249 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 Oreammnos 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 
