CLASSIFICATION. 5 



Rhodosperme^. Plants rosy-red or purple, rarely 

 brown-red or greenish-red, Fructijication of two 

 kinds, dicEcious, always formed on separate indivi- 

 duals. 1. Spores (genanules, 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, gemmiiles, 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. 



Chlorosperme.e. Plants green, rarely a livid purple. 

 Fructijication 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 {Coniocysto}, Ag.) or external vesicles 

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

 finally separating from the frond. Marine, or (more 

 generally) found in fresh-icater streams, ponds and 

 ditches, or in damp situations. (The marine species 

 of this sub-class are alone described in the present 

 work J . 



