150 PHYSIOLOGICAL SERIES. 



anticus. One head, the largest, rises as usual from the 

 front of the tibia ; the other (indicated by black paper) 

 by a long narrow tendon from the external condyle 

 of the femur in close contact with the tendon of origin of 

 the extensor longus digitorum. This femoral origin of the 

 tibialis anticus is frequent among the Caviidse. 

 Parsons, Proc. Zool. Soc. 1894, p. 288. 



C. 215. Bight hind-limb of a Beaver ( Castor fiber], showing the 

 superficial muscles of the shank. The flexors of the foot, 

 and particularly the plantaris, are remarkably developed. 

 The soleus joins the outer head of the gastrocnemius in its 

 distal third, but the two gastrocnemial heads are separate 

 throughout their length. The tendons of the gastrocnemius 

 and plantaris are twisted round one another, in such a way 

 that the tendon of the inner gastrocnemial head passes 

 superficial to that of the outer head and of the plantaris to 

 be inserted external to both upon the outer surface of the 

 os calcis. The tendon of the plantaris meanwhile passes in 

 the same direction superficial to that of the outer head of 

 the gastrocnemius. This spiral twisting of the component 

 parts of the tendo Achillis appears to be of very general 

 occurrence among mammals. 0. C. 64 z /. 



Parsons, Joui\ Anat. & Physiol., vol. xxviii. 1894, 

 p. 414. 



C. 216. Nerves and superficial muscles of the left hind-limb 

 of an Elephant (Eleplias africanus). The ensheathing 

 character of the muscles noticed in the case of the fore- 

 limb, and calculated to give support and rigidity to the 

 joints under the great superincumbent weight, is here 

 even more marked. The external gluteal sheet (tensor 

 fasciae latse, gluteus maximus, biceps cruris) in particular 

 is remarkable. It forms a continuous layer coated 

 (especially in its dorsal parts) by yellow elastic tissue. 

 From the knee to the foot the muscle-fibres to a great 

 extent give place to fibrous tissue, which at the back of 

 the leg is confluent with a similar fibrous expansion of 

 the semitendinosus (divided longitudinally in the speci- 

 men to show the underlying muscles). The following 



