53G Colonel R. Meinertzhagen 07i [Ibis, 



We find many examples o£ this, the most remarkable 

 being the case of the Chaffinch (Fringilla Calebs). In the 

 Canary Islands, as already pointed out by Bannerman (Ibis, 

 July 1920), we find undoubted geographical races of the 

 (Jhaflinch living alongside Fringilla teydea, and tending to 

 vary in the same direction as a geographical race, as F. teydea 

 does as a species. We believe that F. teydea was once but a 

 geographical race of F. coelehs, but that isolation has pro- 

 duced a species. The more recent invasions of Chaftinches 

 to the Canary Islands are moving along the same path of 

 evolution as did F. teydea, and are undoubtedly incipient 

 species. 



Though, therefore, we accept the fact that isolation pro- 

 duces a true species from an original geographical race, such 

 can only occur under conditions of complete isolation. By 

 far the majority of geographical races are not incipient 

 species, and stand little chance of gaining that status so 

 lono- as thev are in actual touch with the parent stock. 



I further wish to endorse the old truth that isolation is the 

 strongest factor working for variation, and is the main factor 

 in the evolution, not only of geographical races but of 

 species. 



4. WJiat is the value of a subspecies ? 



We are not clear as to what is intended by this question. 

 To him who asks what is the value of trinomial nomen- 

 clature, we reply that it has been found the shortest, most 

 convenient and scientific way of referring to geographical 

 variation. Its critics have not j^et suggested a better way. 



To him who asks of what value to science is the recogni- 

 tion of slight geographical variation, we reply that it helps 

 to solve the problems of migration, evolution, and distribu- 

 tion among birds, and that such value has been recognised 

 by the leading ornithologists of the world. 



But there are still a few who regard the trinomial system 

 as a simple and quick way of gaining notoriety, whilst others 

 look on the method as a confusing and unnecessary inven- 

 tion of the Devil. 



