248 THE ARTISTIC ANATOMY OF ANIMALS 



but more blunted in the dog. Their superior border is 

 convex and thick. We may say, therefore, that a claw is 

 a sort of hollow tube, in the form of a cone flattened in the 

 transverse direction, in which the third phalanx is set, and 

 which is itself set in a groove formed by a kind of osseous 

 hood which occupies the base of this third phalanx (see 



Fig- 37' P- 57)- 



This definition is exact, as regards the general appear- 

 ance ; but, when more closely scrutinized, it is not 

 sufficient. The tube in question is not formed of a single 

 piece ; each of the claws is formed by a lamina later- 

 ally folded, but of which the borders are not exactly 

 joined together inferiorly ; they leave between them a 

 small interval, and this is filled by a layer of more friable 

 horny substance, to which has been given the name of 

 plantar nail. This arrangement, which is clearly defined 

 in the dog (Fig. 93), is comparable to that which we shall 

 afterwards meet with in connection with the sole of the 

 hoof of the horse (see Fig. 100, p. 257). In the dog and 

 the cat, the weight of the limb resting on the inferior 

 surface of the phalanges, it was necessary that the region 

 of the plantar surface of the foot corresponding to these 

 latter should be protected ; this is the function of certain 

 fibro-adipose pads, which are situated there, and which 

 are designated by the name of plantar tubercles. 



Plantar Tubercles (Fig. 94). — These tubercles, or dermic 

 cushions, are divided, in each paw, into tubercles of the digits 

 (or of the toes), a plantar tubercle, and, on the fore-limbs, a 

 tubercle of the carpus. 



The tubercles of the fingers (or of the toes) are of the same 

 number as the latter. That which belongs to the thumb 

 is but little developed, but the others are more so. They 

 are in relation with the plantar surfaces of the second and 

 third phalanges, so that when the paw is in contact with 

 the ground the articulation which, in each of the fingers or 

 toes, joins these phalanges, rests on the corresponding pad. 



The plantar tubercle is larger than the preceding. It is 

 of a more or less rounded form ; sometimes it is triangular, 

 and then comparable in outline to the ace of hearts, the point 



