LAKID.'E — THE GULLS A^D TERNS — LARUS. 



243 



ms^'^» 



equal quantities, with brownish slate and grayish huffy white, the latter bordering the feathers, and 



forming Ijroad irregular burs, mostly beneath the surface ; i)rimary coverts, remiges, and rectrices 



dusky black, the inner primaries more gray- 

 ish, the primary-coverts narrowly tipped 



with white and ihe outer tail-feathers with 



irregular broken bars of the same. Head, 



neck, and lower parts mottled or clouded 



with grayish white and brownish gray, the 



latter prevailing on the head and neck — 



nearly uniform on the nape. Bill dusky, 



black at the tip and brownish basally ; iris 



brown ; legs and feet brownish (in the dried 



skin). Downy young : Grayish white, purer 



white centrally beneath, where immaculate ; 



head marked by irregular dusky black spots, 



of indefinite arrangement, but most numerous 



above ; upper parts clouded with dusky gray- 

 ish. Bill black, tipped with pale yellowish 



brown. 



Total length, 21.50 to 23.00 inches ; 



extent, 51.00 to 55.00 inches ; wing, 15.00- 



16.75 (average, 15.54); cuhnen, 1.65-2.15 



(1.83) ; depth of bill through angle, .60-.75 (.64) ; tarsus, 2.00-2.60 (2.25) ; middle toe, 1.70- 



1.95 (1.88). [Fifteen adults.] 



The salient points distinguishing this well-marked species from others occurring in the same 



regions consist in the peculiar shade of the mantle, which is a deep cinereous-blue, intermediate 



between the plumbeous of occidentalis and the pearl-blue of argentatus, and exactly as in L. cachin- 



nans, Pallas, of the Palaearctic Region and 

 Northwestern America ; the red mandibular 

 spot of argentatus, etc., combined with a 

 more or less complete black band near the 

 end of the bill, as in ddaicarensis, although 

 there is rarely, if ever, a complete band, as 

 in the latter species. The dark-brown irides 

 and pea-green feet of the perfect adult dis- 

 tinguish it at once from all its allies, which, 



except L. occidentalis,'^ have, when adult, yellow or whitish irides and flesh-colored feet. 



As in other species of this group, the white pictura; of the primaries increase in size with the 



age of the bird ; as coincident with this change, it may be mentioned that in the older individuals 



the black spots of the bill are sometimes almost obsolete, being most distinct in younger specimens. 



This is an exclusively northwestern and northern species, and is found nn the 

 Pacific coast in the winter ; but retires to its breeding-places in the summer, Mr. 

 Bernard Eoss claims to have met with it on the Mackenzie Elver. Dr. Cooper writes 

 that he found this Gull not rare on the Pacific coast in the neighborhood of San 

 Diego during the winter ; and he also states that it winters along the entire coast as 

 far north as Puget's Sound ; but that it retires in the summer to its breeding-places 

 in more northern regions. He describes this species as being less vigorous in flight 

 than L. occidentalis, more inclined to dive for fish, and not so varied in its auode 

 of obtaining its subsistence. He thinks it probable that this species is one of those 

 Gulls which breed on Mono Lake and on other salt bodies of water in the interior 

 basin. 



1 L. occidentalis Las brown irides, and yellow, though, according to the labels of some coUectois, 

 flesh-colored feet ! 



