the open bottom of the alveolus. The canal, which usually communicates through the fang with the pulp cavity, is filled up with coarse cementum. At the summit of the extra-alveolar portion of the fang, from the loss of the crown, the bottom of the pulp cavity of the latter is exposed. The aperture is obliquely oval, and measures nine lines in the long diameter and six in the short diameter. From the aperture the cavity extends into the fang, in the form of a cone, an inch and a half in depth.
Behind the fang just described, the fossil retains one-half of an alveolus, which is interesting, from its exhibiting a thin plate of bone, as seen in Fig. 1, 7, the remains of the fang which once occupied it. The plate is coossified with the alveolus, and formed part of the wall of the cavity of a successional tooth which is lost.
Gal MOSASAURUS.
2. A fragment, apparently from the forepart of the lower jaw, containing the fangs of four teeth, from Burlington County, New Jersey, presented to the Academy of Natural Sciences by Dr. S. G. Morton. The fragment is ten inches long, and was sufficient to accommodate six teeth. At its widest part, opposite the position of the fifth tooth from the anterior extremity, it measures two inches and a half. The inner and outer surfaces are straight longitudinally and convex vertically. The outer surface, about an inch and a half from the alveolar edge, and near the broken border of the specimen, presents a transverse row of four large vasculo- neural foramina, communicating with the remains of the dental canal within.
The four fangs of teeth, contained in the specimen, are about three inches in length, of which about three-fourths are inserted within alveoli. The exserted or extra-alveolar portions of the fangs form truncated cones at the border of the jaw surmounted by the fractured borders of the lost crowns. The loss of the latter has exposed the base of the large interior pulp cavities, which measure from half to three-fourths of an inch in diameter and extend in an inverted conical manner within the fangs.
At the border of the jaw, the bases of the extra-alveolar portions of the fangs range in transverse diameter from fourteen to twenty-two lines.
The intra-alveolar portions of the fangs are cylindroid, moderately curved, and terminate in rounded extremities just internal to the position of the dental canal.
The first and third fangs of the specimen are loosely inserted in their sockets, with which they appear never to have been coossified. The second and fourth fangs are firmly coossified with their alveoli, and are deeply excavated postero-internally into large cavities which accommodated successional teeth, but which are lost from the specimen.
The second, third, and fourth fangs are separated by thin osseous partitions of the alveoli.
The fourth fang presents in its postero-internal part a small cavity for a succes- sional tooth.
The first fang encroached so much on the position of the second as to have depressed its anterior part. It presents the remains of a very small cavity for a successional tooth in the same position as the other fangs, and exhibits what appears to be a portion of a second and larger one at the forepart.
3. A tooth, from Monmouth County, New Jersey, loaned to me for examination, from the collection of Rutger’s College, by Prof. Cook. The specimen, represented in Fig. 2, Plate X, resembles the tooth in the jaw fragment first described, or is of the form which is usually viewed as, characteristic of Mosasaurus. It is pertect, except that the apex and anterior carinated ridge of the crown are worn, and it measures five inches and a half in length.
The length of the enamelled crown in its present condition is twenty-two lines ; the antero-posterior diameter at base thirteen lines, and the transverse diameter fourteen lines. 'he outer and inner surfaces are defined by acute, linear ridges, which become more carinated towards the apex of the crown. The unworn poste- rior ridge is minutely denticulated, and traces of the same condition are visible on the anterior ridge. The outer surface of the crown is nine lines wide at the bottom
MOSASAURUS. 55
and eight lines at the middle. It forms less than one-sixth of a circle, whose radius is about eight lines, and is irregularly subdivided into four planes below, extending into three towards the apex. The inner surface forms about three-fourths of a circle, whose radius is six lines, and is irregularly subdivided into eleven planes. The circumference of the crown at the enamel border is three inches and three-quarters, of which the inner sur- face is two inches and eleven lines, the outer surface ten lines. The accompanying outlines, No. 1, represent transverse sec- tions of the crown at its base, a short distance above the base, and near the middle,
The exserted portion of the fang, or that which extends the cone of the crown, is from nine to ten lines high, and seventeen lines in diameter at base. The inserted portion is cylindrical, three inches in length, and rounded at the bottom. It was coossified with its alveolus, as indicated by firmly attached portions of bone to its inner side. Its canal of communication with the pulp cavity of the tooth is completely occupied by a coarser ossific substance. On the inner side posteriorly there exists an excavation, one inch and a half deep and three-quarters of an inch wide, being part of the cavity for a successional tooth.
