Durnford tells us that he found it common at Baradero in April in small parties, and watched one flock for some time. These individuals kept circling over a mill-pond, which evidently held a good supply of small fishes; for they constantly kept darting into the water. This species, Durnford adds, has a note quite unlike that of any other Tern; it is nearly similar to the cry of the "Tero-tero" (_Vanellus cayennensis_), for which he had often mistaken it. 412. STERNA MAXIMA, Bodd. (GREAT TERN.) +Sterna maxima+, _Scl. et Salv. Nomencl._ p. 147; _iid. P. Z. S._ 1871, p. 567; _Saunders, P. Z. S._ 1876, p. 655, et 1882, p. 521. _Description._--Crown and crested nape black; neck, lores, throat, and underparts pure white; black pale grey; quills darker grey, with white on most of the inner webs; tail pearl-white; bill orange; legs and feet black: whole length 18·0 inches, wing 14·5. _Young_: darker on upper parts. [Illustration: Head of _Sterna maxima_. (P. Z. S. 1871, p. 568.)] _Hab._ Coasts of America from Massachusetts to La Plata, and northwards to California. This large Tern seems to occur on the Rio Paraná, according to Azara. It is certainly found in Southern Brazil, where Mr. Rogers obtained a series of specimens now in the collections of Messrs. Salvin and Godman and of Mr. H. Saunders. 413. STERNA TRUDEAUII, Aud. (TRUDEAU'S TERN.) +Sterna trudeauii+, _Scl. et Salv. Nomencl._ p. 147, _iid. P. Z. S._ 1871, p. 570; _Durnford, Ibis_, 1877, p. 200 (Buenos Ayres); _Saunders, P. Z. S._ 1876, p. 660. +Sterna frobeenii+, _Phil. et Landb. Wiegm. Arch._ 1863, pt. i. p. 125 (Chili). _Description._--Above light grey; head white, with a dark transocular line on each side; rump white: beneath light grey; bill black, base and tip yellow; feet yellow: whole length 12·5 inches, wing 10·0. The young are pure white below, and have darker quills. _Hab._ Coasts of S.E. Brazil, Argentina, and Chili. This beautiful Tern, peculiar for its white head in the adult dress, was observed by Durnford on Flores Island in the Rio de la Plata, and in other places on the coast of the Argentine Republic. One was obtained near Punta Lara, in October 1876; and many more since by Mr. E. Gibson, Commander MacFarlane, and others. 414. STERNA HIRUNDINACEA, Less. (CASSIN'S TERN.) +Sterna hirundinacea+, _Saund. P. Z. S._ 1876, p. 647; _Durnford, Ibis_, 1878, p. 404 (Centr. Patagonia). +Sterna cassini+, _Scl. et Salv. Nomencl._ p. 147; _iid. P. Z. S._ 1871, p. 570; _Durnford, Ibis_, 1877, p. 201 (Buenos Ayres). _Description._--Head and nape black; mantle and wings grey, darker on the quills; rump white; tail pearl-white, darker on the outer streamers; underparts greyish white; bill blood-red; feet orange-crimson: whole length 15·0 inches, wing 11·5. _Young_: streaked on the head and mottled on the upper parts with blackish.