BLACK-TAILED SKIMMER 209 
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 Scissor-bill during his ex- 
cursion up the Parana in October, 1833, and speaks 
of it as follows (Wat. Journ., p. 161) : 
“ T 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 
oO II 
