OF THE CLASS MAMMALIA. 299 



the deserts of Asia and Africa. It is exceedingly temperate 

 as to the use of water, a quality which has been ascribed to 

 the peculiar form of its stomachs ; in two of these large cells 

 exist, which either serve as reservoirs or which have the 

 power of secreting water. In Arabia it is held to be the 

 most valuable of animals. Of the long hair which it casts 

 annually, the Arabs make tents and clothing ; they use the 

 milk ; and as a beast of burden and of sudden flight it is 

 invaluable. 



Finally, the llama, of which there are several species, is 

 peculiar to South America. It resembles the camel in many 

 respects, and especially in the structure of its stomach ; but 

 it has no hump. 



Fig. 274. Sperm Whale. 



422. The fish-formed mammals comprise only a single 

 order that called cetacea. They are strictly aquatic, and 

 resemble fish somewhat in their forms. In these the pelvic 

 limbs are wanting, and the pectoral are converted into 



Fig. 275. Skeleton of the Korqual Giganteus.* 



swimming paws or fins ; the tail is terminated by a broad 

 horizontal flipper composed of two flanges. The marsouins 

 (porpoises) (Fig. 193), the dolphins, the cachalots, (sperm 



* This specimen was dissected by myself and brother ; it measured eighty 

 feet in length. The upper jaw and cranium weighed a ton and a half; the 

 lower jaw-bones two tons. R. K. 



