PLATE XXIII. 



A. CALLITHAMNION, page 171. 



Fig. 1, C. Borreri ; the natural size. 2, a pinnated 

 branch, or plumule of the same, bearing tetraspores 

 on the ramuli. 3, a ramulus with tetraspores. 4, a 

 favella on a truncated plumule ; magnified. 



B. GRIFFITHSIA, page 167. 



Fig. 1, G. corallina ; the natural size. 2, part of a 

 branch with involucrated tetraspores. 3, an involu- 

 cre, to whose ramuli tetraspores are attached, sur- 

 rounding a fragment of the stem. 4, a tetraspore. 

 5, part of a branch with favellae ; magnified. 



C. SEIROSPORA, page 170. 



Fig. 1, S. Griffithsiana ; the natural size. 2, part of 

 the main stem. 3, dichotomous ramulus, partly con- 

 verted into strings of spores. 4, tetraspores ; all mag- 

 nified. 



D. WRANGELIA, page 199. 



Fig. 1, W. multifida ; the natural size. 2, fragment 

 of stem with whorled ramuli, bearing a whorled and 

 pedunculate favella. 3, spores from the favella. 4, 

 ramulus with tetraspore. 5, a tetraspore ; all mag- 

 nified. 



