392 Clark, Black Forms of the Genus Coereba. [oct* 



THE WEST INDIAN BLACK FORMS OF THE GENUS 



CCEREBA. 



BY AUSTIN H. CLARK. 



Among the West Indian members of the genus Careba are two 

 peculiar forms, one known as Coereba atrata (Lawr.) from the 

 island of St. Vincent, and the other, C. wellsi (Cory), from the 

 island of Grenada, which are entirely black. Mr. Ridgway has 

 suggested (Proc. U. S. Nat. Mus., Vol. VIII, 1885, p. 28) that 

 these may prove to be merely phases of plumage of the normally 

 colored birds inhabiting the same islands, and I shall in the present 

 paper advance reasons for this supposition. 



In the genus Ccereba, all the species are (except in these two 

 cases) dark above, with a light superciliary stripe, and yellow, or 

 yellow and white, below. Most of them have a yellow or yellowish 

 patch on the rump, and all have the bases of the primaries (forming 

 a wing spot) and the tips of the outer rectrices white. It is evident 

 then, that the genus has a definite and well marked color-pattern. 

 In the black forms there is an olive tinge on the underparts (except 

 the throat) and rump, corresponding to the yellow markings of 

 the normally colored birds inhabiting the same islands. The 

 black forms are of the same color from the first appearance of 

 feathers, and not of more normal coloration in the younger stages 

 as we might expect were these forms simply species widely divergent 

 from the generic type. 



The black birds are identical in size, coloration of naked parts, 

 actions, notes, and nesting habits with the normal birds of the 

 same islands. In the case of Ccereba wellsi the eggs are exactly 

 alike. 1 



In the genus Ccereba no two species are known to inhabit the 

 same locality. 



In certain mammals (for example, Canis occidentalis Rich., 

 Vulpes fulvus Desm., and Sciurus earolinensis Gmel.) melanistic 



1 1 have never seen the eggs of the normal form of C. atrata. 



