4 RiDGWAY on ait Apparoitly New Heron from Florhla. 



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 

 Dichroinanassa r7ifa, the colored phase being darker than 

 in the latter species. Upon the whole, even admitting the possi- 

 iMlity 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 uusolvable, and which may be briefly stated thus : — 



The large " blue" Herons obtained by Mr. Ward are, in every 

 respect as regards size and proportions, identical with Ardea 

 occidentalis Aud. and A. xvurdeinanni 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. ■wnrdefuanni 

 are dichromatic phases of one species, it necessarily follows that 

 white individuals of the bird in question would be absolutely in- 

 distitiguishable from white examples of A. occidentalis I Still, 

 in view of the fact that the colored phase differs from A. nvurde- 

 ■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 oi A. wWrdemanni does not represent 



