256 S. W. WILLISTON NEW GENERA OF PERMIAN VERTEBRATES 



the skull has been somewhat pressed down upon the palatal bones, but 

 there was evidently in life a high cavity for the nasal region, in which 

 are various indeterminate bone remains, doubtless the ethmoidal and 

 turbinate. A little in front of the basisphenoid the pterygoids give off 

 a rounded or subangular process much as in the allied forms, narrowing 

 the opening of the infratemporal fossa, which is broad and deep behind, 

 where its thin upper posterior roof forms the anterior inferior wall ©f 

 the otic cavity. 



The basisphenoid is concave in the middle; on either side it has a 

 flattened basisphenoid process, as in Trematops, directed downward and 

 backward, underarching a rather deep fossa. Opposite these on either 

 side is the root or base of the pointed, stylelike stapes, which is directed 

 outward and backward to terminate, as already described, at the upper 

 angle of the quadrate, in the auditory vacuities. Whether or not it has 

 a foramen at its base I can not say. Above and in front of this, turned 

 upward to reach nearly to the inner surface of the superior tympanic 

 ridge, is the prootic bone. 



A comparison of the structure of the basicranial region with that of 

 Trematops shows great similarity, quite confirming my suggestion that 

 the pseudotemporal vacuity is in reality merely the closed otic notch for 

 the opening of the external ear. The opening in Trematops, however, is 

 far smaller than in Cacops, and extends somewhat further forward to- 

 ward the orbit. The small size of the parasphenoid in the present genus 

 also explains its apparently entire absence in Trematops, though it is not 

 improbable that the rhinencephalic canal in Trematops, were it preserved 

 complete in the type specimen, would show the remains of the para- 

 sphenoid coalesced with it as in Cacops. 



The maxillary teeth in Cacops are all small and of nearly uniform size, 

 in an uniform closed series. I count about 20, but it is possible there 

 may have been a few more. 



The mandible is remarkable for its slenderness. Posteriorly it has a 

 broad expansion, but the ramus from the middle of the orbits forward 

 is slender. A deep fossa is present in front of the condyle, and the 

 median symphysis in front is a little expanded. It has apparently the 

 same number of teeth as in the maxillae, and all, like them, are of uni- 

 form size. 



VERTEBRA . 



(Plate 9) 



The vertebral column of the mounted skeleton was apparently quite 

 complete as it lay in the niatrix in associ9,tion with skull and limbs. In 



