Order CETACEA. 



This order embraces those mammals which have been 

 modified for a wholly aquatic life, and include the Whales, 

 Dolphins and Porpoises. 



The head is long, with usually a wide mouth ; the body 

 IS fish-like, and there is no apparent neck. 



At the posterior end of the body there are two 

 horizontally placed fins resembling the tail of a fish, and 

 which are known as flukes. There are no hairs on the 

 body, which is smooth, and there are only a few bristles 

 round about the mouth. In place of the hairy covering 

 of the terrestrial mammals, these animals have a thick 

 layer of fatty material under the epidermis ; this is known 

 as the blubber, and forms a lucrative article of commerce, 

 for which the unfortunate whales are continually being 

 hunted. 



The skull has a rounded brain-case, with a beak-like 

 rostrum ; the teeth, when present, are simple and uniform 

 and are not preceded by milk teeth. 



Sub-Order MYSTACOCETI. 



Whales with the palate provided with a large number 

 of plates of baleen (so-called whalebone), and with teeth 

 never developed after the birth of the animal. 



Sternum or breastbone composed of a single piece, and 

 connected to only one pair of ribs. 



Family BAL.ENID.^. 

 Geaus BAL^NA. 

 The skin of the throat is smooth, and there is no dorsal 

 fin. 



