240 On the Coloration of Marine Animals. 



the porpoises, and some, like the killer, are boldly blotched 

 ^vith wiiite, as also is the arctic seal. Moreover, the hump- 

 backed whale {Meqapicra loiujimana) has pure white flippers 

 12 feet long, whilst the smaller rorqual has a bold white 

 band across the flipper. The well-known Beluga is dull 

 whitish all over. As all cetaceans come to the surface to 

 breathe, they must frequently expose a black or brownish- 

 black surface. Now black is a tint which is conspicuous in 

 the sea, and accordingly the fishermen use black flags in 

 preference to white on their dandys, since they are so easily 

 recognized in the darkness or dull light of the early morning. 

 That black should be a protection to these animals, and tliat 

 species are whitish all over or have pure white flippers or 

 bands, is a condition of things creative of uncertainty in 

 regard to the theories alluded to. The bold white touches, 

 for example, of the killer can scarcely be held to be recog- 

 nition-markings, like the white tail of the rabbit. The 

 variegated hues of the arctic seal may subserve protection. 

 If they do, those of other colours are at a disadvantage. 

 Considerable variety, indeed, occurs in the group ; thus the 

 elephant-seal is dull greyish above, light beneath, and the 

 sea- leopard is spotted yellowish white and dark grey on the 

 back, with a yellowish under surface. The sirenians are dull 

 brownish dorsally and ventrally, so that the lighter hue seen 

 against the sky is absent in their case ; but, on the other 

 hand, they are not oceanic. 



A general survey of the coloration of marine animals raises 

 doubts as to the interpretations which have been brought 

 forward to explain it. Some of these explanations, it is true, 

 are more or less in agreement with facts ; but, so far as can 

 be seen, other facts are adverse, and demonstrate the extreme 

 caution necessary in dealing with such interpretations. 

 Before anything definite can be produced a much more exten- 

 sive, more exact, and long-continued series of observations 

 on the subject is imperative. That the coloration, often so 

 varied and so beautiful, is of importance to n)arine animals 

 can scarcely be doubted, for Nature is ever prescient ; but it 

 is not always easy to adapt the theories of the day to her 

 workings. 