4. A tooth, from the Green-sand of Freehold, Monmouth County, New Jersey, belonging to Dr. C. Thompson, and loaned to me for examination through Prof. Cook. It is represented in Fig. 1, Plate X, and is rather larger than the preceding specimen, which it resembles in form.
The enamelled crown, broken at the apex, when perfect measured about two inches and a half in length; its diameter at base antero-posteriorly is fourteen lines, transversely fourteen lines and a half. The outer and inner surfaces are defined by well-marked acute ridges, which are minutely denticulated. The outer surface is an inch wide at the bottom of the crown, three-fourths of an inch at its middle, and is subdivided into three planes. The inner surface forms more than half a circle, whose radius is about seven lines, and it is dis- tinctly subdivided into eleven planes. ‘The circumference of the crown at the enamel border is four inches, to which the inner surface contributes two inches ten lines; the outer sur- face fourteen lines. The accompanying outlines, No. 2, represent sections at the base of the crown, and from the lower and upper third.
The fang is three inches and three-fourths in length, and appears not to have been coossified with its alveolus; at least it exhibits no traces of attached portions of the jaw. The bottom of the fang pre- sents a wide elliptical pit, narrowing into a fissure, continuous with the canal of communication with the pulp cavity of the tooth. The inner side of the fang posteriorly presents an excavation (Fig. 1, d) for a successional tooth, and a second (c), shallower impression, to accommodate a successor to the functional tooth in advance,
5. The shed crown of a tooth, from near Woodbury, Gloucester County, New
No. 1.
No. 2.
56 MOSASAURUS.
Jersey, belonging to the museum of the Academy of Natural Sciences. It is represented in Fig. 3, Plate X, and was previously indicated and figured by Harlan’ and Morton.” In form it resembles the corresponding portion of the teeth above described, but is slightly larger. Its dividing ridges are distinctly denticulated; the outer surface is divided towards the base of the crown into four planes, which diminish and finally disappear towards the apex; the inner surface is divided into eleven planes, which also diminish and become obsolete towards the apex. The length of the crown when perfect has been about two inches and three-quarters ; the antero-posterior diameter at base about thirteen lines; and the transverse diameter is fourteen lines and a half.
The base of the specimen is excavated in a trumpet-like manner, extending to a thin edge at the periphery of the crown. ‘This condition evidently indicates the specimen to have been shed during the life of the animal, notwithstanding the little wearing to which the tooth appears to have been subjected.
The accompanying outlines, No. 3, represent sections from the base, middle, and near the apex of the specimen.
6. The shed crown of a tooth, from Burlington County, iNew Jersey, presented to the Academy of Natural Sciences by Mr. L. T. Germain. ‘The specimen, repre- sented in Fig. 6, Plate X, has the apex and base broken, but when perfect appears to have been less than two inches and a half long, about thirteen lines in diameter antero-posteriorly and twelve lines transversely. The ridges of the crown are distinctly denticulated, but separate the surfaces less unequally than in the preceding specimens, The outer surface is subdivided into nine planes, passing into seven and then becoming obsolete towards the apex of the crown. The inner surface is subdivided into about twenty planes, diminishing and finally disappearing towards the apex of the tooth. The sub- divisional planes are more or less obscured. by longitudinal striation of the enamel, more especially on the inner side. This striation diminishes and finally disappears towards the apex. It does not exist in the specimens previously described.
The accompanying outline, No. 4, represents a transverse section of the crown below its middle.
‘The base of the specimen is excavated towards the central pulp cavity in a salver- form manner from a broken edge at the periphery about a line and a half thick.
7. An entire tooth, from Monmouth County, New Jersey, loaned to me for exami- nation, from the collection of Rutger’s College, by Prof. Cook. The specimen represented in Fig. 3, Plate IX, I suspect to belong to the forepart of the lower jaw of Mosasauwrus. It is smaller, but has the same general form as the entire teeth previously described.
The crown is more curved than in any of the preceding specimens, but like them
No. 3.
No. 4.
* Journ. Acad. Nat. Sci., Vol. IV, Plate XIV, Figs. 2, 3, 4; Med. and Physical Researches. ? Synopsis of Organic Remains, &c., Plate XI, Fig. 9.
