LARUS. 27 



f 1 . Wing 17.00, or less ; culmen 1.90, or less. Adult : Exactly 

 like L. leucopterus, except in the coloration of the pri- 

 maries; length about 23.00-24.00, wing 15.00-17.00, 

 culmen 1.60-1.90, depth of bill through angle .55-.6G, 

 tarsus 2.10-2.40, middle toe (with claw) 2.15-2.30. 

 Hob. Western coasts of North Atlantic, from Cum- 

 berland Gulf south, in winter, to New York. 



45. L. kumlieni BREWST. Kumlien's Gull. 



/ 2 . Wing 18.25, culmen 2.35. Adult : In plumage exactly like 



L. kumlieni ; depth of bill through angle .80, tarsus 3.05, 



middle toe (without claw) 2.40. Hab. Norton Sound, 



Alaska 46. L. nelsoni HENSH. Nelson's Gull. 



e 2 . Second quill deep ash-gray, either to the extreme tip, or else with 

 very small white tip and small white spaces some distance 

 from the tip, on one or both webs. 



Adult: Mantle pearl-gray, darker than in any of the pre- 

 ceding. In winter, head and neck clouded (not streaked) 

 with sooty gray. Young : Prevailing color deep ash- 

 gray, nearly uniform, and inclining to plumbeous, be- 

 low, but above relieved by a coarse irregular spotting 

 of grayish white or pale dull buff, the head and neck 

 indistinctly streaked with the same. Immature (second 

 year f) : Similar, but mantle mixed with pearl-gray, 

 and lower parts with whitish. Length 23.70-27.75, 

 wing 16.25-17.30, culmen 2.20-2.60, depth of bill 

 through angle .80-.90, tarsus 2.35-2.90, middle toe 

 (without claw) 2.05-2.45. Eggs 2.88-2.03. Hab. 

 Coasts of the North Pacific and Bering's Sea, from 

 Japan northward, across through Aleutian chain, and 

 south, in winter, to California. 



44. L. glaucescens NATJM. Glaucous-winged Gull. 

 d*. Darker spaces on primaries black. 



e 1 . Shafts of primaries, in black subterminal spaces, white. 



Adult: Mantle dark slate, the primaries mostly black, 

 with white tips and spots near end ; rest of plumage 

 pure white. In winter, top of head and hind-neck 

 streaked with dusky. Young : Above dusky, the feath- 

 ers bordered with pale buffy; quills blackish, with 

 narrow whitish tips ; tail dusky, crossed by a narrow 

 subterminal band of grayish, or brownish, white ; 

 head, neck, and lower parts white, the top of head and 

 hind-neck streaked, the lower parts clouded or irregu- 

 larly spotted with grayish brown. Downy young: 

 Grayish white, the upper parts marbled or irregu- 

 larly spotted with dull grayish ; head with numerous 



