3 
tilian in their single occipital condyle, ossification of the basicranial carti- 
lage, and single vomer. 
Thus the reptiles and batrachia of the Permian period resembled each 
other and the Mammalia, more closely than do i corresponding existing 
forms. 
PELYCOSAURIA. 
THEROPLEURA Cope. 
Paleontological Bulletin No. 29, May, 1878, p. 619, Proceed. Amer. 
Philos. Soc., 1878, p. 519. 
A more complete specimen of the Theropleura uniformis than any 
hitherto obtained gives the following generic characters. 
The teeth are generally similar to those of Olepsydrops and Dimetrodon, 
having compressed crowns with fore and aft cutting edges. The incisors 
are distinguished by the presence of a diastema. Posteriorly to this the 
teeth increase in size, and then diminish; one tooth near the middle of the 
series is the largest, but does not in this species very much exceed the 
others. There is at least one large incisor tooth. The bones of the head 
are smooth, and not sculptured ; a character distinguishing the genus from 
Eetocynodon. The symphysis of the mandible is short. 
The neural arches of the vertebre are all distinct from the centra. In- 
tercentra are not present in any of the thirteen vertebre preserved, but 
there was probably one below the centrum of the atlas. The ribs are two- 
headed, the capitular process extending downward to the anterior border 
of the centrum. The neural spines of some of the vertebre are greatly 
elevated as in the species of Clepsydrops and Dimetrodon. The scapula is 
long; the ilium is similar to that of the genera named. A character 
which has not been detected in either of the genera named is the presence 
of dermal rods, which from their position adherent to the vertebra, I sus- 
pect to be abdominal, and similar to those of the genus Oéstocephalus. 
This is a batrachian character. The neural spine of the axis is extended 
fore and aft. The odontoid is distinct and is of large size. It has lateral 
and inferior articular surfaces. 
THEROPLEURA UNIFORMIS Cope. 
Paleontological Bulletin No. 29, p. 519, 1878. 
This species is about the size of one of the larger Varanide, and about 
equal to the Clepsydrops natalis. It is characterized by a long and acuminate 
head, with a large lateral nostril on each side, well forwards, and approach- 
ing near the border of the diastema. In the specimen thé top of the head 
is crushed and the postorbital portion is wanting. Anterior to the large 
lateral tooth there are nine teeth ; posterior to it there are eighteen. The 
anterior cutting edge of the crown does not extend so near the base as the 
posterior, and is best marked on the auterior teelte In the crowns pre- 
served the edges are not serrate. 
