302 A HISTORY OF BIRDS 



distinct species, are only local races of one and the same di- 

 morphic species. 



There is no Ornithologist in Great Britain, perhaps in 

 Europe, whose work carries more weight than that of the late 

 Professor Newton, nevertheless, we venture to question whether 

 the facts really justify this contention of dimorphism. Rather 

 they seem to us to show that the Carrion and Hooded Crows 

 are really to be'regarded as good species, but very closely allied. 

 And in this case there is nothing strange in this inter-breeding 

 where they overlap one another. 



A precisely similar case is that of the Great Grey Shrike 

 [Lanius excubitor) which inter-breed with two distinct but 

 closely allied species. In the northern limit of its range, 

 Scandinavia, L, excubitor — which is distinguished from its allies 

 by the presence of a double white bar in the wing — meets 

 and inter-breeds with another species, L. major, distinguished 

 by the presence of only one bar of white in the wing. In 

 South Russia L. excubitor meets with a third species, the 

 white-winged Grey Shrike (Z. leucopterus), and inter-breeds 

 therewith, producing apparently an intermediate race known 

 as L. homigeri. 



The " Flicker or Golden- winged Woodpecker " {Colaptes au- 

 ratus) may be cited as a further illustration of inter-breeding 

 species. A native of North America it ranges from the Atlantic 

 Coast as far southwards as Louisiana and north to Canada. 

 Still farther northward, to Alaska, its place, says Professor 

 Newton, " is taken on the greater part of the Pacific side by a 

 species which, avoiding Southern California, reaches the table- 

 lands of Mexico — a species more brilliantly tinted, for ruby 

 appears in its plumage instead of gold, the C. mexicanus or 

 vulvicatus of authors. But in an intervening broad belt running 

 north-westward from Texas to British Columbia there occur 

 birds presenting almost every combination of the distinctive 

 coloration of the two species just named. . . ." 



If further facts of this point are required they may be 

 found among the Game-birds, the phenomena of intermediate 

 races being particularly well illustrated in the case of the 

 " Silver Pheasant ". 



More obscure are the facts which Professor Giglioli has 

 brought together in what he calls The Strange Case oj 



