522 : MR. H. SAUNDERS ON LARIDE [June 6, 
STERNA HIRUNDINACEA, Less. 
Sterna hirundinacea, Lesson, Tr. d’Orn. p. 621 (1831); Saund. 
P22. 8. 1876,p.'647. 
Sterna cassinii, Scl. P. Z.S. 1860, p. 391; Scl. & Salv. op. cit. 
1871, p. 570. 
[No. 30 (juv.), no. 31 (adult), Callao Bay, August 1881; nos. 35 & 
36 (juv.), Coquimbo Bay, Nov. 1881. Eyes dark brown. | 
One adult, and three birds of the year in progressive stages of 
winter plumage. Callao, in 12° S. lat., is a considerable advance of 
range over that of Coquimbo in 30° S., the furthest previously re- 
corded (Cunningham, ‘Ibis,’ 1870, p. 500). The head-quarters of 
this southern species are on the coasts and islands of the Chilian 
archipelago, the Straits of Magellan, Patagonia, and the Falkland 
Islands; but on the Atlantic side of the continent its range north- 
wards is not known to extend beyond Rio de Janeiro, in 23°S. lat. 
STERNA EXILIs, Tsch. 
Sterna exilis, Yschudi, F. Per. Aves, p. 306 (1846); Scl. & 
Salv. P. Z.S. 1871, p.572; Saund. op. cit. 1876, p. 663. 
[Nos. 37 & 38, Paracas Bay, Peru, October, 1881. Eyes brown. ] 
I have now examined five, and possess three specimens of this 
very distinct, although little-known member of the Sternula sub- 
division. 
Itis a purely South-Pacific species, which may be briefly described 
as a long-winged S. minuta, washed all over with shades of smoke- 
grey, and with more black on the bill. Its immature plumage and 
its breeding-places are still unknown. 
RHYNCHOPS MELANURA, Sw. 
Rhynchops melanura, Swainson, An. in Menag. p. 340 (1838). 
[No. 66 (¢), Coquimbo Bay, November 1881. Eyes brown.] 
Adult. 
In their excellent treatise on the Neotropical Laride (P. Z. S. 
1871, p. 566) Messrs. Sclater and Salvin deemed it advisable to 
unite under the specific name of &. nigra both the northern white- 
tailed form and the southern black-tailed one. This caution was 
mainly due to the fact that, amongst Mr. Salvin’s white-tailed spe- 
cimens obtained during winter in Central America, one example 
shows some dark markings in the middle of the lateral rectrices, 
thus intergrading with the southern dark-tailed bird. Recent 
examination of this specimen and the others in Mr. Salvin’s exten- 
sive series, besides my own, leads me to the conclusion that the 
two forms are entitled to specific distinction, for the following 
reasons :—In the northern adult the upperside of the rectrices is 
almost entirely white, with only a little dusky colour in the central 
ones, the underside being pure white; the under wing-coverts are 
white; the secondaries are to a great extent white, and the upper 
primaries show a considerable margination of that colour. In 
the southern form, on the other hand, the rectrices on both their 
