CLASSIFICATION. 5 



2. RHODOSPERME^E. Plants rosy -red or purple, rarely 



brown-red or greenish-red. Fructification of two 

 kinds, dioecious, always formed on separate indivi- 

 duals. 1. Spores (gemmules, Ag.) contained either in 

 external or immersed conceptacles, or densely aggre- 

 gated together and dispersed in masses throughout 

 the substance of the frond. 2. Spores (called tetra- 

 spores, gemmules, Thw.) red or purple, either external 

 or immersed in the frond, rarely contained in proper 

 conceptacles ; each spore enveloped in a pellucid 

 skin (perispore), and at maturity separating into four 

 sporules. Antheridia (not observed in all) filled with 

 yellow corpuscles. Marine, with one or two excep- 

 tions. 



3. CHLOROSPERME.E. Plants green, rarely a livid purple. 



Fructification dispersed through all parts of the frond, 

 the whole colouring matter being capable of conver- 

 sion into propagula. 1. Spores (Sporidia, Ag.) green 

 or purple, formed within the cells, often (always ?) at 

 maturity vivacious, moving by means of vibratile cilia. 

 2. Gemmules (Coniocystae, Ag.) or external vesicles 

 containing a dense, dark- coloured, granular mass, and 

 finally separating from the frond. Marine, or (more 

 generally) found in fresh-water streams, ponds and 

 ditches, or in damp situations. (The marine species 

 of this sub-class are alone described in the present 

 work) . 



