No. 635] THE HAIR OF MAMMALS 507 



The hair type chosen to be shown as the most repre- 

 sentative of each species is that type which, it was found, 

 in most cases constitutes the major portion of the body 

 covering, i.e., the fur, or under hair. This usually under- 

 lies a comparatively more or less sparse growth of 

 longer, coarser, stouter hair, which is termed the pro- 

 tective, or over hair. In typically aquatic mammals, such 

 as the seals, walruses, etc., the protective hair is thicker 

 than in those forms which are merely amphibious, such 

 as the platypus, muskrats, beavers, etc. In such mammals 

 as the whales, porpoises, etc., which are wholly aquatic, 

 the fur hair has apparently vanished altogether. The 

 only remaining hairs upon the body are, as a rule, con- 

 fined to a very few stout stubs of hairs, located commonly 

 in the region about the muzzle. In such hairs the cuticu- 

 lar scales are always of one type, illustrated by the muz- 

 zle hair of the dugong {Dugong dugong) (Fig. 159). 



In identification, however, it is sometimes necessary 

 to prepare for examination shafts of both the fur and the 



