BIRDS OF NORTH AND MIDDLE AMERICA, 183 



[Prem7ioplex] brunnescens Sharpe, Hand-list, iii, 1901, 74, part (Costa Rica; 



Panamd). 

 [Margarornis] brunneimuda Lawrence, Ann. Lye. Nat. Hist. N. Y., viii, 1867, 



130, in text (Costa Rica; coU. U. S. Nat. Mus.). 

 Premnoplex brunnescens brunneicauda Bangs, Proc. Biol. Soc. Wash., xxi, July 



27, 1908, 159 (Costa Rica, Chiriqui and Veragua, Panama; crit.).— Carriker, 



Ann. Carnegie Mus., vi, 1910, 647 (highlands of Costa Rica, 2,000 ft. to 



timber-line; crit.)- 



Genus ACRORCHILUS Ridgway. 



Acrorchilusc Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. (Type 

 Synallaxis erylhrops Sclater.) 



Small wrenlike Furnariidte (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 antise slightly greater than 

 its depth at same pomt 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 m contact with loral feathermg, narrow (a 

 longitudmal slit), overhung by a broad, convex, membraneous oper- 

 culum. Rictal bristles absent, and feathers of clmi, etc., without 

 terminal setae. 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 wmg, stout, 

 very distmctly scutellate; middle toe, "W'ith claw, decidedly shorter 

 than tarsus; outer toe, without claw, not reachmg to middle of 

 subtermmal 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 (sometmies for nearly the whole) 

 of its length to outer toe, for nearly as much to inner toe; claws mod- 



0-a.Kpuc, pointed; dpx'i^og, wren. 



