454 Mr. W. R. Ogilvie-Grant on the Genus Turnix. 



together with two others (7". rostrata and T. blakistoni), 

 which I shall discuss, are merely climatic varieties of one 

 and the same bird, but also to point out the reasons which 

 lead to such a strange diversity of plumage. 



Mr. Hume allows that the only difference which can be 

 relied on for distinguishing T. taigoor from T. plumbipes is 

 that " the prevailing tint of the interscapuiary region and 

 back in the Indian Bustard Quail is rufous, in the Indo- 

 Malayan bird brotvn ;" and he goes on to say, " there are 

 differences of markings, but no weight must be attached to 

 these, as they are individual. Scarcely any two specimens 

 of either species are precisely alike, but almost every varia- 

 tion in markings in one species will be found also in some 

 specimens in the other. It is solely, so far as I can ascertain, 

 by the prevailing tone of the colour of the upper surface that 

 the two species can be separated." He adds, " This may 

 seem an insufficient reason for making two species of the 

 form ; but it has to be noted that, if taking a large series 

 from all parts of the empire you separate the two forms, you 

 find that all the really red birds (the present species) are 

 from one geographical area, and all the brown ones from 

 another." Our series includes specimens from a number of 

 localities not represented in Mr. Hume's collection, and these 

 entirely upset his theory; for I find it impossible to draw 

 any line between his two species. I have before me inter- 

 mediate forms neither brown nor red, but a mixture of both, 

 inhabiting localities where the rainfall is not excessive, and 

 I am convinced that there is really only one species [T. 

 taigoor) which ranges through India, Burmah, Malay, Siam 

 and China to Formosa and the Loo Choo Islands, and that 

 the key to the constant variety in the tone of the plumage is 

 to be found in the effect of the amount of annual rainfall in 

 the country which the birds inhabit. By going through the 

 whole of our huge series and comparing tlie tone of the 

 plumage with the amount of rainfall in the habitat of the 

 bird, I find this theory exactly borne out; for where rain is 

 abundant the prevailing colour of the upper parts is dark 

 •brown, where it is moderate the tone is more rufous, and 



