356 ORNITHOLOGICAL EXPLORATIONS. 



But if it is true then that T^ible XIX disproves the climate as the 

 cause of the absence of representatives of the genera contained in 

 Tables XVII and XVIII, what can be the reason of such an extraordi- 

 nary phfenomenon ? 



Evidently we have to look for an explanation in the way by which the 

 jieninsula became inhabited. Kamtschatka is one of the most typical 

 and well defined peninsulas on the globe, and the climatological and 

 physical conditions of the part connecting it with the continent are 

 such as to make it a true island, zoologically speaking. Besides, there 

 seems to be reason to assume that it has been a real island at no very 

 distant period. The usual maps, it is true, indicate a high mountain 

 ridge at the narrowest point of the peninsula, connecting the mountains 

 of the latter with the orographical systems on the continent to the 

 north. But I have heard Mr. Kennan, the celebrated traveler, who has 

 traversed those regions in company with the Koriaks, denounce the 

 maps as entirely wrong in that respect. He said that the country 

 at the point in question is flat from sea to sea. From the observations 

 I made on Bering Island, I have evidence that the latter island, at least, 

 has been subject to a considerable rise during recent periods,.and there 

 are reasons to believe that this rise of land has taken place in the region 

 generally. Under these suppositions the narrow neck of the peninsula 

 has once been submerged. Looking apart from the connection to the 

 north there is only one regular way by which Kamtschatka can have 

 been invaded by species which do not voluntarily cross wide seas in 

 search for new homes, and this way is by the Kuril Islands from Japan. 

 The character of these islands, however, is such as to form a barrier 

 rather than a highway to all species which need trees and woods as an 

 essential condition for their existence. Besides a glance at Tables XVII 

 and XVIII shows how surprisingly many forms have not availed them- 

 selves of extending their limits northwards over the Kurils, to which 

 the treeless nature of these islands is no obstruction. We have seen 

 above that some migrating birds enter Kamtschatka by some other 

 route than from the extreme north or south, a route by which, there- 

 fore, the species in all probability have originally invaded the country, 

 but the Table XVII is plain evidence demonstrating that it is not fre- 

 quented by a great many forms which might reasonably be expected. 



This fact of so many birds staying away from a country of the size, 

 climate, and resources possessed by Kamtschatka is not satisfactorily 

 explained by the present isolated position alone. It requires the hy- 



