154 NATURAL DEATH IN THE ANIMAL WORLD 



by the shoal being enclosed by ice in a small hole, where 

 the water could not receive a fresh supply of oxygen. 

 This is a common form of natural death among fish 

 in cold countries ; but the explorer remarks it for 

 the following reasons. * I mention this,' he observes, 

 ' because such examples of " self-dead " vertebrate 

 animals are found exceedingly seldom. They therefore 

 deserve to be noted. . . . During my nine expedi- 

 tions in the Arctic regions, where Arctic life during 

 the summer is so exceedingly abundant, the case just 

 mentioned has been one of the few in which I have 

 found remains of modern vertebrate animals which 

 could be proved to have died a natural death. Near 

 the hunting grounds there are often to be seen the 

 remains of reindeer, seals, foxes, or birds that have 

 died from gunshot wounds, but no ll self-dead " Polar 

 bear, seal, walrus, white whale, fox, lemming, or other 

 vertebrate. The Polar bear and the reindeer are found 

 there in hundreds ; the seal, walrus, and white whale in 

 thousands, and birds in millions. These birds must die 

 a " natural death " in untold numbers. What becomes 

 of their bodies?' Of this we have at present no idea ; 

 and yet we have here a problem of immense importance 

 for the answering of a large number of questions con- 

 cerning the formation of fossil-bearing strata. It is 

 strange in any case that on Spitzbergen it is easier to 

 find the vertebrae of a gigantic lizard of the Trias than 



