LARID.E — STERNIN^— TERNS, SEA SWALLOWS. 1005 



to but larger than those on its sides, which are rough ; hind toe extremely small ; outer lateral 

 nearly as long as middle toe and claw, which is 1.65. Adult (J 9 > in breeding plumage : Bill 

 vermilion red, lighter and somewhat "diaphanous" toward the tip. Pileum and occipital crest 

 glossy greenish-black, extending below the eyes, and occupying the termination of the feathers 

 on sides of upper mandible to the exclusion of white; lower eyelid white, forming a noticeable 

 spot ; a white streak along sides of upper mandible, not extending to the end of the feathers. 

 Mantle pearl-blue, the line of demarcation between it and the white indefinite, both on nape 

 and rump ; most tail-feathers, especially the central ones, having a more or less pearly tint. 

 Shafts of primaries yellowish-white ; primaries grayish -black, but, when new, so heavily sil- 

 vered over as to appear of a light hoary gray, especially on their upper surfaces. On the inner 

 web of all there is a central light field ; this is very narrow, even on the first primary, although 

 it runs for some considerable distance, and on the others it rapidly grows less ; and it has no 

 trenchant line of division on any of the primaries from the darker portions of the feather. 

 Whole inner web of secondaries pure white, outer pearl-blue. Feet black. Adult, winter 

 plumage : Chiefly distinguished by a diminution in the briglitness of the bill, and by a change 

 in the character of the pileum. The vermilion is replaced by light orange-red, growing still 

 yellower toward tip of bill and along tomia. Forehead white, usually quite pure ; crown white, 

 with narrow, distinct shaft-streaks of brownish-black. On the sides of the head, before and 

 behind the eyes, and over the auriculars, black is more mixed with white ; and on the nape 

 black prevails, being only slightly variegated with white. Y(jung-of-the-year : much smaller 

 than tlie adult, the bill especially shorter and weaker, and of a duller red, more inclining to 

 orange. Upper parts as in the adult, but the pearl -blue everywhere spotted with rather small 

 roundish or hastate spots of brownish-black, largest on the inner secondaries. Forehead gtay- 

 ish-white; vertex speckled with grayish-white and black, the latter color increasing in amount 

 until it becomes nearly or quite pure on the short occipital crest. Wings much as in the adult. 

 Tail much shorter and less forked ; the rectrices with brownish spaces near the tips, chiefiy on 

 the inner webs. Under parts dull white. Feet blackish. Downy young : Grayish-white above, 

 faintly mottled with blackish not aggregated into spots ; white below, dusky across throat. 

 Nearly cosmopolitan. In North America irregularly distributed, not only during the extensive 

 migrations, but also during the breeding season ; known to breed at various points on the At- 

 lantic coast N. from Texas, in the interior from Great Slave Lake to Lake Michigan, Nevada, 

 and California, but seldom observed on the Pacific coast. Eggs 2-'i, in hollow scooped in dry 

 sand without nest, 2.65-2.75 X 1.80-L90, broader and more elliptical than those oi S. max- 

 ima, with smoother and harder shell ; ground-color pale olive-buflF, evenly marked all over 

 with small spots of dark-brown and lavender. Breeds commonly by single or few pairs. 

 This greatest of all Terns may be worthy of the generic distinction accorded to it by many 

 authors, under the several names of Thalasseus, Hydroprogne, Gi/lochelido)!, and Helopus; 

 but I do not alter the status I gave it in former editions of the Key, as this is sanctioned by 

 tlie A. 0. U. I could not, however, follow tlic A. 0. U. in changing the established name 

 caspid, given by Pallas in 1770, to the barbarous designation tscliegrava bestowed by Le- 

 I'KCiiiN a few pages before caspia, in the saine Part of the same Vol. of the same publication 

 of tl)e same date — why then the change ? See A. 0. U. List, 2il edition, p. 28. But S. cas- 

 2na (as always in the Key), A. 0. U. Suppl. List, Auk, Jan. 18i)!», )>. !>9. The North American 

 Thalasseus has been separated as T. imperator CouES, 1862 {Sterna caspia var. imperator 

 RiDCiW. 1874), on the ground of average greater size. 



(Subgenus Actochelidon.) 



S. (A.) maxima. (Lat. maxima, largest; not true of this species, if the Caspian Tern is 

 kept in tlie genus /S^/er«a. Fig. ()i»J.) Cayenne Tern. Royal Tkun. Bill about as long 



