HYPOPHYSIS OF PETROMYZON AND AMIA 



277 



is incompatible with the theory which I am putting forward 

 here. The strip of tissue in question is probably a portion of 

 the pars anterior the cells of which are slightly modified since 



Text-fig. 23. 



/■ 



Diagrammatic comparison between (o) Squalus, (6) Amia, and 

 (c) Petromyzon showing the position of the hypophysis and 

 infnndibulum. 



here they act as an epithelium and line a cavity. Swale 

 Vincent does not describe this structure in the text, so that 

 not much importance must be placed upon his figure. The 



