940 SYRINX 
VII. Most of the Oscines seem to possess five or seven pairs of 
syringeal muscles—no case of six pairs being known. In the 
Corvide they are arranged as follows:—(1) m. tracheo-bronchialis 
ventralis, from the Trachea to the anterior ventral end of the 2nd 
semiring ; (2) m. tr.-bronch. obliquus, to the ventral end of the 3rd 
semiring ; (3 and 4) m. tr.-bronch. dorsalis longus et brevis, to the 
dorsal end of the 2nd semiring, and to the inner tympaniform mem- 
brane near the pessulus ; (5) m. syringeus ventralis, to the ventral end 
of the 2nd semiring—shorter than and covered by No. 1; (6) m. 
syr. ventri-lateralis, covered by No. 2, inserted on the membrane 
between the 2nd and 3rd semirings; (7) m. syr. dorsalis, to the 
dorsal end of the’ 2nd semiring. 
According to the position of the sound-producing membranes, 
three types of Syrinx are distinguishable :—Tracheal, Bronchial 
and Tracheo-Bronchial. 
DIAGRAM OF A TRACHEAL AND A BRONCHIAL SYRINX. 
t.c. tracheo-clavicular muscle. 
I. Syrinz trachealis, in which the lower portion of the Trachea 
consists of thin membranaceous walls, about six of the rings being 
extremely thin or, as often happens, deficient. Both inner and 
outer tympaniform membranes exist in the Bronchi as well as 
some vibratory tracheal membranes. The few muscles, generally 
but one pair, are wholly lateral. The birds thus furnished are the 
TRACHEOPHON, their voice is very loud, and while it is being 
sounded the lower part of the throat swells out. They belong 
entirely to the Neotropical Region, and comprising the Dendro- 
colaptidxe, Formicartide, Pteroptochide and Conopophagidx, form a 
tolerably well-marked group of the Passeres Clamatores. Indica- 
tions of such a tracheophonous Syrinx exist in various Cotingidx 
and Pittidx, as well as in Columbx and Galline—but the last cases 
are clearly only analogous. 
Il. Syrinx bronchialis, in which outer tympaniform membranes 
exist between two or more successive bronchial semirings, while an 
