V 
4 Ridgway on an Apparently New Heron from Florida. 
is merely a white phase of this species. As to the comparative 
rarity of these large white birds, in the locality where observed 
by Mr. Ward, militating against any theory of their specific 
identity with the dark-colored birds, it should be remembered that 
in the case of nearly every dichromatic species of bird this con- 
dition is more or less variable with locality. A pertinent exam- 
ple may be cited in the case of .Demiegretta sacra , a Heron 
of wide distribution in the Far East. This species inhabits a con- 
siderable number of islands in the Polynesian group, and it has 
been noticed and recorded by naturalists who have visited that 
region, that on some islands all or nearly all the birds of this 
species are dark-colored, on others all or nearly all are white, 
while on others still there may be a more equal proportion of 
the two phases. It may be remarked that the two phases in this 
species are even more distinct in coloration than in the case of 
Dichromanassa rufa , the colored phase being darker than 
in the latter species. Upon the whole, even admitting the possi- 
bility of the white young bird seen by Mr. Ward having of its 
own volition taken up its abode in a nest containing dark colored 
young, I am strongly inclined to believe that it belonged to the 
same species with the latter, the question of its parentage (i.e . § 
whether its parents were white or dark-colored birds) being a 
comparatively unimportant consideration, as affecting the main 
question. But in adopting the view of their specific identity a 
problem arises which in the light of our present knowledge ap- 
pears unsolvable, and which may be briefly stated thus : — 
The large u blue” Herons obtained by Mr. Ward are, in every 
respect as regards size and proportions, identical with Ardea 
occidentalis Aud. and A. wurdemanni Baird; in coloration 
they agree exactly with the latter, except only in the pattern of the 
head and tint of the neck, which are precisely as in A. herodias. 
The bird in question is apparently “ dichromatic,” having a white 
phase ; hence, assuming that A. occidentalis and A. wurdemanni 
are dichromatic phases of one species, it necessarily follows that 
white individuals of the bird in question would be absolutely in- 
distinguishable from white exa?nples of A. occidentalis l Still, 
in view of the fact that the colored phase differs from A. wurde- 
manni in its most essential feature of coloration, i.e., the pattern 
of the head markings, it seems impossible to unite them, unless it 
can be shown that the type of A. wiirde?nanni does not represent 
