BIRDS OF NORTH AND MIDDLE AMERICA. 188 
[Premnoplex] brunnescens Suarre, Hand-list, iii, 1901, 74, part (Costa Rica; 
Panamé4). 
[Margarornis] brunneicauda Lawrence, Ann. Lyc. Nat. Hist. N. Y., viii, 1867, 
130, in text (Costa Rica; coll. U. 8. Nat. Mus.). 
Premnoplex brunnescens brunneicauda Banas, Proc. Biol. Soc. Wash., xxi, July 
27, 1908, 159 (Costa Rica, Chiriquf and Verdgua, Panamé; crit.)—CarrikEr, 
Ann. Carnegie Mus., vi, 1910, 647 (highlands of Costa Rica, 2,000 ft. to 
timber-line; crit.). 
Genus ACRORCHILUS Ridgway. 
Acrorchilus @ Ripaway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. (Type 
Synallaxis erythrops Sclater.) 
Small wrenlike Furnariide (length about 130-140 mm.) with tail 
about as long as wing (sometimes longer), graduated, the rectrices 
(12) usually acuminate at tip; tarsus much less than one-third as 
long as wing; basal phalanx of middle toe not wholly united to outer 
toe, and tail and wings rufescent and plumage without streaks (ex- 
cept, sometimes, on pileum). 
Bill much shorter than head, rather stout, slightly decurved, and 
moderately compressed, its width at loral anti slightly greater than 
its depth at same point and equal to about one-third the distance 
from nostril to tip of maxilla; culmen distinctly ridged, gradually and 
rather strongly decurved from near base, the tip of maxilla not 
uncinate; maxillary tomium more or less distinctly concave, man- 
dibular tomium similarly convex, both without trace of subterminal 
notch; gonys nearly to quite straight, not prominent basally. Nos- 
tril exposed, posteriorly in contact with loral feathering, narrow (a 
longitudinal slit), overhung by a broad, convex, membraneous oper- 
culum. Rictal bristles absent, and feathers of chin, etc., without 
terminal sete. Wing rather large and pointed, the longest primaries 
exceeding secondaries by about distance from nostril to tip of maxilla; 
seventh and eighth, sixth, seventh, and eighth, or sixth and seventh 
primaries longest, the tenth (outermost) about two-thirds as long as 
the longest, the ninth longer than secondaries. Tail very nearly as 
long as wing to decidedly longer, graduated for nearly to more than 
half its length, the rectrices (12) usually abruptly attenuated termi- 
nally, sometimes with tips acute (but not denuded). Tarsus much 
longer than whole culmen, less than one-third as long as wing, stout, 
very distinctly scutellate; middle toe, with claw, decidedly shorter 
than tarsus; outer toe, without claw, not reaching to middle of 
subterminal phalanx of middle toe, the inner toe slightly shorter; 
hallux about as long as inner toe, but much stouter; basal phalanx of 
middle toe united for half or more (sometimes for nearly the whole) 
of its length to outer toe, for nearly as much to inner toe; claws mod- 
@éxpoc, pointed; dextdoc, wren. 
