686 STERNA MACRURA, ARCTIC TERN 



,Stenm argenlata, Brehm, Beitr. iii, 1822, 692; V. D. 1831, 782, pi. 38, fig. 5. 

 Sterna argeniavca, Brehm, V. D. 1831, 783. 



Sterna nihschii, Kaup, Isis, 1824, 153.— Brehm, V. D. 1831, 786.— Bp., C. R. 1856, 772. 

 Sierna hrachytarsa, Graba, Reise nacb Faroe, 1830, 218. 

 Sterna hrachypus, Swainson, B. W. Afr. ii, 1837, 252. 

 Sterna eocchmrostris, Reich, {fide Gray). — Bp., Coiiipt. Rend. 1856, 772. 

 Sierna pikei, Lawk., Ann. Lye. N. Y. vi, 1853, 3 ; B. N. A. 1858, 853, j)!. 95.— Bp., Coinpt. 

 Rend. 1856, 772 {'' pyUi").—CovKS, Pr. Pbila. Acad. 1862, 550. 



Diag. St. rostro gracile, rithro ; i^edihus irerissimis, riibris ; corpore ca'rtdescente-plumbeo, 

 subtiis dilutiore; caudd, uropygio, tectricibusque caudalibus infe7'ioribu8 albis ; rectrice 

 laterali valde elongatd, pogonio externo griseo-fusco. 



Hab:—EuToi^e. Asia. Africa. North America generally, south to the Middle States, 

 and on the Pacific side to California. Breeds from Massachusetts northward. No valid 

 extralimital record south of the United States ; compare, however, Phillippi, Cat. 1869, 

 49 (Chili!!?). 



Adult in breeding plumage. — Bill shorter than the head, equal to the middle toe and 

 tarsus together, slender, compressed, acute. Culmen somewhat broad and flattish 

 toward the base, more compressed and narrower anteriorly ; about straight to beyond 

 the nostrils, declinato-convex for the rest of its length. Commissure very slightly 

 curved. Gouys about as long as the rami ; perfectly straight ; the outline of the latter 

 a little concave. Inter-crural space very narrow; about half filled with feathers. 

 Nasal groove rather long, but becoming obsolete before it reaches the tomia. A quite 

 promiuent stria proceeds from its anterior extremity to the tomia, but little behind the 

 tip of the bill. The bill is deep carmine, or lake red ; usually without any black, but 

 this color sometimes appears in a limited degree. 



The feet are remarkably small and weak. The tibije are bare for a moderate dis- 

 tance. The tarsi are exceedingly short, being less than the middle toe without its 

 claw, or, at least, only equal to it. The toes are rather long for the size of the feet ; 

 the outer falls but little short of the middle one, while the tip of the claw of the inner 

 hardly reaches beyond the third articulation of the middle one. Hallux of ordinary 

 relative length. Webs rather narrow ; moderately emarginated ; the inner, as usual, 

 the most so. The feet are a lighter tint of the color of the bill, somewhat tending 

 toward vermilion or coral-red, but are not so light as those of hirttndo. 



The wings are very long ; the primaries attenuated, narrow, tapering to their round- 

 ish but slender apices. The tertials are short, and do not reach half way to the tips of 

 the primaries iu the folded wing. The shafts of all are white, with scarcely darker 

 tips. The outer web of the first primary is grayish-black, lightening into silvery-gray 

 at its tip; its inner web is white, with only a very narrow line of grayish-dusky along 

 the shaft. This longitudinal dusky space is very much narrower and lighter tban in 

 hirundo, so much so, that it is placed as a diagnostic feature by Naumann in his 

 " Keunzeichen der Art." The next four or five primaries are silvery -gray, darkest 

 toward their tips; their inner webs mostly white (wholly so at their bases); but the 

 white does not extend so far toward the tips of the feathers as on the first primary, 

 and it runs up farther in the centre of the web than on the edge of it. The inner pri- 

 maries are the color of the back, broadly tipped and margined iuternallj' with white. 



The tail is exceedingly long, the exterior feather being as much lengthened, and a? 

 narrow, tapering and acute, as iu S. paradisea. The tail feathers reach beyond the tips 

 of the folded wings. The under coverts reach to the extremity of the broad and 

 rounded central rectrices; the upper ones fall short of this length. The tail is pure 

 white, the outer web of its exterior feather being grayish-black, lighter basally, and 

 its inner web, and the outer webs of the next two rectrices, having a considerable wash 

 of pearl-blue. ' 



The pileum is pure, lustrous greenish-black, so broad on the cheeks as to leave only 

 a slender line of white to extend along the edge of the feathers on the side of the 

 upper mandible. The whole upper parts, as far as the superior caudal rectrices, and 

 including the alar coverts, pearl-blue, of about the same shade as in hirundo. This 

 color, however, fades into white at the tips of the tertials and inner secondaries. 

 The under parts are but a little lighter shade of the color of the back, this color fading 

 insensibly into whitish on the chin, throat, Jind edges of the black pileum, and ending 

 abruptly at the uuder tail-coverts, which are i)ure white, iu marked contrast to the 

 rest of the under parts. The inferior alar rectrices and axillary feathers are also pure 

 white. 



Winter plumage of the adults. — Differs from the ahove-described summer plumage 

 chiefly in the color of the feathers of the head, as usual in the subfamily. The fore- 

 head is white; tbe crown white, but marked with narrow shaft-lines of black, which 

 increase from before backward until, on the nape, tbe black is nearly or quite pure. 

 A lateral stripe, more or less pure and distinct, extends forward on the sides of the 

 bead over the auriculars, to just in front of the eye, leaving, however, the eyelids 

 white. Upper j)arts much as in summer, but the under parts from the chin to the vent, 



