KEY TO THE SPECIES OF THE FRESH WATER ALG^E. 



1. LEMANEA. 



A. Filaments straight, 4-5 in. long, fluviatilis, 52 



A. arcuately curved (a). 



a. 1-2 in. long, olive green, black with age torulosa 51 



a. 5 in. long, violet in mass; regularly constricted . . catenata, 52 



2. TUOMEYA. 



A. Much and irregularly branched; tufts 1-2 in. long . fluviatilis, 53 



A. Not branched, grande, 53 



3. BANGIA. 

 Filaments about i in. long; in lax purple tufts . atro-purpurea, 55 



4. BATRACHOSPERMUM. 



A. Branches sometimes setigerous, internodes naked or nearly so; 



gelatinous. Variable moniliforme, 56 



A. Branches not setigerous, whorls imperfectly developed, the branch- 

 lets often impacted; color bluish green vagum, 57 



5. THOREA. 

 Much branched, ramuli horizontal, long and short alternating, 



ramosissima, 58 



6. CHANTRANSIA. 



A. Tufts i in. long; filaments with many straight branches; fertile 



branches very short macrospora, 59 



A. Tufts 1-6 mm. long (a). 

 a. Parasitic on other plants (b). 



a. Not parasitic (c). 



b. Fresh water; bright violet, 2 mm. long; branches erect, ends obtuse, 



violacea, 59 



