VOYAGE OF THE 'ECLIPSE.' 129 



portant point, viz. the mode of their survival. Both find it 

 necessary to retire from the surface to obtain their food ; there- 

 fore each must be able to exist in a state of activity for a longer 

 or shorter period with the respiratory organs secluded from 

 the atmosphere. Provision to permit this therefore becomes 

 necessary, suited, however, to different requirements and circum- 

 stances. In the first instance, we find that a large store of 

 blood, and perhaps a sluggish circulation, are perfectly com- 

 patible with the slowness of motion of the Greenland Eight 

 Whale ; that this is the case we have only to regard the robust- 

 ness of the animal and its clumsy appearance. In the second 

 instance, however, a large store of blood, and necessarily also 

 great bulk, are not compatible with the active habits and swift 

 movements of the Blue Whale. Although undoubtedly the 

 fullest possible advantage of this alternative is taken, yet if 

 provision so obtained were alone inadequate, we should expect 

 to find some other alternative taken advantage of to the extent 

 required. If so, then some trace of this in the organization of 

 the creature will be found. I allude, of course, to dermal 

 respiration, the possibility of such playing the part required has 

 only to be remembered to lead us to ex^^ect that sucb a simple 

 and convenient means of eft'ecting her end would not be over- 

 looked by stature. The numerous plicce along the under surface 

 of the body, of which no reasonable explanation has yet been 

 given, have evidently the function of increasing the surface of 

 the skin exposed to the surrounding medium, and these are, 

 I venture to think, simply an adaptation to the additional 

 respiration carried on by the dermis, as rendered necessary by 

 the circumstances already explained. 



Eegard now all the Whalebone Whales, and to them as a 

 class apply the same argument. Living upon food of the same 

 nature, all the members of this group agree in so far as they 

 are supplied with a similar apparatus for its capture, viz. the 

 characteristic baleen-plates. As we have already seen, however, 

 some for their survival depend upon their ability to withstand 

 pressure, others on their speed. Accordingly, as some belong 

 to the former class and may be called " divers," others belong to 

 the latter and may be called "non-divers ; " they differ from one 

 another essentially only in the special characters rendered 

 necessary. With the first group, the smooth whales (Balcenidce) 



