TRA CH3GPII OUAE. 
Mesomyodian passeres Vvith (usually) a single 
pair of syringeal muscles attached to the middle 
portion of the bronchial semirings, the syrinx 
tracheal, the lower end of the trachea consist¬ 
ing of thin, membraneous Vval Is 'about six of the 
usual semirings extremely thin, sometimes obsolete, 
the bronchi with both outer and inner tympaniform 
membranes, vibratory tracheal membranes being al¬ 
so present,* the few muscles (usually only one pair) 
wholly lateral,' a processus vocal is , a lateral 
cartilaginous pillar set on to the bronchial ring 
by a broad base, present. Tenth primary long, 
eleventh vestigial. 
' - •» 
a. Only one pair of trachoo-bronchial muscles; 
metasternum 4-notched, or else (in Formicariidae) 
tensor p>atagii brevis tendon normally passerine 
and nares holorhinal; tarsal envelope not 
exaspidean (endaspidean, taxaspidean or holaspi- 
dean)• 
b. Metasternum 4-notched; tensor patagii brevis 
~~ tendon guasi-picarian (returning portion con¬ 
cealed by muscular fibers at origin of extensor 
metacarpi muscle. 
c. Interorbital septum perforate; mesorhinium 
compressed and arched or else expanded into 
a flattened oval shield; intrinsic muscles 
present; nostrils conspicuously operculate; 
tarsal em r elope taxaspidean or holaspidean. 
pteroptochidae . 
cc . interorbital septum wanting; intrinsic 
muscles wanting; mesorhinium normal; 
nostrils not conspicuously operculate; 
tarsal envelope exaspidean. 
Qonop opha g ida e 
