articular face is a transverse oval. The size of the animal is similar to that of the Plesiosauri of medium dimensions, perhaps ten feet in length, admitting elongate neck and tail, of which there is no evidence.
Position.-Bed Q. Hayden's Section of Great Lignite basin of Nebraska. (Trans. Am. Philos. Soc., 1860, 135.) perhaps of the Cretaceous age; from the Moreau River.
I refer the following species to this genus provisionally, and with doubt.
PLESIOSAURUS LOCKWOODII, Cope.
This reptile is represented by but few remains, which are in the private collection of Dr. Samuel Lockwood, of Monmouth County, N. J. A single dorsal vertebra, which he kindly lent me for description, presents characters which are so marked when compared with other marine Sauria as to require notice.
The centrum is of the general form of Plesiosaurus and Cimoliasaurus, and the arch has a sutural attachment as in the former. The suture is the surface of a sub-round pit, almost like that of Ichthyosaurus, and not like that typical of Plesiosaurus, or the young of Cimaliosaurus magnus. In the latter the suture is an oval concavity which extends throughout the length of the centrum. The pit in this species measures little more than one-third the length of the centrum. The floor of the neural canal is quite flat. The sides of the centrum are strongly and regularly concave, rather less strongly below than laterally. The margins flare regularly, and are not striate grooved or ribbed as in many species. There is a strong venous foramen a short distance below the neural arch and two medially below.
The species is further characterized by the regularly concave articular faces, without median plane or prominent portion, as in Cimoliosaurus species. They are more concave than those of the Elasmosauri also. The form of the surface is entirely circular.
| In. | Lin. | |
| Width articular surface, | 2 | 8 |
| Depth"" | 2 | 7.8 |
| Width pit neural arch, | 8.4 | |
| Length centrum, | 1 | 11.6 |
This species I have dedicated to its discoverer, Dr. Lockwood, who has contributed in various ways to the progress of Natural Science.
It is the earliest sea saurian from this country, as it was derived from the clays which underlie the lower green sand bed. It was dug from a brick clay pit near Matteawan, Monmouth County, N. J.
Cimoliasaurus and Discosaurus, Leidy. Proceed. Academy Nat. Sei., Phila., 1851, 325-1854, 72, tab. ii, figs. 4, 5, 6, and 1851, 326; Cretaceous Reptiles, 22 and 25, tabs. IV., V., VI. Brimosaurus Leidy, Pr. A. N. Sci., Phila., 1855, 472.
This genus has been chiefly illustrated by Leidy, who has described remains of its species from the cretaceous deposits of many of the States east of the Mississippi. It has remained for the discovery of Elasmosaurus to prove that the two supposed genera named by Leidy, are really one, his supposed caudals of Discosaurus[1] being really caudals of Cim-
- ↑ This genus was originally proposed on two vertebræ from Georgia, and a vertebra from New Jersey described by Dekay. He afterwards added vertebra from Alabama, Mississippi and New Jersey. Some of these were regarded as cervicals; they are, however, anterior caudals. As Leidy observes, there are several species among them, and it may be several genera, but as the genera cannot be distinguished by the caudal vertebrae, it appears to me that Discosaurus cannot be preserved. While distinguishing the genus from Cimoliasaurus, Leidy adds, "The supposed caudals of Discosaurus I have suspected to be anterior cervicals, notwithstanding the apparent provision for the articulation of ehevron bones. If all the vertebræ be viewed as belonging to one animal, they represent cervicals, dorsals and lumbars of Discosaurus; otherwise they represent a cervical and caudals of the latter, and dorsals and lumbars of Cimoliasaurus." In case of their identity, it may be observed, Leidy refers them all to Discosaurus. Cimoliasaurus was, however, proposed first.
