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. 
