34 



I am of opinion that the successive changes are as follows : — 



(1) Nestling : covered with thick down of a uniform blackish-brown colour. 



(2) First season's plumage : blackish-brown, with black legs {i.e., the P. glaucus of my second 

 edition). 



(3) Second year : changes to metallic black ; ample crest ; but no alar bar, and no dorsal patch. 



Several of the black forms sent me by Marklund presented scattered white feathers on the 

 upper abdomen and sides of the body, whilst one of them had, besides numerous white feathers on 

 the under parts, a pure white patch on the left side. One of these parti-coloured forms I sent to 

 the Cambridge University Museum. This may be due to intercrossing ; but, thinking it might 

 indicate a change of plumage due to immaturity, I wrote to my collector on this point, and he 

 replied as follows: — 



" The Black Shags are more plentiful than the Black-and- White ones. The two kinds seem 

 to live together, and their habits, mode of flight, &c, are just the same. And still they must be 

 two distinct species, because there are young ones, about twelve months old, of both kinds ; and if 

 one sees a pair together, it will either be two Black-and- White or two Black ones. Those in good 

 plumage are rather scarce and difficult to get, especially the Black-and- White, which are always 

 very shy and wary. I may mention that the colour of their eyes and of the soft parts around the 

 eyes, also at the root of the bill, is just the same in both birds. Their eyes are peculiar — quite 

 unlike those of any other Shag; rather large and of a light-brown colour, and the pupil just a tiny 

 black spot. The Black-and- White birds have not regained their crests as yet, and their plumage 

 is very dull, but as the young are now coming out they must improve shortly. The two kinds, of 

 which I have sent you specimens, never build on trees, but outside on the rocks, and there they live 

 in perfect harmony, nesting right alongside of one another. But, after careful watching, I am 

 certain they do not intermix, and I am persuaded they each constitute a species by itself." 



Writing again on February 6th, he says : — " I am forced to believe that they represent two 

 distinct species, for these reasons : — 



"1st. They build separate nests, although at the same rookery ; and on dissecting mature 

 specimens of both kinds I have procured eggs — the eggs of both Shags being quite similar in 

 size and appearance. 



" 2nd. I have shot young birds of both kinds — the young of the Black Shag showing a slaty- 

 black colour. Part of this it retains in the second year of its life, not getting its full plumage 

 before the third year. The Black-and- White kind do not show the white spots on the wings 

 and back before the second summer, and then only imperfectly ; and the greenish-blue gloss does 

 not reach perfection before the third winter." [In another letter he states, what is really 

 very important, that the young of the latter species are pied from the nest.] " The mottled 

 appearance of the skin in your possession is, I suggest, due to a freak of nature rather than 

 indicating a transition from one plumage to another." 



I ought to mention, also, that, in one of his letters, Marklund states that in the Black Shag 

 the bare skin towards the rami of the lower jaw is all red instead of being dark blue, as in 

 the pied bird. 



Three or four of the specimens received from Marklund in the early part of September are 

 crestless— both the black-and-white and blue-black form. It is evident, therefore, that this is 

 a seasonal character. It is not a sexual character, because I have both male and female 

 crested, and male and female uncrested, of both kinds. 



The species is thus distinguished in the ' British Museum Catalogue ' : — 



Adult in breeding plumage.— Yery similar to the adult of P. graculus (of Western Europe), but the bill is 

 somewhat stouter and more hooked at the extremity ; the feathers of the upper back and scapulars, bronze- 



