PLATE XIV. 



Fig. 26. Similar section to 24 through the hjo-opercularis vein. Structure 

 is very similar to the lymphatic trunk, but the red corpuscles greatly predom- 

 inate. X 450. Reduced ^. 



Fig. 27. A diagrammatic transverse section through three pairs of branchial 

 filaments of Polyodon. 



