i 



I 



PLATE XX. 



A. DuMONTiA, page ]47. 



Fig. 1, D. JiUformis ; 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 ; magnijied. 



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 magnijied. 



C. Cruoria, page 151. 



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

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

 fi'ond. 3, filaments of which the frond is composed \ 

 all magnijied. 



D. Naccaria, page 152. 



Fig. 1, N. Wiggliii ; 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 magnijied. 



