326 STUDIES IN THE EVOLUTION OF ANIMALS 



clefts of the plate-commissures, into which the blood supplied to the 

 plates found its way much as the intra-lobular veins of the liver 

 receive the blood from the veinlets of the lobes. Whether this be 

 so or not may perhaps one day be ascertained by dissection of the 

 skin of the Rhinoceros, and also of the skin of the Armadillo. It 

 might thus be easily ascertained whether the commissures of the 

 plates have any corresponding veins. 



That the superficial veins of the Horse, or their nervous 

 apparatus, play some part in the distribution of pigments seems 

 likely. The ungulate character of the Horse's hands and feet 

 would naturally lead one to surmise a close relationship between 

 this animal and the Rhinoceros, but we should not forget that the 

 Great Armadillo on its hind feet has hoofs, and not claws.^ Both 

 the Horse and the Rhinoceros furnish indications of descent from 

 carapaced ancestors, but the question is whether the Horse came 

 to be what it is through the ruminant branch, or through some 

 Rhinocerotoid branch of ancestors. In another place I have shown 

 that there is reason to believe that the Horse and the ruminants 

 are closely allied. From features that I have indicated in the R. 

 Sondaiats, especially in his astonishing tail, encased in rings of 

 bone-plates, there can be no reasonable doubt that he, at all events, 

 descended from armour-plated ancestors. 



The degradation from bone-armour to picture-armour might at 

 first sight appear a great disadvantage for subsequent races, but in 

 reality it has resulted in giving natural selection a totally different 

 direction. It has resulted in the evolution of fleetness in the 

 Horse, Antelopes, and Deer, and in the astonishing springs of the 

 carnivora that feed on them. In other words, it has resulted in the 

 development of great muscular and brain power — with a suitable 



^ See also p. 132, Mammalian Descent, by Professor Parker, about 'ungulate 

 Lemurs. ' 



