VARIATION UNDER DOMESTICATION 23 



their structure, with the wild rock-pigeon, yet are 

 certainly highly abnormal in other parts of their 

 structure ; we may look in vain throughout the whole 

 great family of Columbidae for a beak like that of the 

 English carrier, or that of the short-faced tumbler, or 

 barb ; for reversed feathers like those of the Jacobin ; 

 for a crop like that of the pouter ; for tail-feathers like 

 those of the fantail. Hence it must be assumed not 

 only that half-civilised man succeeded in thoroughly 

 domesticating several species, but that he intention- 

 ally or by chance picked out extraordinarily abnormal 

 species ; and further, that these very species have since 

 all become extinct or unknown. So many strange con- 

 tingencies seem to me improbable in the highest degree. 

 Some facts in regard to the colouring of pigeons well 

 deserve consideration. The rock-pigeon is of a slaty- 

 blue, and has a white rump (the Indian sub-species, C. 

 intermedia of Strickland, having it bluish); the tail has 

 a terminal dark bar, with the bases of the outer feathers 

 externally edged with white ; the wings have two black 

 bars ; some semi-domestic breeds and some apparently 

 truly wild breeds have, beside the two black bars, the 

 wings chequered with black. These several marks do 

 not occur together in any other species of the whole 

 family. Now, in every one of the domestic breeds, 

 taking thoroughly well-bred birds, all the above marks, 

 even to the white edging of the outer tail-feathers, 

 sometimes concur perfectly developed. Moreover, 

 when two birds belonging to two distinct breeds are 

 crossed, neither of which is blue or has any of the 

 above-specified marks, the mongrel offspring are very 

 apt suddenly to acquire these characters ; for instance, 

 I crossed some uniformly white fantails with some 

 uniformly black barbs, and they produced mottled 

 brown and black birds ; these I again crossed together, 

 and one grandchild of the pure white fantail and 

 pure black barb was of as beautiful a blue colour, with 

 the white rump, double black wing-bar, and barred and 

 white-edged tail-feathers, as any wild rock-pigeon ! We 

 can understand these facts, on the well-known principle 



