416 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 97 
the Brazo Casiquiare are different enough from each other in dorsal 
paleness or duskiness to represent as many “‘races”’ of some nighthawk 
species. If they are all resident birds it is strange indeed that the 
same species should show such excessive local speciation on the 
Lower Amazon, where between Obidos and Santarém, an air-line 
distance of not over 75 miles, three races are currently recognized. 
The six females show a rather unusual type of variation apparently 
wholly individual in character. Three of them have a single large 
transverse buffy spot on the inner webs of the outer remiges; the other 
two have three such markings and have them somewhat lengthened, 
producing on the successive remiges the appearance of two bands. 
These three specimens (one from the Rio Cauabury, one from Isla 
Yagrumo, and one from the Brazo Casiquiare, Upper Rio Negro) 
have the blackish streaks on the top of the head narrower than do the 
other three. 
The female from Cachoeira Destacamento is considerably larger 
than the other examples, wing 155 as against 147-150; tail 123 as 
against 107-114 mm. in the others. 
The male collected on February 1 at Raudal San Sebastian is in 
molt. 
The present series constitutes an extension of the known range of 
this nighthawk southwestward to the Casiquiare and Rio Negro in 
extreme southern Venezuela and also into adjacent parts of Brazil, 
to the avifauna of which country it appears to be an addition. 
On December 14, 1930, at Cachoeira Destacamento, Amazonas, 
Brazil, Holt found and photographed a ‘‘nest’’ and two eggs of this 
bird. 
Family NYCTIBIIDAE: Potoos 
NYCTIBIUS GRANDIS (Gmelin): Grand Potoo 
Caprimulgus grandis GmELINn, Systema naturae, vol. 1, pt. 2, 1789, p. 1029 
(Cayenne). 
SPECIMENS COLLECTED 
1 ad. ?, Brazil, Rio Cauabury, below mouth of Rio Maturacd, November 7, 
1930. 
lad. 9, Venezuela, San Antonio, Upper Orinoco, March 8, 1931. 
The Brazilian bird is in a much paler phase than is the Venezuelan 
example. 
NYCTIBIUS GRISEUS GRISEUS (Gmelin): Gray Potoo 
Caprimulgus griseus GMELIN, Systema naturae, vol. 1, pt. 2, 1789, p. 1029, No. 5 
(Cayenne). 
SPECIMEN COLLECTED 
lad. ¢ Brazil, Serra Imeri, Rio Maturacd, near Salto do Hud, November 27, 
1930. 
This bird is in rather worn plumage. 
