546 Capt. SaniNE's Memoir on the Birds of Greenland, $c. 
conjecture, may have been caused by sickness or by scan ty su pply 
of food. | 
20. Larus AncENTATUs. Silvery Gull. 
The bird now under consideration does not appear to have 
been described in any of the books which are referred to in this 
memoir. It is necessary therefore to explain why the name of 
argentatus or silvery, which has been used before, has been at- 
tached to it. A Larus argentatus was introduced by Brünnich, 
who was followed by Gmelin; but the bird to which the name 
was applied is evidently the Larus fuscus or Herring Gull of La- 
tham, in winter plumage: as is also the Silvery Gull of the Arctic 
Zoology and of Latham’s Synopsis. In this opinion Temminck 
concurs, as is shown by his quotations in his Manuel under the 
head of Larus glaucus. Latham in the Index Ornithologicus takes 
up the Larus argentatus of Drünnich, but considers it erroneously 
as an aged bird of the Larus marinus or Great Black-backed Gull. 
Montagu finding the term argentatus at liberty, applied it in his 
Dictionary to his Less Black-backed Gull; but it will be seen by 
reference to the Manuel of Temminck that the Less Dlack-backed 
Gull is the Larus fuscus of Linneus and Gmelin. 
I apprehend that the reason why the bird under consideration 
has not been hitherto distinctly described is to be found in its 
general resemblance to the Larus glaucus: it will be therefore 
best distinguished by a comparative description. In the general 
character of the plumage they are alike, differing from the other 
large species of this genus in the entire absence of black in the 
primary quill-feathers; the shade of the ash-colour of. the back, 
scapulars, and coverts, varies in different specimens from almost 
the lightest percéptible tint to a darker than the darkest Larus 
glaucus that was killed on the voyage; the principal distinction 
between 
