PLATE III. 



A. ALARIA, page 29. 



Fig. 1, A. esculenta ; the natural size. 2, part of cross 

 section of a sorus. 3, spores from the same ; mag- 

 nified. 



B. CHORDA, page 31. 



Fig. 1, Chorda filum ; the natural size. 2, vertical 

 section of the frond. 3, vertical section of a small 

 portion of the wall, showing the large internal cells 

 and the stratum of spores. 4, spores from the same. 

 5, an antheridium ? ; all magnified. 



