ORDER CETACEA. 483 



small distance from the anus, is a mamma situated, with a 

 longitudinal folded furrow, the skin of which is less hard 

 than that which covers the rest of the body. This mamma 

 is flatted, and not much apparent, except when the animal 

 is giving suck. This lacteal reservoir then expands so 

 much as to equal about the fiftieth part of the entire length 

 of the body. The Whale's milk very much resembles that 

 of the Cow, but contains more cream and a greater quantity 

 of nutritive matter. 



The orifice of the anus, which consists in a round or oval 

 aperture, is situated between the parts of generation and the 

 extremity of the tail. 



The skin of the Balsenas without scales, tubercles, or 

 hairs, is very strong, though penetrated by a multitude of 

 large pores. In certain species it is more than eight inches 

 thick. 



The epidermis is very smooth, porous, and composed of 

 several layers. It shines because it is penetrated with a 

 sort of oil, which in the rays of the sun makes it appear 

 like polished metal. This oil besides diminishing the 

 rigidity of the skin, preserves it from those injurious 

 changes it might otherwise experience by the alternate so- 

 journ of the animal under water, and on its surface. 



The mucous tissue or rete mucosum, which separates 

 the epidermis from the true skin, is thicker than in other 

 mammifera. Its colour which is communicated to the epi- 

 dermis, varies much, not only in the different species, but 

 in individuals of the same kind, by reason of age, sex, and 

 probably the temperature of the usual habitat. In some, it 

 is of a pure and deep black, in others, of a black shaded 

 with gray. Many species are half brown and half white, 

 while the under parts of the body are of a dazzling white. 

 Almost all the Whales of Spitzbergen are entirely white. 

 Some Cetacea are marked irregularly with white upon a 

 black or gray ground, but this appears to be the result of 

 wounds which have become cicatrized. 



