471 
Paraguay, Bolivia , and Southern Brazil. 
It was found breeding on the Rio Paraguay, as I have 
described under Phaethusa magnirostris. The nest was a 
mere hollow scraped in the sand, but deeper and larger than 
that of its neighbour. The full clutch is apparently four, 
though several nests were taken with three eggs. 
Twenty-five eggs brought home were taken on the 9th of 
September at Colonia Risso. 
264. Phaethusa magnirostris. 
Phaethusa magnirostris Arg. Orn. ii. p. 194 ; Saunders, 
Cat. B. xxv. p. 23. 
a. $ imm. Tayru, Paraguay. Aug. 5, 1909. 
b. $ ad. Colonia Risso, Paraguay. Sept. 8, 1909. 
c. d. <$ $ nestling. Colonia Risso, Paraguay. Sept. 9, 
1909. 
e. S' acl. Near Puerto Braga, Paraguay. Sept. 24, 1909. 
f, g,h. ? ad. „ „ „ Sept. 24, 1909. 
i. ? juv. „ „ ,, Sept. 24, 1909. 
j, k, l. S ad. Colonia Risso, „ Oct. 26, 1909. 
This Tern was very plentiful on both the Parana and 
Paraguay Rivers, and was observed as far south as Parana, 
but not below. 
It was especially common on the Rio Paraguay as far north 
as we went; and breeding colonies were observed or visited 
on the 9th, 10th, 24th, and 29th of September, and on the 
return southwards these were noted or visited again on the 
14th and 26th of October. 
The first colony was visited on the 9th of September, when 
this species was found breeding in company with Rhynchops 
melanura and Sterna superciliaris . 
The Skimmers and Great-bills were nesting together at one 
end of a long sand-bank and the Terns ( Sterna super ciliar is) 
were in a small colony of their own at the other end, where 
there was a little rough grass growing. 
When we went ashore the Terns flew right away, the Skim¬ 
mers flew round and round the bank out over the water in 
pairs, uttering their single mournful cry ; but they were most 
aggressive, a flock of many hundreds keeping us company, 
2 k 2 
