LARIDyE — LAIilN^: GULLS. 983 



through nearly all the species ; they are ivhite, with a darker mantle (stragulum) , and in most 

 cases with black crossing tlie primaries near the end, and tips of the quills white. The shade 

 of the mantle is very variable in the same species, according to climate, action of the sun, 

 friction, and other causes : the pattern of the black on the quills is still more so, since it con- 

 iinually changes with age, until a final stage is reached. Incredible as it may appear, species 

 and even genera have been based upon such shadowy characters. One group of species (genus 

 Chro'icocephalns) has the head enveloped in a dark hood in the breeding season, tlie under 

 parts tinted with peach-blossom hue. The sexes are always alike; the moult appears to be 

 twice a year, so that a winter plumage more or less different from that of summer results ; the 

 young are never quite like the old. The change is slow, with some of the larger species gen- 

 erally requiring 2-3 years; in the interim, birds are found in every stage. Young are always 

 darker than old ones, often quite dusky ; usually with black or flesh-colored bill ; and if with 

 black on primaries when adult, the young usually have these quills all black. There being no 

 peculiar extralimital species, those of our country give a perfect idea of the whole group. Some 

 7.5 species have been current ; but there are hardly over 50 good ones. Mr. Howard Saunders, 

 the latest monographer oi Laridce, and a judicious one, describes 51 species of Larince. He 

 has very ably completed the rescue of these much-abused birds from the clutches laid upon 

 them by Bruch and Bonaparte in 185.3-56, extricating them from tlie confusion which had 

 been only partially done away with by my earlier writings. He adopts 7 genera, placing no 

 fewer than 44 species in the single genus Larus ; his only extralimital genera being Gahianus 

 (pacifieus), and Leucophccus (scoresbii). Regarding North America, I only differ with my 

 friend in continuing to keep Chrdicoeeplialus apart from Larus proper, and in now recognizing 

 Creagrics apart from Xema. Creagrus is sanctioned by the A. 0. U., but Chrdicoeeplialus is 

 not. The only change from the 2d edition of the Key 1 now make is in adopting Creagrus. 



Analysis of Genera. 

 Tail square. 



Head never hooded ; under parts never rosy-tinted ; size medium and large ; bill etout. 

 Hallux well developed, with perfect claw. 



Adult white, with a colored mantle, or dark, with white head Larus 



Adult entirely white : feet black Pagophila 



Hallux usually defective. (Tail emarginate in the young) Rissa 



Head in summer hooded, and under parts rosy-tinted ; size medium and small ; bill slender . . Chroicocephalus 



Tail wedge-shaped ; head not hooded, but neck collared ; size small. Highly Arctic Rlwdostethia 



Tail forked ; head hooded. 



Size small; wing under 12.00 ; bill short : feet black Xema 



Size large ; wing about IG.OO ; bill long ; feet red. (Extralimital ?) Creagrtis 



LA'RUS. (Gr. \apos.i laros, Lat. larus, a gull.) Gulls. Bill shorter than head or tarsus, 

 more or less robust, usually very stout, deep at base, higlier than broad, compressed through- 

 out, apex not very acute and never much attenuated. Culmen about straight to beyond nos- 

 trils, then convex, the amount of curvature increasing toward the end, varying in different 

 species. Commissure slightly sinuate at its extreme base, then about straight to near end, 

 where it is more or less arcuato-ueclinate. Emineutia symphysis prominent and well-defined, 

 rather obtuse, seldom acute. Nostrils placed rather far forward in well-defined nasal fossae, 

 rather broader anteriorly than posteriorly. Feathers of foreliead extending considerably far- 

 ther on sides of upper mandible than on culmen, but falling considerably short of nostrils. 

 Wings when folded reaching beyond tail; 1st primary longest, 2d but little shorter, rest rap- 

 idly graduated. Tail of moderate length, never forked nor rounded. Legs of moderate length ; 

 tiliiiu bare for a considerable distance above the joint, the naked part smooth. Tarsus about 

 oi\\u\.\ to or a little longer than middle toe and claw, varying but slightly in proportions among 

 the different species; anteriorly scutellate, posteriorly and laterally reticulate. Hallux fully 

 d(!velopcd. Anterior claws stout, little curved, rather obtu.se, inner edge of midille one dilated. 

 Webs scarcely incised. Comprising the largest and m.iiiy medium-sized species of the sub- 



