1850.] Remarks on the variation of affined species* 225 



lands of Ceylon, as compared with Pr. caprata, a larger size is com- 

 bined with a proportionally larger bill. The same is more strong- 

 ly shewn in Garrulax. pectoralis as compared with G. moniliger, 

 and in Hiaticula Geoffroyi as compared with H. Leschenanltii ; the 

 plumage, and the seasonal changes of plumage of the two last named 

 species, being absolutely alike. Emberiza palustris would resemble 

 Emb. schceniculus, only that the beak is altogether of a different shape. 

 So with Montifringilla nivalis and Plectrophanes nivalis^ all the differ- 

 ence is in the bill (so far as we can remember) . Treron curvirostris 

 and Tr. malabaricus are alike in size and plumage, but their bills are 

 of a very different form, and there is a bare space surrounding the eye 

 of the one and not of the other. Pomatorhinus schisticeps resembles 

 in plumage P. leucogaster 3 but has a larger bill and much more deve- 

 loped and straighter claws. Calornis affinis, nobis (Turdus colum- 

 binus ? Gmelin), has merely a larger size and generally duller plumage 

 than C. cantor. It is easy to multiply examples, grading from absolute 

 similarity to the exhibition of every amount and variety of dissem- 

 blance. 



In some instances where slight differences of colour only, especially 

 of shade of hue, constitute the sole diversity, we have the presumptive 

 evidence afforded by a series of many analogous cases, subject to the 

 same conditions of climate, &c, manifesting the same phaenomenon, 

 which is therefore to be ascribed with the greater probability to the 

 operation of a cause inducing the particular variation. Thus several 

 Indian birds are much darker and more intensely coloured in Ceylon ; 

 — ~e. g. Corvus splendens, Acridotheres tristis, and the female of Cop- 

 sychus saularis : Dicrurus leucopygialis of Ceylon thus differs from 

 D. ccerulescens of India in having only the vent and lower tail-coverts 

 white.* Pomatorhinus melanurus of Ceylon has the colours more 

 fully brought out, as compared with P. Horsfieldi of peninsular India. 

 Palumbus Elphinstonei of Ceylon wants the ruddy margins of the 

 dorsal feathers seen in the corresponding race of the Nilgiris. Lori- 



* Dicrurus longicaudatus of Ceylon quite resembles that of India ; whereas D. 

 macrocercus of that island is constantly smaller. On the other hand, D. macro- 

 cercus is undistinguishable in India, Burma, and Java, while in Burma D. longi- 

 caudatus is replaced by the smaller but otherwise similar D. intermedius, nobis. 

 The small Ceylon race of D. macrocercus I have elsewhere termed D. minor. 