MOSASAURUS. 57
presents its inner and outer surfaces separated by minutely denticulated ridges, and subdivided, though less distinctly, into narrow planes. ‘The length of the crown is twenty-two lines; its antero-posterior diameter at base eleven lines; its transverse diameter twelve lines; its inner circumference twenty-eight lines; and its outer circumference eleven lines. ‘The inner surface is obscurely subdi- vided into nine or ten planes, disappearing towards the apex of the crown ; the outer surface into three or four planes, equally obscure, and disappearing in the same manner. The accompanying out- lines, No. 5, represent sections at the base and near the apex of * the crown.
The fang is moderately curved, cylindroid, and measures about two inches and a half in length, of which the extra-alveolar portion comprises about half an inch. ‘The bottom presents an elliptical funnel-shaped pit narrowing into the canal of communication with the pulp cavity. The sides of the fang exhibit no trace of excavations corresponding with cavities for succes- sional teeth. .
8. A tooth, from Monmouth County, New Jersey, presented to the Academy of Natural Sciences by Dr. J. H. Slack. The specimen, represented in Fig. 2, Plate IX, resembles that last described so nearly that it looks as if it might have been derived from the same individual, though it is considerably smaller.
The crown is seventeen lines long, with the base eight lines in diameter antero- posteriorly and seven lines and a half transversely. ‘The surfaces of the crown are less unequally divided than in the preceding specimen by the usual ridges, which in this case are rather obscurely denticu- lated. The outer surface of the crown is subdivided into four planes, merging into three and disappearing towards the apex; the inner surface is subdivided into eight planes, likewise becoming obsolete towards the apex. The accompanying outlines, No. 6, represent transverse sections of the crown from near the base and apex.
The fang is twenty-three lines long, and closely resembles that of the preceding specimen, in its form, the entrance to the pulp cavity, and in the absence of an excavation produced by a successional tooth.
9. A mutilated tooth, which accompanied the latter specimen, from the same locality and donor. It is larger and has a proportionately shorter and more robust fang than the preceding. The crown is more equally divided by the usual ridges, and the surfaces are more distinctly subdivided into planes; the outer surface exhibiting five, the inner surface nine, ‘These indistinctly multiply near the base of the crown, and diminish in number and finally become obsolete towards the apex. ‘The antero-posterior diameter of the base of the crown is eleven lines; the transverse diameter nine lines. The accompany- ing outline, No. 7, represents a transverse section near the base of the crown.
The fang is compressed from without inwardly, and measures two inches in
length ; sixteen lines antero-posteriorly, and twelve lines transversely. It presents 8 April, 1865.
No. 5.
No. 6.
No. 7.
No. 8.
58 MOSASAURUS.
no trace of a cavity for a successor, and the entrance to its pulp cavity is like that in the preceding specimen.
10. A mutilated tooth, from Burlington County, New Jersey, presented to the Academy of Natural Sciences by Charles C. Abbott. It is intermediate in form and size with the specimens numbered 7 and 8. ‘The outer surface of the crown, corresponding with the antero-posterior diameter, is eight lines and a half, and it exhibits three planes. The inner surface exhibits eight planes, and the transverse diameter equals the former one. The accompanying outline, No. 8, represents a section near the base of the crown. ‘The fang is curved cylindroid, slightly com- pressed, and measures two inches and a quarter in length. Its ner side posteriorly exhibits a small lenticular excavation, three lines long, produced by a successional tooth.
11. Two teeth, which have lost their fangs, from Monmouth County, New Jersey, presented to the Academy of Natural Sciences by E. D, Cope. The specimens, represented in Fig. 5, Plate X, and Fig. 12, Plate XI, look as if they had béen derived from the same individual. They correspond in form with the more familiar one viewed as characteristic of Mosasaurus, but they are smooth or devoid of subdivisional planes, or at most exhibit only the feeblest disposition to their development at the base of the crown. The pulp cavity, within the specimens, presents the outward form of the crown. The length of the more perfect specimen, Fig. 5, from the enamel border of the base of the crown to the worn apex, is twenty-two lines; its antero-posterior diameter at base is eleven lines; its transverse diameter the same. The accompanying outlines, No. 9, repre- sent transverse sections near the base of the crown, and just below and above the middle. The length of the crown of the other specimen, Fig. 12, is two inches.
12. An entire tooth, from Monmouth County, New Jersey, presented to the Academy of Natural Sciences by Dr. J. H. Slack. It is represented in Fig. 4, Plate
IX, and is intermediate in size with those of the approximate Figs. - 2 and 3, to which it also bears a general resemblance in form. The unworm crown is twenty lines long, and is nearly circular in transverse section, as represented in the accompanying outlines, No. 10, taken from the base and below the middle. The diameter of the base of the crown antero-posteriorly is ten lines and a half; the transverse diameter nine lines and a half. The ridges separating the surfaces of the crown are minutely denticulated, and both surfaces are smooth or entirely devoid of subdivisional planes and striations. The inner surface is a little more extensive than the outer one, as represented in the accompanying sections.
