212 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
gonys faintly convex basally, straight or faintly concave terminally, 
the tip of maxilla sometimes slightly decurved. Nostril exposed, 
posteriorly in contact with loral feathering, rather small, roundish 
or broadly oval, non-operculate, but margined above by very narrow 
membranous rim. Rictal bristles wanting, and feathers of chin, 
etc., without terminal sete. Wing moderate, much rounded, the 
longest primaries exceeding secondaries by much less than length of 
bill from nostril (except in A. leucophthalmus, in which the difference 
between tip of secondaries and longest primaries nearly equals length 
of exposed culmen); sixth, seventh, and eighth, sixth and seventh, 
fifth, sixth, and seventh, or fifth and sixth primaries longest, the 
tenth (outermost) less than two-thirds to three-fourths (A. leucoph- 
thalmus) as long as the longest, the ninth longer than fourth (A. 
leucophthalmus) to shorter than second (A. rubiginosus). Tail six- 
sevenths as long as wing (A. leucophthalmus) to as long as wing, 
graduated (graduation. equal to from less than one-fourth, in A. 
leucophthalmus to more than one-third, in A. verx-pacis, its total 
length), the rectrices (12) rather broad, with tip rounded or slightly 
subacuminate. Tarsus shorter than culmen (from base), a little 
more than one-fourth (in A. leucophthalmus) to nearly one third (in 
A. vere pacis) as long as wing, distinctly scutellate; middle toe, with 
claw, shorter than tarsus; outer toe, without claw, reaching to or 
slightly beyond middle of subterminal phalanx of middle toe, the 
inner toe slightly shorter; hallux nearly as long as outer toe, but 
much stouter; basal phalanx of middle toe united for about half its 
length to outer toe, for less than half to inner toe; claws moderate to 
rather large, strongly curved, that of the hallux decidedly shorter 
than the digit. 
Coloration.—Above plain brown (sometimes darker on pileum and 
hindneck), the upper tail-coverts and tail (sometimes rump also) 
cinnamon-rufous or chestnut; beneath plain tawny, cinnamon-brown, 
or pale buffy (more brownish laterally), the throat light russet, tawny, 
ochraceous, buff, or whitish; foreneck sometimes faintly squamated 
with brown or dusky; sometimes a tawny or ochraceous supra- 
auricular stripe. Sexes alike. 
Range.—Southern Mexico to British Guiana, Peru, and south- 
eastern Brazil. (About eighteen species.) ¢ 
‘a Of these I have examined, in this connection, only the following: A. rubiginosus 
(Sclater), A. verepacis Salvin and Godman, A. guerrerensis Salvin and Godman, A. 
umbrinus Salvin and Godman, A. cervinigularis (Sclater), A. ochrolemus (Tschudi), 
A. pallidigularis Lawrence, A. leucophthalmus (Maximilian), and A. rufipectus Bangs. 
All these agree very well in structural characters except A. leucophthalmus, which is 
conspicuously different in its relatively longer and much more pointed wing, much 
less graduated tail, and much shorter gonys. 
