72 



tered through the frond or produced in special branches. Frond 

 sometimes tubular, but more commonly of a compacted mass of 

 cells, the outermost cells sometimes joined to form vertical 

 threads. RHODYMENIACE.K. 



Sterile threads of the fruit few. Fruit-bearing threads, simple or 

 branched, ripening at about the same time. 



Fruit-bearing threads jointed, bearing spores in many of the upper 

 joints. Spores single or many in each joint. Tetraspores min- 

 ute, more or less oblong, scattered through the slightly changed 

 frond, or collected in superficial or external spots with a covering 

 of threads. Exterior cells of the frond rounded and sometimes 

 joined into vertical threads. Interior threads more longitudinal, 

 inmost sometimes thread-like. SPHJEROCOCCOIDE^:. 



Fruit-bearing threads producing a single spore in the larger, termi- 

 nal, club-shaped cell. Tetraspores in the cortical stratum of the 

 frond, or in warts made up of threads. Frond tubular or solid, 

 made up of threads or cells not arranged in straight lines. 



CHONDRIE.S. 



160. Frond hardened by an incrustation of carbonate of lime, coral- 

 like. Fruit spores produced by fours. CORALLINACEJE. 

 , Frond soft, flexible, seldom incrusted. 



Fruit without a proper placenta, the threads lying in bundles within 

 the frond. Fertile threads but little branched; when young, 

 bead-like, with very short, rounded joints. Spores few, large, 

 grouped in no special order, held together by mucus. Frond 

 often gelatinous. DUMONTIACE^:. 



Placenta central. 162 



Placenta basal or from the sides of a central dissepiment, parting 

 two adjoining fruits. 161 



Placenta parietal. Spore-bearing threads converging towards the 

 centre from a net work of threads next the wall. Spores sin- 

 gle, borne in the terminal joints of the branches of the fertile 

 threads. 



Fruit compound, the parts being arranged in no special order. 



Spores pear-form. HYPNEACE^E. 

 Fruit simple. Spores club-shaped. CH^TANGIACE^B. 