The fang is straight, cylindroid, and measures two inches and a half in length and thirteen lines in diameter. It exhibits no evidence of having been coossified with its alveolus, and on the inner side posteriorly, as represented in Fig. 4, 6, it presents a small excavation for the accommodation of a successional tooth. At the free extremity it presents a funnel-shaped pit, prolonged into the central canal of communication with the pulp cavity.
No. 9.
No. 10.
MOSASAURUS. 59
13. A tooth, which has lost its fang, from Monmouth County, New Jersey, pre- sented to the Academy of Natural Sciences by Charles C. Abbott. It is represented in Fig. 11, Plate X, and measures two inches in length. Its apex is worn, and it is invested with enamel to the extreme base of the specimen. It bears a near resemblance to the crown of the preceding speci- bites men, but is much larger. ‘The base is circular in section, and measures an inch in diameter. The inner surface is slightly more extensive than the outer one, as seen in the accompanying sections,
No. 11, taken from the base and above the middle of the crown.
Both surfaces are devoid of the faintest trace of subdivision into
planes, and are separated by the usual minutely denticulated ridges.
The centre of the broken base of the crown exhibits the funnel-shaped summit of the pulp cavity, the wall of which at the broken border of the specimen is four lines thick.
14. Nine teeth, coossified with small attached portions of the jaw, from Mon- mouth County, New Jersey, presented to the Academy of Natural Sciences by Dr. J. H. Slack. They were found together in the same marl pit, and have every appearance of having belonged to the same individual.
One of the specimens, represented in Figs. 8, 9, Plate X, is about five inches and a half in length. The apex of the crown is worn off more than in any other speci- men of the kind I have ever seen. ‘The dividing ridges are also considerably worn, though enough of one remains to ascertain that they were minutely denticulated. In its present condition the crown is two No. 12. inches long, and its nearly circular base measures fourteen lines and a half antero-posteriorly and fourteen transversely. The inner side is more extensive than the outer; the former being twenty-six lines in circumference at its base, the latter twenty lines. The inner surface is distinctly subdivided intonine planes; the outer into seven. The accompanying outline, No. 12, repre- sents a transverse section near the base of the crown.
The extra-alveolar or exserted portion of the fang continues the cone of the crown, and is fourteen lines long by about two inches in diameter at the base. The intra-alveolar portion of the fang is two inches and three-quarters long, and appears to be a constituent portion of the jaw, so intimately is it coossified and continuous with its alveolus. Its inner side posteriorly is deeply excavated, as represented in Fig. 8, c, for the accommodation of a successional tooth.
A second specimen, represented in Fig. 7, Plate X, closely No. 13. resembles the former, except that the inner and outer surfaces of the crown are nearly equal in extent, and are each divided into six principal planes, of which one presents a partial but feeble subdivision. The crown, very much worn at the apex and along the anterior ridge, in its present condition is two inches in length, and thirteen lines in transverse diameter at base, while the antero-posterior diameter has been about fourteen lines. The inner circumference of the base is about twenty-three lines, the outer twenty-two lines.
60 MOSASAURUS.
‘The accompanying outline, No. 13, represents a transverse section taken from near the base of the crown. The fang is three inches and three-quarters in length, and exhibits a cavity for a successional tooth like that of the preceding specimen.
Attached to the same specimen, but not represented im the figure, there is a coossified fragment of the fang of the tooth, which was situated in advance, and which was about one-half excavated to accommodate a successional tooth.
A third specimen, much mutilated, nearly resembles the former one. The inner and outer surfaces of the crown are nearly equal in extent, and each is subdivided
into seven planes. The antero-posterior diameter at the base
No. 14. is fourteen lines and three-quarters; the transverse diameter thirteen lines. The outer of the accompanying outlines, No. 14, represents a section at the base of the crown.
The fang is half excavated away at the inner side and bot- tom for the accommodation of a successional tooth. The ex- cavation just below the level of the extra-alveolar portion of the fang communicates with the pulp cavity its entire breadth.
