242 ^'I^-^V VORK ZOOLOGICAL SOCIl-.TV. 



Canadian relatives and ilie t>])c from the Cascade Mountains 

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

 all other goats, both American and Canadian. 



C.\USE.S GOXT.RXtXr, DISTRIP.T'TIOX. 



The distribution of tlie genus is limited by the character of 

 tlie moimtain ranges, rather than an\ other consideration, and 

 too nuich 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 ])recipitons j)eaks and ridges, which even the 

 mountain sheep seldom approach. 



The extreme north and south ranges of Orcaimu's in the main 

 Rockies present several i)roblems of great interest. The south- 

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

 ruggedness of the mountains lliemseKes. wbicb, 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 oi" their present limit. A \-i'ry dillercnt 

 condition prevails in the north. At ibe extreme northern limit 

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

 but are still of considerable size and (|uite rugged enough 

 to provide a suitable home for Oreaiiiiios. White sheep are 

 found all through tlu'se mountains, u]) to the very coast of the 

 Arctic Ocean and westward through the Komanzott Mountains in 

 northern Alaska. These sheep are certainly not better erpii])ped 

 to resist arctic cold than are the goat, so we nuist st'ck tor souie 

 cause other than climatic or topographical conditions. There 

 must be some unknown and unfavoral)le condition of food supply 

 whicli prevents Orcaiiiitos from reaching the extreme north. This 

 is perhaps the most interesting and difficult of the ])ro1)lems affect- 

 ing the distribution of the genus. 



Along the Pacific coast of the Cnited .States the niouniains are 

 not sufficientK- ])recipitous to attract the goat, and conse(|ueiitly 

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

 western I'ritish Columbia and southern Alaska, the Rockies a|)- 

 proach the coast in stn])endons chains, which ■-wing wx'Stward 

 through the Mt. St. Julias range. Tbrou-b all ibis country the 

 goat occupies the coast region from I'rinct- W illiam ."^ound south 

 nearly to the American border. They ar^' not louud in an\- of 

 the adjacent islands. 



Along these coast ranges goat ari- much niore numerous than 

 in the main Rockies, owing probabK to ibe prisence ot forests 



