CROW. 283 



Thus it will be seen that though our knowledge of the 

 subject is still imperfect as regards a few minor details, it 

 admits of our arriving at some important generalizations, 

 and the result shews that the geographical distribution of the 

 two forms supplies no better proof of their specific distinctness 

 than does any of the other characteristics before considered. 

 The Black Crow is found at the extreme western as at the 

 extreme eastern limits of the range of both, while the Grey 

 Crow occupies the most northern as well as the most southern 

 countries frequented by either. It cannot therefore be said 

 that one is a western and the other an eastern race, or that 

 one is a northern and the other a southern. So far the only 

 rational mode of regarding the Black and Grey Crows would 

 appear to be as members of a single dimorphic species, and 

 the inability to point out why this species should possess 

 that admittedly exceptional quality is no more an argument 

 against that view, than is the inability to explain why a 

 wholly black plumage should prevail in nearly all the species 

 of Corvus, while in a few others the black should be varied 

 by grey or white. It must also be remembered that the 

 present case does not stand as one of simple local variation as 

 is that of so many other birds — some of them even belong- 

 ing to the same genus, as the Daw, presently to be noticed, 

 and the C. splendens of the Indian Region, of which Hima- 

 layan examples have an ash-coloured breast and collar, which 

 is darker in specimens from Bengal and Southern India, 

 and darker still in those from Ceylon (Ann. Nat. Hist. ser. 2, 

 xiii. p. 214), while in some of those from Burma and Siam 

 nearly all trace of the grey is lost (Ibis, 1867, p. 298)*. 



A more important objection, however, to the view above 

 taken may be raised, and one that has not before been stated. 

 By many naturalists it has long been held that the infertility 

 of hybrids between any two forms affords the strongest 

 ground for considering them distinct species — whether the 



* Mr. Hume suggests (Stray Feathers, 1874, p. 480 and 1875, p. 144), tliat 

 these deserve specific recognition. Mr. Sharpe notices (Cat. B. Br. Mus. iii. 

 p. 33) a specimen, said to be from Malacca, of the ordinary dark form. When 

 more is known about the dark-eyed and white-eyed Crows of Australia the case of 

 our own birds may be further illustrated (r/. E. P. Ramsay, Ibis, 1865, p. 303). 



