50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



normal in M eniscotherium. For Phenacodus Cope listed the number 

 as three or five. His illustration (1884b, pi. 57h) shows four. 



Anteriorly the fused transverse processes, preserving nevertheless 

 the intervertebral foramen, show a strong and deep attachment to the 

 ilium. The anterior spines are not preserved, but the posterior two, 

 although incomplete, were evidently low and backward directed. 



Caudal vertebrae. — There are 14 caudal vertebrae (see fig. 9) 

 belonging to one specimen, but most of these were not found articu- 

 lated, so that any sequential arrangement of these would likely be 

 very incomplete. The first caudal is in articulation with the sacrum 

 described above. Although a little shorter, it is nearly as large as 

 the last sacral and has heavy, laterally directed transverse processes. 

 Posteriorly the caudals become a little shorter as well as smaller in 



SEE) 



Fig. 9. — M eniscotherium robust um Thorpe. Caudal vertebrae, not an articulated 

 series (U.S.N.M. 18283), dorsal view. J / 2 X natural size. Knight member, 

 Wasatch formation, Green River Basin, Wyo. 



diameter than the first, with more slender, shorter, and backward 

 directed transverse processes. After about the eighth of those at 

 hand their length increases again and the processes and pedicles are 

 reduced to vestiges. Only the first four or five or those represented 

 show evidence of a neural spine, and the anterior caudals lack a 

 distinct ventral keel, but posteriorly the latter is better defined. 



SCAPULA 



The scapula of M eniscotherium is relatively elongate and, although 

 in the one well-preserved example at hand (see pi. 6) the margins 

 are not everywhere complete, the suprascapular border would appear 

 to be rounded somewhat as in Phenacodus, but the coracoid or 

 anterior border may not expand forward so abruptly near the proxi- 

 mal extremity. The prescapular fossa is distinctly convex and, as in 

 Phenacodus, is much wider than the postscapular fossa. The latter is 



