Capt. SaBinr’s Memoir on the Birds of Greenland, &c. 543 
which were obtained, and which were very numerous, were all of 
the latter plumage, which is certainly that of the perfect adult 
bird. The white feathers on the forehead are found only on young 
birds of the first year considerably advanced towards maturity. 
In astill younger state it is supposed to be the S. obscura or Brown 
‘Tern of Gmelin and Latham, and perhaps also the S. nigra of the 
Fauna Suecica, Müller and Brünnich. There is a remarkable dif- 
ference between the Greenland common Terns and those of the 
European coasts, in their bills and legs ; the bills of the Greenland 
birds are one-third shorter than the European ones, and the tarsi 
of the former are only half the length of the latter. 
18. Larus Marinus. Great Black-backed Gull. 
L. Marinus. Fabr. 109. Temm. 490. 
MATURE. L. Marinus. Gmel.i.598. Lath. Ind. Orn.ii. 813. — Brün. no. 145. 
Faun. Suec. 55. Müll: no. 163.—Black-backed Gull. Lath. Syn. vi. 371. Br. 
Zool. ii. 179. Arct. Zool. ii. 527.—Great Black-backed Gull. Mont. Dict. & App. 
IMMATURE. L. Nevius. Gmel. i. 598.— Wagel. Lath, Syn. vi. 575. Br. 
^ Zool. ii. 189. rct. Zool. ui. 598. 
The largest of the known Gulls. This bird was once, and once 
only, seen from the ships, when they were high up in Baffin’s Bay, 
but at a distance too great to obtain a specimen. It was known 
to Fabricius both in its mature and immature plumage; but he 
was probably mistaken in considering the L. varius of Brünnich ` 
asa synonym of the young bird : that from its size is probably an 
immature Herring Gull. -The L. marinus is too well known to 
need a particular description. 
19. Larus Graucus. Glaucous Gull. 
L. Glaucus. Gmel. i. 600. Fabr. 100. Briin. no. 148. Müll. no. 169. Lath. Ind. 
Orn. ii. 814.—Glaucous Gull. Lath. Syn. vi. 374. Arct. Zool. ii. 539. & Supp. 70. 
Notwithstanding the confusion in which the larger species of 
Gulls 
