OSTEOLOGY AND ARTHROLOGY 



35 



that is to say, the phalanges (Fig. 23) ; or the extremities of 

 the fingers only — that is to say, the third phalanges (Fig. 2.|). 

 This last position, which is certainly difficult to maintain, 

 should here be regarded rather as theoretical. 



We shall meet with each of these modes of support in 

 certain groups of animals. Thus, the bear, badger, and the 

 majority of rodents, have the paws applied to the ground 

 by the whole extent of the palmar surface of the hand, from 

 the wrist to the tips of the fingers. They are therefore called 

 plantigrade, from the analogy, in this case, of the palm of 

 the hand to the plantar surface, or sole of the foot. 



Fig. 22.- 



EJ^.C. 



-The Human Hand resting for its Whole Extent on its 

 Palmar Surface : Left Side, External Surface. 



In others, such as the lion, tiger, panther, cat, wolf, and 

 fox, the support is made no longer on the whole extent of 

 the palmar surface, but on the corresponding surface of the 

 fingers only — the metacarpus is turnea back, and, conse- 

 quently, the wrist — that is to say, the carpus — is removed 

 from the ground. These are the digitigrades. 



Lastly, the ruminants (sheep, oxen, deer, etc.), and also the 

 pig, ass, and horse, rest on the third phalanx only. In 

 them not only is the metacarpus turned back, but also the 

 two first phalanges. The wrist is very far removed from 

 the ground. In these animals, the third phalanx is 

 enclosed in a case of horn, a nail (the hoof), and because 



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