64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



slightly toward the distal extremity, that of the third digit being 

 broadest. The proximal extremity of each is the deeper, correspond- 

 ing to the distal extremity of the metacarpal, but through the shaft 

 and distally they are rather flattened. The second phalanges in II 

 to V are about two-thirds the length of the first in each, also slightly 

 tapering and more flattened distally. The distal phalanges are about 

 the length of the penultimate in each, with a slender shaft but distally 

 spatulate. The dorsal surface is convex, and the ventral or palmar 

 surface is flat. They have a surprisingly human appearance, and in 

 all probability possessed a primatelike nail rather than hoofs or claws, 

 as suggested by Marsh (1892, p. 448) . 



The Phenacodus phalanges are relatively shorter and much broader, 

 and the broadly spatulate form of the distal or ungule phalanges in 

 digits II to IV extends to the proximal extremity. The latter have 

 been described as subungulate in character and are quite unlike those 

 in Meniscotherium. 



PELVIC GIRDLE 



The innominate bone of Meniscotherium is moderately elongate 

 with a strongly curved ilium flaring outward craniad to the auricular 

 or sacral surface (see fig. 8). The ilium is essentially triangular in 

 cross section from the acetabulum through most of its length, with the 

 lateral (acetabular) border converging with, and then paralleling, 

 the medial ventral (pubic) border toward the anterior superior spine 

 at the ventrolateral extremity of the supra-iliac border. The external 

 iliac or gluteal surface is strongly concave transversely in its mid 

 portion, opposite the sacral surface, and the uniformly curved crest 

 of the ilium commences caudad about opposite the posterior margin 

 of the rugosity for the sacrum and swings forward and outward to 

 the somewhat recurved anterior superior spine. This anterolateral 

 extremity of the long crest of the ilium is distinctly rugged, possibly 

 implying importance to the sartorius and tensor muscles, but surely 

 significant for the superficial gluteus muscle which would be inserted 

 on the third trochanter of the femur. The acetabular border has a 

 curvature similar to that of the crest of the ilium and terminates 

 caudad in a prominent and rugged anterior inferior spine extending 

 forward from the margin of the acetabulum for the rectus femoris, 

 a part of the extensor group for the shank. 



The margin of the acetabulum is well separated by a broad dorsal 

 surface from the ischial border and by a broad ventral surface from 

 the pubic border. The cotyloid notch is deeply impressed and 