A fourth specimen, much mutilated, bears a near resem-
blance with the former two, but is considerably smaller. The crown, from its worn apex to the base, is sixteen lines long; its antero-posterior diameter at base is twelve lines and a half; the transverse diameter ten lines. The inner and outer surfaces are nearly equal in extent, but the latter is even slightly the greater, and is divided into seven planes, while the former is divided into six. ‘The inner of the accompanying outlines, No. 14, represents a section of the crown near the base, —appearing more elliptical than in preceding sections,
The fang is about two inches and three-quarters long, and is nearly half exca- vated for a successor. The excavation communicates with the open canal of the pulp cavity.
The fifth specimen, represented in Fig. 5, Plate IX, consists of a tooth, together with the fang of a second, coossified with an alveolar fragment of the jaw.
The crown of the tooth has its apex broken and its posterior ridge worn. When perfect it appears to have been about two inches long; and its elliptical section at base measures fifteen lines antero-posteriorly and thirteen transversely. The inner and outer surfaces are nearly equal, the former being subdivided into six, the latter into eight unequal planes. The accompanying out- lines, No. 15, represent sections near the base and middle of the crown.
The fang of the tooth is three inches and three-quarters long; and is one-half excavated antero-internally for the accommodation of a successional tooth, as represented in Fig. 5, e. The excavation communicates with the pulp cavity on a level with the bottom of the extra-alveolar por- tion of the fang, as seen at f
The fang of the other tooth is about one-third excavated postero-internally, as represented on the right of Fig. 5, e, and the excavation has exposed the pulp cavity of the tooth as seen at f.
No. 15.
MOSASAURUS. 61
The contiguous sides of the two fangs are likewise excavated together for the accommodation of a successional tooth, as seen at the middle of Fig. 5, e, and thus the two teeth exhibit cavities for the accommodation of three successors,
The sixth specimen is represented in Fig. 6, Plate LX, and consists of a tooth of nearly the same size and form as that in the specimen last described.
The crown when perfect has measured over two inches in length; and at base it measures fourteen lines in diameter antero-posteriorly, and twelve lines and a half transversely. ‘The inner surface is rather more extensive than the outer, and is divided into seven planes, while the latter presents six planes. ‘The curve of the base of the inner surface measures two inches, that of the outer surface twenty lines. The lower of the accompanying outlines, No. 16, repre- sents a section near the base. The fang upon its inner part is almost one-half excavated to accommodate a successor, as represented in Fig. 6, e. The excavation has exposed the lower half of the pulp cavity, seen at f.
The seventh specimen consists of an entire tooth, repre- sented in Fig. 10, Plate X, nearly resembling the two last described teeth.
The crown is two inches in length, elliptical in transverse section, and measures at base antero-posteriorly fourteen lines and a half; transversely twelve lines. ‘The inner and outer surfaces are nearly equal, and are rather less distinctly subdivided into planes than in the preceding specimens which accompanied this one. The upper of the accompanying outlines, No. 16, represents a section near the base of
No. 16.
the crown.
The fang anteriorly and postero-internally presents two excavations for the accom- « modation of successional teeth, as represented in Fig. 10,c,d. The postero-internal excavation communicates with the pulp cavity, as seen at e.
The eighth specimen, represented in Fig. 4, Plate X, has the general form and proportions of its companions, but is smaller, except the fourth specimen above indicated, which it most nearly resembles.
The crown is twenty-two lines long, elliptical in transverse section, and measures fourteen lines in diameter at the base antero-posteriorly, and eleven lines and a half transversely. Its most remarkable peculiarity consists in the possession of a single carina or ridge situated posteriorly along the concave border; the ridge being minutely denticulated as in those of preceding specimens. ‘The anterior border of the crown is thick and convex, and towards the apex presents several prominent vertical folds. The inner and outer surfaces, of equal extent, are feebly subdivided into traces of from four to six planes. ‘The upper pair of accompanying outlines, No. 17, represent transverse sections near the base and apex of the crown. The fang is deeply excavated postero-internally, as seen in Fig. 4, d, for the accommo- dation of a successor, but the excavation has not exposed the pulp cavity of the tooth.
The ninth, or remaining specimen of the series under exami- nation, is represented in Fig. 5, Plate XI, and. is a miniature resemblance of the
No. 17.
62 MOSASAURUS.
tooth last described. ‘The crown when perfect has measured less than three-fourths of an inch in length, is elliptical in transverse section, and measures at base five lines and three-quarters antero-posteriorly, and four lines and a half transversely. Its single posterior carinated ridge is minutely denticulated as in the large teeth, and the surfaces are devoid of planes.
