S3 LLOYD'S NATURAL HISTORY. 



has the nostrils, which may be either single or double, placed 

 near the top of the crown, and thus far removed from the 

 muzzle ; this feature at once serving to distinguish Cetaceans 

 from Sirenians. Both the eye and ear are small; the latter 

 merely forming a minute aperture in the skin, placed some 

 distance behind the former, and showing no trace of a conch. 

 The majority of Cetaceans have a vertical fin in the middle of 

 the back, very similar in appearance to the fin of some fishes, 

 although lacking the bony .internal skeleton found in the latter. 

 With the exception of a few fine bristles in the neighbourhood of 

 the mouth, which are frequently lost in the adult, the skin is 

 entirely naked, and smooth and glistening in appearance; 

 while beneath it lies a thick layer of oily fat the blubber 

 to protect the body from the chilling effects of submersion 

 in the water. In all existing members of the Order in which 

 they are present, the teeth are of an exceedingly simple 

 structure. 



The foregoing characters being sufficient to distinguish the 

 Cetaceans from all other Mammalian Orders, are all that need 

 be mentioned here. 



As regards their mode of life, it is almost superfluous to 

 observe that all Cetaceans are purely aquatic Mammals, pass- 

 ing the whole of their time in the water, and becoming im 

 mediately utterly helpless when once stranded on the shore. 

 Whereas the majority are denizens of the ocean some keep- 

 ing exclusively to the open sea, while others more generally 

 frequent the vicinity of the coast a few are inhabitants of 

 certain large rivers of the warmer regions of the globe, many 

 of them, which are normally marine, occasionally ascending 

 tidal rivers. Carnivorous in their diet, Cetaceans vary greatly 

 in the nature of their food, some of the largest species feeding 

 on organisms of the most minute size. While many of the 

 smaller kinds live on fish, the ferocious "Killer" Whale alone 



