EXTERNAL FEATURES 



ceti organ, but its abundance until harried by man proves that speed was 

 not requisite to the filling of its stomach and its lack of capacity for swift- 

 ness, as well, indeed, as in the case of other large, slow whales, is doubt- 

 less a secondary acquisition. At least most of the larger, pelagic Odon- 

 toceti feed largely on squids and other cephalopods, which are among 

 the most agile of sea forms, and how some of the slowest swimming of 

 whales manage to secure the vast quantities which they require is a 

 puzzle. 



Among the baleen whales or Mysticeti, the speed of the more slender 

 sorts, the rorquals, is astonishing for a body that sometimes approaches 

 a length of 100 feet. By a possible speed estimated to be above thirty 

 miles per hour they can often escape the killer whale, which is one of the 

 most relentless enemies of the slower genera, and in addition, such speed 

 probably secures for them a relative freedom from ectoparasites. At least 

 it is a fact that these pests are rarely found upon the fast rorquals, while 

 they usually abound upon the slower mysticetes. The baleen whales do 

 not secure their food by direct pursuit but by swimming leisurely with 

 mouth partly open through hordes of crestaceans and small fish. Hence 

 the speed of the rorquals has been developed either for the purpose of 

 escaping from thir enemies, or very likely partly to enable them to travel 

 rapidly from one feeding ground to another; for the half -inch crusta- 

 ceans which constitute their favorite food are local and may not be easily 

 found in the quantities necessary for such vast appetites, so that fre- 

 quently it should be necessary for the whales to cover great distances 

 between meals. 



The very appearance of these vast cetaceans bespeaks of speed, with 

 their relatively slender bodies and great bulge of muscles and tendons 

 above and below the peduncle. And equally eloquent are the shorter, 

 more ponderous bulks of the gray, humpback and balaenid whales. They 

 are much slower and the grays, at least, often succumb to onslaughts of 

 the killer whale; but in spite of this they occurred within their rather 

 restricted range in prodigious numbers until the depredations of the 

 whalers decimated their ranks so sadly. 



When a mammal reaches the stage when it spends most of its time 

 in the water it must either have developed a quality of pelage that will 

 retain the air that fills the interspaces or have modified its skin to with- 

 stand any detrimental action of the water. Especially if it be of boreal 

 or even temperate habitat will the tendency rather be for the underfur 

 to take on a fine and particularly dense texture, and accompanying this 

 will usually if not always be fine adjustments in the functioning of the 



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