spores in the terminal cells of the branches. Tetraspores divided 

 in zones. Frond tubular or very compact, made up of elongated 

 threads or shorter cells. Pericarp at length having an open 

 mouth. CH^TANGIACE^:. 



Placenta basal. 159 



Placenta central. 



Spore threads radiating from a central cell. Tetraspores appearing 

 in somewhat definite patches or sori, rather large, rounded, 

 divided triangularly. Frond flat, leaf-like, sometimes ribbed and 

 veined, cells of the veins elongated. DELESSERIACE.S. 



Placenta in the middle of the fruit, and apparently central. Fruit 

 spores obconical, held together by a web of very fine threads. 

 Tetraspores immersed in the frond, divided triangularly. Frond 

 tubular in the upper part and subdivided by cellular diaphragms. 

 Tube surrounded by a cellular, cortical stratum. 



LOMENTARIACE.E. 



159. Fruit within the pericarp surrounded by a net work of very fine 

 anastomosing threads. Spore-bearing threads jointed and anas- 

 tomosing so as to form a network, producing rounded or angular 

 spores in the joints. Tetraspores divided crosswise or triangu- 

 larly. Frond tubular, divided by diaphragms, or close and cell- 

 ular within, often with the outer cells joined into vertical threads. 



CHAMPIE^E. 



Spore-bearing threads commonly branching, but not anastomosing 

 to form a net work. 



Pericarp not having a distinct mouth, one celled or two celled, 

 Spore-bearing threads in very dense rows, having single spores in 

 the terminal joints of the branches. Tetraspores produced among 

 the cortical threads of the frond, divided crosswise. Frond made 

 up of cells, or of fibres very densely interwoven. Pericarp half 

 immersed. G-ELIDIACE.S:. 



Pericarp usually having a distinct mouth. 



Threads of the fruit much branched, many of them sterile. Upper 

 branches of the fruit-bearing threads ripening earlier than the 

 lower. Fruit more or less lobed, each lobe producing numerous 

 spores grouped in no special order, in mucus. Tetraspores scat- 



