Shufeldt: Osteology of Lasiopyga and Callithrix. 77 



in the skeleton of Lasiopyga. A large, ovate, elongate patella is 

 present in all the apes here being considered, it being uniformly 

 convex anteriorly, and very shallowly doubly concave posteriorly, a 

 very faint mid-longitudinal elevation appearing between the two 

 concave surfaces. 



Callithrix has a femur presenting a number of points unlike those 

 just described for Lasiopyga. The head of the bone comes consider- 

 ably nearer being a complete sphere. The upper fourth of the bone> 

 or down as far as the well-developed lesser trochantei, is gently bent 

 anteriorly, while below the " trochanterian line" there is an extensive, 

 circumscribed triangular surface, which is not found in Lasiopyga at 

 all. Its shaft is quite straight, for its posterior third wide, and 

 flattened in the antero-posteio direction. 



In the short external lateral ligament, just above the head of the 

 fibula in Callithrix, a minute sesamoid is present, but I fail to find its 

 counterpart in either species of Lasiopyga. 



The Tibia. The tibia of Lasiopyga griseoviridis is 14.3 cm., of L. cal- 

 litrichiis 12.4 cm., and of Callithrix jacchus 5.4 cm. in length; the fibula 

 in any case being but very little shorter. Essentially all the characters 

 we find in the human tibia and fibula are repeated in the same bones 

 in these apes, even including Col ithrix. Apart from the matter of the 

 great difiference in size in such a comparison, it is truly remarkable 

 how similar they really are. Lasiopyga has the upper ithird of its 

 shaft more compressed transversely, and here it is quite concave in the 

 longitudinal direction as far down as the juncture of the middle and 

 upper thirds. This is not as evident in Callithrix, in which form the 

 tibia exhibits considerable compression for its entire length until we 

 neai the enlarged distal extremity in both genera, when the bone is 

 somewhat flattened in the opposite direction to accommodate itself for 

 articulation with the astragalus. The tibial crest is much rounded 

 ofi" in these apes, and the tubercle for the insertion of the ligamentum 

 patellae is very rudimentary. The internal malleolus is prominent, 

 and its long axis is in line with the axis of the tibial shaft. 



The Fibula. The fibula is a slender bone, extremely so in Cal- 

 lithrix, straight, more or less cylindrical, barring the moderately flat- 

 tened surfaces for muscular insertion, and presenting the usual enlarged 

 ends for articulation with the tibia above, and below with the astrag- 

 alus, its malleolus being quite as long as that process in the tibia. 

 This is a departure from what we find in man, where the fibula ex- 



