Wyman.] 



270 



[June 1 



ment of the fibula in the Ornitliorhynclius may justly be compared 

 with the great development of the olecranon in the Armadillo or the 

 Mole, as a means of increasing the power of the particular muscles 

 attached to it, but this resemblance is physiological only, and has no 

 bearing whatever on its homology. The head of the fibula in the 

 Ornithorhi/nchus is, however, not developed in relation to the extensor 

 muscles of the leg, but of some of the unusually large muscles of the 

 foot, which take their origin from it; viz., the large head of the gas- 

 trocnemius, the soleus, the two peroneal muscles, the common fiexor of 

 the toes, the long extensor of the great toe, the common extensors of 

 the toes and posterior tibial muscle, but has not that relation to the mus- 

 cles of the leg which the olecranon has to those of the fore arm. The 

 mere form of the process of the fibula is no proof that the fi])ula and 

 ulna are homotypes. although in many respects it resembles an ole- 

 cranon. (Fig. 14, B.) The prolonged upper end of the tibia in 



Fig. 13. 



Fif?. 14. 



Fig. 13. From a grebe. A, tibia; b. fibula; c, upper pud of tibia prolonged so as 

 to form a process analogous to the olecranon; d, femur. 



Fig. 14. From an Ornithorhynchus. a, tibia; b, fibula, with a process analo- 

 gous to an olecranon ; c, patella ; T>, femur. 



