NORTH AMERICA AND THEIR VERTEBRATE FAUNA. 



169 



UNASSIGNED FORMS, REPTILIA. 



A femur, No. 3363 (plate 24, fig. 5, fig. 42, a and b), is rather short and 

 heavy, but not radically different from some known forms. The proximal 

 articular face is rather narrow, slightly thicker at the inner side, and confined 

 entirely to the end, except where it descends a little upon the inner edge. The 

 process is sharply set off from the inner edge and terminates well below the end 

 of the bone in a flat, oval face looking nearly straight upward. From the base 

 of the process a sharp adductor ridge runs oblicjuely across the lower face of 

 the bone to the opposite of the distal end. Aside from this ridge the shaft is 

 nearly circular in section. The lower end is expanded and the articular face 

 has a continuous articular area; the inner part is the broader and is partly 

 cut off from the outer by a deep groove on the anterior face of the bone. This 

 part of the articular face looks obliquely inward and backward. The outer 

 part is narrow antero-posteriorly and looks obliquely outward and backward. 

 This bone resembles in many respects the bone figured by Case (Publication 

 55, Carnegie Institution of Washington, plate 5, fig. 7) as the femur of Clepsy- 

 drops and by Williston (American Permian Vertebrates, plate 24, figs. 5, 6, 7) 



X ?3. No. 3404. Dorsal plate. 



44 ^^ 



a, upper face; b, an- 



FiG. 41. — Unnamed amphibian. 



terior edge. 

 Fig. 42. — Unnamed reptile. X %■ No. 3363. Articular face.s of femur shown in plate 24, 



fig. 5. a, distal face; b, proximal face. 

 Fig. 43. — Unnamed reptile. X Jj. No. 3354. Articidar faces of humerus shown in figures 



I and 4, plate 24. a, proximal face; b, distal face. The faces are arranged in their 



natural position. 

 Fig. 44. — Archeria robinsoni. X /3. No. 3246. Articular faces of the humerus shown in 



plate 23, figs. 7 and 8. a, proximal face; b, distal face. 



as the femur of Captorhinus illinoisensis. There is much doubt that it is the 

 femur of a true captorhinid, as that group does not occur in the Wichita 

 formation nor in the Illinois beds. The vertebrae of the captorhinids are so 

 characteristic and bones from the vertebral column are so much more abun- 

 dant than from other parts of the skeleton that they could scarcely fail to 

 be recognized if present. The femur is tentatively associated with the 

 humerus described below (No. 3354). 



There are two types of humeri which are different from forms previously 

 described. The first type, No. 3354 (plate 24, figs, i to 4, fig. 43, a and b), is 

 represented by six good specimens of different size. The group forms a series, 

 the extremities of which might be regarded as belonging to diff'erent species, 



