IN YERTEBRATED ANIMALS. 151 



orly. The bones of the carpus (e) are represented by four 

 nearly square little bones ; but in these, again, there are 

 considerable variation in different fishes, and in some genera 

 they are much more irregular in form. The fingers are but 

 imperfectly represented by the rays of the fin (<?), which are 

 composed of an infinitude of minute bones, articulated with 

 each other. As to the humerus and shoulder, their analogies 

 are variously interpreted by different anatomists. 



286. The form of the members is so admirably adapted to 

 the especial offices which they are designed to perform, that by 

 a single inspection of the bones of the arm, as represented in 

 the preceding sketches, one might infer the uses to which they 

 are to be put. The arm of man, with its radius turning upon 

 the ulna, the delicate and pliable fingers, and the thumb op- 

 posed to them, bespeak an organ for the purpose of handling. 

 The slender and long arm of the sloth, with his monstrous claws, 

 would be extremely inconvenient for walking on the ground, 

 but appropriate for seizing upon the branches of trees, on 

 which these animals live. The short fingers, armed with re- 

 tractile nails, indicate the lion, at first glance, to be a carnivo- 

 rous animal. The arm of the stag, with his very long cannon- 

 bone, and that of the horse also, with its single finger en- 

 veloped in a hoof, are organs especially adapted for running. 

 The very slender, and greatly elongated fingers of the bat are 

 admirably contrived for the expansion of a wing, without in- 

 creasing the weight of the body. The firm and solid arm 

 of the bird indicates a more sustained flight. The short arm 

 of the whale, with his spreading fingers, resembles a strong oar. 

 The enormous hand of the mole, with its long elbow, is con- 

 structed for the difficult and prolonged efforts requisite in bur- 

 rowing. The twisted arm of the tortoise can be applied to no 

 other movement than creeping ; and, finally, the arm of the 

 fish, completely enveloped in muscles (fig. 76), presents, ex- 

 ternally, a mere delicate balancer, the pectoral fin. 



287. The posterior members are identical in their struc- 

 ture with the anterior. The bones of which they are com- 

 posed are, 1. The pelvis (figs. 125 and 169), which corre- 

 sponds to the shoulder blade ; 2. The thigh bone, or femur, 

 which is a simple bone like the humerus ; 3. The bones of the 

 leg, the tibia and fibula, which, like the radius and ulna, some- 

 times coalesce into one bone ; and lastly, the bones of the foot, 



