1891.] Ill [Cope. 



time. It is doubtful whether the family of the Mesosauridse on -which 

 the Proganosaurian order was founded by Baur, really belongs to this 

 series, while the genus Procolophon Owen probably does. This genus has 

 been regarded as the type of a group, the Procolophonina, by Seeley, and 

 the genus Prolerosaurus has been made the tj^pe of another group by the 

 same author, under the name of Proterosauria. I have shown that the 

 postorbital bar of the Pelycosauria (? Theriodonta) is different from that 

 of the Anomodonlia, and that the Cotylosauria (Pariasauria) is entirely 

 distinct as an order. Tlie Theromora as an order will then include the 

 suborders, Placodonta, Proterosauria and Anomodonta, The problemati- 

 cal genera above named will all fall within the limitsof the Proterosauria, 

 as I have defined it under the name of Proganosauria. 



E.MBAPHIAS ciRCULOSUS, gen. et sp. nov. 



Char. gen. Cervical vertebrae short, with the parapophysis and dia- 

 popliysis distinct at the base and articulating freely with the centrum. 

 Articular faces of the centra concave in the cervical and dorsal regions. 

 Suture of neural arch with centrum, persistent. 



The limbs of this genus are not certainly known. The three vertebrae 

 on which it is established were found associated with a considerable num- 

 ber of the vertebrae of Elasmosaurus, and a number of bones of the arches 

 and extremities. The proper location of the latter has not yet been made. 



This is a short-necked genus, and need not be compared especially with 

 Plesiosaurus, Elasmosaurus and Polycotylus. It differs from Uronautes, 

 Orophosaurus and Trinacromerum in the distinctness of the basal parts of 

 the dia- and parapophyscs, and from the first two in the strong concavity 

 of tlie vertebral centra. It approaches nearest in its vertebral characters 

 to Pliosaurus, but here the dorsal vertebne are amphiplatyan as in 

 Plesiosaurus. I note here that the vertebral characters of Trinacromerum 

 Cragin, as described by him,* agree with those of Orophosaurus.f 



Char, specif. Cervical centrum a regular transverse wide oval, withoiit 

 lateral longitudinal angulation. Dia- and parapophysial facets compressed 

 so as to be vertical, and occupying a line from near the level of the inferior 

 face to the base of the neural arch, and fused together at their bases. The 

 bases of the dia- and parapophyscs (which are lost) were thus vertically 

 compressed, presenting a character ditierent from that of any Plesiosauroid 

 known to me. On other cervicals than the single one preserved, this char- 

 acter may not be so pronounced, but it is not likely to have been entirely 

 wanting on any of them. The outlines of the dorsal vertebral centra are 

 circular, and the slightly concave sides are without angulation. The 

 fossa for the neurapophysis is an anteroposterior oval, which does not 

 extend over the entire length of the centrum. Arches lost, except the 

 bases, which adhere within the fossae. An epipliysis-like band of ver- 

 tically lined surface, narrows the median longitudinally lined surface of 



* American Geologist, 1888, p. 404 ; 1891, p. 171. 

 ^American Naturalist, 1887, p. 56 1, j 



