REPTILIA: NOTHODON 21 



outer. The sigmoid fossa of the ulna is large and concave; evi- 

 dently the humerus has a considerable trochlear surface; the olec- 

 ranon is not much produced, and was largely cartilaginous; near 

 the extremity on the outer side there is a stout rugosity for mus- 

 cular attachment. The radial border is deeply concave and stout; 

 the inner border is thin and nearly straight. The distal extremity 

 is considerably expanded, thick and angular on the radial side, 

 thinner and rounded at the inner angle; doubtless a pisiform articu- 

 lated here. Marsh speaks of an ossified carpus and tarsus. Among 

 the numerous carpal bones there is none which I can positively 

 refer to Nothodon. The ungual phalange shown in Plate XXXIV 

 may belong with Nothodon, but since Eryops has similar ungual 

 phalanges it may belong in that genus. 



There are numerous vertebrae in the collection from different 

 parts of the column which in much probability belong with 

 Nothodon. For the most part the arches are separate, or have been 

 so broken into fragments and dispersed that only a few have been 

 restored to anything near completeness. The spine is stout, with 

 a thick upper extremity (Plate XXXVI, Fig. 2), convex above 

 and not much longer than broad; on each side above there is a 

 ribbed thickening in the middle. The zygapophyses are rather 

 stout, but there is no vestige of a hyposphene, so characteristic of 

 Diadectes. The articular surface for the capitulum forms a dis- 

 tinct facet just back of the front margin of the centrum, and very 

 low down. In this vertebra there is a small hypopophysial pro- 

 tuberance in the naiddle below and between the two capitular facets 

 that reminds one of Elcohrosaurus Case. The centrum has a high 

 and thin keel in the middle. The diapophyses were evidently of 

 moderate length, but broken off in the specimen figured. 



The type of vertebra described is very unlike that characteristic 

 of the species of Diadectes from Texas, which resembles more the 

 pariotichid type than the pelycosaurian, as does this. That these 

 vertebrae belong with either Sphenacodon or Ophiacodon seems 

 improbable, since no known forms of that group have elongated 

 thickened spines; furthermore, the much greater number of verte- 

 brae of the pelycosaurian type in the collection agrees better with 

 the preponderance of skeleton and skull bones of the pelycosaurian 

 forms. 



