PASSERE?. 



11 



of the essential features of this organ, in so far as tliey conceni 

 the systeiiiatist, may be welcome. 



The syrinx is tlie term applied to the lower end of the wind- 

 pipe and the adjacent ends of the bronchi in birds, wlierein tiiese 

 portions have become variously moditied to form the organ of 

 voice, which, in Mammals, is formed by the larynx — the upper 

 end of the windpipe. But while in the Mammals tlie larynx is a 

 comparatively stable structure, in the birds the syrinx presents a 

 very remarkable range of differences both in regard to its funda- 

 mental structural characters, as well as of musculatui-e. 



For the present it nuist sulfice to give a brief survey of the 

 essential features of the syrinx in the Passeres and, for systematic 

 purposes, tlie musculature is the dominant factor. 



• The syrinx, then, in this Group presents wide contrasts, 

 even among Grenera of the same Family, but nevertheless it 

 conforms in its essential characters with that of the Aves as a 

 whole. That is to say, it is formed of a number of bony or 

 cartilaginous rings and semi-rings — some of which may be com- 

 pletely or partially welded — held together by thin membranes 

 which serve not merely to support the framework, but also in the 

 production of the " voice." 



In the Anisomyodi the syringeal muscles are inserted either in 

 the middle or on to the dorsal or ventral ends of the semi-rings. 



''C^ 



Syrinx (if Z^///a «;/(/(;few,?/s (after Garrod, P. Z. S. 1876, pi. liii). showing tlie 

 Anisomyodian attacltnient of the intrinsic muscles at the middle of tlie bronchial 

 semi-rings. There is also a single pair of bronchial muscles, continued down 

 from the sides of the windpipe, insignificant in size, quite lateral, and termi- 

 nating by beir.g inserted into the middle of the outer svirface of the second 

 bronchial semi-ring. 



In the Diacromyodi these muscles are inserted into both ends 

 of the serai-rings. They may be limited always to one pair as 

 in Clamatores, to two as in Oligomyodi and some Tracheoplionce 

 or there may be as many as seven pairs as in the Oscines. 

 Btit the structure of the syrinx itself, as apart from its 

 muscidature, has been, and still is, a feature of importance in 



