bb. Hetasternum 2-notched; tensor pata£;ii 
- brevis tendon normally x^s serine. 
Formicariidae . 
aa. Two |)Girs of tracheo-bronchial muscles; 
metasternum 2-notched tarsal envelox^e 
endaspidean. 
_b. Hares schizorhinal; interorbital 
sej^tum perforate; outer toe decidedly 
(usually much} shorter than middle toe 
and not conspicuously longer than inner 
toe (except in Sclerurus and Tyf ?arrhicus ) 
and united to middle toe for not more 
(usually less) than whole length of basal 
phalanx of latter; hallux (vdthout claw) 
as long as inner toe (without claw) or 
longer, much stouter. 
Furnariidae. 
bb . Hares holorhinal, interorbital sex:>tum 
imperforate; outer toe as long as middle 
toe, much longer than inner toe; united 
to middle toe for more than whole length 
of basal phalanx of the latter; hallux 
(without claw) shorter than inner toe 
(without claw), little, if any, stouter. 
Dendrocolaptidae. 
