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88 BULLETIN 133, UNITED STATES NATIONAL MUSEUM
in dried skins they appear closely similar. The following may be of
aid in separating the two species:
a/ Head (in life) mainly yellow; general coloration more uniform, blacker,
sheen of feathers of dorsal surface with green predominating, purple
restricted or nearly absent; wing coverts black without distinct paler
edgings C. urubitinga.
a'. Head (in life) mainly red; general coloration less dark, more variegated
with brownish edgings to feathers, sheen of feathers of dorsal surface
with purple predominating, green restricted or nearly absent ; wing
coverts distinctly margined with brownish, this color often exten-
sive
C. aura.
The color of the shafts in the outer primaries is not of definite
value, as it is variable in both species. It has been alleged that in
urubitinga the feathering on the back of the neck extended farther
forward. This, however, is merely an age character, as immature
birds of either species have the neck more or less feathered to the
base of the cranium or even onto the nape, while in adults this area is
naked.''°
That aura and urubitinga are distinct species there can be no doubt.
Though aura has a much greater zonal range, in tropical and sub-
tropical regions, aura and urubitinga are found together throughout
extensive areas, while they are sufficiently distinct to controvert any
theory that might consider them color phases of one species.
The specimen from Las Palmas has the following measurements:
Wing, 514; tail, 217 (culmen defective) ; tarsus, 60; middle toe with
claw, 76 mm. These dimensions are somewhat larger than those of
birds from eastern Brazil, British Guiana, and Venezuela, so that it
is possible that a race characterized by slightly greater size inhabits
the basin of the Rio Paraguay.
CATHARTES AURA RUFICOLLIS Spix
Cathartes ruflcolUs Spix, Avium Spec. Nov. Brasiliam, vol. 1, 1824, p. 2.
(Interior of Bahia and Piauhy.)
The geographical forms of the turkey vulture and the nomencla-
ture applied to them have been involved in much confusion and un-
certainty, a state that has not been remedied by the recent action of
Chubb '^^ in adopting ruficoUis as the proper name for the j^ellowheaded
vulture. A review of the entire group has shown that there
are apparently five forms of aura that may be recognized, two from
North America and the West Indies and three from South America.
In general it may be said that turkey vultures from North America
and the West Indies differ from those of South America in browner
coloration and more distinct brown edgings on the wing coverts.
«» See Bangs and Penard, Bull. Mus. Comp. Zool., vol. 62, April, 1918, p. 34.
61 Birds of British Guiana, vol. 1, 1916, p. 211.