291 MR. H. SAUNDERS ON THE GREY-CAPPED GULLS. [May 5. 



brown one, similar to that of our European L. ridibundus. Prince 

 Max. v. Wied first noticed its occurrence amongst the grey-capped 

 species (Beit. iv. p. 854), and was inclined to refer it to L. ridi- 

 bundus ; but it is undoubtedly L. glaucodes, Meyen, Obs. Zool. 

 p. 115 — L. albipennis, Licht., Gavia roseiventris, Gould (I only 

 give the principal synonyms) — a species which ranges from the 

 south of Brazil down to the Falkland Islands, throughout Pata- 

 gonia, and for some distance up the coast of Chili. This is the 

 species of whose breeding near Buenos Ayres Mr. W. H. Hudson 

 (P. Z. S. 1 87 1, p- 4) has given an interesting account ; but although 

 he distinctly calls it (P. Z. S. 1870, p. 802, and 1871, p. 258) the 

 black-headed gull, the very name we apply to our L. ridibundus , 

 yet he identifies it with L. cirrhocephalus, whose head, as I have 

 repeatedly remarked, is of a pale grey, and nothing approaching 

 either to black or brown. Excepting that to a casual observer 

 all Gulls of nearly the same size are much alike, it is difficult 

 to understand how the two species can have been confounded even 

 in immature plumage ; for the smoke-colour of the under wing- 

 coverts so noticeable in L. cirrhocephalus is entirely absent in L. 

 glaucodes, to say nothing of the markings of the primaries, which 

 differ even in very young birds. That L. glaucodes itself should 

 have been subdivided is not at all surprising ; for it requires a large 

 series to show how the primaries, which in the early stages have 

 merely a patch of white near the apex, gradually become barred 

 with black and white (in which stage the brown head of maturity 

 is assumed) and gradually lose all but a streak of black on the 

 outside of the inner web, so that the principal primaries appear to 

 be entirely white. L. maculipennis of Burmeister, however, is L. 

 cirrhocephalus. 



The sum of my observations is briefly this- — that L. phceocephalus, 

 Sw., and L. cirrhocephalus, V., are fairly separable, that L. phceo- 

 cephalus is totally distinct from L. hartlaubi, Bruch, which never 

 has a hood of any colour whatever, and that L. cirrhocephalus has 

 been unnecessarily confounded with L. glaucodes. My warmest 

 thanks are due to Professor Burmeister, of Buenos Ayres, for 

 promptly furnishing me with sexed and dated specimens of both the 

 South-American species, and to Professor Newton for the loan of 

 Swainson's (supposed) type of L. phcsocephalus from the Cambridge 

 Museum. 



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