152 PHYSIOLOGICAL SERIES. 



gain a most effective action by their advantageous insertion 

 upon the backwardly prolonged calcaneum. The reduction 

 in the number of the toes and the consequent shifting of 

 the muscle-insertions renders the homology of several of 

 the shank-muscles very uncertain. The following details 

 are noteworthy: The size of the biceps, and the extension 

 of a slip from its posterior border to the heel. The origin 

 of the sartorius midway between the crest of the ilium and 

 the pectineal process. The large size of the gracilis. 

 The slender and rudimentary character of the soleus. 

 0. 0. 64 xy. Presented by Colonel Burgess. 



C. 220. Deep muscles of the left hind-limb of a Calf (Bos 

 taunts). A large prse-semimembranosus is present, 

 accompanied by a poorly developed semimernbranosus. 

 The several components of the extensor cruris are sharply 

 marked. The tibialis anticus is in two parts one rising 

 from the front of the tibia, the other in conjunction with 

 part of the extensor longus digitorum from the femur. 

 There are two short extensors rising from the dorsal 

 surface of the tarsus and inserted upon the digits ill. & IV.; 

 they are joined in the middle of their course by the 

 tendon of the extensor longus digitorum. The tendons of 

 the flexor fibularis and flexor tibialis unite just distal to 

 the heel, and the common tendon thus formed passes, when 

 on a level with the phalanges, through a loop formed by 

 the plantaris tendon. The tibialis posticus is absent. 

 The short flexors of in. & IV. have been modified as in the 

 Horse to form the suspensory ligament of the fetlock. 

 0. C. 64 x h. Presented by Colonel Burgess. 



C. 221. Superficial muscles of the right hind-limb of a Seal 

 (Phoca vitulina). The limb shows great adaptation to a 

 swimming life. As far as the ankle it is closely applied to 

 the body, and is capable mainly of strong rotatory move- 

 ments. The most important of these (produced by the 

 gracilis, semimembranosus, semitendinosus, and popliteus) 

 takes place inwards and turns the sole of the foot backwards 

 during the stroke. Rotation in the opposite direction is 

 due to the long head of the biceps. The foot is free and 



