576 MANUAL OF ZOOLOGY. 



watery vapour of which is suddenly condensed on its entrance 

 into the cold atmosphere. With the expired air there may be 

 such water as may have gained access to the nose through the 

 blow-hole, for the expulsion of which proper provision exists 

 in the form of muscular diverticula of the nasal cavity. It is 

 also possible that the column of air in being forcibly expelled 

 from the blow-hole may take up with it some of the super- 

 incumbent water. 



The skin in the Right Whale is perfectly smooth and naked, 

 but it is underlaid by a thick layer of subcutaneous fat, which 

 varies from eight to fifteen inches in thickness, and is known 

 as the "blubber." The blubber serves partly to give buoy- 

 ancy to the body, but more especially to protect the animal 

 against the extreme cold of the medium in which it lives. It 

 is the blubber which is chiefly the object of the whale-fishery, 

 as it yields the whale-oil of commerce. 



The whale which is captured in the Antarctic regions is not 

 the same species as the Greenland Whale, and is termed the 

 Balcena australis. It is much about the size of the Right 

 Whale, averaging about fifty feet, but the head is proportion- 

 ately smaller. This whale is an inhabitant of the greater part 

 of the Pacific out of the regions of the tropics ; but it is chiefly 

 captured when approaching land, which the females do for the 

 purpose of bringing forth their young. 



The only remaining members of the Balcenidce which require 

 notice are the Rorquals and Hump-backed Whales, constitut- 

 ing the group of the " Furrowed " Whal-es. These are collec- 

 tively distinguished by having the skin furrowed or plaited to 

 a greater or less extent, whilst the baleen-plates are short, and 

 there is a dorsal fin. The specific determination of these 

 animals is a matter of great difficulty, but there would appear 

 to be probably three well-marked genera: i. The genus. 

 Megaptera, including the so-called Hump-backed Whales, in 

 which the flippers are of great length, from one-third to one- 

 fifth of the entire length of the body. 2. The genus Balcznop- 

 tera, comprising the so-called Rorquals or Piked Whales, in 

 which the flippers are of moderate size. 3. The Finner 

 Whales proper \Physalus}. 



In all these genera there is a dorsal adipose fin, so that they 

 are all " Finner Whales/' The Balanoptera reach a gigantic 

 size, being sometimes as much as eighty or one hundred feet 

 in length. They are very active animals, however, and their 

 whalebone is comparatively valueless, so that the whalers 

 rarely meddle with them, though they are not uncommon, and 

 are often driven ashore on our own coasts. 



