412 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 97 
SPECIMENS COLLECTED 
4 ad. o, 2ad. 9, Venezuela, Isla Yagrumo, Rio Negro, January 25, 1931. 
This fine series of a bird still rare in collections, together with five 
others, including the types of zyostictus and zaleucus, suggests that 
there are no recognizable subspecies of this nighthawk. There is a 
slight dichromatism in the six Isla Yagrumo birds, which more than 
offsets the supposed color characters of zyostictus and zaleucus. As 
for the supposed size characters, it must ‘be pointed out that in the 
case of zaleucus Oberholser (U. S. Nat. Mus. Bull. 86, 1914, p. 118) 
calls the type an adult female, while admitting that it is marked 
“male” on the original label, while in ryostictus (ibid., p. 116) he gives 
the type as an adult male, but it is actually an unsexed bird. In his 
table of measurements he records two specimens of xyostictus, a male 
(the type) and a female, but neither of the specimens bears any sex 
mark on the label. In other words, such slight size characters as he 
gives for these two races are based on purely arbitrary sexing and have 
no factual basis. 
Three of the present examples show signs of molting in the wings; 
one of the males (U. S. N. M. No. 326819) is in the “ gray”’ phase; the 
other specimens are in the “brown” phase. 
The bird appears to be an addition to the known avifauna of 
Venezuela. 
CHORDEILES ACUTIPENNIS ACUTIPENNIS (Hermann): South American Nighthawk 
Caprimulgus: acutipennis HERMANN, Tabula affinitatum animalium, 1783, p. 230 
(Cayenne). 
SPECIMENS COLLECTED 
1 ad. 9, Venezuela, San Carlos, Rio Negro, January 28, 1931. 
3 ad. o, Venezuela, Puerto Ayacucho, Rfo Orinoco, May 21-23, 1931. 
Two of the males are rather small, having wings only 156 mm. long, 
while the third has a wing length of 166 mm. However, in their color 
characters all agree very closely, and the small birds are larger than 
the minimal measurements given by Oberholser in his account of this 
nighthawk (U.S. Nat. Mus. Bull. 86, 1914, p. 95). 
NYCTIPROGNE LEUCOPYGA EXIGUA Friedmann: Northern Small-billed Nighthawk 
Nyctiprogne leucopyga exigua FRIEDMANN, Proce. Biol. Soc. Washington, vol. 58, 
1945, p. 117 (right bank of Upper Orinoco, opposite Corocoro Island, 
Venezuela). 
SPECIMENS COLLECTED 
2 ad. o, Venezuela, Brazo Casiquiare, below mouth of Rio Pacila, February 12, 
1931. 
lad. #, 1 ad. 9, Venezuela, Upper Orinoco, right bank opposite Corocoro 
Island, March 12, 1981. 
Two of the males, one from each locality, were noted by the 
collectors as being in breeding condition. 
