LARID.E — THE GULLS AND TERNS — LARUS. 



243 





iiM^-^'-^'-:f':jJtaiffli 





equal <inautities, with brownish slate aiul grayish bulYy white, the latter bordering the feathers, and 



lurmiiig l)road irregular bars, mostly beneath the surlace ; primary coverts, remiges, and rectrices 



dusky black, the inner primaries more gray- 

 ish, the primary-coverts narrowly tipped 



with white and the 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. Ijill dusky, 



black at the tip and browinsh basally ; iris 



brown ; legs and feet brownish (in the dried 



skin). Dou-ny youmj : 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 ; M'ing, 15.00- 



16.75 (average, 15.54); culmen, 1.G5-2.15 



(1.83) ; depth of bill through angle, .C0-.75 (.04) ; tarsus, 2.00-2.00 (2.25) ; middle toe, l.TO- 



l.!)5 (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-l)lue, intermediate 

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



iums, Pallas, of the Pala?arctic Region and 

 Northwestern America ; the red mandiluilar 

 spot of argentatus, etc., combined with a 

 more or less complete black l)and near the 

 end of the bill, as in ddawareusis, 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 ficturcfi 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 on the 

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

 Bernard Ross claims to have met with it on the Mackenzie Eiver. Dr. Cooper writes 

 that he found this Gull not rare on the Pacific coast in the neigliborhood 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 mode 

 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 has brown irides, and yellow, though, according to the labels of some collectors, 

 flesh-colored feet ! 



