1886.] ON THE SYRINX ETC. OF CAPRIMULGID^. 147 



4. On the Syrinx and other Points in the Anatomy of the 

 Caprimulgidee, By Frank E. Beddard, 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 

 CaprimulgidBe and Crotophaga among the Cuculidse 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, iii^tead 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 oi 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 ; hke 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 Crotophaga the 

 menbrana tympaniformis extends back unto the entrance of the 

 bronchus into the lung ; in Steatornis the membrana tympaniformis 



1 Huxley, 'The Anatomy of Vertebrated Animals,' London, 1871, p. 315; 

 Gregenbaur's ' Comparative Anatomy,' French Trans, by 0. Vogt, p. 776. 



- Berioht d. Akad. Wiss. Berlin, 1841, p. 172; Mlill. Arch. 1842, p. 1; 

 Stimmovg. d. Passerinen, Berlin, 1847, p. 9. 



8 Coll, Papers, p. 188. * P. Z. S. 1885, p. 173, 



