THK VOYAGE OP THE ' CHALLENGER.' 



411 



bronchial rings, including the muscular one, are firmly co-ossified 

 together, and free from the rest. There is no complete pessulus, the 

 bony box formed by the rings terminating posteriorly in a straight and 



Fig. 29. 



Syrinx of Dlomedea exulans, from before. 

 About natural size. 



Fig. 30. 



The same, from behind. 

 About natural size. 



free margin, which a cuneate bar, formed by the inturned anterior ends 

 of the fourth bronchial rings, does not reach. The syrinx of Phcebetria 

 as yet I only know from a young specimen, in which the bronchial rings 



