536 EXTINCT AND VANISHING MAMMALS 



accomplished hardly more than a quarter of a century later, 

 by 1768. 



On various occasions expeditions have since visited the 

 islands without finding any further evidence as to the precise 

 date of extermination. Nordenskib'ld, however, believed from 

 what he could learn that it might have persisted into the 

 nineteenth century, but there seems no definite ground for 

 this supposition. Bones have been collected by various natu- 

 ralists. J. F. Brandt in his Symbolae Sirenologicae (1846 and 

 1861-68) described and figured the skeleton and added a 

 resume of the animal's history from the account of Steller. 

 According to Kuntze (1932), the Russian naturalist Dybowski 

 in 1879-85 collected reports and skeletal remains at Bering 

 Island; he was told by the natives there that the great sea-cow 

 still survived at the time of the arrival of the permanent 

 settlers, which would extend the period of its existence to about 

 1830. He mentions also as a contributing factor to its extinc- 

 tion the formation of ice along the coast from time to time, thus 

 restricting still further its available territory. Stejneger (1887), 

 who visited the islands and collected many skeletal remains, 

 has written an excellent account of the history of its passing. 

 He believes that its supposed abundance may have been exag- 

 gerated, for Steller only says that he found it numerous. 

 Stejneger would regard "fifteen hundred as rather above than 

 below the probable number . . . There are hardly more 

 than fifteen places on the [Bering] island which could afford 

 them suitable grazing grounds, and if each of these were 

 regularly visited by an average of one hundred animals, one 

 would easily be impressed by their number." At the neigh- 

 boring Copper Island there were probably even fewer, for in 

 1754, when Jakovleff visited it, the sea-cows had already been 

 exterminated, only nine years after the island's discovery. 

 From 1743 until 1763, "hardly a winter passed without one or 

 more parties spending eight or nine months in hunting fur- 

 animals there [Bering Island], during which time the crews 

 lived almost exclusively on the meat of the sea-cow. But that 

 is not all, for more than half of the expeditions which wintered 

 there did so for the express purpose of laying in stores of sea- 

 cow meat for their farther journey, which usually lasted two to 

 three years more . . . From 1763 the visits to Bering 

 Island seem to grow scarcer . . . probably due to the 



