BLACK-TAILED SKIMMER 309 



appearing in pairs or small flocks in the neighbour- 

 hood of Buenos Ayres during the month of October. 

 Its chief breeding-ground is on the extensive mud- 

 banks and islets at Bahia Blanca on the Atlantic 

 coast. The return migration occurs in March. 



Darwin met with the Sdssor-bill during his ex- 

 cursion up the Parana in October, 1833, and speaks 

 of it as follows {Nat, Journ,, p. 161) : 



" I here saw a very extraordinary bird, called the 

 Scissor-beak {Rhynchops nigra). It has short legs, 

 web feet, extremely long-pointed wings, and is of 

 about the size of a Tern. The beak is flattened 

 laterally, that is in a plane at right angles to that of 

 a Spoonbill or Duck. It is as flat and elastic as 

 an ivory paper-cutter, and the lower mandible, dif- 

 ferent from every other bird, is an inch and a half 

 longer than the upper. I will here detail all I know 

 of the habits of the Scissor-beak. It is found both on 

 the east and west coasts, between latitudes 30 and 

 45, and frequents either salt or fresh water. The 

 specimen now at the Zoological Society was shot at 

 a lake near Maldonado, from which the water had 

 been nearly drained, and which in consequence 

 swarmed with small fry. I there saw several of these 

 birds, generally in small flocks, flying backwards 

 and forwards, close to the surface of the lake. They 

 kept their bills wide open, and with the lower man- 

 dible half buried in the water. Thus skimming the 

 surface, they ploughed it in their course ; the water 

 was quite smooth, and it formed a most curious 

 spectacle to behold a flock, each bird leaving its 



O II 



