Shufeldt: Osteology of Lasiopyga and Callithrix. 75 



The bones of the metacarpus are proportionally longer, more curved, 

 and narrower than in man; but, together with the phalanges, are the 

 same in number. These last are also more curved than they are in 

 man, the distal pha anges being compressed from above, downwards, 

 except in Callithrix, where the compression is in the other direction, 

 being curved, as in some birds, and sharply pointed, having the form 

 of the distal d'gital thecae which encase them. In Lasiopyga, a pair 

 of sesamoids are found on the palmar aspect at the metacarpo- 

 phalangeal joints, and also at the joints beyond the index and mini- 

 mus digits. 



The Hind Limb. (Plate XVIII, fig. 21; Plate XIX, fig. 22, and 

 Plate XXI, fig. 25). 



The Pelvis. DifTering considerably in form from the pelvis in Homo, 

 and likewise from the big pelvis in Troglodytes with its great, broad ilia, 

 the ilium as a who'e in Lasiopyga is much elongated and comparatively 

 narrow. Either ilium rises considerably above the sacral articulation 

 to a point opposite the middle of the penultimate lumbar vertebra in 

 the articulated skeleton. Its crest is moderately convex and rough- 

 ened, and it is here that the bone is broadest, gradually narrowing as 

 it approaches the acetabulum. Upon its outer surface it is concave, 

 and correspondingly convex upon its inner surface, where it presents 

 an extensive roughened area for articulation with the sacrum. The 

 anterior border is sharp, while the posterior border is rounded, the 

 thickest part of the bone being just anterior to the cotyloid cavity. 

 This causes the greater sacro-sciatic notch to be long and shallow, 

 while the lesser one is hardly deserving of a name. In form, the 

 acetabulum very closely approaches what we find in man, and the bone 

 at its base is very thin, though never exhibiting any perforations. 

 There is an interval of bony surface between the cotyloid notch and 

 the large subcircular obturator foramen. 



Pubis and Ischium. Deep and prominent, the symphysis pubis is in 

 life firmly united by ligament, and the pubic arch presents the same 

 sexual characters as we find in the pelvis of man. The tuberosity of 

 the ischium, with the adjacent ramus of the pubis and ischium, is 

 curved forward, thus forming a concave surface anteriorly below the 

 obturator foramen. This tuberosity is most extensive externally, 

 gradually narrowing as it approaches the pelvic outlet or pubic arch, 

 and its surface is much roughened for attachment of the ischial callos- 

 ities in this genus. 



