74 



ANIMAL MECHANISM. 



that anatomists have described under various names the same 

 muscle in different species. 



Still, in the greater number of cases, the homology is not 

 doubtful ; it is implicitly admitted by the fact of an identical 

 designation being applied to certain muscles in different 

 species. These are precisely the muscles which we shall take 

 for an example, to show the harmony which exists between 

 the function and the organ. 



Fig. 15. — Skeleton of the wing and sternum of thie sea-swallow (Hirundo 

 marina)— showing the extreme shortness of the sternum, and the great 

 length of the wing. 



Thus the femoral biceps is easily recognized in all mam- 

 mals ; and it varies considerably, especially in its lower attach- 

 ment. In certain quadrupeds it is inserted all along the leg, 

 almost to the heel; in these animals the leg is never ex- 

 tended upon the thigh ; in animals which have the power of 

 leaping, the lower attachments of the biceps is more elevated ; 

 it is still more so in the simise, which can almost extend 

 the leg upon the thigh and stand upright. In man the biceps 



