All viviparous

quadrupeds are hair-coated, whereas man has only a
few short hairs excepting on the head, but, so far as the head is
concerned, he is hairier than any other animal. Further, of
hair-coated animals, the back is hairier than the belly, which
latter is either comparatively void of hair or smooth and void of hair
altogether. With man the reverse is the case.

Man also has upper and lower eyelashes, and hair under the
armpits and on the pubes. No other animal has hair in either of
these localities, or has an under eyelash; though in the case of
some animals a few straggling hairs grow under the eyelid.