MAMMALIA. 309 
Order III. Whales (Cefacea). General Characteris- 
tics—We now come to the largest living animals, milk- 
givers, that live entirely in the water, and are in form fish- 
like. The fore-limbs are paddles, having bones similar to 
those of the arm and hand of man; the hind-limbs absent 
or rudimentary, the caudal extremity being provided with 
a horizontal, fish-like tail that is the principal locomotive 
organ. They are often confused with fishes, but are vivip- 
arous, suckling their young (Fig. 334), giving rich, creamy 
FIG. 334.—-The humpback-whale suckling her young. (After Scammon.) 
milk. They breathe air by means of lungs, having a pro- 
vision that enables them to remain under water for over 
an hour without breathing. This consists of a large num- 
ber of reserve blood-vessels that line the interior of the 
chest and spaces between the ribs, only a portion of this 
blood passing into-circulation from time to time. The 
nostrils are upon the top of the head, and form blow-holes 
through which vapor, #ot water,* is forced. The jaws of 
* This error is found in many works, but the whale no more spouts 
water through its nostrils than can « human being. The so-called 
spouting is vapor, the moisture of the breath and mucus from the 
nostrils, 
15 
