BIRDS OF NORTH AND MIDDLE AMERICA. 479 



a. Tail shorter than combined length of tarsus and middle toe (with 

 claw), very little, if any, more than two-thirds as long as 

 wing; bill slender-subulate, the culmen straight to near tip; 

 ninth primary longer than secondaries; middle toe (without 

 claw) more than two-thirds as long as tarsus; rump with 

 concealed white spots (as in Thryothorus, _Thryomanes, and 



most species of Troglodytes) Olbiorchilus (p. 595) 



hh. Rectrices 10; tail less than two-thirds as long as wing; hallux nearly 



as long as middle toe (without claw) ThryoroMlus (p. 605) 



ff. Maxillary tomium with a distinct subterminal notch; nostril non- 

 operculate, small, roundish or oval, in lower anterior portion of nasal 



g. Tail only half as long as wing, not much longer than tarsus. 



Henioorhina (p. 607) 



gg. Tail much more than half as long as wing, at least half as long again 



as tarsus. 



h. Tail less than two-thirds as long as wing; exposed culmen not 



longer than middle toe (without claw); wing less than 55 mm. 



Nannorchilus (p. 617) 



hh, Tail more than two-thirds as long as wing (sometimes nearly as 



long), or else exposed culmen longer than middle toe (without 



claw); wing more than 55 mm Thryophilns (p. 620) 



bb. Lateral toes very unequal in length, their ends (at base of claws) forming a 

 very oblique line with the penultimate joint of the middle toe, the inner toe 

 (without claw) not reaching as far as the latter, 

 c. Tail at least two and a half times as long as tarsus, the latter less than one- 

 third as long as wing; bill from rictus much less than half as long as wing; 

 rectrices normal (firm-webbed and broadly rounded at end), not uniform in 

 color. 

 d. Hallux weaker (not thicker than anterior toes), shorter than outer toe; 

 inner toe not reaching to subterminal joint of middle toe, the outer toe 

 reaching to but little beyond; under parts of body whitish (sometimes 

 flecked or barred with dusky) ; tail varied with grayish brown and black, 

 crossed near tip by a broad band of pale cinnamon preceded by another 



of black - Salpinctes (p. 643) 



dd. Hallux stouter, equal in length to outer toe; inner toe reaching to subter- 

 minal joint of middle toe, the outer toe reaching nearly to middle of 

 subterminal phalanx of middle toe; under parts of body rufescent; tail 



cinnamon-rufous barred with black Catherpes ( p. 653 ) 



cc. Tail not more than one and one-third times as long as tarsus, the latter 

 nearly half as long as wing; bill from rictus more than half as long as wing; 



rectrices lax-webbed, subacuminate, uniform sooty Hylorchilus (p. 663) 



aa. Tail less than half as long as wing, shorter than tarsus. 

 b. Mesorhinium normal; nostril in lower anterior portion of nasal fossa, without 

 rim, broadly oval, or closed anteriorly by the very broad, convex, and decum- 

 bent membraneous operculum Microceroulus ( p. 665 ) 



bb. Mesorhinium elevated and compressed; nostril in center of nasal fossa, small, 

 circular, rimmed Leucolepis (p. 670) 



