PERMIAN VERTEBRATES 709 



portions of the skeleton of the species are described by Cope in the Proc. Am. 

 Phil. Soc, 1878, p. 523 and figured in the same, 1882, Plate II. The synonymy 

 of C. heteroclitus and C. discophorus was also recognized by Cope in Proc. 

 Am. Phil. Soc, 1878, p. 523. 



[No. 6517 (the t)-pe specimen), 6518 (type of C. discophorus), 6519, and 

 6520]. 



Cricotus gibsoni Cope, Plate I, Figs. 15^, 15^, 15^. 



Cvicotus gibso?ii Cope, 1877, Proc. Am. Phil. Soc., p. 185. 

 (Pal. Bull., No. 26.) 



Represented in the collection by several vertebras, all of one form. Cope 

 considered the type specimen as probably from the caudal region. He says, 

 "On this vertebra there. is no trace of diapophysis, and the neurapophysis 

 rises from the external side of the superior face. The wall of the neural 

 canal is not preserved, but the inference is that the diameter of the latter is 

 large. This fact and the absence of definite chevron articulations leads me 

 to doubt the caudal position of the vertebra ; but the usual marks of the dorsal 

 and cervical vertebrae are totally wanting from it. As in C. heteroclitus, the 

 fora.7iie?i chordae dorsalis is large, its diameter being one third of the total. 

 The articular faces descend steeply into it, that of one extremity more so than 

 the other. The rim of the latter face is beveled outwards, the plane thus pro- 

 duced appearing on the inferior face something like the united faces of the 

 chevron bones. 



" The centrum is a little deeper than wide, and the inferior face is trun- 

 cate so as to give a subquadrate outline. The inferior plane is concave, the 

 concavity being divided by a longitudinal rib. The sides are somewhat con- 

 cave, with a longitudinal rib at the middle. Diameters of centrum : ver- 

 tical .oio m ; transverse .009 111 ; longitudinal .oo8 m . Width of inferior plane 

 .oo5 m ; width above, including neurapophyses .oo8 m . 



"As compared with C. heteroclitus this species differs in the presence of 

 parallel ridges inclosing a median fossa on the inferior side of the centrum. 

 The small size maybe considered, but it is uncertain whether the two animals 

 represented by the vertebrae are fully grown." 



[Nos. 6521 and 6522.] 



Cricotus sp. Plate V, Figs. 13.2, 13b, 14a, 14b, 15, 16. 



There are several phalanges of Cricotus. They are much stouter than 

 those of C lepsy drops ; even in the members of the distal series, where the 

 phalanges are very short, they are still very stout, almost as broad as long. 

 They show a delicate sculpture over the entire surface ; the articular surfaces 

 are less well defined than in the reptilian forms. In the middle series they 



