NOV 'R 18f"' 



Brahi* and Pineal Structures of Polyodon folium. 309 



eiif'losing stalk; D, line representino- boundarj'^ of chanuel. 

 li. Garnia)} del. 



Fi(>-. 10. Pineal end organ and stalk of Acipenser mhl- 

 cundus. Letters as in Fig. 9. H. Garman del. 



Plate XXL 



Fig. 11. Part of the bonj' exoskeleton of head of 

 Polyodon. with the elliptical foramen under whioli the 

 pineal end organ lies. Natural size. From a photograph. 



