194 LARIDjE. 



was wild, irregular, and rapid; they then also uttered loud, harsh cries. 

 When these birds are fishing, the length of the primary feathers of the 

 wings is seen to be quite necessary, in order to keep the latter dry. 

 When thus employed, their forms resemble the symbol by which many 

 artists represent marine birds. The tail is much used in steering their 

 irregular course. 



" These birds are common far inland along the course of the Rio 

 Parana; it is said they remain during the whole year, and breed in the 

 marshes. During the day they rest in flocks on the grassy plains, at 

 some distance from the water. Being at anchor, as I have said, in one 

 of the deep creeks between the islands of the Parana, as the evening 

 drew to a close, one of these Scissor-beaks suddenly appeared. The 

 water was quite still, and many little fish were rising. The bird con- 

 tinued for a long time to skim the surface, flying in its wild and irre- 

 gular manner up and down the narrow canal, now dark with the growing 

 night and the shadows of the overhanging trees. At Monte Video I 

 observed that some large flocks during the day remained on the mud- 

 banks at the head of the harbour, in the same manner as on the grassy 

 plains near the Parana ; and every evening they took flight direct to 

 seaward. From these facts, I suspect that the Rhynchops generally 

 fishes by night, at which time many of the lower animals come most 

 abundantly to the surface. M. Lesson states that he has seen these 

 birds open the shells of the Mactrte, buried in the sand-banks on the 

 coast of Chile ; from their weak bills, with the lower mandible so much 

 produced, their short legs and long wings, it is very improbable that 

 this can be a general habit." 



411. PHAETHUSA MAGNIROSTRIS (Licht.). 

 (GREAT-BILLED TERN.) 



Sterna magnirostris, Bwm. La-Plata Reise, ii. p. 519 (Rio Parana) ; Sounders, 

 P. Z. S. 1876, p. 643 ; Barrows, Auk, 1884, p. 316 (Entrerios). Phaethusa 

 magnirostris, Scl et Salv. Nomencl p. 147; iid. P. Z. S. 1871, p. 567; 

 Durnford, Ibis, 1877, p. 200 (Buenos Ayres). 



Description. Crown, ear-coverts, and nape black ; mantle slate-grey, passing 

 into white at the tips of the secondaries ; wing-coverts white ; quills black ; 

 tail slate-grey lores and entire underparts glossy white ; bill yellow, with a 

 greenish tinge at the base of under mandible ; legs and feet olive-yellow : 

 whole length 14-5 inches, wing 11-5. In the young the crown is grey ; the 

 mantle browner grey. 



Hab. Coasts and rivers of South America. 



