GENERAL HISTORY. 91 



and, on the other side of the Atlantic, the shores of Greenland 

 and Arctic America westward to the western shores of Hudson's 

 Bay and Fox Channel. There is thus left between these two 

 regions nearly the whole of the coast of Asia bordering on the 

 Polar Sea on the one hand, and almost the whole of the coast 

 of North America formed by the Arctic Sea on the other. 



In the later portion of his chapter on the distribution of the 

 'Walruses he devotes a few pages to a consideration of their 

 migrations, and the physical causes which limit their distribu- 

 tion. Their migrations, he believes, are very imperfectly known, 

 but he inclines to the opinion that they only periodically visited 

 such points in their former range as Sable Island and other 

 southerly lying islands. The causes which limit their range he 

 considers to be mainly temperature, since he finds the southern 

 boundary of their distribution is deflected northward and south- 

 ward in accordance with the curves of isothermal lines. 



The former range of the Walruses is also considered at length, 

 to which subject are devoted nearly twenty-five pages. A short 

 account is given of their reproduction and food, the paper clos- 

 ing with an inquiry into their systematic relationship to other 

 animals. The map accompanying his memoir shows not only 

 the distribution of the Walruses as at that time known, but 

 indicates also the region over which they are known to have 

 formerly occurred, and also the habitat of the BJiytina, or Sea- 

 cow of Steller. 



The reception in London, in 1853, of a young living Walrus 

 gave rise to a paper by Owen * on its anatomy and dentition, 

 and another by Gray,t " On the Attitudes and Figures of the 

 Morse." A short paper was contributed by Sundevallf in 1859 

 on its general history. 



Leidy, in I860, published an important paper on the fossil 

 remains of Walruses found on the eastern coast of the United 

 States, while Gratiolet, Defrance, Lankester, and Van Beneden 

 have also written about those that have been met with in 

 France, England, and Belgium. 



Malrngren, in 1864, in a paper on the Mammalian Fauna of 



*Proc. Zool. Soc. Lond., 1853, pp. 103-106. 



tlbid., pp. 112-116, figs. 1-10. 



t Oin Walrossen, Ofversigt K. Vet. Akad. Fork. (Stockli.), xvi, 185'J, pp. 

 441-447 ; also translated in Zeitschr. gesammt. Naturw. Halle, xv, 1860, pp. 

 270-275. 



$ Sec antea, pp. 61-65. 



