GELOCHELIDOX. — STERNA. 



89 



Total length 325 mm., culmen 16, wing 305. tail 117, 

 tarsus 32, middle toe and tla%v 29. 



Adult female. Similar to the adult male. Wing 295 mm. 



The description of the male is taken from an example obtained 

 on tbe Abary River, September 1906. 



Breeding-season. Unknown in Brirish (Tuiana. 



y^est. Unrecorded in British Guiana. 



Eggs. Undescribed from British Guiana. 



Range in British Guiana. Abary River (McConnell collection^. 



E.ctralimital Range. Brazil and Argentina (in South America). 



Habits. Unrecorded in British Guiana. 



Genus STEENA Linn. 



Sterna Linne, Syst. Xat. lUth ed. i. p. 137. 1^7^. Type .S'. Jiirundo 

 Linn. 



In this genus — the typical Terns — the birds are comparatively 

 small, with short legs, short and slender bill, wings long, tail 

 deeply forked, tarsus short and never exceeding the middle toe 

 and claw in length. 



Ket/ to the Species. 



A. Larger, wing more than 200 mm. ; tail 



more than 100 -S'. h irt/nJo, p. 90. 



B. Smaller, wing less than 200 mm. ; tail 



less than 100. 

 a'. Smaller, wing less than 170 mm. ; biU 



yellow tipped with black ; entire 



priinary-quills blackish S. melanorTtyncha, p. 91. 



h'. Larger, wing more than 170 mm. ; bill 



green tipped with yeUow; only the 



three outer priman'-quills black <S'. supercih'aris, p. 92. 



Fig. 19 — To illustrite the j oiutcd bill and the long gonys. 



