348 



COMPARATIVE ZOOLOGY. 



7. Cetacea, or Whales, have the form and life of Fishes, 

 yet they possess a higher organization than the preceding 

 orders. They have a broad brain, with many and deep 

 foldings; the foramen magnum of the skull is entirely 

 posterior; the whole head is disproportionately large, and 

 the jaws greatly prolonged. The body is covered with a 

 thick, smooth skin, with a layer of fat (" blubber") under- 



Fiq. 341 — Outline of the Sperm-whale (Physeter) : a, blow-hole ; 6, the case contain- 

 ing spermaceti ; c, junk ; tZ, bunch of the neck— between it and the corner of the 

 mouth is the eye ; h, hump ; i, ridge ; k, the small ; /, tail, or flukes. Between 

 the dotted lines are the spiral strips of blubber. Maximum length, sixty feet. 

 South Atlantic. 



neath ; there are no clavicles ; the hind-limbs are want- 

 ing, and the front pair changed to paddles; the tail ex- 

 pands into a powerful, horizontal fin ; neck and external 

 ears are wanting ; the eyes small, with only two lids ; the 

 nostrils ("blow-holes") — double in the Whale, single in 

 the Porpoise — are on the top of the head. All are carniv- 

 orous, and essentially marine, a few Dolphins only be- 

 ing found in the great rivers. In the Whalebone Whales,, 

 the teeth are absorbed, and disappear before birth, and 

 their place is supplied by horny "baleen" plates. "The 

 Whale feeds by putting this gigantic strainer into opera- 

 tion, as it swims through the shoals of minute Mollusks, 

 Crustaceans, and Fishes, which are constantly found at the 

 surface of the sea. Opening its capacious mouth, and al- 

 lowing the sea- water, with its multitudinous tenants, to fill 

 the oral cavity, the Whale shuts the lower jaw upon the 

 baleen plates, and, straining out the water through them, 

 swallows the prey stranded upon its vast tongue." In the 