The fang, independent of the alveolar fragment with which it is coossified, measures about an inch and a half long, and has at its inner side posteriorly a deep excavation for a successional tooth, as seen in Fig. 5, a.
15. A perfect tooth, coossified with a fragment of the jaw, from Monmouth County, New Jersey, loaned by William Cornell, through Prof. Cook. The speci- men was received after the present memoir and its accompanying plates were nearly completed. It closely resembles the eighth specimen of the series above described. The crown is unworn, is twenty lines long, and is elliptical in transverse section. Its base is one inch in diameter antero-posteriorly, and nine lines and a half transversely. It possesses a single ridge, situated along its posterior or concave border; and the surfaces are smooth, except that the outer one presents a feeble disposition to subdivision into four planes. The lower of the accompanying outlines, No. 17, represents a section from near the base. The fang is three inches long.
16, Two teeth, from Monmouth County, New Jersey, presented to the Academy of Natural Sciences by Dr. J. H. Slack. One of the specimens resembles the two large ones last described. The crown has the apex broken off, but is otherwise perfect. Its transverse section is elliptical, and measures at base antero-posteriorly thirteen lines; transversely ten lines and a half. It possesses a single carina, situated posteriorly, and the surfaces are totally devoid of planes. The accompa- nying right hand outline, with one point, No. 18, represents a section near the base. The fang is about three inches long, and exhibits on its inner side near the centre a slight excavation, five lines long, as the commencement of a cavity for a successor. The canal communicating with the pulp cavity through the fang is open.
The second specimen, represented in Fig. 7, Plate IX, is nearly perfect, and measures about four inches and a half long. It corresponds in all its anatomical characters with the teeth described by Prof. Owen as characteristic of a distinct genus, to which he has given the name of Letodon.
The crown is twenty-one lines long, elliptical in transverse section, as represented in the accompanying left hand outline, with two points, No. 18, and measures at base antero-posteriorly thirteen lines; transversely eleven lines. Minutely denticu- lated ridges divide it in the usual manner into inner and outer surfaces of nearly equal extent and convexity and totally destitute of subdivisional planes.
The fang is straight, and presents no trace of having been coossified with its alveolus, as is also the case with that of the preceding specimen. It further exhibits no trace of a cavity for a successional tooth.
No. 18.
17. The shed crown of a tooth, from St. Georges, New Castle County, Delaware, contained in the museum of the Academy of Natural Sciences. — It is represented in Fig. 11, Plate IX, and resembles the corresponding part of the tooth just
MOSASAURUS. 63
described. It also bears a near resemblance to a specimen described by Prof. F. Emmons,' under the name of Elliptonodon compressus.
The enamelled crown is an inch and a half long, and is elliptical in transverse section, as represented in the accompanying outlines, No. 19, representing sections below the middle and at the base. The latter measures an inch antero-posteriorly, and ten lines transversely. ‘The acute ridges Syarte divide the crown into two surfaces about equal in extent and con- vexity. The surfaces exhibit a faint disposition to subdivide towards the base, but for four-fifths of their length are smooth.
The transverse annulation, represented by the artist in the figure,
is only one of staining of the enamel, though there is a feeble
constriction of the crown corresponding with the band above its middle. The base of the specimen is excavated in a funnel-shaped manner from a thin sharp edge at the periphery to the central pulp cavity.
18. Two specimens of teeth, from Mount Holly, Burlington County, New J ersey, contained in the museum of the Academy of Natural Sciences.
One of the specimens, represented in Fig. 9, Plate LX, consists of the shed crown of a tooth, much worn at the apex. In its present condition it measures nineteen lines long, extending from the enamel border at the base, and in transverse section is elliptical, as represented in the outer of the accompanying outlines, No. 20. The antero-posterior diameter at base, in the perfect condition, measured sixteen lines, and the transverse diameter is thirteen lines and a half. The surfaces, about equally divided by the anterior and posterior acute ridges, are entirely devoid of subdivisional planes. The enamel is more rugose than in any of the preceding teeth, but otherwise I can see no important difference between it and several of those last described. ‘The base is excavated in a salver-form manner, from a broken edge about a line in thickness, to the central pulp cavity.
The second specimen, represented in Fig. 10, Plate IX, Apa consists of a comparatively small tooth, with the apex of the crown broken off so as to expose the summit of the pulp cavity.
In color and general character the specimen looks as if it may have belonged to another part of the dental series of the same individual as its larger companion.
