HYDROCHELIDON.—GELOCHELIDON. 399 
plumis auricularibus nigris; prapectore laterali plumbeo, plagam conspicuam formante ; subalaribus 
pallide cineraceis ; axillaribus et remigibus intus plumbescentibus. Long. tota circa 9°5, ale 7-9. (Descr. 
maris adulti ex Cay Dolores Channel. Mus. nostr.) 
Hab. Norv Averica, from Alaska and the Fur Countries ; breeding from the Middle 
United States, west of the Alleghanies, northward ® to Hudson's Bay 3.—Mexico‘, 
Sinaloa (Streets 23), Matamoros (Dresser *), Laguna Verde, Vera Cruz (Trujillo®), 
Putla (Boucard 8), Laguna de San Baltazar, Laguna de Chapulco, State of Puebla 
(Ferrari-Perez *), near the city of Mexico (White}?), Mazatlan (Grayson ?°1°), 
Manzanillo (Xantus 21), Acapulco (Mrs. H. H. Smith *), Gulf of Tehuantepec, San 
Mateo (Swmichrast 1° 2°); Brirish Hoypuras, Southern Water Cay 1416, Curlew 
Cay, Cay Dolores Channel® (0. 8. & F. D. G.); Guatemana, Coban (0. S.% 1); 
Honpuras®; Costa Rica, Punta Arenas (Zeledon®); Panama (M:Leannan |} 1),— 
Guiana’; Peru’; Cue’. 
The present species is the representative in America of the Black Tern (H. nigra) of 
Europe, which it very closely resembles in its winter plumage, but is distinguished in 
summer by the sooty-black under surface and by the more conspicuous line of white 
along the carpal edge of the wing. 
H. surinamensis is a bird of somewhat irregular distribution in North America, 
breeding in the north in the marshes of the Fur Countries, and in similar localities 
throughout the interior of the United States. It is common in flocks in many places 
in Central America, appearing at Mazatlan, according to Grayson, in September and 
October, and remaining all the winter’. It has been more frequently observed on 
the Pacific coast than on the Atlantic side or in the interior, and extends its range in 
winter to Peru and Chile ®. 
The American Black Tern is a marsh-loving bird in the breeding-season, and feeds 
more on insects than on fish, showing great activity in pursuit of the former. 
The nest is generally made of reeds placed on tussocks, and is often of large size. 
The eggs resemble those of H. nigra, being of a pale buff colour or brownish-buff, 
heavily blotched or spotted with reddish-brown or blackish-brown. 
GELOCHELIDON. 
Gelochelidon, Brehm, Vég. Deutschl. p. 774 (1831) ; Saunders, Cat. Birds Brit. Mus. xxv. p. 25 
(1896). 
This genus belongs to the section of Terns in which the outer tail-feathers are 
pointed and longest. The tarsus is unusually lengthened, exceeding the dimensions of 
the middle toe and claw, while the tail is less than half the length of the wing. The 
pill is conspicuously stout and obtuse, whence the trivial English name of the “ Gull- 
billed” ‘fern is applied to the only species of the genus Gelochelidon. 
The single representative is found over the greater part of the temperate regions of 
