CHAPTER III 



EPIDERMIC PRODUCTS OF THE TERMINAL 

 EXTREMITIES OF THE FORE AND HIND LIMBS 



We will first recall to mind that among the quadrupeds 

 some are found of which the fingers and toes have their 

 third phalanges terminated by claws — these are the un- 

 guiculates ; and that in others the terminal extremity of 

 each limb is completely encased in a horny envelope, the 

 hoof — these are the ungulates. 



In the first group, the claws remind us to a certain extent 

 of the arrangement of the nails in man ; the inferior aspect 

 of the paws is covered by an epidermic layer, thick and pro- 

 tective, which may be likened to the skin, correspondingly 

 thick, which covers in the greater part of its extent the 

 plantar surface of the foot in the human species. 



In the second group, the surface by which the third 

 phalanx rests on the ground is correspondingly protected, 

 but this time by a layer of horn which belongs to the hoof. 



After the preceding remarks, our study will be found to fall 

 into a natural division, and it is in the order which we have 

 just followed for the purpose of indicating its existence that 

 we now proceed to study the nature and form of the different 

 elements which complete or protect the digital extremities 

 of the thoracic and abdominal limbs. 



Claws. — These horny coverings of the third phalanges, 

 which we have to consider only in the dog and cat, may be 

 compared with the nails of man, with which, however, they 

 present, as is well understood, characteristic differences. 



The claws are compressed laterally, curved on themselves, 

 and are terminated in front by a sharp point in the felide, 



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