756 SYSTEMATIC SYNOPSIS —LONGIPENNES — GAVIjE. 
Webs incised (Group Sterner). 
Webs moderately incised. Tail well-formed, generally more than half as long as the wing. Under 
parts white or light. 
Upper parts pearl-gray. Cap in summer black, or a black bar through eye. 
Bill short and very stout, somewhat gull-like, black. Tarsi much longer than the toes, 
black. Tail lightly forked. Medium size Gelochelidon 
Bill long, large, bright colored, or with yellow tip. An occipital crest. Feet black 
Forking of tail variable. Of large size Thalasseus 
Bill moderate, slender, usually bright colored, like the feet. No crest. Tail long, deeply 
forked. Size medium and small Sterna 314 
Upper parts dusky. Cap like the back. 
Bill and feet black. A white fi-ontal crescent Haliplana 
Webs deeply incised (feet little more than semipalmate). Tail merely emarginate, hardly or not half 
as long as the wing. Under parts in summer black Hydrochelidon 315 
Nostrils nearly median. No frontal antise, the feathers extending further on culmen than at the sides. 
Tail double-rounded. Tarsi very short. Toes lengthened, the lateral nearly as long as the middle, with 
full webs. (Group Anoe^e.) 
Color fuUginous . Anoits 316 
314. STER'NA. (Latinized from English stern or tern.) Terns. Form typical of the sub- 
family. Nostrils sub-basal. Frontal antise prominent. Tail more or less forlved. Tarsus 
not shorter than middle toe without claw. Lateral toes much shorter than middle. Webs 
moderately incised. Under parts of adult white, or like back. (Characters of the subfamily, 
exclusive of Hydrochelidon and Anoiis.) 
Analysis of Subgenera and Species (adults). 
Gelochelidon. Bill very stout, almost gull-like, black. Tarsus much longer than toes, black. Tail 
lightly forked, contained about 2^ times in wing. Size moderate. 
Head crested. Cap black. Pearly mantle extending over rump and tail anglica 792 
Thalasseus. Bill long, large, tern-Hke, bright colored or with yellow tip. Feet black. Head crested. 
Size large to largest. 
Tail merely emarginate, contained nearly or about 3 times in wing. Primaries without white space 
on inner webs. Bill red. Largest: wing about 16.00; tail 5.50; bill nearly 3.00 caspia 793 
Tail forked. Primaries with white space on inner webs. Bill orange, stout, about 2.50, 0.50 or more 
deep at base; gonys about 1.00 long. Wing 14.50 maxima 794 
Tail forked. Primaries with white space on inner webs. Bill orange, slender, about 2.50, under 0.50 
deep at base, gonys about 1.50 long. Wing 12.50 elegans 795 
Tail deeply forked, with iiarrow outer feathers. Primaries with white space on inner webs. Bill 
slender, black, yellow-tipped • . . . cantiaca 796 
Sterna proper. Bill long, slender, acute. Tarsus not longer than middle toe and claw. Tail more or 
less forked, with acute or very narrow lateral feathers, one-half or more as long as wing. Head not 
decidedly crested. Size medium to smallest. 
Mantle pearly-blue. 
No black cap. 
Head whitish, with black bar through eye ; under parts like the mantle trtideaui 802 
A black cap. 
No white frontal crescent ; black cap reaching bill. 
Bill wholly or mostly red or reddish. 
Bill red, blackening at end; feet coral-red. Outer web of cuter tail-feather white ; 
inner gray or dark. Tarsus 0.90 or more forsteri 798 
Bill red, blackening at end; feet coral-red. Outer web of outer tail-feather gray or 
dark, inner white; under parts paler than upper. Tarsus about 0.75 . . hirundo 797 
Bill wholly red ; feet vermilion ; outer tail-feather as in the last. Tarsus 0.65 or less. 
Under parts nearly like upper macrura 799 
Bill black, or only red at base. Feet reddish dougalli 800 
A white frontal crescent. 
Bill yellow, tipped with black. Feet yellow antillarum 801 
Bill and feet black aleutica 803 
Mantle dusky. A white frontal crescent. Bill and feet black. (Haliplana.) 
Mantle blackish-brown ; cap the same fuliginosa 804 
Mantle sooty-gray ; cap black anoisthetica 805 
Obs. Above analysis based on adult summer birds, and not entirely available for young and winter ones, 
in which the chars, of the cap, and colors of bill and feet, may be entirely different. These must be de- 
termined by reference to the detailed descriptions. 