In form the crown has nearly resembled that of the specimen described as No. 12, represented in Fig. 4, Plate IX. When perfect it has measured about thirteen lines long; and its circular base is eight lines in diameter. It is irregularly divided by the acute ridges, of which the anterior is almost entirely obliterated by wear. The inner surface is much more extensive than the outer, and both are smooth, presenting neither trace of subdivisional planes nor rugosities. The inner curve of the base is fifteen lines and a half, the outer curve eleven lines. The inner of the accompanying outlines, No. 20, is a transverse section from the base of the crown.
The straight fusiform fang is two inches and a quarter long, and appears as if it had not been coossified with its alveolus. Just back of the centre of the inner side
* North Carolina Geological Survey, 222, figs. 41, 42.
64 MOSASAURUS.
of the intra-alveolar portion it exhibits a shallow niche, about five lines long, as a commencing cavity for a successor.
19. The shed crown of a tooth, from Freehold, Monmouth County, New Jersey, sent to me for examination from the collection of Dr. C. Thompson, through Prof. Cook. It is represented in Fig. 8, Plate IX; is somewhat water- worn, and has lost its apex. It resembles the crown of the last de- scribed specimen, but is larger and has its surfaces equally divided by the anterior and posterior ridges. The diameter of the nearly circular base, represented in the accompanying outline, No. 21, is ten lines and a half antero-posteriorly, and ten transversely.
20. A tooth, coossified with its alveolus, from Monmouth County, New Jersey, loaned by O. R. Willis, through Prof. Cook. It is represented in Fig, 10, Plate XI, and is two inches and three-quarters long.
The crown resembles that of the specimens described under Nos. 16, 17, 18, and represented in Figs. 7,9, 11, Plate IX, except that it is more compressed and curved in relation with its length. It presents the form viewed as characterizing the genus Leiodon, and is about equally divided by the usual pair of ridges into two surfaces,
which are smooth. The length of the crown is fifteen lines; its No. 22. antero-posterior diameter at base ten lines and a half; its transverse diaméter seven lines. The transverse section is elliptical, with acute poles, as represented in the accompanying outline, No, 22. The fang is of unusual breadth, in comparison with its length, and is compressed from without inwardly. Postero-internally it is deeply excavated, as seen in Fig. 10, c, for the accommodation of a successional tooth.
21. The fragment of a jaw containing two teeth, from Monmouth County, New Jersey, presented by Dr. J. H. Slack to the Academy of Natural Sciences. It is represented in Figs. 6, 7, Plate XI, and bears a near resemblance to the corre- sponding portions of a specimen figured by Dr. Morton ' and loaned to him by Dr. De Kay as characteristic of Geosaurus Mitchelli.
‘The jaw fragment is three inches and a half long, and is broken away along the line of the dental canal, at the bottom of the alveoli. Its outer surface is verti- cally moderately convex, and presents at the broken border a row of three vasculo- neural foramina communicating with the remains of the dental canal. The two extremities of the specimen exhibit portions of alveoli, from which teeth appear to have been lost together with their fangs. Postero-internally to the portion of the anterior alveolus (/) there is an excavation (e) for a successional tooth.
The intermediate portion of the fragment contains the fang (¢) of a shed tooth, coossified with the jaw and containing a successor (d), and an entire tooth (a) occu- pying a functional position behind the former.
The fang (c) of the shed tooth is so intimately coossified with the jaw as almost to appear as a constituent portion of the latter. The extra-alveolar portion of the fang presents a funnel-shaped excavation or crater, communicating at bottom by
No. 21.
1 Synopsis of the Organic Remains of the Cretaceous Group, etc., p. 28, Plate XI, Fig. 10.
MOSASAURUS. 65
an orifice with the excavation for the successional tooth. The latter excavation nearly involves the whole of the intra-alveolar portion of the fang. The contained tooth (Fig. 6, 7, Fig. 7) is a fully developed crown, with a large interior pulp cavity, extending to the thin edge of the developing fang as usual in dentition. It resembles that of the last described specimen, but is shorter and more robust in its proportions. Further, the acute ridges divide the crown unequally, the outer surface being more extensive and convex than the inner. ‘The surfaces also are strongly wrinkled longitudinally, especially towards the base, and there exists an evident disposition to subdivide into planes, especially on the outer surface, as represented in Fig. 7. The crown is thirteen lines and a half long, elliptical in transverse section, as represented in the accom- panying outline, No. 23. The antero-posterior diameter of the slightly contracted base is nine lines; the transverse diameter eight lines. The inner curvature of the base is nine lines and a half, the outer curvature fifteen lines and a half.
