204 THE MYOLOGY OF THE RAVEN. 



and tibial heads of the gastrociiexnius merge with each 

 other, while between their free edges above passes the 

 exceedingly delicate tendon of the semimembranosus 

 muscle. 



All of the fibres of this complicated origin of the gastro- 

 cnemius muscle now converge and pass directly down 

 the back of the leg of the bird. They also merge with 

 each other in such a manner that, were we to examine 

 the muscle at about the middle third, of the leg, we should 

 find it composed of two well-defined bellies, rather thin, 

 nearly of equal size, united somewhat firmly by an 

 intervening fascia, and each being convex on their 

 superficial aspect and the reverse on their under sides, 

 which concavity accurately moulds itself to the deeper 

 layer of muscles of the leg, which the gastrocnemius 

 completely covers. 



At the lower fourth of the tibial shaft the fibres 

 terminate in a broad, flat, and glistening tendon, which 

 passes flat-wise over the shallow and longitudinal groove 

 of the tibial cartilage, at which point the tendon is 

 considerably thickened. Next, crossing the tibio-tarsal 

 joint, it becomes internally attached to the hinder surface 

 of the hypotarsus of the metatarsal bone, below which 

 protuberance it finally merges into the deeper layer of 

 the podothecal sheath confining the flexor tendons. 



110. The soleus 1 is exposed when we remove 

 the tibial division of the gastrocnemius. It is found 



1 Provisionally, at least, I still propose to regard this muscle as 

 the soleus, being by no means yet satisfied that it can be considered 

 the homologue of the plantaris of the Mammalia. Aside from 

 everything else, however, attention is especially invited to the fact 

 that in the vast majority of birds it arises from the tibia, and its 

 tendon below merges with the gastrocnemius. In support of its being 

 the homologue of the plantaris, Gadovv has said : 



" Bei einigen Yb'geln entspringt der Muskel weiter proximalwiirts, 



