143 



increased steadily and largely during the past twenty years. But altliougli herrings 

 have been somewhat scarcer in some years than others, there is absolutely no evidence 

 that the supply has gradually decreased. On the contrary, the foUowing figures vpill 

 show that the supply has on the whole increased as the number, efficiency, and size 

 of boats ajid nets increased, but has not increased continuously in proportion to the 

 increase in the apparatus of capture, nor decreased after a certain maximum in 

 consequence of the great number annually captured. In fact as far as we can see at 

 present the abundance of herrings in different years fluctuates in consequence of 

 conditions not only beyond human control, but at present unknown. The number of 

 barrels of herrings cured in Scotland was : — 



833,160 



1,000,-561 



841,796 



1,473,600 



1,111,155 



1,697,952 



;, 1,118,872 



But, on the other hand, we know that human rapacity and recklessness have entirely 

 or nearly exterminated certain species of animals which were at one time very 

 abundant in certain region.^. The Dodo and the Ehytina were exterminated by man, 

 and the Greenland whale and the American bisoji seem to be rapidly approaching the 

 same end. The Dodo was confined to the island of Mauritius, and seems to have 

 been more persecuted by the domestic animals introduced by the Dutch discoverers of 

 the island than by the Dutch themselves : it could only have been sayed by being 

 domesticated, and apparently it was not sufficiently valuable to be worth keeping. 

 The Rhytina was a kind of Manatee which lived on Behring's Island and Copper 

 Island in the North Pacific, and was extremely numerous on the former in 1741, when 

 the island was first discovered. It was exterminated in less than fifty years by Russian 

 hunters and tradei's who lived upon its flesh. The Rhytina was of enormous size, and 

 quite harmless, and its extinction was doubtless largely due to these circumstances, 

 which made its slaughter easj', and to its slow rate of multiplication. 



The history of the northern fur seal of the Behring Sea is less mournful, and at the 

 same time most interesting and instructive. This species, CaUorhinus ursinus, breeds 

 only on two islands of the Pribylov group off the coast of Alaska, on the Commander 

 Islands in Behring Sea, and one other in the same region. The seals arrive at these islands 

 late in spring, and remain on shore until the beginning of November. The females bring 

 forth their pups soon after landing, and before the mothers leave the islands these pups 

 are weaned, and able to travel with them. During the winter months the seals seem to 

 disperse and live in the sea, but I have found no account of their mode of life during this 

 period. In 1870 the Alaska Commercial Company of San Francisco received a lease 



