124 AMERICAN PERMIAN VERTEBRATES 



the specimens as preserved showed a downward curvature of the 

 tail in this region. The last intercentrum is between the second 

 and third caudal centra, and is of extraordinary size, in marked 

 contrast with the small ones found between the sacral vertebrae. 

 Chevrons begin in the next interval, that is, at the hind end of the 

 third vertebra, the usual place for the chevrons to begin in the 

 Permian reptiles, and several were found in No. 657 quite in posi- 

 tion. They are rather short; those found in position were broadly 

 and firmly connected, articulated in the intercentral space, and 

 broadly connected proximally. They articulate in a very oblique 

 position, the upper posterior surface being grooved for more than 

 half their length for the lodgment of vessels; some are slightly 

 expanded at the distal end. Other chevrons from succeeding 

 vertebrae are very short and broad. From the eighteenth vertebra 

 to the extremity the chevrons must have been very small, which, 

 with the entire absence of spines, rendered the tail for the greater 

 part of its extent nearly cylindrical. The tail shows conclusively 

 that the animal was in no degree whatever natatorial in habit. 



Pectoral girdle and extremity (Plates XIX, XX). The material 

 of the pectoral girdle is, unfortunately, not complete. No clavicles 

 have yet been found with either of the specimens; that is, no 

 clavicles which indubitably belong with this form. A solitary 

 interclavicle, figured in Plate XIV, Fig. 6, probably belongs with 

 this form, since it cannot belong with either Varanosaurus, Cacops, 

 Seymouria, or Captorhinus, the only other genera found in the bone 

 deposit. It was found isolated. Two scapulae were recovered 

 associated with specimen No. 655; of the left one, the upper end 

 is missing, and of both, the anterior border is more or less muti- 

 lated. The interclavicle figured differs materially from that 

 of Varanosaurus in the shortness of the posterior stem, shortness 

 that would seem to agree better with the large flat trunk of this 

 genus. The specimen is shaped much like a small spoon, and is not 

 quite complete on its anterior, dilated part. The dilated part 

 is concave on the upper side, convex below, and is somewhat 

 rugose on each side for the articulation of the clavicles. The 

 posterior part is slender and nearly straight, a little wider and 

 thinner posteriorly. The scapula-coracoid is remarkable for the 



