PLATE XX. 



A. DUMONTIA, page 147. 



Fig. 1, D. Jiliformis ; the natural size. 2, small por- 

 tion of the frond, in fruit. 3, favellidium, attached 

 to the inner face of the wall of the frond ; magnified. 



B. CATENELLA, page 151. 



Fig. 1, C. Opuntia ; the natural size. 2, a frond mag- 

 nified. 3, a tetraspore. 4, a favellidium, immersed 

 in one of the ramuli. 5, vertical section of the frond ; 

 all magnified. 



C. CRUORIA, page 151. 



Fig. 1, C. pellita, growing on a portion of rock; the 

 natural size. 2, vertical section of the skin-like 

 frond. 3, filaments of which the frond is composed ; 

 all magnified. 



D. NACCARIA, page 152. 



Fig. 1, N. Wigghii ; the natural size. 2, portion of 

 one of the branches, with fertile ramuli. 3, filament 

 bearing a spore from the ramuli. 4, transverse sec- 

 tion of the stem ; all magnified. 



