154 SYSTEMAiZIC SYNOPSIS. —LONGIPENNES — GAVIZ. 
e 
bill black at base, white at end; eyes and feet red; eyelids orange; claws black. Length 
about 2 feet. ‘California’ (?) The foregoing is compiled from the original description. 
Only three specimens of this excessively rare gull are known: one ascribed to Monterey, Cali- 
fornia; another, adult, from Chatham island, one of the Galapagoes. The latter, in the 
British Museum, is thus described: ‘ Head, neck, and throat, of a sootier color than in X. 
sabinii, darkening toward the base of the hood, but not forming a distinct black collar, as in 
this species; a white frontal band; under parts and tail pure white, the latter more deeply 
forked than in sabinii ; mantle pale pearl-gray, somewhat darker on the wing-coverts; prima- 
ries blackish-brown on outer webs and continuation of inner webs, thence white, except at tip; 
secondaries white, tinged with gray at their tips; bill blackish, tipped with horn-yellow from 
the angle. Wing 16.50 inches; tarsi nearly 2 inches; middle toe the same; hind toe very 
small, but bearing a well-developed claw.” A third has lately been announced from Paracas 
Bay, Peru; this is a young one, with black bill, reddish feet, the mantle spotted and the tail 
barred with blackish. Adult and young are figured by Saunders, P. Z. 8., 1882, p. 523, pl. 
34; see also P. Z. 8., 1878, p. 210. The species is very questionably N. Am. 
72. Subfamily STERNINA: Terns. 
Covering of bill continuous (no cere), hard and horny 
throughout. Bill paragnathous, relatively longer and slenderer 
than in the gulls, very acute, the commissure straight or nearly 
so to the very end. Curve of culmen gentle and gradual from 
base to apex. Symphysis of inferior mandibular rami much 
more extensive than in Lestridine or Larine, but the eminentia 
symphysis less marked. Interramal space narrow. Eneroach- 
ment of feathers on the bill as in Larime.  Nostrils linear- 
oblong, lateral, direct, pervious, varying with genera as regards 
degree of approximation to the base of the bill. Wings ex- 
tremely lengthened, narrow, and acute, the first primary much 
the longest, the rest rapidly graduated. Secondaries short and 
inconspicuous. Tail usually much elongated and deeply forked, 
Fic. 511.—Roseate Tern. (From the lateral feathers being more or less attenuated and filiform ; 
Tenney, after Audubon.) only oceasionally short and broad (Gelochelidon), or graduated 
(Anoiis, ete.). Legs placed rather further back, and less decidedly ambulatorial than in 
Larine. Tibia denuded for a varying distance. Tarsi short and usually slender; scutellate 
and reticulate, as in Larine. Toes of moderate length, and of the usual relative proportions. 
Webs rather narrow, and (except in Anoiis, etc.) more or less incised. Claws small, com- 
pressed, but much curved and acute. Size moderate, or very small. General form slender 
and delicate. Plumage as in other subfamilies, but the pteryle narrow; the sexes hardiy 
differing in coloration, but the variations with age and season very great. 
The terns are not distinguished from the gulls by any strong structural peculiarities, but 
they invariably show a special contour, in the production of which the longer, slenderer, and 
acutely paragnathous bill is a conspicuous element. Only one species has the bill in any no- 
ticeable degree like that of a gull. A few of the terns are as large as middle-sized gulls, but 
the normal stature is much less; and they are invariably of a slenderer build, more trim in 
shape, with smoother, closer-fitting plumage. The great length and sharpness of the wing 
relative to the bulk of the body confer a dash and buoyancy of flight wanting in the gulls; in 
flying over the water in search of food, they hold the bill pointing straight downward, which 
makes them look curiously like colossal mosquitoes ; and they secure their prey by darting 
impetuously upon it, when they are usually submerged for a moment. The larger kinds feed 
principally upon little fish, procured in this way; but most of the smaller ones are insectivo- 