The tooth (Fig. 6, a) occupying a functional position behind the preceding has the crown considerably worn at the apex, and the enamel is also partly worn away at the base antero-externally, and on several positions of the dividing ridges. It resembles the unworn crown occupying the cavity in advance, but the appearance of a tendency in the surfaces to subdivide into planes is less obvious, and, indeed, is hardly evident on the external surface, where it is most so in the other tooth.
The fang is intimately coossified with its alveolus, and a deep excavation (>) exists at its posterior part internally for a successional tooth. The exserted portion . of the fang is eight lines long, and at the alveolar margin occupies a breadth antero- posteriorly of sixteen lines, transversely thirteen lines.
22, Fragments of both sides of the lower jaw, and of both pterygoid bones, with teeth, from the same individual. The specimens were obtained from the Green- sand of Holmdel, Monmouth County, New Jersey, and have been submitted to my examination by Prof. Reiley, of Rutger’s College, through Prof. Cook. The teeth preserved in the fragments resemble those above described which have the laterally compressed, smooth crown, and correspond with those which have been viewed as characteristic of the genus Leiodon.
A fragment of the back part of the right dental bone, represented in Fig. 3, Plate XI, contains a perfect tooth, apparently the penultimate, a portion of the alveolus behind, and portions of the two alveolj in advance.
The outer surface of the bone is a vertical plane, rounded at the alveolar border and broken at the lower. The back end is broken off, and the oblique border below is that for articulating with the coronoid hone behind. A large vasculo-neural foramen, opening into the dental canal along the middle of the specimen, is situated below the tooth retained in the specimen. Part of a similar and smaller foramen is also situated rather higher at the anterior broken border.
The tooth preserved in the fragment has its fang coossified with the alveolus and the border of the jaw. It bears a near resemblance with the specimen described under No. 20, The crown, situated
somewhat obliquely with its outer face directed forward, is an inch 9 April, 1866.
No. 23.
No. 24.
66 MOSASAURUS.
long, and is divided by minutely denticulated ridges into two smooth surfaces, of which the outer is slightly the larger. The transverse section, as represented in the accompanying outline, No. 24, is elliptical, and the antero-posterior diameter at the slightly constricted base is nine lines and three-quarters; transversely six lines and a half. ,
The extra-alveolar portion of the fang is half an inch high; sixteen lines in diameter antero-posteriorly at the alveolar border, and eleven lines transversely. The intra-alveolar portion of the fang is an inch long, and encroaches for half its length within the dental canal.’ Postero-internally, together with the contiguous portion of the jaw, it is excavated into a cavity which contains the crown of a successional tooth.
The alveolus in advance retains the outer half of a coossified fang, which was about a third excavated for a successor. The portions of the alveoli at the anterior and posterior border have the appearance as if their former occupants had been lost entire, crown and fang together.
A fragment of the left dental bone, of which Fig. 4, Plate XI, represents an inner view of part of the specimen, nearly corresponds with the former one cf the opposite side. The entire tooth it contains corresponds in position with that in advance of the one preserved in the former. The tooth larger than in the preceding specimen is like it in form. The crown, with its apex considerably worn, thus reduced, is thirteen lines long; is nine lines and three-quarters in diameter at base antero-posteriorly, and seven lines and a half transversely. The fang is two inches long, and the dental canal pursues its course just external to its bottom.
The specimen is especially interesting from the circumstance that the successional tooth (c), inclosed in the cavity of the fang (4) in advance, having been accidentally partially broken away, exhibits in the interior a minute successor (d). It thus appears that in the succession of development of the teeth of Mosasaurus a new tooth originates within its predecessor, while this is still contained in the excavated fang of the tooth occupying a functional position at the border of the jaw. As the latter is displaced by its successor it would appear that as the crown of this pro- trudes from the jaw the new tooth is excluded from its place, and is made to assume a position on the exterior of the fang of its parent. The new tooth, as if desirous of once more obtaining admission into the position from which it had been excluded, in its growth induces absorption of the fang of its predecessor so as to accommodate its increasing size.
Two fragments of the right pterygoid bone, represented in Figs. 1, 2, Plate XI. The larger fragment contains a tooth and the fangs and alveoli of four others; the smaller fragment contains two teeth, part of another, and part of a large succes- sional cavity which appears to correspond with a similar part at the end of the larger fragment. It would thus appear that there were eight teeth to the full series, corresponding in this respect with the number of pterygoid teeth in the Maestricht Monitor. The anterio