VARIATION 305 



there seems but little doubt but that all the examples of the so- 

 called Athene chiaradicE were the progeny of the same pair of 

 birds — themselves abnormal. Convinced of this, they, with 

 their last brood, though taken alive, have been deliberately 

 slaughtered to make museum specimens, whereas one would 

 naturally have expected that some attempt would have been 

 made to induce the adults to breed in confinement, while a 

 similar experiment could have been made with the offspring. 



In its way as striking as any instance of mutation yet cited 

 in these pages is the case of Shore's Woodpecker {Tiga sJiorei). 

 As was first pointed out by Mr. Ogilvie Grant, this bird, in the 

 matter of the coloration of its plumage so closely resembles an- 

 other species {Chrysocolaptes giUticristatus) that the one could 

 easily be mistaken for the other. Indeed the only ready means 

 of discrimination lies in the fact that the last named has four 

 and the first mentioned only three toes. Though by Ornitho- 

 logists this difference in the number of the toes is regarded as 

 justification for placing these two birds, not only in separate 

 genera, but in separate sections of the same family — containing 

 respectively four and three-toed genera — it would seem to be 

 more in accord with the evidence if the Tiga shorei were to be 

 set down as a mutational form of Chrysocolaptes gutticristatns. 



With these facts before us the question naturally arises : 

 What light, if any, do they throw on the problem of the origin 

 of species? Will they afford any clue as to the possible origin 

 of specific characters such as, for example, distinguish the Cole 

 and the Marsh-tits one from another, or the different races of 

 these two species, and of the Long-tailed Titmouse ? Or to 

 select a yet more striking illustration, of the strange permuta- 

 tions and combinations of colour which the various species of 

 some genera present. Out of a possible thousand illustrations 

 of this last kind let us take a few from the Genus Hirundo, the 

 Common Swallow (//. rustica), being well known, serving as 

 the type. This bird, as every one knows, is of a steel-blue 

 above, with a red forehead, a red throat, bounded by a black 

 gorget, and a rufous-tinted breast and belly. As variants of 

 this we have four birds regarded by many as sub-species 

 only : — 



H. savignii (Egypt), with deep chestnut belly ; H. eiythrogas- 

 ier (East Siberia, Burma, North and South America), with a 



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