374 BROOKLYN INSTITUTE) MUSEUM. SCIENCE BULLETIN 2. 6. 



Pliacthusa magiiirosfris Berlepsch & Hartert, p. 132. 



Native name Guanaguanare. 



Eye seal brown ; bill canary yellow, lightest at the base ; feet sul- 

 phur yellow. 



One of the most abundant and characteristic of birds along- the 

 Orinoco. It is likely to be the first species one will see on entering the 

 mouth of the great river, and as he proceeds towards the head-waters 

 it will follow him, and even when he crosses through the Cassiquiare and 

 down the Rio Negro to the Amazon. 



The nesting season begins in December and lasts until February. 



Sterna supercilaris Vieillot. 



Sterna superciliaris Vieill., Nouv. Diet. XXXII. 1819. p. 126; Berlepsch 



& Hartert, p. 132. 



Native name Tenten. Not abundant but observed everywhere both 

 on the lower and upper stretches of the river. Fresh birds have the eye 

 seal brown; bill dark Naples yellc^v; feet dusky sulphur yellow. 



Rynchops nigra cinerascens (Spix). 

 Rhynchops cinerascens Spix, Av. Bras. II. 1825. p. 80, PI. 102. 



Rhynchops nigra cinerascens Berlepsch & Hartert, p. 132. 



Native name Gaviota. Common all along the middle and lower 

 stretches of the river. 



Larus atricilla (Linnaeus). 

 Lanis atricilla Linn., Syst. Nat. I, 1758, p. 136 (Bahamas). 



Often seen in company with the Large-billed Tern (Phaethusa 

 chloropoda) about the mouths of the Orinoco and common at alniost 

 all points along the shore of the Bay of Paria. 



