30 Darwinism and Other Essays. 



One of the most striking peculiarities of the 

 equine genus including the horse, ass, zebra, 

 and quagga is the modification of the limbs, so 

 that what appears to be the horse s fore-knee is 

 really his wrist, and what in the hind-limb looks 

 like a reversed knee is really his heel, while the 

 lower halves of the legs are really feet terminat 

 ing in the middle toe armed with its nail, which 

 we call the hoof. The two adjacent toes are rep 

 resented only by splint-bones on either side of 

 the middle metacarpal or metatarsal, and the ra 

 dius and ulna in the fore-limb, as well as the tibia 

 and fibula in the hind-limb, are almost completely 

 fused together. Now according to the Darwinian 

 theory, such a highly specialized animal as the 

 horse must be descended from a less specialized 

 mammal in which the limbs were like ordinary 

 mammalian limbs, ending in ordinary feet with 

 five separate toes each. The embryology of the 

 horse points to this conclusion, and here, as usual, 

 but with unwonted emphasis, palaeontology con 

 firms the inference. Already in Europe had been 

 found the three-toed hipparion, in which the two 

 side toes were like dew-claws, and the older an- 

 chitherium, in which all three toes were complete. 

 But the discoveries of Professor Marsh have set 

 before us a much more perfect series. Going 



