VOl i899 VI ] MuRDOCH > A historical Notice of Boss's Rosy Gull. \ 47 



known with a wedge-shaped or cuneate tail. With the exception 

 of the genus Xema, which has a forked tail, all other Gulls have 

 the tail feathers of equal length, but Ross's Gull has the middle 

 pair of feathers longer than the rest, with the lateral feathers 

 graduated in length towards the middle. Hence it has sometimes 

 been called the Cuneate-tailed Gull. This one character serves 

 to distinguish the species infallibly. The other striking charac- 

 teristic, though a less constant one, is the color of the under- 

 pays. Many of the smaller Gulls and at least one species of 

 Tern have the white of the breast and belly tinged during the 

 breeding season with a delicate rosy pink or peach blossom color, 

 which is very evanescent and soon disappears when the bird is 

 skinned. In the fully developed Rosy Gull, the rose color 

 spreads over all the underparts and is so deep as to be almost a 

 salmon color. This color fades after death, when exposed to the 

 light, but a particularly brilliant specimen in our collection which 

 had been kept carefully in the dark, showed no perceptible change 

 in a year. On the other hand, Gatke reports that some pink 

 feathers of his Heligoland specimen, which he kept shut up in an 

 envelops, faded as badly as the mounted bird. 1 For the rest, the 

 ' mantle,' as the back and wings are called in a Gull, are of the 

 well known 'gull blue,' and the head and tail are white. The 

 adult in summer has a narrow black collar round the neck, which 

 is wanting in the winter plumage. The young birds in the 

 autumn have the back and the wing-coverts more or less mottled 

 with dark feathers, black feathers in the wing, and a black bar 

 across the tip of the tail. Several stages of immature plumage 

 have been described, and it is quite probable that, as is the case 

 with many other Gulls, the bird needs several years to reach the 

 full adult plumage. It is, however, impossible to establish this 

 at present, as the birds have been observed in large numbers only 

 in the autumn. The amount of rose color varies a great deaL 

 Two thirds of the young birds that I have examined were quite 

 white, and more were very rosy, while one of the adults had all 

 the white parts except the tail deeply suffused. I have never 

 had the good fortune to see an adult in summer — indeed, very 



1 Heligoland as an Ornithological Observatory, p. 558. Edinburgh, 1895. 



