38 PROCEEDIN-GS OF THE NATIONAL MUSEUM vol.73 



spectively (35 in a cat). Perhaps the latter comparison is the more 

 significant from a phylogenetic aspect, although this is difficult to 

 decide. In major details this bone is very similar in the two animals. 

 The shaft is expanded laterally, being practically twice as broad in 

 this direction as sagitally. The greater trochanter is laterad of the 

 head and is greatly developed, as high as the head in Zalophus and 

 slightly higher in Phoca. The summit of this trochanter in the lat- 

 ter is wedge-shaped and there is a deep and distinct trochanteric or 

 obturator fossa, this being due to the tendency toward complete 

 fusion of the tendons of the gemelli and obturator muscles which 

 insert therein. In the Zalophus the insertions of all these muscles 

 are separate, the trochanteric fossa therefore being less well defined 

 and nothing but a shallow groove, reaching the summit of the greater 

 trochanter, so that it has the shape of an inverted comma. Zalophus 

 has a lesser trochanter, upon which insert the pectineus, adductor 6, 

 and the psoas magnus and iliacus element. The Phoca has no indi- 

 cation of a lesser trochanter and in the situation corresponding to its 

 position in the otariid there is only the somewhat extensive and 

 fleshy insertion of the pectineus. From the lesser trochanter to the 

 distal part of the greater there is in the ZaJloyhus a slight ridge, 

 marking the insertion of adductor 4, absent in the phocid. In the 

 former the adductor 3, and in the latter the adductor anticus (prob- 

 ably homologous) is inserted in a line passing (approximately) from 

 the medial epicondyle to the greater trochanter. There is in the 

 otariid the suspicion of a ridge marking its location, corresponding 

 evidently to the usual linea aspera. The epicondyles of the Phoca 

 are the better developed, being broader, and extending farther proxi- 

 mad more in the nature of definite ridges. This seems to have been 

 influenced by the better development in the phocid of the gluteus 

 maximus, gastrocnemius medialis, and plantaris. In the Zalophus 

 the patellar " fossa " is broad and slightly convex, while in the Phoca 

 it is narrow and quite deeply concave. This detail varies consider- 

 ably within the family, but it is probable that in the otariids the 

 patella is never in quite as close relation to the femur as in phocids. 

 In the small Zalophus dissected the femur was flexed to such a degree 

 that the patella was situated at the apex of the angle formed by the 

 thigh and shank segments and was almost entirely distad of the 

 femur. 



In the otariid the two condyles were of equal size, were directed 

 exactly at a right angle to the shaft, and the outer was sufficiently 

 proximad of the more medial so that a line passing laterad through 

 the center of both would form an angle of about 79° with the axis 

 of the shaft. In the Phoca the condyles were directed not quite 

 so far as at a right angle to the shaft, the medial was but about two- 

 thirds the size of the lateral, and a line through their centers would 



