SILVERY GULL. 169 



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 ISf 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 2^; tarsus 2i; middle toe 2, its claw y|. Weight 22 oz. 



From 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 argent atus 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 marinas, 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 3i inches; 

 gall-bladder 1 inch 4 twelfths long, S twelfths wide. (Esophagus 10-|- 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, 1^- 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. 



Vol. VII. 25 



