1886.] ON THE SYRINX ETC. OF CAPRIMULGID. 147 
4, On the Syrinx and other Points in the Anatomy of the 
Caprimulgide. By Franx E. Bepparp, M.A., F.R.S.E., 
Prosector to the Society. 
[Received March 1, 1886.] 
It has been known for a long time, and the fact is recorded in most 
text-books of comparative anatomy’, that Steatornis among the 
Caprimulgidz and Crotophaga among the Cuculide are distinguished 
from the other genera of their respective families, as well as from all 
other birds, by the possession of a bronchial syrinx. The voice-organ 
of these two birds, instead of being situated at the junction of the 
trachea with the bronchi, as in the vast majority, or being formed by 
a modification of the lower portion of the trachea, as in the tracheo- 
phone Passeres, is produced by a modification of certain of the bron- 
chial rings some way from the bifurcation of the bronchi. The 
structure of the syrinx of the Guacharo was first made known by 
Johannes Miiller*, and subsequently described and figured by Garrod’. 
I am unacquainted with any exact description of the syrinx of Croto- 
phaga, which, as I have myself indicated*, presents the following 
resemblances to, and differences from, the syrinx of Steatornis. In 
both types the bifurcation of the trachea to form the bronchi takes 
place precisely as it does in the Mammalia ;- that is to say, the ante- 
rior bronchial rings are complete rings, and in no way different from 
the rings of the trachea. The membrana tympaniformis does not com- 
mence until about the tenth (Crotophaga) or thirteenth (Steatornis) 
bronchial rings; at this point the rings not only cease to be complete 
rings but alter in their character, being narrower and softer than the 
anterior bronchial rings, and separated from each other by wider inter- 
vals of fibrous tissue; the single intrinsic muscle is inserted on to the 
first of these modified bronchial rings ; the last two or three rings 
before that on which the muscle is inserted are semirings, the mem- 
branous intervals between their inner extremities, which constitute the 
upper part of the membrana tympaniformis, becoming gradually less 
and less, until it disappears entirely and the rings are complete rings. 
These, however, although they support the anterior part of the mem- 
brana tympaniformis, agree in their structure with the tracheal and 
anterior bronchial rings; like them they are placed close together 
and ossified ; there is no transition between the anterior and posterior 
bronchial semirings ; their character abruptly changes at the semiring 
on to which the intrinsic muscle is attached. In Cvofophaga the 
menbrana tympaniformis extends back unto the entrance of the 
bronchus into the lung ; in Séeatornis the membrana tympaniformis 
1 Huxley, ‘The Anatomy of Vertebrated Animals,’ London, 1871, p. 315; 
Gegenbaur's * Comparative Anatomy,’ French Trans. by O. Vogt, p. 776. 
* Bericht d. Akad. Wiss. Berlin, 1841, p. 172; Mill. Arch. 1842, pu; 
Stimmorg. d. Passerinen, Berlin, 1847, p. 9. . 
3 Coll. Papers, p. 188. 4 P.Z.8. 1885, p. 173. 
