LABIDJE — STEBNIN^ : TEENS. 
757 
793. S. (G.) an'glica. (Lat. anglica, Anglican, English.) Gull-Billed Tern. Marsh Tern. 
^ ^ , in summer : Bill rather shorter than head, robust, not very acute, compressed ; culmen 
nearly straight to beyond nostrils, then very declinato-convex to the tip ; gonys about straight ; 
rami slightly concave ; symphyseal eminence well marked ; tomia of lower mandible inflected ; 
commissure gently curved. Height of bill at base a third of total length. Nasal groove 
short and broad, not deep ; nostrils short, widely oval, placed very near base of bill, just 
beyond the termination of the feathers. Wings exceedingly long and acute, each primary 
surpassing the next by a full inch ; the secondaries short, soft, obliquely incurved at their 
extremities. Tail short, contained 2i times in the wing; deeply emarginate, but its lateral 
feathers not elongated nor attenuated. Feet long and stout for this subfamily. Tarsus 
shorter than bill, longer than middle toe and claw. Hind toe remarkably developed ; inner 
shorter than outer ; interdigital membranes deeply incised, especially the inner. Tibia naked 
for half an inch. Crown and long occipital crest glossy greenish-black, extending on to lower 
border of eye, leaving only a very narrow line of white to run along the edge of the feathers 
on side of upper mandible. Neck all round and under parts, white. Mantle light pearl- 
blue, this color extending on rump and tail, quite to -the tips of the rectrices; taU-feathers, 
indeed, deepest colored at their tips, fading into nearly pure white toward their bases, on that 
portion of each feather which is covered with the next one. The color of the mantle extends 
quite to tips of tertials, but dilutes a little toward the tips of the secondaries. Shafts of 
primaries yellowish-white. Primaries all grayish-black, deepest on the outer vane of the 
first ; but this color so heavily silvered as to appear much lighter. All the primaries have 
on their inner webs a space of white, which extends toward their apices for a varying distance 
on each ; on the first the white is largest, purest, and extends furthest ; is distinctly defined 
from the black, and has not a margin of black along its inner border, except just at its apex. 
The amount of the white diminishes in length and breadth with each successive primary, 
until on the last one it is inconspicuous ; still it is quite perceptible on all. Bill black, 
with or without a minute yellowish tip ; legs and feet greenish-black ; iris brown. In winter : 
Differs in restriction of the black cap, chiefly to the hind head and nape, on sides of head 
reaching forward to eye ; sometimes extinct, except in dusky eye-stripe and spot before eye, 
when whole head otherwise white. Young: Bill blackish- brown, pale at base below; feet 
dull brownish. Upper parts pearl-blue, interrupted by numerous crescentic or hastate spots 
of dull brownish, one on each feather, the extreme tip of which is whitish. A brownish- 
black bar along lesser wing-coverts. Forehead and most of crown white, with dark shaft- 
lines, increasing to exclude white on hind head and nape ; blackish spot before and behind 
eye. Neck all around, upper tail-coverts, and whole under parts, white. Tail-feathers 
whitening at ends, each with a dusky space. Length 13.00-15.00; extent 33.00-37.00; 
bill 1.40 ; along gape 2.00 ; its height at base 0.45 ; tibite naked 0.50 ; tarsus (average) 1.30 ; 
middle toe and claw 1.10 ; hind toe and claw 0.40 ; wing 11.75-12.25 ; tail 5.50, forked 
1.20-1.75. Nearly cosmopolitan; in N. Am., not abundant, and chiefly in Eastern U. S., 
Texas to New England. Not a beach-nester ; breeds in marshes, like the black tern ; 
eggs 3, laid on broken-down reeds or grasses, 1.75 X 1.30, olivaceous, largely and irregularly 
splashed with umber-brown and blackish, especially about the largest part, but very variable, 
like all terns' eggs. 
793. S. (T.) cas'pia. (Of the Caspian Sea. Fig. 512.) Caspian Tern. Imperial Tern. Of 
maximum size. Length 20.00-23.00; extent 50.00-55.00; wing 15.00-17-00, usually about 
16.00 ; tail only 5.00-6.00, forked about 1.50, middle feathers broad to their rounded ends, rest 
growing successively more acute, but lateral without any slender filamentous development. 
Bill extremely large, 2.75 along culmen, 4.00 along gape, 0.90 deep at base, 0.50 wide at 
nostrils ; about as long as head, with culmen regularly curved from base to tip ; outline of 
mandibular rami slightly concave ; gonys about straight ; angle "not very well marked. 
