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slight traces of yellow on the sides of the neck. Feathers of the 
hack hero and there narrowly edged with a lighter brown, and tlie 
abdomen and under tail-coverts, neither wholly barred as in the 
young bird, nor of an oven brown as in the adult ; but of a dirty 
white tint, like the breast, with some barred feathei-s. Middle 
tail-feathers projecting two inches, broad tips and twist; feet 
black, front of tarsi bluish. 
Iho last two specimens, which are now in my collection, are 
particularly interesting, as showing the gradual assumption of the 
chief features Avhich in this species indicate matuiity. In both 
these birds the feathers of the wings and back are on uniform hair 
brown, as in the lully adult, exce 2 )ting a few light marginal ti 2 )s 
amongst the latter. It seems, therefore, that this portion of the 
jtlumago attains a mature .state long before the under surface is 
lierfected (see IS os. 9 and 12). The under and ujrper tail-coverts 
ate still barred, thougli in both the middle tail-feathers have 
attained a considerable elongation. The feet, also, are entirely 
black, the tarsi only retaining the lighter tints of the bird of the 
year ; and imperfect as is the jjlumage of the throat and neck 
(especially in !Mo. 17), those 2 )arts had still attained a tinge of 
yellow, perceptible enough when I first saw them. 
However much the adult birds may vary inter se as to the depth 
of colouring in the pectoral-baiul, there appear to bo three decided 
indications of maturity in the Pomatorhino Skua. 
1. Iho under tail-coverts being a pure sooty black, and the 
upper, of course, without bars. 
2. Black legs and feet. 
3. A more or loss vivid yellow colouring on the neck. 
Of those throe I perfectly agree with Mr. Cecil Smith (‘Field,’ 
December Gth, 1879) that the first is, after all, the surest guide ; as 
it will be seen by an examination of the above list of specimens 
that Iso. -I, with but slight dark markings across the chest, has 
still one barred feather in tlie under tail-coverts, whilst No. 5. 
much barred across the chest, has the under tail-coverts perfect. 
No. 10, with a broad dark band on the chest, has still barred 
feathers amongst the under tail-coverts; and in No. 11 the latter 
are perfect, though with an equally broad dark band on the chest. 
No. 12, as if just to prove the exception, with a dark chest, a few 
immatuie feathers on the back, and barred on the ujijier taiL 
I 2 
