On Species S- Varieties in Birds. 141 



almost impossible to procure in Great Britain a specimen of 

 true Phasianus colchicus, interbreed but seldorn m a native 

 state, and so far as I know the offspring is sterile Arnongst 

 the Grouse one finds, not so infrequently, wild hybrids, tor 

 instance between the Ptarmigan and Black Grouse, the Red 

 Grouse and Black Grouse, the Hazel Grouse and Black 

 Grouse, the CapercaiUie and Black Grouse the American 

 Ruffed Grouse (Bonasa umbellus) and the Canada Grouse 

 {Tetrao canadensis), &c., &c., but so far as I know there is no 

 instance on record of the offspring being fertile Amongst 

 the Ducks wild hybrids are occasionally found, but they are 

 not of frequent occurrence, and are, I believe, sterile, whereas 

 in a state of semi-domestication they have been found to 

 interbreed to the third and fourth generation. 



Interbreeding has been noticed far less aniongst the 

 Passerine birds, but it does occur, and it has been long known 

 that some of the Pici and Coccyges regularly interbreed with 

 closely allied species ; thus in eastern North America there is 

 one form of Flicker, Colaptes auratus, and in the west and 

 south another perfectly distinct species, Colaptes mexicanus 

 but where the range ot the two species meets they interbreed 

 regularly, and every gradation between the two species may 

 be found, whereas only a few miles on the one side pure bred 

 birds of the one species are found, and on the other side of 

 the other species, and the same thing occurs in Asia where 

 Coracias indiciis and Coracias affinis meet. ,• „ :, 



One of the most curious instances of this interbreeding is 

 that of Corvus corone and Corvus comix. In the northern 

 portion of continental Europe the Elbe forn.s the boundary 

 line between the two species, and whereas a few miles to the 

 east of this river one finds only true Corvris comix ,^n^ to the 

 west only Corvus corone, all along the Elbe hybrids of every 

 sort between the two species are seen, and comparatively 

 seldom a pure bred bird. r .„„ 



A curious circumstance was related to me by one ot my 

 correspondents in Austria. Some years ago in one particular 

 district Corvus corone and Corvus comix were nearly evenly 

 balanced in numbers, and interbred freely, but by degrees the 

 former increased until now, although many hybrids are found 

 they all resemble Corvus corone more than Corvus comix, and 

 ere long, without doubt, all trace of the latter species will 

 have disappeared, it having proved the weaker in the struggle 

 for existence. In Siberia where the two species meet they 

 also interbreed as in Europe, and I am enabled, by the 

 kindness of Mr. H. Seebohm, to exhibit here a large series ot 

 specimens showing all the gradations between the two species. 

 This gentleman has lately been investigating the subject ot 



