126 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 7$ 



tendinous. The lesser trochanter, occurring in the Otariidae only^ 

 is rather small and supports narrow insertions of the sixth adductor, 

 pectineus, and psoas magnus and iliacus element. In Phoca the only 

 one of these muscles which insert in this vicinity is the pectineus,. 

 and this more broadly. The more decided and sharp epicondylar 

 ridges of Phoca are doubtless attributable to the stronger action of 

 the muscles originating therefrom. In the skeletons at hand the 

 patellar " fossa " of the otariid is undifferentiated and this part of the 

 femur is convex. In the sea lion dissected the patella also rested at 

 the junction of the thigh with the shanli rather than upon the femur,, 

 because of the flexed position of the latter bone. In some other mem- 

 bers of the Otariidae, however, there is considerable variation in 

 this detail, and I shall not attempt to account for this condition. 

 In the Phoca there is a deep, concave patellar fossa in the usual 

 situation. As previously noted, a line passing through the center of 

 the two femoral condyles describes an angle with the axis of the 

 shaft of about 79° in Zalophus and 63° in the Phoca. This is attrib- 

 utable to the lateral condyle being somewhat more proximad than 

 the medial in the otariid, and much more so in the phocid. This will 

 be discussed in relation to the shank. 



The pinniped tibia has experienced some shortening but not nearly 

 to the same degree as the femur. In the cat this bone is 36 per 

 cent of the body length, in the Zalophus 22 and in the Phoca 29 per 

 cent. From another angle, the femur of the cat is 97 per cent of 

 the tibia length, in the Zalophus 50 and in the Phoca 40 per cent. 

 The shank is of the usual carnivore type, that of the sea lion rather 

 straight except that the fibula is slightly rotated, and of the phocid 

 more curved, but with the fibula nonrotated. 



The head of the tibia differs from that of the ordinary fissiped in 

 having the anterior edge quite sharply angular instead of sloping, 

 which is undoubtedly due to the fact that in pinnipeds the shank 

 is never really extended in respect to the thigh. The head of the 

 fibula in the Phoca is even and continuous with the tibial head, but 

 in Zalophus it slopes directly distad from the latter and is continu- 

 ous in this direction with the shaft. This is a provision in the 

 otariid for excessive flexion of the shank in respect to the thigh, the 

 femur fitting down over the sloping head of the fibula in a sharper 

 angle than is mechanically possible in the phocid. As mentioned, 

 the lateral femoral condyle of Zalophus is situated a bit more proxi- 

 mad than the medial, but in the markedly flexed static position of 

 the shank the only effect which this condylar position has is to place 

 the shank in a more pronated posture. The lateral tuberosity of 

 the shank in this animal, however, is placed more distad than the 

 medial, and this has the effect, in the position assumed by the limb 

 segments, of elevating the shank and ankle toward the dorsum. The 



