% 
562 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
Bill moderately to strongly compressed, but exceedingly variable 
as to relative depth and width, the culmen always more or less de- 
curved terminally, the tip of the maxilla overhanging or overreaching 
that of the mandible to a greater or less extent; gonys shorter 
(usually much shorter) than mandibular rami, the gonydeal angle 
more or less prominent, sometimes conspicuously so; nostrils lateral, 
near middle of maxilla or posterior to the middle, narrow, longitudinal, 
pervious, usually broader and rounded at anterior end, narrower and 
acute posteriorly; frontal feathering always advancing farther on 
sides of maxilla than at base of culmen, forming a prominent, usually 
obtuse but sometimes acute, angle in nearly direct line behind nostril. 
Primaries relatively shorter and broader and secondaries relatively 
longer than in Sternide. Tail usually truncate or very slightly ° 
rounded, rarely forked, still more rarely cuneate or graduated; when 
forked, the bifurcation only moderate, and the lateral rectrices in- 
stead of being attenuated as in most Sternidz are broad and rounded 
at tips, like the middle ones. Tarsus distinctly compressed, the 
acrotarsium regularly transversely scutellate, the planta tarsi and 
sides of tarsus with small roundish or hexagonal scales (reticulate); 
upper surface of toes continuously transversely scutellate; anterior 
toes fully webbed; hallux usually well-developed though small, 
rarely (in one genus only) rudimentary or nearly obsolete. 
The Laride are cosmopolitan in their range, though most numerous 
in both species and genera in the Northern Hemisphere. America 
possesses about thirty-five species, belonging to nine genera, of which 
only eight species and one genus are extralimital to the present work. 
The birds of this family frequent the sea-coasts, estuaries, and 
larger inlana waters. Their food consist: of various marine animals 
(including fishes), offal, insects, garbage from vessels, and, in fact, 
anything eatable. They nest upon rocks, aloag beaches (behind the 
surf-line), and in marshes. Eggs several, variable as to ground-color, | 
but always spotted. 
KEY TO THE GENERA OF LARIDE, 
a. Exposed culmen decidedly more than two-thirds as long as tarsus; tail truncate, 
very slightly rounded, emarginate, or forked. 
b. Hallux obsolete or rudimentary; tarsus shorter than middle toe without claw. 
Rissa (p. 564). 
bb. Hallux well developed; tarsus longer than middle toe without claw. 
ce. Tail truncate or very slightly rounded. : 
d, Hallux joined to inner toe by a rugose or serrate membrane; tibia with less 
than lower third unfeathered. 
e. Depth of bill at gonydeal angle much less than distance from anterior end 
of nostril to tip of maxilla and not greater than its depth at base; color 
of plumage entirely white (sparsely spotted with dusky in young). 
Pagophila (p. 575). 
