146 



AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



Figure 50, a and b, gives a restoration of a small skull No. 45SO(2, with 

 such sutures as are certain. The whole skull is slender and elongate, with 

 small, subequal, conical teeth showing along the edge of the maxillaries. 

 The extremity of the snout is broken away just posterior to the nostrils, 

 but the larger skull shows that the nostrils were nearly terminal. The orbits 

 and nares looked largely upward. The sculpture, so far as can be seen, 

 consists of small pits and rugosities. The supraoccipital plates are small 

 and short, as are the tabulare. There are no prominent posterior angles 

 on the tabulare. It is not possible to detect a suture between the postorbital 

 and postfrontal, and the ends of these bones extend nearly to the anterior 

 edge of the orbit. The lower jaw is very deep posterior to the middle; the 

 angle does not project beyond the quadrate region. On the inner side 

 there is a narrow, elongate opening into the Meckelian cavity. 



F 



Fig. 51. 



A. C. hypantricus. No. 4552 Am. Mus. X f. Anterior view of a dorsal vertebra. 



B. Same. Lateral view of a dorsal intercentrum and pleurocentrum with neural arch detached. 



C. Same. A caudal intercentrum with attached chevron. 



D. Same. Anterior view of a dorsal pleurocentrum, showing hypantropophyses on sides of 



neural canal. 



E. Same. Sacral pleurocentrum and intercentrum, showing facets for rib head. 



F. C. heteroditus. No. 4550a Am. Mus. X §. Neural arches and transverse processes of three 



dorsal vertebrae with rib heads. 



G. Same. Several caudal vertebrse showing elongate neural spines, and relation of neural arches 



and chevrons to pleurocentra and intercentra. 



The vertebral column of the most complete specimen shows thirty- 

 seven presacral vertebrae, but this is not the complete number, as there are 

 at least two missing from the anterior end. Even the most anterior vertebrae 

 are embolomerous. The presacrals are all of similar form; the intercentra 

 and centra are as described by Cope (see the original description). The 

 neural arches are free from the centra; the spines are low, with considerable 

 fore-and-aft extent; the zygapophyses are horizontal; there are well-devel- 

 oped transverse processes, to which are attached fairly long, slightly curved, 



