Jan.
While I do not pretend to explain this unusual degree of variation, I can see no reason for making it the basis of a theory that neoxena is a color-phase of exilis. Only three of the fourteen known specimens depart widely from what is evidently the type of coloration, and in every instance these differences are clue to albinism or melanism, not one of the specimens showing any approach to exilis. Nor do the known cases of dichromatism among Herons give us any ground for asserting that neoxena is a dichromatic phase of exilis. Aside from the important differ- ences exhibited by the young and female, a careful comparison of the adult males shows no substitution of colors such as we find in the phases of Ardea rufescens, Megascops, Fulmarus, or even Stercorarius. This is especially marked in the under parts, which in exilis are essentially all buffy, while neoxena has a chestnut forneck, a chestnut and black belly, and, in every instance, jet black under tail-coverts.
It is natural that the variability of neoxena should cause us to regard it with suspicion, but beyond the fact that the two birds are generically related and of the same size, there is not one grain of evidence implicating exilis. This latter bird is represented in our collections by hundreds of specimens not one of which has given reason for believing the species is dichromatic.
For the loan of specimens of this rare bird I desire to heartily thank Messrs. William Brewster, J. H. Ames, Charles B. Cory, J. H. Fleming, Jas. R. Thurston, and L. W. Watkins.
BIBLIOGRAPHY.
Gives collector's name and approximate place of capture of the type specimen.
Description of Ardetta neoxena.
