THE VOYAGE OF THE ' CHALLENGER/ 



405 



This, however, is not (vide fig. 18, a) a complete septum, but is incom- 

 plete, the incurved posterior ends of the rings not reaching the anterior 

 wall of the trachea by some little way. Its vertical extent is small, 

 ceasing about *85 inch above the bronchi. 



Fig, 17. 



Zool. Chall. 

 Exp. vol. iv. 

 pt. xi. p. 37. 



Syrinx of Ossifraga gigantea, from before. 



Fig. 18. 



The same, from behind. 



The peculiar genus Bulweria is, perhaps, as far as regards tracheal Ibid. p. 38. 

 structure, nearer the small Storm-Petrels (Procellaria and Cymochorea) 

 than any other group, judging at least from my examination of the 



