ART. 15 ANATOMY OF THE EARED AND EARLESS SEALS HOWELL 07 



and from the deep fascia covering the extensor hallucis. Its broad 

 tendon passed mediad to an insertion upon the medial margin of 

 metatarsus 1. Origin in the Phoca was very similar, being from 

 the better defined anterior tibial fossa and slightly from the adjoin- 

 ing interosseous membrane. Its tendon passed through the deep 

 tibial groove upon the front of the instep, went deep to the extensor 

 hallucis tendon and inserted upon the medial border of the base of 

 metatarsus 1, as in Zalophus. There were said to be two tendons in 

 Eumetopius^ the second inserting upon the first tarsale. 



M. extensor hallucis (figs. 13, 25, 26) was a weak muscle in the 

 Zcdophus arising from the interosseous membrane and slightly from 

 the adjoining borders of both tibia and fibula. Its tendon passed 

 over the instep between those of the tibialis anticus and extensor 

 digitorium longus to insert upon the base of the first phalanx of the 

 hallux. In the Phoca its origin was from the proximal part of the 

 cranial ridge of the fibula. It lay mostly deep to the extensor digi- 

 torum longus and its slender tendon passed over the instep just 

 laterad to that of the tibialis anticus. It then crossed superficial to 

 the last and ventrad of the base of the first metatarsal, after which 

 it extended dorsad once more to insert upon the lateral side of the 

 dorsum of the first hallucial phalanx. This was said to be of unusual 

 volume in Eumetopias. 



M. extensor digitorum longus (figs. 12, 13, 25, 26) in the Zalophus 

 arose very slightly from the lateral epicondyle of the femur, from 

 the capsule of the joint adjoining, from a small area OA^er the part 

 of the tibial head adjacent to the fibula, and from two-thirds of the 

 cranial border of the fibular shaft. In addition the deeper fibers 

 were in intimate relationship with the extensor hallucis and with 

 the peroneal aponeurosis. In the Phoca origin was from the cranio- 

 lateral head of the tibia. In both the tendon passed over the middle 

 of the instep and split into four branches, which extended to the 

 four lateral digits. Murie reported no tibial origin for Ewnietopias 

 and Odol)enus. 



Stretching from the head of the fibula to the most prominent part 

 of the external malleolus of Zalophus there was a sort of ligament, 

 here termed the peroneal ligament. It is a development of the usual 

 involved aponeurosis of the peronei, and in addition had connection 

 with the aponeurosis of insertion of the hamstring muscles. Such 

 an aponeurosis was present in the Phoca as well, but no definite 

 ligament was encountered nor was direct involvement with the ham- 

 string aponeurosis noted, possibly because of the more tender state 

 of the tissue in the latter. 



M. peroneus longus (figs. 12, 25, 26) arose from the lateral epicondyle 

 of the femur. In the Zalophus it passed beneath the peroneal liga- 

 ment and over a groove immediately caudad of the most prominent 

 86377— 2S 7 



