On the Tarsus and Carpus of Birdsx 143 



"Below this bridge the bone is deeply scooped, and the 

 concavity between the condyloid margins of the trochlea is 

 very considerable. Query. Is the lower articular portion 

 of the tibia an epiphysis of the tibia itself, or is it the homo- 

 loofue of the mammalian astragalus?" 



Gegenbaur's discoveries confirm the supposition of Mr. 

 Parker, and prove that the term tarso-metatarsus is appro- 

 priately applied to that segment of the leg bearing the pha- 

 langes. 



Besides the discovery of Gegenbaur's, above mentioned, of 

 the two tarsal bones and the two centres of ossification in 

 the upper, or proximal one, he recognizes and figures two 

 carpal bones, one corresponding to the radius, the other 

 corresponding to the ulna; these he designates, respectively, 

 the lYidiale and the idnare. 



In considering these points, and reflecting upon the char- 

 acter of these bones in the higher classes of vertebrates, it 

 seemed to me that further investigation should reveal more 

 carpal bones in birds ; that bones representing the distal 

 carpal series should be present, and that the calcaneum and 

 astragalus should be more clearly demonstrated. 



In the land tortoises, the chelonians, monitors, crocodiles 

 and even in the low batrachians, whatever the number of 

 ossicles the carpus and tardus respectively present, there 

 appear to be at least two ossicles in the first, or proximal 

 series, as in the ^3es, for instance, where there is one corres- 

 ponding to the tibia, and another corresponding to the fibula. 



In the carpus, likewise, according to the demonstrated 

 homology between the fore and hind limbs, we should expect 

 to find other carpal bones anchylosing with the proximal ends 

 of the metacarpals, leaving the joint between the first and 

 second carpal series, as in the tarsus. With no prejudice in 

 favor of these views, nor- doubting the ol)servations of 

 others, I yet determined to satisfy myself, and so took up 

 the study of these features, as revealed in the embryonic 

 stages of the class. 



