I crossed black barbs (of two excellent strains) with purely-bred, snow-white fantails. The mongrels were generally quite black, with a few of the primary wing and tail-feathers white: others were dark reddish-brown, and others snow-white: none had a trace of wing-bars or of the white croup. I then paired together two of these mongrels, namely, a brown and black bird, and their offspring displayed wing-bars, faint, but of a darker brown than the rest of body. In a second brood from the same parents a brown bird was produced, with several white feathers confined to the croup. I crossed a male dun dragon belonging to a family which had been dun-coloured without wing-bars during several generations, with a uniform red barb (bred from two black barbs); and the offspring presented decided but faint traces of wing-bars. I crossed a uniform red male runt with a white trumpeter; and the offspring had a slaty-blue tail, with a bar at the end, and with the outer feathers edged with white. I also crossed a female black and white chequered trumpeter (of a different strain from the last) with a male almond-tumbler, neither of which exhibited a trace of blue, or of the white croup, or of the bar at end of tail: nor is it probable that the progenitors of these two birds had for many generations exhibited any of these characters, for I have never even heard of a blue trumpeter in this country, and my almond-tumbler was purely bred; yet the tail of this mongrel was bluish, with a broad black bar at the end, and the croup was perfectly white. It may be observed in several of these cases, that the tail first shows a tendency to become by reversion blue; and this fact of the persistency of colour in the tail and tail-coverts[344] will surprise no one who has attended to the crossing of pigeons. {200} The last case which I will give is the most curious. I paired a mongrel female barb-fantail with a mongrel male barb-spot; neither of which mongrels had the least blue about them. Let it be remembered that blue barbs are excessively rare; that spots, as has been already stated, were perfectly characterized in the year 1676, and breed perfectly true; this likewise is the case with white fantails, so much so that I have never heard of white fantails throwing any other colour. Nevertheless the offspring from the above two mongrels was of exactly the same blue tint as that of the wild rock-pigeon from the Shetland Islands over the whole back and wings; the double black wing-bars were equally conspicuous; the tail was exactly alike in all its characters, and the croup was pure white; the head, however, was tinted with a shade of red, evidently derived from the spot, and was of a paler blue than in the rock-pigeon, as was the stomach. So that two black barbs, a red spot, and a white fantail, as the four purely-bred grandparents, produced a bird of the same general blue colour, together with every characteristic mark, as in the wild _Columba livia_.