92 A BOOK OF WHALES 



The body of the Sirenia is, however, more hairy 

 than that of whales ; yet the hair is scant and 

 coarse. Dr. Kiikenthal has discovered that formerly 

 these animals possessed, in addition to the sparsely- 

 scattered strong hairs, a covering of finer hairs. In 

 these animals, therefore, as in the whales, the aquatic 

 life leads to the loss of the hairy covering of the 

 body, so characteristic of land mammalia. It may 

 be mentioned, moreover, that the hairs are especially 

 strong upon the upper lip, thus recalling the only 

 hairs that are left in the whales, which clothe, or 

 rather are found upon, the same region. Sweat 

 glands, moreover, fail entirely, as in whales. Only 

 in an embryo of Manatus latirostris did Kiikenthal 

 find some after all rather doubtful traces of these 

 glands. They are, of course, absent in whales. 



Finally (so far as concerns the skin), the sebaceous 

 glands, such constant companions of the hairs in 

 mammals generally, are beginning to vanish alto- 

 gether in the Sirenia. They occur, however, though 

 in a rudimentary shape, in the fcetus, while they are 

 completely absent in the few hairs of the whales. 



As in the whales, the skin of the Sirenia is under- 

 laid by a copious blubber, which doubtless plays the 

 part, that should be performed by the hair, of pre- 

 serving the heat of the body. It has, however, been 

 remarked that in the Sirenia the blubber is unlike 

 that of the whales in that there is no free liquid 

 oil comparable to the spermaceti of the Sperm and 

 other whales. 



The Sirenia have, like the whales, the fore limb of 



