/2 -Vl'HAI.EBONE AND WHALEBONE WHALES. 



yellowisli colour. Their flukes are, moreoTsr, less expanded 

 than are those of the right whales ; while, as already said, 

 their heads are relatively smaller and lower, with the 

 cavity of the mouth much less vaulted. In their skeletons, 

 the vertebrse of the neck differ from those of the right 

 whales in being longer and completely disconnected from 

 one another ; and in this respect the Pacific grey whale 

 holds a position intermediate between the two groups. 

 Hump-backs, of which there is but a single species, are 

 specially characterized by the shortness and depth of 

 the body, which behind the shoulder rises above the level 

 of the back-fin, and by the exceeding elongation and 

 slenderness of the flippers, which are about equal to 

 one-fourth the total length of the animal. The female 

 hump-back, which somewhat exceeds her partner in size, 

 attains a length of from forty-five to fifty feet, or about the 

 same as that of the Greenland whale. An enormous whale, 

 believed to belong to this species, became some years ago 

 entangled in the telegraph cable line ofl' the coast of 

 Baluchistan with three turns of the cable round its body. 

 On the other hand, in the rorquals, the body is long and 

 slender, while the flippers are small and pointed. Of the 

 ibur well-established species of this genus, the blue or 

 Sibbald's whale (Ji. sibhahli] — the " sulphur-bottom " of 

 the American whalers — enjoys the proud distinction of 

 being the largest of all known animals, whether living or 

 extinct, attaining the enormous length of from eighty to 

 eighty-five feet ; while the common rorqual {B. musculun) 

 comes in a good second with a length of from sixty-five 

 to seventy feet. Both the others are, however, con- 

 siderably smaller. 



As regards their distribution in time, whalebone whales 

 Jiave left their remains commonly enough in the Plio- 

 cene strata of all parts of the world, and they likewise 

 occur in those of the Miocene period ; but, although a 

 single vertebra from the Eocene beds of Hampshire has 

 been assigned to a member of this group, there is at 

 present no decisive evidence that they had come into 

 existence at such an early date. Since most of the Pliocene 

 species are of smaller dimensions than their living repre- 



