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Dr. Arthur G. Butler,



more than a century old, and looked it, and had been a victim of

early aviculture, for the wings were slightly injured and the tail badly

broken, as if through confinement in too small a cage. The colours,

however, were still recognisable. The bare skin round the eye was

red ; the beak dull yellow ; neck and shoulders dirty white; breast,

hack, and wings, blue-black; tail, dull crimson ; feet red. The label

read: “ F-uningns mtidissimus ( Scop). M. Sonnerat. I. Maurice.”



DEVELOPMENT OF PATTERN IN BIRDS.


By Arthur G. Butler, Ph.D.


The order in which the patterns and colours of bird plumage

were evolved is a question which has long interested me, and is, I

think, worth considering. It probably explains some of the resem¬

blances between allied forms which have been assumed to be mimetic

upon insufficient evidence. Nature works in a very orderly manner

as a rule; and therefore there is every reason to expect related

species to inherit from their common ancestor a tendency to throw

out similar varieties. Should these become fixed by the action of

natural selection, the result would be close resemblance between

two forms (possibly inhabiting widely separated localities), and

which, had they occurred together, would in all likelihood be

assumed to be mimetically assimilated.


I hinted at this point in a short article on the Bed-breasted

Starlings which I published in our Magazine in March, 1908, where

I demonstrated that although Leistes super ciliar is and Trupialis

defilippii, which closely resemble each other in pattern, colouring,

and habits, both occur in the Argentine Bepublic ; L. guianensis

and T. bellicosa, which also are equally alike, do not inhabit the

same regions.


Similar patterns in birds occur in widely different groups.

One of the most frequent divides the colouring of the body into

well-defined areas—head, collar, back, rump, breast, abdomen—the

wings and tail being smoky, with the outer webs coloured like the

back or rump ; or occasionally crossed or terminated by pale bands.

The Gouldian Finch and Chestnut-breasted Finch may be cited as

examples of the first type, the European Chaffinch a slightly modi-



