148 THE DESCENT OF MAN. Part I. 



cephalic ; for instance, of two skulls of nearly equal 

 breadth, the one from a wild rabbit and the other from 

 a large domestic kind, the former was only 3*15 and the 

 latter 4*3 inches in length. 75 One of the most marked 

 distinctions in different races of man is that the skull 

 in some is elongated, and in others rounded ; and here 

 the explanation suggested by the case of the rabbits 

 may partially hold good ; for Welcker finds that short 

 " men incline more to brachycephaly, and tall men to 

 dolichocephaly ; " 76 and tall men may be compared with 

 the larger and longer-bodied rabbits, all of which have 

 elongated skulls, or are dolichocephalic. 



From these several facts we can to a certain ex- 

 tent understand the means through which the great 

 size and more or less rounded form of the skull has 

 been acquired by man ; and these are characters emi- 

 nently distinctive of him in comparison with the lower 

 animals. 



Another most conspicuous difference between man and 

 the lower animals is the nakedness of his skin. Whales 

 and dolphins (Cetacea), dugongs (Sirenia) and the hip- 

 popotamus are naked ; and this may be advantageous 

 to them for gliding through the water ; nor would it 

 be injurious to them from the loss of warmth, as the 

 species which inhabit the colder regions are protected 

 by a thick layer of blubber, serving the same purpose 

 as the fur of seals and otters. Elephants and rhino- 

 ceroses are almost hairless ; and as certain extinct 

 species which formerly lived under an arctic climate 

 were covered with long wool or hair, it would almost 

 appear as if the existing species of both genera had lost 



75 'Variation of Animals,' &c, vol. i. p. 117 on the elongation of the 

 skull; p. 119, on the effect of the lopping of one ear. 



76 Quoted by Schaaflhausun, in ' Anthropolog. Review,' Oct. 1868, 

 p. 419. 



