87 



green tissue of the Marchantialcs, thick-walled cells of \arious 

 types ha\e repeatedly been noted in other parts of the thallus, 

 especially in the more complex genera of the Marchantiaceae. 



Fig. I. RicciA bistriata Evans. 

 A. Cross section of thallus in apical region, X 22. B. Cross section of same 

 thallus near basal end of median sulcus, X 22. C. Cross section of same thallus 

 in older part, X 22. D. Section of green tissue parallel with surface of thallus, 

 X 300. E. Section of green tissue perpendicular to surface of thallus, showing 

 bands of thickening in section and surface view, X 300. F. Spore, X 400. The 

 figures were all drawn from the type specimen. 



In addition to the tuberculate rhizoids which are of almost uni- 

 versal occurrence, the epidermis in many cases is distinguished 

 by a definite cuticle and conspicuous trigones, while the cells 



