1899.] 



INTEBXAL ANATOMY OF NOXORNIS. 



95 



to be independent of any ring, and present a concavity on tbeir 

 outer faces. It is, however, possible that when ossification is 

 complete these two bones will ankylose with the ends of the 

 ring b. 



Fig. 5. 



The syrinx of Notornis, ventral view (slightly more enlarged than fig. 4). 



Letters as in fig. 4. 



The remaining syringeal rings (e, /, g) call for little remark. 

 They are all closely apposed, and ventrally curve very sharply 

 round the bronchus to reach the membrana tympaniformis interna, 

 while dorsally the incurved region is very slight. 



The ring g, owing to its curvature, is much arched forwards 

 at the side, so that between it and the first unmodified bronchial 

 (I) there is a considerable space, across which is stretched the 

 membrana tympaniformis externa. This ring (I) is almost straight, 

 while II is concave upwards ; between them is also the thin 

 membrane : another part of it lies between II and III, but this 

 space is much narrower than either of the preceding. On the 

 dorsal side between the ends of each of the rings II/III and 

 III/IV is a small ossicle (s). 



Passing from the syrinx itself, I would refer to a slip of muscle 



