OF ARTS AND SCIENCES. 219 



Ravenelia glabra, C. and K. 



Fig. 20. A cross-section of a spore- mass treated witli potassic hydrate and 

 mounted in balsam. 



Ravenelia stictica, Bk. and Br. 



Fig. 21. A cross-section of a spore-mass treated with potassic hydrate and 

 mounted in balsam. 



