26 E. C. CASE 



supporting the capitulum stands out as a rather prominent ridge 

 separated from the obtuse keel of the lower line of the centrum 

 by a deep pit ; the whole effect is to give the vertebrae a triangu- 

 lar appearance in section. There are broad intercentra attached 

 to the caudals, but not in position ; there is no trace of chevron 

 bones. The lower edges of the anterior faces of the caudals are 

 reflected, making a face for the intercentrum, but those which 

 are found on the vertebras are too large to have been located 

 between the vertebrae. The whole series of caudals decreases 

 rapidly in size, indicating a short tail. 



Length on bottom line of second caudal .... 0.0205"" 



Length on bottom line of third caudal ... - 0.018 



Length on bottom line of fourth caudal ----- 0.015 



The accompanying restoration is largely from the specimen 

 described above, but some parts have been taken from other 

 specimens, and the ribs have been supplied in tcto by compari- 

 son with the living SpeiiodoJi. The spines of the vertebrae are 

 largely absent and have been supplied from a specimen of Dime- 

 trodon in which the length of the limb bones was almost exactly 

 the same as in the present specimen. The posterior foot has 

 been drawn with Cope's figure of the posterior foot of Clepsydrops 

 as a model. The notable weakness of the base of the spines of 

 the sacral vertebrae has suggested that they were in all proba- 

 bility shorter than the others. Four vertebrae have been supplied 

 in the anterior dorsal region, as there is an evident hiatus in the 

 series at that point. The total number of presacral vertebrae is 

 represented as thirty-one, and this cannot be very far from the 

 correct number ; this determination is made from the vertebra 

 of the present specimen and from the figure of the vertebral 

 column of Dimetrodo?i published by Cope.^ As explained above, 

 this figure probably does not represent the complete column. 



The body is drawn somewhat elevated from the ground. At 

 first it seemed probable that the belly was dragged on the 

 ground, but an attempt to place the bones of the fore limb in 

 such a position showed that the relation of the femur to the 

 cotyloid cavity and the head of the radius to the articular 



' Proc. Am. Phil. Soc, August, 1880, Figs. 3 and 3a, PI. VI. 



