404 VERTEBRATE ZOOLOGY 



commodity has been greatly depressed. A single large whale pro- 

 duces several tons of whalebone, and, since a ton used to be worth 

 about ten thousand dollars, the capture of a single baleen whale 

 meant a small fortune to the whaler. 



Rorquals are a type of whalebone whale with comparatively 

 small heads, a distinct dorsal fin, and with a throat deeply corrugated 

 into longitudinal furrows. The flipper has only four fingers, but 

 each finger is very long, having many extra joints. They range 

 in length from forty to nearly seventy feet; one species has a 

 record of eighty-five feet in length. The cervical vertebrae are all 

 separate. 



Right Whales are the more typical baleen whales. They have 

 no dorsal fin; the head is very large, being about one-fourth of the 

 entire length; the baleen is very long; the throat is not corrugated; 

 the cervical vertebrae are fused into a solid mass. The Greenland 

 right whale is, perhaps, the best known of all whales. It has a very 

 limited distribution, being confined to the Arctic Ocean. It grows 

 to be about seventy feet in length. The pursuit of whaling used to 

 be one of the most romantic and dangerous of human occupations; 

 but with the advent of whaling guns, with which the great creatures 

 may be harpooned at a safe distance, the danger is largely eliminated, 

 though much of the romance remains. The southern right whale, a 

 close relative of the Greenland species, has. a wide range, avoiding 

 only the Arctic regions. The two species never occur in the same 

 territory. It is less prized by the whaler on account of the relatively 

 short and coarse whalebone. 



Whales as a whole are much less numerous than they were a cen- 

 tury ago and it seems probable that, unless some protection is given 

 them, they are likely to become extinct before another century rolls 

 by. Man seems to have no compunctions in his lust for commercial 

 profit, and even these noble creatures of the deep may soon go the 

 ways of the giants of ages past. 



THE DEVELOPMENT OF MAMMALS 



It is much more difficult to give a concise account of development 

 of mammals than of any other of the vertebrate classes, because 

 there is such a wide range of diversity of conditions. In the first 

 place it will be recalled that some of the mammals lay large eggs es- 

 sentially as in reptiles, that others have a sort of uterine gestation 



