CROWS. 



527 



as intricate as that of the red-shafted and 

 yellow-shafted flickers of our continent. 

 The carrion-crow is entirely black ; the 

 hooded-crow is gray, with the head, throat, 

 wing, and tail black. The former inhabits 

 in Europe the southern parts, while the 

 hooded-crow is northern and eastern ; but 

 the areas of both overlap, and in those dis- 

 tricts innumerable intermediate specimens 

 occur. Hybridization easily accounts for 

 these, inasmuch as the interbreeding of typi- 

 cal birds of both species is an established 

 fact. But that was not the greatest diffi- 

 culty which presented itself in the apparent- 

 ly western carrion-crow coming to light again 

 in eastern Siberia, to the east of the hooded 

 species. Seebohm has attempted to show 

 that the true explanation is that the black 



I . u 



one is originally an eastern Species, which FlG . 2C0 ._ Urocissa erythrorhynchus, red-billed jay. 

 has invaded southern Europe, establishing 



a western colony there after having crossed the area inhabited by its gray cousin. To 

 me the problem seems even easier; for I think it possible to separate the east Asiatic 

 birds, at least subspecifically, from the European form. 



