130 PROCEEDINGS OP THE NATIONAL MUSEUM vol.73 



middle digits of the pes in the Otariidae is solely because of this 

 fuction of scratching and combing the hair. I am, however, at 

 somewhat of a loss to explain the retention upon all the digits of 

 the pes in Plioca of such long nails. Jones believes that the posi- 

 tion of the pes of this animal inhibits any appreciable scratching by 

 the nails, to which I subscribe, and that the limited toilet is then 

 performed by the claws of the manus, in which I do not agree, for 

 any such action by the manus is well nigh as limited as by the pes. 

 And yet it seems that the claws must be of some definite use, for the 

 Phocidae are certainly sufficiently ancient for their claws to have 

 disappeared entirely were they not of practical value to the animal 

 in some respects. 



The details of pedal movement are not easily followed either in 

 the reconstructed foot, or from the embalmed specimen after most 

 of the tissue and many of the muscles have been cut away. The 

 ankle joint of Zalopkus is such that the tibial facet of the astragalus 

 dips but slightly medioventrad from the horizontal, while in Phoca 

 it and the fibular facet are both at 45°. The result is that if one 

 hold the shank vertical and bend the foot, the transverse plane of 

 the phocid foot is at practically 90° to the shank, while in the otariid 

 it is nearer 45°. In other words, in such a free limb, disarticulated 

 from the body, the tendency is for merely the lateral border of the 

 foot to rest upon the ground — not the entire sole. The full planti- 

 grade position may be assumed, however, either by forced pronation 

 through the ankle joint and the tarsal articulations, or more likely 

 by the slight adduction of the proximal shank toward a knock- 

 Ijneed position, the rotation of the shank at the knee joint in a 

 direction toward pronation, and of the femur in a direction toward 

 supination. This is less complicated than it sounds; but the strange 

 part is that could Phoca place the sole flat upon the ground in the 

 same fashion as can Zaiophiis, none of this rotation or adduction of 

 the shank and femur would be needed. In the otariid the crotch, or 

 angle between the hind limb and the tail, was at the calcaneal tip, 

 while in the phocid this point was situated some 20 mm. farther 

 distad; so the difference in this respect is not by ixny means so great 

 as alone to prevent the phocid foot from assuming a plantigrade 

 posture did other anatomical details allow it to do so. Murie (1874) 

 considered that the phocid's " incapacity to use its hind foot on land 

 depends more on the different proportion of femur to leg bonos 

 and lowered attachment of integumentary caudal expansion than to 

 absolute difference in the constriction of the bones forming the ankle 

 joint"; but none of the three points mentioned are of primary 

 importance in inhibiting such an act. 



As already mentioned, the static position of the trailing feet when 

 submerged seems to be with the palms steeply V-shaped in Zcdophus^ 



