136 BULLETIN 133; UNITED STATES NATIONAL MUSEUM 



crow, and entirely different from that of other gulls that I know in 

 life, a call so characteristic that it distinguishes it at once. I found 

 the birds in pairs, apparently mated though I saw no nests, that 

 frequented the vicinity of the killing pens at Los Yngleses where 

 they searched for waste scraps of meat. Others beat back and 

 forth across the open pampa or came to hover over a fallen com- 

 panion. The flight is steady and direct. The adult female taken 

 had the soft parts colored, as follows : Bill madder brown, becoming 

 diamine brown at base; iris naphthalene yellow; bare eyelids drag- 

 on's-blood red ; tarsus and toes dragon's-blood red ; nails black. The 

 light iris in this species is peculiar. 



GELOCHELIDON NILOTICA (Gmelin). 



Sterna nilotica Gmelin, Syst. Nat., vol. 1, pt. 2, 1789, p. 606. (Egypt.) 



The gull-billed tern was found in small numbers. At the port 

 of Ingeniero White, a few kilometers from the city of Bahia 

 Blanca, Buenos Aires, I watched about 50 on December 13, 1920, 

 as they fed over shallow bays or rested on muddy points. They 

 circled about with chattering calls, frequently diving for small fishes 

 in the tidal channels. One flew over my head with one of the 

 abundant crabs {C hasmagiiathus granulata) in its bill and after 

 alighting in shallow water pulled off the animal's claws and then 

 swallowed it. Six or eight gull-billed terns were observed at Lake 

 Epiquen near Carhue, Buenos Aires, on December 15 and 18, and 

 several were noted in company with Royal Terns below Carrasco, 

 near Montevideo, Uruguay, on January 9, 1921, 



Mathews ^^ has separated gull-billed terns from South America 

 as Gelochelidon n. gronvoldi stating that they differ from North 

 American birds Gelochelidon n. aranea (Wilson) in longer bill and 

 wing. It is unfortunate that I secured no specimens of the South 

 American bird as there are none available in the National Museum. 

 Gull-billed terns are said to nest on Mexiana Island near the mouth 

 of the Amazon, and along the coast of Brazil, while the winter home 

 of the North American bird is not certainly known. Southern 

 records may therefore not be allocated under subspecies without 

 study of specimens. 



This tern was first properly designated by Linnaeus in Hassel- 

 quist's Reise Palastinum, German translation (1762, p. 325). Ac- 

 cording to opinion 57 of the International Commission on Zoological 

 Nomenclature names in this work are untenable as the first edition 

 appeared in 1757. It hardly seems that this attitude is proper, 

 however, since binomial nomenclature is taken as beginning on 

 January 1, 1758, and this German translation appeared four years 



"Birds of Australia, vol. 2, pt. 3, Sept. 20, 1912, p. 3H1. 



