482 Bangs, Dichromatic Herons and Hawks. [oct. 



extreme brunescens plumage. This skin, now M. C. Z. no. 72982, 

 was taken March 22, 1902, at Madeira Hummock, Florida, and was 

 in beautiful, fresh spring plumage. Its neck is a little darker than 

 in specimens in normal plumage, is unicolor lacking all traces of 

 either whitish or dusky markings even on the throat and chin; 

 the belly is dark and reddish and but slightly contrasted against 

 the color of the neck; the wing-edge has no whitish on it whatever; 

 the wing coverts are all very narrowly edged with dark rusty 

 brown, with no creamy or whitish anywhere. It affords the fol- 

 lowing measurements — wing, 166 mm.; tail feathers, 53; tarsus, 

 51 ; exposed culmen, 62. 



Unfortunately the measurements taken from this example are 

 not positive proof that it was bred in Florida. The chance how- 

 ever, of its having wandered from Cuba to where it was killed 

 seems rather remote, and I regard it as pretty certainly an instance 

 of erythrism of the continental Green Heron — Butorides virescens 

 virescens (Linn.). In his Revision of the subspecies of the Green 

 Heron (Proc. U. S. Nat. Mus., Vol. 42, pp. 529-577) Oberholser 

 gives in his list of measurements, the length of wing in females of 

 B. virescens virescens, as ranging from 160 to 185. In females of 

 his B. virescens cubanus from 155 to 174. The Cuban form does, 

 of course, average smaller in all measurements than B. virescens 

 virescens, but single individuals cannot be separated, if their meas- 

 urements happen to fall — as in the case of the specimen I have just 

 described — between the extremes. 



Cory's Least Bittern, Ixobrychus neoxenus (Cory), is a similar 

 case of nothing more or less than erythrism of the common Least 

 Bittern, Ixobrychus e.xilis (Gml.) as I have wholly satisfied myself 

 by an examination of specimens, which vary among themselves 

 as to the degree of erythrism shown. It crops out, here and there, 

 anywhere, within the range of the species, and has no distinct 

 range of its own. 



Another dichromatism common among herons, and now thor- 

 oughly well understood, is the very striking one, of a pure white 

 — albinistic — phase, and a normally colored, — usually bluish 

 and reddish — phase shown by the same species. The three 

 species showing this extraordinary tendency, and now admitted by 

 nearly all systematic ornithologists to be dichromatic, are the Red- 



