LARID.E — STERNIN.E: TERNS, SEA SWALLOWS. 



1009 



between the foregoiug large crested Sea Terns and the smaller species following ; but the former 

 agree best with it, and may be brought under the same genus, Thalasseus being now restricted 

 to the Caspian Teru.) 



(Subgenus Sterna.) 



S. tnideau'i. (To Dr. James Trudeau.) Trudeau's Tern. White-headed Tern. Size 

 and proportions nearly as in S. forsteri, the bill especially of same size and shape. Coloration 

 very different, unique in the subfamily. Adult : Bill straw-yellow at end, brighter yellow on 

 basal half, with a broad black intervening baud. Whole head pure white, dee[)eniag insen- 

 sibly into pearly color all around the neck. A narrow bar of slaty-black on side of head, 

 passing through eye from the auriculars, where the fascia widens and bends down a little. 

 Rest of the plumage, below as well as above, uniform pale pearly, with the following excep- 

 tions : Under surfaces of wings pure white ; tail, with its coverts and rump, white, with an 

 appreciable pearly tint ; tips, and part of inner vanes of secondaries white ; primaries with a 

 white space on inner webs, their darker portions beautifully silvered ; shafts white above and 

 below, except at extreme tips. Feet reddish. Length 14.00; wing 10.25; tail 6.50, forked 

 2.75; bill along culmen 1.50-1.70; its depth at base 0.38; length of gonys 1.75; tarsus 0.90; 

 middle toe and claw 1.05. A rare and remarkable South American species, questionably oc- 

 curring in North America, ascribed to New Jersey and Long Island by Audubon. (Phaetusa 

 sellovii Light. 1854. Sterna frobeenii Ph. and Ldb. 1863.) 



S. for'steri. (To John Reinhold Forster. Figs. 50, 694.) Forster's Tern. Havell's 

 Tern. Similar to S. hirundo (see next); larger; bill longer, stouter; wings shorter, tail 

 longer'; feet larger. Length about 15.00; extent 30.00; 

 wing 9.50-10.50; tail 5.00-8.00, forked 2.50-5.00; bill along 

 culmen 1.50-1.75, averaging 1.60, its depth at base 0.40; 

 tarsus 0.90-1.00; middle toe and claw 1.00-1.10; whole foot 

 averaging 2.00. Adult $ 9 > breeding plumage : Bill orange- 

 yellow, black for nearly its terminal half, the extreme points 

 of both mandibles yellowish ; robust, deep at base, and 0.10- 

 0.20 longer than that of S. hirundo. Black cap not extend- 

 ing so far down on sides of head as in hirundo, barely em- 

 bracing eye (the lower lid of which is white), thus leaving a 

 wider white space between eye and edge of upper mandible. 

 Mantle perhaps a shade lighter than that of hirundo. Wings 

 absolutely a little shorter (though forsteri is a larger bird) ; 

 primaries strongly silvered; outer web of I.';! not black, but 

 silvery like the others ; all wanting the decided white space 

 on the inner webs which exists in hirundo and parudisca ; 

 there are indications of it on the 3 or 4 outer primaries, the 

 others are nearly uniform dusky gray, moderately hoary. 

 Entire under parts white, with scarcely a trace of th(> ])linii- 



1 us so evident in hirundo, and so decided in jxirddiscd. 



'i":iil slightly lighter than the mantle, separated from the lat- 

 tiT for a short space l)y the decidedly white rump; lateral feathers much more streaming than 

 in hirutido, the clougation generally equalling and sometimes exceeding that oi paradisca. The 

 two streamers are white on the outer web, dusky-gray on the inner. (This being exactly the 

 reverse of hirundo, and a very noti(reable feature, was the first to draw attention to forsteri; and 

 this character being so convenient, writers have perhaps laid too much stress upon it.) Feet 

 bright orange, tinged with vermilion ; tarsus shorter than middle toe and claw ; feet longer and 

 stouter by over 0.10 of an inch than the same parts in hirundo. Adult, winter plumage: Bill 



til 



Fio. C04. — Tail of Forster's Teni, 

 about jj iiat. size. (From EUiot.) 



