320 TYPES OF ANIMAL LIFE 



Its most remarkable character is the great length of its 

 fin-like arms, and it differs also from the true whales in 

 having numerous long grooves, or folds, extending 

 beneath the throat. 



Certain whales, known as rorquals, finbacks, or razor- 

 backs, have still more numerous folds beneath the throat ; 

 they have also a dorsal fin, but only four fingers are 

 enclosed in their relatively short limb. These are the 

 commonest kinds of whales, and some of their varieties 

 are to be found all over the world except in extreme polar 

 regions. The blue rorqual is the largest animal known, 

 attaining sometimes a length of seventy feet. It feeds 

 on fishes and largely on herrings, but other varieties 

 feed exclusively on shrimp-like creatures. 



The rorquals have much shorter whalebone and much 

 less blubber than have the right whales, so that they 

 were little cared for till of late, when on account of the 

 increasing rarity of the more valuable species, rorquals 

 have begun to be regularly fished. The grey rorqual 

 frequents the western shores of the United States from 

 December to March, and the females enter the lagoons 

 of Lower California to bring forth their young. In 

 October and November they skirt the coasts of Cali- 

 fornia and Oregon going southward. 



The toothed whales are far more numerous in species 

 than are the whalebone whales. They ought rather to 

 be called " whaleboneless " than toothed, as a few kinds 

 have no teeth, while a whole section of the group is 

 without any teeth in the upper jaw, and there may be 

 but a pair in the lower jaw. 



The sperm whale, or cachalot, is the giant of the 

 group, attaining a length of from fifty-five to sixty feet. 

 One-third of this total length is occupied by the head, 

 which, seen in profile, has a rectangular anterior end, 



