34 THE EXTINCT BATRACHIA, REPTILIA 



phalia (Sphenodon Hyperodapedon.) I have not observed it in any of the Crocodilia, 

 but the palatal roof of several genera of this order is unknown. No such structure is 

 known among the Streptostylicate Reptilia. 



This order appears first in time, in its Sauropterygian and Thecodontian representatives 

 in the Trias, and in the genus Protorosaurus Meyer, even in the Kupferschiefer, a member 

 of the Permian. At the same time it is the only one of the characteristically extinct 

 types, which remains to the present day. This it does in the lihynchocephalia and 

 especially the Crocodilia, the most persistent reptilian type. It must also be observed 

 that the Trias of Scotland has yielded a type (Leptopleurum), which Huxley refers to 

 the Lacertilia. 



SAUROPTERYGIA. 

 POLYCOTYLTTS, Cope. 



This genus is established on a series of vertebra? with portions of pelvic arch and pos- 

 terior extremity, discovered in the upper Cretaceous of Kansas by W. E. "Webb, Superin- 

 tendent of the land office in Topeka, Kansas. The point at which the remains were 

 found is about five miles west of Fort Wallace on the plains near the Smoky Hill river, 

 Kansas, in a yellow Cretaceous limestone. 



The animal thus indicated is of interest in American vertebrate palaeontology, as the 

 first true Plesiosauroid discovered within our limits. That its affinities are nearer to 

 Plesiosaurus than to Elasmosaurus will be apparent from the following description. 



There are wholes or portions of twenty-one vertebra;, of which but two retain their 

 neural arches, and six are represented by neural arches only. Four centra may be referred 

 to the caudal series, the remainder to the dorsal ; there is nothing to indicate the characters 

 of the cervical vertebra?. All of these vertebrae, except the distal caudals, are remarkable 

 for their short anteroposterior diameter and deeply concave articular faces. This concavity 

 is not however of an open conic form, as in Ichthyosaurus, but is flattened at the fundus 

 thus exhibiting a small slightly disciform area. The usual pair of venous foramina appears 

 on the under side of the centum. The neural arch is continuous with the latter, and 

 exhibits no trace of connecting suture. The diapophyses arise from the neural arch in all 

 the dorsals ; they are compressed and vertical in section. The arch is of course narrow 

 anteroposteriorly, and presents a pair of moderately prominent zygapophyses in each 

 direction, the posterior as usual articulating downwards, the anterior upwards. On some 

 of the vertebrse they become closely approximated. The neural spines are narrow antero- 

 posteriorly, but much stouter transversely than in Elasmosaurus ; they are strongly grooved 

 at the base, both anteriorly and posteriorly, most so posteriorly. 



