MAMMALIA. 



309 



Order III. Whales (Cetacea). 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, not 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 a human being. The so-called 

 spouting is vapor, the moisture of the breath and mucus frofn the 



nostrils. 



22 



