240 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
Bill about as long as head to decidedly longer, nearly straight, 
much compressed, its width at latero-frontal anties much less than 
its depth at same point and contained from three and a half to nearly 
six times in distance from nostril to tip of maxilla; culmen distinctly 
to obsoletely ridged, straight for basal half (more or less), gently 
decurved terminally, the tip of maxilla rather strongly decurved but 
scarcely uncinate; tomia more or less decurved terminally, without 
trace of subterminal notch; gonys straight or (sometimes) very faintly 
concave, slightly prominent basally, sometimes very faintly decurved 
at tip. Nostril exposed, posteriorly in contact with latero-frontal 
feathering, roundish or broadly oval, nonoperculate. ictal bristles 
absent. Wing moderate, rather pointed, the longest primaries exceed- 
ing secondaries by less than to decidedly more than length of tarsus; 
seventh and eighth, sixth, seventh, and eighth, or sixth and seventh, 
primaries longest, the tenth (outermost) about three-fourths as long 
as the longest, the ninth longer than fourth, usually (2) longer than 
fifth. Tail less than four-fifths to more than six-sevenths as long as 
wing, graduated for about one-third its length, the rectrices (12) 
conspicuously acuminate, with the very strong and rigid shaits 
decurved and somewhat twisted terminally. Tarsus shorter to 
slightly longer than bill from nostril, less than one-fourth as long as 
wing, rather slender, distinctly scutellate (endaspidean) ; middle toe, 
with claw, slightly longer than tarsus; outer toe (with or without 
claw) as long as middle toe; inner toe (without claw) reaching to 
subterminal articulation of middle toe, its claw falling short of base 
of middle claw; hallux decidedly shorter than inner toe, scarcely 
stouter; middle toe united for whole of first and part of second 
phalanx to outer toe, for whole of first phalanx to inner toe; claws 
large, those of anterior toes very strongly curved and acute, that of 
hallux less strongly curved, less acute, as long as or longer than the 
digit. 
Coloration.—Rump, upper tail-coverts, tail, and remiges (at least 
partly) plain cinnamon-rufous or chestnut; pileum, hindneck, and 
back brown, olive, or black, usually streaked or spotted with buff; 
under parts brown, buffy grayish, or olive, striped or spotted with 
buffy, sometimes squamated with black on a buffy ground; chin and 
throat buff, sometimes immaculate, sometimes spotted or barred 
with olive. Sexes alike. 
Range.—Southern Mexico to Cayenne, eastern and central Brazil, 
Bolivia, and Peru. (About thirty species and subspecies.*) 
KEY TO THE SPECIES AND SUBSPECIES OF XIPHORHYNCHUS. 
a. Under parts striped or streaked with buffy. 
b. Back black, with broad streaks of buff; under parts striped vith black and buff, 
( Xéphorhynehus lachrymosus.) 
@ About half of them have not been examined in this connection. 
