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 Rhynchocephalia 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.
POLYCOTYLUS, Cope.
This genus is established on a series of vertebræ with portions of pelvic arch and posterior extremity, discovered in the upper Cretaceous of Kansas by W. E. Webb, Superintendent 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 palæontology, 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 vertebræ, 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 vertebrae. 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 ceutum. 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 vertebræ they become closely approximated. The neural spines are narrow anteroposteriorly, but much stouter transversely than in Elasmosaurus; they are strongly grooved at the base, both anteriorly and posteriorly, most so posteriorly.
