52 
SILYEEY GULL. 
the upper part of the head darker, the lower parts minutely mottled with 
pale yellowish-grey ; the feathers of the upper parts, and the upper tail- 
coverts, irregularly edged and barred with greyish-white. Primary quills 
greyish-brown, their inner webs paler, their tips whitish ; tail of the same 
colour, its base and outer webs of lateral feathers irregularly mottled with 
whitish, the tips brownish-white. 
Length to end of tail 183 inches, to end of wings 20 ; extent of wings 51 ; 
wing from flexure 16 ; tail 6 ; bill along the ridge 2, along the edge of lower 
mandible 2J ; tarsus 2\ ; middle toe 2, its claw f|. Weight 22 oz. 
Prom the examination of individuals of this species, it would appear that 
little reliance can be placed on the markings of the quills as affording a spe- 
cific character. Four undoubted specimens of Larus argentatus now before 
me, have a white spot, varying in length from one to two inches, and 
including both webs, near the end of the first quill. One has no spot on 
the second quill ; another has a spot on both webs of the second quill of one 
wing, and a smaller spot on part of the inner web of the same quill of the 
other wing ; the third has a very small spot on part of the inner web of the 
same quill of both wings ; the fourth has a large circular spot on the inner 
web of that quill also in both wings. 
Male. The mouth is of the same structure as in Larus marinus, 1 inch 
4 twelfths in width, The tongue is 1 inch 10£ twelfths long, and similar to 
that of the species just named. Lobes of the liver 3 inches, and 33 inches ; 
gall-bladder 1 inch 4 twelfths long, 8 twelfths wide. (Esophagus 103 inches 
long, at the commencement 2 inches wide, on the neck 1 inch 10 twelfths, 
and within the thorax 2 inches ; it is thus very wide, and its walls are of 
moderate thickness, the muscular fibres distinct, and the inner coat longitu- 
dinally plicate. The stomach is proportionally small, of an elliptical form, 
2 inches long, 1 inch 9 twelfths in breadth, its lateral muscles thin. It con- 
tains bones and scales of fishes. The epithelium in all respects as in Larus 
marinus. Coeca \ inch long, 3 twelfths broad ; cloaca globular, 13 inches 
in diameter. Trachea 10 inches long, from 5 twelfths to 4 twelfths in 
breadth, moderately flattened, its rings 150, feeble. Bronchi wide, each of 
28 half rings. 
