LAEUS ARGENTATUS, HERRING GULL. 627 



Adult. — Bill ratber less than tlie tarsus, shorter than the head ; robust, its height at 

 the angle slightly more than at the base. Culujen nearly straight at the nostrils ; then 

 rapidly convex to the stout, deflected, overhanging apex. Outline of rami sli<>htlv 

 concave ; gonys about straight ; eminence at symphysis large and i^rominent. but its 

 apex not very acute. Wings long-pointed ; the first primary always longest. Tail 

 even. Feet of moderate size ; tarsi compressed, anteriorly scutellate, laterally and 

 posteriorly reticulate. Membranes full and broad, scarcely incised. Claws obtuse, 

 but little arched ; the inner edge of the middle oue dilated, but not serrated. 



Breeding plumaijc. — Bill bright chrome, its tip diaphanous; a vermilion spot at the 

 angle, with sometimes a small black one just anterior to it. Legs and feet jiale flesh- 

 color; the claws blackish. Mantle typical "gull-blue," much lighter than in occi- 

 denialis ; lighter than in hrachyrlnjnchus ; of much the same shade as in delaicarensis or 

 glaucescens ; darker than in glaitcits or leucoptcrus. The bases of the prinuiries are the 

 same as the back, or very slightly lighter, not so light, nor of so great extent (being 

 exceedingly short on the first primary), nor so broad at the end, as in caJifornicus. On 

 the first primary this light basal portion is very short, hardly reaching within six or 

 seven inches of the tip of the primary. It is not lighter at its junction with the black, 

 nor does it extend further on the central portion than ou the edge of the feather. On 

 the second, third, and fourth piimaries the bluish of the basal portions of the feather 

 extends about the same distance on each (within four inches of the tip of the second), 

 and runs up further on the centres of the feathers than on their edges, aud grov.s 

 nearly white at its junction with the black portion of the leathers. First primary 

 with a suha])ical white spot near its tip ; small, rounded, not much over an inch in diaui- 

 eter ; generally not longeron the outer vane than on the inner; sometimes wanting 

 on the former ; in oldest birds this spot enlargiug to coalesce with the white tip of the 

 feather, but such state rarely observed ; second primary usually without a subapical 

 spot, or if one is present it is very small. All the primaries with small rounded white 

 apices, and black from these apical sj^ots to their bluish-white bases; this baud of 

 black growing narrower from the first toward the seventh, where it is a mere point. 



Winter plumage — The head aiul neck are streaked with dusky. The bill is less 

 brightly colored. Otherwise as in summer. 



Immature. — Thejeathers of the back have gray margins, and the upper wing coverts 

 are mottled with duskj^ gray- An imperfect subierminal bar of dusky on the tail. 



Young of first uinter.- Head, ne<k, aud whole under parts more or less thickly mot- 

 tled with dusky, as are the wing-coverts, secondaries, and tertials. The gull-bhie of 

 the upper j)arts appears in irregular patches, mixed with gray. Remiges and rectrices 

 brownish-black, with very narrow whitish tips, the former wanting both apical aud 

 subapical white spots. Bill flesh-color, its terminal third black. Feet dull flesh-color. 

 Younger. — Entirely a deep dull brownish; the throat lightly streaked aud the rump 

 transversely barred with whitish ; the feathers of the back with yellowish or grayish- 

 white edges ; wings aud tail black; bill black; legs and feet dusky flesh-color. 



Dimensions of adult. — Length, 24 to 25 inches ; extent, .'34 to 58 ; wing, 17.25 to 18.00 ; 

 bill along culmen, 2.40 ; height at nostril, 0.75 ; at angle, 0.80 ; tarsus, 2.75 ; middle toe 

 and claw the same. Female a little and young considerably less than the above. 



Other variations. — These are very considerable as regards size aud proi)ortions. The 

 bill along the culmen varies from 2.55 to 2.20 inches, being, however, iu adult birds, 

 generally very near the former measurement. The tarsus will vary more than a fourth 

 of an inch — from 2.75, its usual length, to about 2.40. The ditference iu the length of 

 the wings is slight for so large a Gull, only about an inch. The younger the bird the 

 smaller it is, the weaker and shorter its bill, aud the slenderer its feet. Very old biixls 

 sometimes become almost abnormally big, as is the case with L. glaucus and others. 



Between the time of leaving the nest and of assuming the comjilete plumage of the 

 adult bird the changes are very great. While the unilurui dusky of the body is turn- 

 ing to pure white and clear blue, and while the black tail is whitening and the black 

 primaries are assuming their peculiar characteristic markings, the variations iu degree 

 anrf <;x/en< of all the colors are endless. It is hardly possible to cliaracterize any dofi- 

 uito stages, as they glide insensibly into each other. But iu adult birds, which have 

 attained their second or third summer, the colors of the whole l)ody aud the markings 

 of the i)rimaries are so constant that, taken in connection with the size, form, and 

 other particulars, they adonl fair varietal characters. I do not mean to assert that 

 there is no variation iu theses points, but that adult birds generally preserve a certain 

 definite i)attern of coloration of the primaries. 



In tliis species this "pattern" may be summed up, briefly, as: The presence of a 

 black band on the first seven i)rimarics, which takes in nearly tlie whole of the first, 

 and rapiilly narrows until on tlie seventh it is a mere spot; bluish biiaes to all the 

 l)rimaiiis, of a width iiiver.-ely as that of the black portion; small white apical spots 

 ou all the primarii's ;*■ and a large rounihul subapical white spot on the first (rar*<ly 

 becoming confluent with the white apical spot), witii or without a smaller one on the 

 second. 



• These may be absent, being worn oft" from very old feathers, jast before the tuoiilt. 



