230 Letters , Extracts from Correspondence, Notices, fyc. 
XXIII.— Letters, Extracts from Correspondence, Notices, fyc. 
We have received the following letters 
To the Editor of c The Ibis. 3 
Hastings, January 8, 1863. 
Sir, —My attention has just been called to a paper published 
in f The Ibis/ No. XVI. Oct. 1862, by M. Charles Bolle, of 
Berlin, in which he describes what he imagines to be a new 
species of Antlius, and proposes to give it the name Anthus 
berthelotii. 
My excuse for troubling you with some remarks on the claims 
of the bird described by M. Bolle to be considered as a new 
species must rest upon the reference M. Bolle has made to my 
delineation of the Anthus pratensis, Bechst., in my f Sketch of 
Madeira/ Murray, 1851, and in the f Annals and Magazine of 
Natural History/ vol. xii. p. 58, and vol. xv. p. 430. 
M. Bolle introduces his reasons for establishing a new species, 
by saying that he has been apt to lay too much stress upon the 
power of climate to influence the tints of the plumage and the 
habits of birds. M. Bolle has doubtless observed that, in the 
climates of which he treats, the tints of the plumage of many of 
our common European species are considerably modified. I 
would instance the Fringilla cannabina, Linn., which retains its 
carmine plumage through the year; the Larus argentatus, 
Briinn., which obtains its mature garb at an earlier period than 
in Europe; the Strix flammea, Linn., which is somewhat darker 
than in Europe; the Sylvia atricapilla , Lath., which assumes 
sometimes so dark a hue as to have led Sir W. Jardine to describe 
it as a different species; with several other examples familiar to 
naturalists who have visited these semi-tropical regions. It is 
well known to travellers in Central Africa that all chemicals are 
so largely affected by the climate as to make photography 
impossible there; and, whether we can account for it or not, 
the fact remains that the chemical secretions which produce 
colour in the plumage of birds are in a greater or less degree 
influenced by the mysterious agency of climate. That the habits 
of birds are modified by climate is proved by the non-migration 
of the Woodcock, the Blackcap, the Swift, the Quail, the Petrel, 
and other birds from the regions of which M. Bolle writes. 
