50 BRITISH MAMMALS 



within it a male foetus which measured nearly 20 ft. in length. 

 In this species the head is much larger proportionately than in the 

 common rorqual, while the flippers are longer and broader. 

 There are also a great many more folds in the throat and belly. 

 The dorsal fin near the tail is reduced to little more than a slight 

 protuberance. The colour of the baleen is deep black, thereby 

 contrasting strongly with the yellowish-gray of the common 

 rorqual's whalebone. The colour of the body is dark gray 

 above, shading into lighter gray on the belly. The gray of this 

 whale is often quite bluish in tone, for which reason it is known 

 amongst whalers as the " blue " whale. Its gray coloration is 

 also varied by small whitish spots on the breast. The upper side 

 of the flippers is black and the under whitish. Off the east 

 coast of America the under parts of this whale have frequently 

 a lemon-yellow tinge. The " blue " whale feeds principally on 

 small pteropods and crustaceans, such as Clione, Euphausia, 

 and 'Thrysanopoda. It also eats small fish, such as sardines 

 and sprats. This whale seems to be distributed throughout the 

 greater part of the Atlantic, Pacific, and Indian Oceans, unless 

 in the last-named sea its representative is a difi^erent species or 

 variety. It is fairly abundant in the North Sea, being much 

 attracted to the coasts of Norway, because of the presence in the 

 fiords of the crustaceans on which it lives. Its occurrence in 

 British waters is a much rarer event than is the case with the 

 common rorqual, but it has been washed ashore at various points 

 of the Scottish coast, in the Hebrides, and on the north-east coast 

 of England. Sibbald's whale yields much more oil proportion- 

 ately than does the common rorqual. 



Balanoptera borealis. Rudolphi's Rorqual 



This whale scarcely reaches to 50 ft. in length. Its flippers 

 are very short proportionately. The whalebone is black, except 

 at the extremities, where it turns white. The upper parts of this 

 whale's body are bluish-black, marked with oblong spots of light 

 gray ; the under parts of the body are whitish-gray. The upper 

 surface of the flippers is entirely black. The throat is streaked 



