1867.] 267 [Wyman. 



FORE-AE^VI AND LEG. 



No portions of the limbs have given rise to more wirlely diffCTrnfi; 

 opinions than these, and it is in connection with them that nearly all 

 the discussion of the homologies of the parts of the limbs have been 

 made. Vicq d'Azyr, comparing opposite sides, considers the tibia as 

 the homotype of the ulna, the fibula of the radius, and the patella of 

 the olecranon. Meckel and others homologize the same parts, but 

 compart limbs of the same side. Gerdy, on the other hand, compares 

 the radius and tibia, the ulna and fibula, but asserts at the same time 

 that the olecranon and patella are homotypes, in which case it is obvi- 

 ous that the patella should be attached to the fibula. He gets over 

 this difficulty by assuming that its union with the tibia is an "anomaly." 



Fig. 11. Fig. 12. 



Fig. 11. Bones of the fore arm of an alligator, a, ulna ; b, radius. 

 Fig. 12. Bones of the leg of an alligator, a, tibia; b, fibula. 



Bourgery, and more recently Cruveilhier, seeking for a solution of 

 the question by studying only the resemblances in the form and uses 

 of parts, adopted the singular " hypothc'se de croisement" which Cru- 

 veilhier states as follows : — 



"1st. No bone of the leg singly represents one of the bones of the 

 fore arms. 



"•2d. In each of the bones of the leg we find characters, some of 

 which belong to the ulna, and some to the radius. 



"3d. We admit that the upper end of the tibia is repi-esented by 

 the upper end of the ulna, and the lower half of the tibia by the lower 

 half of the radius ; while the fibula is represented by the upper half 

 of the radius, and the lower half of the ulna."* 



Martins homologizes the parts in question as follows : " The femoral 

 end of the tibia in Monadelph mammals is formed by the humeral heads 



♦Traits d' Anatomic Descriptive. Paris, 1843. T. i,, p. 342. 



