502 NATATORES. LARUS. GUM,. 



tion to each other as that between the Greater and Lesser 

 Black-backed Gulls (L. marinus and L.fuscus). This, upon 

 further investigation, was found to be actually the case ; and 

 some interesting remarks upon the new species, by the same 

 gentleman, were afterwards published in the latter part of 

 the fourth volume of the Wernerian Society's Memoirs, 

 where he has appropriated to it the specific title of Islandi. 

 cus, having then ascertained that the larger species previously 

 noticed, and to which he had applied the term, was already 

 recorded, and generally known by the name of Larus glau- 

 cus. In point of priority, therefore, this name ought to be 

 adopted for the present species, in preference to that of La- 

 rus arcticus given to it by Mr MACGILLIVRAY, or that of 

 L. leucopterus, under which it is described by RICHARDSON 

 and SWAINSON, in the Fauna Americana Borealis, and by 

 the Prince of Musignano, in his Synopsis. Captain SABINE, 

 in his Memoir on the Birds of Greenland, in the twelfth vo- 

 lume of the Linnean Transactions, has described the same 

 bird under the title of Larus argentatus, and this in deference 

 to the opinion of Monsieur TEMMTNCK, who at that time 

 considered it as a variety of the Herring Gull, occasioned 

 by the rigours of a polar climate. The fact, however, of the 

 true L. argentatus having been found with its characteristic 

 markings unchanged in those regions, together with the per- 

 fect and undeviating whiteness of the wings of the other 

 bird, and the difference of proportions observable in the bills 

 of the two species, might justly have made the former author 

 hesitate before yielding even to the authority of a naturalist 

 so deservedly eminent. The present species, in all its states 

 of plumage from adolescence to maturity, bears the closest 

 resemblance to the Glaucous Gull, and can only be distin- 

 guished by its striking inferiority of size, and by the greater 

 length of its wings, which reach, when closed, upwards of an 

 inch beyond the end of the tail ; whereas in the other bird 

 they scarcely reach that part. Like its prototype it is a 

 winter visitant to the Shetland Isles and the northern parts 



