240 Lawrence 071 the White-'.vlnged Gull in Neiv Tork. [.T"ly 



would do so) , and that successive generations would eventuall}' 

 become pure white, with little if any red tinge.* 



The geographical range of the two species suggests, from this 

 standpoint, such a relationship between the two species, E. ruber 

 being strictly tropical, and scarcely extending beyond the parallel 

 of 3o° north latitude, except as an accidental straggler, while E. 

 albiis is decidedly more northern, its centre of abundance lying 

 between the parallels of 20° and 30° north. 



The importance of this case as affecting the status of certain 

 so-called dichromatic species of water-birds (notably among 

 Herons) is very great. Probably no one would be willing to 

 consider Eiidocimiis ruber and E. albits as dichromatic phases 

 or races of one species ; yet they are apparently as much so as 

 Ardea occldeittalis and A. wurdemannl or A. ivardi on the one 

 hand or Dichromanassa rufa and D. pealei on the other ; or 

 at least, the probability of their common origin is evident. 



A nearly parallel example is afforded by the Snow Goose 

 {Chen hyperboretis) and Blue-winged Goose (C ccerulescens) . 

 In 'North American Water Birds,' Vol. I, page 437, the abso- 

 lute similarity of size and proportions, involving all structural 

 details, in these supposed species, notwithstanding the great 

 difference of colors, is alluded to, as "a fact which suggests the 

 mere possibility of their being white and colored phases of one 

 species, as in some Herons," and that, the chief variations in A. 

 ccertilescefzs being a tendency to increased extent of the white 

 markings, "the possibility of such a relationship should be borne 

 in mind." 



ON THE OCCQRRENCE OF THE WHITE-WINGED 



GULL {LARUS LEUCOPTERUS FABER) IN 



THE STATE OF NEW YORK. 



BY GEORGE N. LAW^RENCE. 



Early in March of this year, I was requested by Mr. John G. 

 Bell, to examine a Gull which had been sent to him to be 



* I am informed by persons who have shot E. albus in Florida that the phimage of 

 living and freshly killed birds is decidedly tinged with pink or rose-color. 



