196 LARID^E. 



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 1OO. 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. 



Hab. Patagonia, Chili, Peru, Argentina, Brazil, and Falkland Islands, 

 up to Rio. 



This is a black-headed Tern with a blood -red bill, which is found 

 abundantly on the coast of Patagonia, and extends up the Atlantic 

 coast to Rio. It was noticed by Durnford near Buenos Ayres, and 

 found breeding by the same excellent observer at Tombo Point, about 

 sixty miles to the south of Chupat, in December 1877. He tells us : 



" I was prepared when I visited this place in December to see a con- 

 siderable quantity of birds ; but the number that met my eyes fairly 

 staggered me. Their nests covered an area about 150 yards square. 

 Allowing three nests and five eggs for every square yard (a very mode- 

 rate computation, it being difficult to walk without treading on the eggs), 

 we arrive at the extraordinary number of 67,500 nests, 135,000 birds, 

 and 112,500 eggs; and, wonderful as these figures may appear, I feel 

 sure that I have rather understated than overstated the numbers. The 

 nests were mere hollows in the fine gravel or shingle, and contained one, 

 two, and sometimes three eggs. The latter generally have the appear- 

 ance of the eggs of the Sandwich Tern, though of course smaller ; and 

 out of many hundreds I did not see two alike/' 



