128 PROCEEDINGS OF THE ACADEMY OF 



were not in good condition, but resembled those of G. cineriarum, 

 Cope, though smaller. 



The Plesiosanroid was new to science, being the third species 

 discovered in the Cretaceous of the Niobrara group. Specifically 

 it was nearest to the Elasmosaurus platyarus. Cope, but was 

 readily distinguished by the relativel}' shorter cervical vertebrae, 

 and the regular acute ridges on the exterior surfaces near the 

 margin of the articular faces, as well as the less contracted form 

 of all the vertebral centra. As the neural arches and the cervical 

 parapoplvyses were not coossified with the centra, the species 

 was referred to the genus PJesiosaurus, with the name P. gulo, 

 Cope, and the following description: 



Specimen represented by eleven cervical, thirteen dorsal, and 

 seven or eight other vertebrae, with portions of scapular and 

 pelvic arch and ribs. 



The cervicals are longer than wide, and considerably com- 

 pressed inform anteriorly, but depressed posteriorly; this is 

 partly due to pressure, but not wholly, and it is likety that the 

 posterior centra are about as transverse as in Gimoliasaurus 

 magnus, Leidy, while the anterior are relatively several times as 

 long. In the length the latter resemble the English Plesiosauri. 

 in which the centra are also compressed. The compressed ante- 

 rior centra exhibit a ridge on the side above the middle. A more 

 massive ridge extends between the articular extremities at the 

 lower part of the side, and presents a pit for the parapophysis. 

 The pit for the neural spine is of nearly similar size. Where the 

 cervicals begin to be depressed, two foramina appear near together 

 on the inferior face, and the articular extremities display an open 

 obtuse emargination below. They are also emarginate for the 

 neural canal above, so as to have a form approaching a transverse 

 figure 8. In the large posterior cervicals the sides are contracted 

 both below and at the sides. In all the cervicals the articular 

 faces are a little concave, in the larger with some median con- 

 vexities. 



In none of the dorsals preserved are the diaphopyses seen to 

 issue from the centra, hence they are probably not posterior in 

 position. The centra soon become smaller than those of the 

 posterior cervicals, and are subround in section, with a well- 

 marked emargination for the neural canal. The sides are gently 

 concave, and are without angulation, but are marked near the 

 articular extremity with short, sharp, and regular undivided ridges, 

 eight in a half inch. The articular faces are slightly concave and 

 without ridges. There are the two inferior foramina, and one on 

 the lower part of each side. The articular face for the neural arch 

 is an oval pit extending the length of the centrum and inter- 

 rupted by some transverse ridges near the middle. The vertebrae 

 diminish in size posteriorly. Two centra, probably sacral, resem- 

 ble the dorsals, but present an extensive vertical articular surface 



