HISTORY OF THE PROBOSCIDEA 



425 



thigh, are very long, so that the knee-joint is brought below 

 the body and free from it to the position of the hock-joint 

 in the Horse ; hence, the hind leg appears to bend in the op- 

 posite direction from the bend in the legs of ordinary quad- 

 rupeds, in which the true knee-joint is concealed. The fore- 

 arm bones are separate and, for most of its length, the ulna 

 is far heavier than the radius, a wide departure from the pro- 

 portions usual in hoofed 

 animals. The femur 

 has no pit in its head 

 for the round ligament 

 and no third trochanter ; 

 the shaft is broad and 

 much flattened, having 

 quite lost the normal 

 cylindrical shape. The 

 bones of the lower leg 

 are also separate, but 

 the fibula, though stout, 

 is very much more 

 slender than the ulna. 

 The long bones have 

 no marrow-cavitifes, but 

 are filled with spongy 

 bone. The feet are ex- 

 tremely short and broad 

 and of columnar shape, 

 the weight resting upon a pad of elastic tissue and the small, 

 nail-Uke hoofs are mere excrescences upon the periphery. 

 There are five digits in manus and pes, but not all of them 

 have hoofs; in the Indian and West African species the 

 number of hoofs is five in the fore foot and four in the hind, 

 in the East African four and three respectively. In the adult 

 the skin is quite hairless, though the young calf has a consider- 

 able quantity of hair. 



FiQ. 224. — Right manus of the Indian Elephant 

 {E. maxirmts). 



