no 
Booth at Yarmouth. This was the first mature melanism of tlris 
species that had come under Mr. Saunders’ notice.'*^ In describing 
his visit last July to the breeding haunts of the Great and 
Bichardson’s Skuas in the Shetland Islands, he says nothing of 
dark varieties of the former, and we may presume that Mr. Gurney’s 
specimen, as figured by Dresser, is a rarity, but as to the smaller 
species he speaks positively as to “ two extreme varieties in the 
adults, — -the one having the breast and under parts of the same 
dusky line as the back ; and the other in which the under parts are 
white. These two varieties breed together, and pairs are found 
consisting of two white-breasted birds, or of one white and one 
dark bird, or of two dark birds. WJiere light forms are mated the 
young are perfectly recognisable, and the same is the case with the 
offspring of two wholly dark birds ; the young of a light and a 
dark form are also distinguishable ; but the question to be solved 
is, wliat are the offspring of these ‘ mixed marriages ’ on attaining 
maturity 1 .... I do not think that the dark plumage is a sign 
of immaturity, or that birds which breed in this plumage will ever 
become light-breasted, for the dark breeding birds have the 
acuminate feathers on the nape of quite as burnished a yellow 
colour as the light forms, and that is a sure sign of age in all Skuas ; 
but whether the half-bred birds which are found breeding with 
partially Avhite breasts ever lose their gorget and become entirely 
Avhite is still unknown to me.” 
In this paper he does not allude to the proportion seen of dark 
to white-breasted birds, but in a communication to the ‘ Zoologist’ 
for January, 1880, on his recent observations in the Shetland 
Islands he says : “ In the adult the dark forms were in the majority ; t 
but there was a fair proportion of the white-breasted ones.” 
* There seems little doubt that the dark specimen in Viscount Hill’s 
collection, described by Mr. Gould (‘Birds of Great Britain’), and also the 
bird described by Macgillivray (‘History of British Birds,’ vol. v. p. 491), — 
even then recognised by him as adult, and stated to be in his own collection, 
— were both examples of the adult melanism in this species ; and others, no 
doubt, Avill now be recognised in public and private museums. 
t Mr. Gould (‘ Birds of Great Britain’) gives a good illustration of the 
difference in plumage between the light and dark forms in this Skua. But 
he terms the light-breasted the normal plumage, and tlie dark a common 
variety. 
