54 REVISION OF THE PELYCOSAURIA. 



Revised description: 



(i) Spines rectangular, oblong below, changing to rounded above, not striate, 

 smooth. 



(2) Third to sixth cervical with axis through neural arch and middle of cen- 



trum vertical. 



(3) Intercentrum in mid-dorsal region larger and with ends enlarged forming 



a capitular facet. 



(4) Mid line of lower surface of lunibars with sharp, low keel. 



(5) Size smaller. 1.2 to 1.6 meters. 



Dlmetrodon platycentrus sp. nov. 



Tj'pe: A portion of the vertebral column, including part of axis and third cer- 

 vical, four posterior dorsals and two lunibars with fragments of long spines, and 

 fragments of amphibian bones. No. 4065 Am. Mus. Nat. Hist, Cope, coll. ; from 

 Deep river, Indian Territory. 



Description: 



(i) Spines similar to those of D. macrospondylus. 



(2) Cervicals with axis through neural arch and middle centrum vertical. 



(3) Intercentrum as in C. macrospondylus. 



(4) Mid line of bottom of lumbar centra not keeled, but broad, flattened, and 



rather rugose. 



(5) Size almost that of C. macrospondylus. 



This specimen is very close to C. macrospondylus in size and general 

 form, but the character of the bottom of the posterior dorsals and lunibars 

 is unmistakably different. 



Dimctrodon obtusldens Cope. 



Theropleura ohtusidens Cope. 



Proc. Am. Phil. Soc, vol. xix, 1S80, p. 41. 



Type : A mixed lot of bones containing many fragments. Several animals are 

 distinguishable from Pelycosaurian, Cotylosaurian, and Amphibian remains. The 

 parts described by Cope as typical are a mass of bones showing fragments of the two 

 lower jaws on one side and the badly crushed posterior portion of the skull on the 

 other, several vertebrae, two humeri, a femur, an imperfect scapula, and fragments of 

 spines. A third humerus in the lot is that of a Cotylosaurian, and there are numerous 

 indeterminate fragments of Amphibian bones. No. 4007 Am. Mus. Nat. Hist., Cope, 

 coll. ; from Texas. 



Homeotype : There is no absolute certainty that the vertebrae and limb bones of 

 No. 4007 American Museum go together and with the fragments of the jaw, but Cope 

 considered and described them as so belonging and it seems probable that he was 

 correct. A second specimen. No. 4062 American Museum, labeled T/ieropleiira by 

 Cope, and containing the basicranium and nearly complete vertebral column, has 

 vertebrae identical with No. 4007 American Museum. It is evident that Cope con- 

 sidered the two as the same, so the more perfect specimen is selected to complete 

 the description. No. 4062 Am. Mus. Nat. Hist., Cope, coll. ; from the mouth of Beaver 

 creek, a tributary of the Big Wichita river, Texas. 



07'iginal description of the type : "This species is represented by nearly all parts 

 of the skeleton, including jaws of both sides with teeth, numerous vertebrae, and 



