1880.] 



ANATOMY OF PASSERINE BIRDS. 



385 



which may or may not be due to Individual variation. The ante- 

 penultimate ring is apparently incomplete on the right side, or is at 

 least exceedingly reduced {vide fig. 5). The penultimate ring is 

 narrowed, and is closely apposed to the terminal ring throughout 

 except in front, where there is a well-marked subtriangular fenestra. 

 The last tracheal ring is produced downwards in front, but is ap- 



Fig. 3. 



Syrinx of Cymbirhynchus, viewed from in front, X 5. 



Fig. 4. 



Fig. 4. The same, X 5, from the side, to show the insertion of the intrinsic 

 syriugeal muscle into the middle of the first bronchial semiring. The 

 sternotrachealis is cut short. 



Pig. 5. The same, x 5, from behind, to show the pessulus. 



parently incomplete on the left side in front ; so that there the penul- 

 timate ring is next to the first semiring, in consequence of this 

 disposition. The pessulus is a well-marked, forwardly-directed 



