276 ZOOLOGY. 



exist, which either serve as reservoirs or which have tin- 

 power of secreting water. Tn Arabia it is held to be t In- 

 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 lama, 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. 



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 

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

 horizontal flipper composed of two flanges. The marsouins 

 (Fig. 170), the dolphins, the cachalots, and the bahenae, or 

 whales properly so called, belong to this group. 



The whales are enormous cetaceans, whose head forms 

 about a third of the.length of the whole body. In the mouth 

 there are no teeth, but numerous plates of whalebone depend 

 at the sides from the mucous surface of the upper jaw. They 

 are so arranged as to form towards the mouth a sieve, 

 calculated to retain very small animals, on which indeed 

 these huge cetaceans live. The volume of water they take into 

 the mouth is expelled through the nostrils ; hence the name 

 of blowers and blow-holes given to their anterior or superior 

 nostrils.* Contrary to what might be imagined, these enor- 

 mous animals live generally not on fishes, but on small mol- 

 lusca, Crustacea, zoophytes, and generally the lowest marine 

 animals. They swim rapidly, and are timid and fearful ; 

 hence they are easily destroyed by the whalers. 



There are several species of whalebone whales, but that 

 which is most sought after, by reason of the length of whale- 

 bone and the abundance of blubber it possesses, is the Green- 

 land whale, or whale of commerce ; formerly perhaps abun- 

 dant in the European seas, but now driven by persecution to 

 take refuge in the Northern and Polar Seas. It has no dorsal 

 fins. 



The cachalot or sperm whale has teeth only in the lower 



* It has been shown by Scoresby, myself, Beale, and a number of other 

 observers, that the pretended ,;>< d'eau is merely the vapour from its lungs. 

 H. K. 



