18 NEW YORK ZOOLOGICAL SOCIETY. 



Canadian relatives and the type from the Cascade Mountains 

 possesses a broad skull, in direct contrast to the narrow skulls of 

 all other goats, both American and Canadian. 



CAUSES GOVERNING DISTRIBUTION. 



The distribution of the genus is limited by the character of 

 the mountain ranges, rather than any other consideration, and 

 too much emphasis cannot be placed on the fact, that of all our 

 North American animals the white goat is the only one abso- 

 lutely confined to precipitous peaks and ridges, which even the 

 mountain sheep seldom approach. 



The extreme north and south ranges of Oreamnos in the main 

 Rockies present several problems of great interest. The south- 

 ern limit is clearly marked by a change in the formation and 

 ruggedness of the mountains themselves, which, together with 

 climatic conditions, and the lack of water in summer on the 

 mountain tops, are sufficient to account for the absence of these 

 animals much south of their present limit. A very different 

 condition prevails in the north. At the extreme northern limit 

 which is about 63 30', the mountains begin to lose their height 

 but are still of considerable size and quite rugged enough 

 to provide a suitable home for Oreamnos. White sheep are 

 found all through these mountains, up to the very coast of the 

 Arctic Ocean and westward through the Romanzoff Mountains in 

 northern Alaska. These sheep are certainly not better equipped 

 to resist arctic cold than are the goat, so we must seek for some 

 cause other than climatic or topographical conditions. There 

 must be some unknown and unfavorable condition of food supply 

 which prevents Oreamnos from reaching the extreme north. This 

 is perhaps the most interesting and difficult of the problems affect- 

 ing the distribution of the genus. 



Along the Pacific coast of the United States the mountains are 

 not sufficiently precipitous to attract the goat, and consequently 

 that animal is found only at some distance inland, but in north- 

 western British Columbia and southern Alaska, the Rockies ap- 

 proach the coast in stupendous chains, which swing westward 

 through the Mt. St. Elias range. Through all this country the 

 goat occupies the coast region from Prince William Sound south 

 nearly to the American border. They are not found in any of 

 the adjacent islands. 



Along these coast ranges goat are much more numerous than 

 in the main Rockies, owing probably to the presence of forests 



