THORACOSAURUS. U 



vertebrae of the Gavialis, or, as we may call it, Thoracosaurus macrorhyncJms, 

 appear also to have possessed the same discrimmating character, as represented 

 by Fig. 22, Plate 59, of the Atlas to Gervais' Paleontologie. 



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 micharacteristic 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 II, 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- 

 saurus 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 obtamed 

 from the Green-sand of Monmouth County, N. J., and are black, dense, and in a 

 good state of preservation. They consist of ten vertebrae, and a fragment of a 

 dermal plate resembhng those above described, aU apparently from the same indi- 

 vidual, which had reached maturity. 



Of the vertebrae, 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 Avith the specimen of a fourth or fifth cervical vertebra above described, and 

 with that described by Prof. Owen as characteristic of the Crocodilus hasifissus, 

 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 vertebree, 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 AUigator. 



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 : — 



' Proc. Acad. Nat. Sci. Phila. VI, 1852, 35. 



