Myxophyceae 255 



D Filaments 12-24 mic. in diameter; false branches in pairs, arising 



between two heterocysts C. vivipara 



E Filaments 10-40 mic. in diameter, interwoven at base, decumbent 



C. pilosa 

 F Filaments 12-40 mic. in diameter, not branched; sheaths yellowish 

 brown C. Crustacea 



2 Plants living in fresh water 



(i) Plants epiphytic 

 A Filaments 5-7.5 mic. in diameter; trichomes 3.4-4 mic. in diameter 



C. epiphytica 

 B Filaments 7-8 mic. in diameter; heterocysts basal, usually in pairs 



C. scytonemicola 

 C Filaments 8-10 mic. in diameter; trichomes 6-9 mic. in diameter, 

 especially constricted at joints; heterocysts basal, in pairs 



C. stagnalis 

 D Filaments 10-12 mic. in diameter, curved and bulbous-inflated 

 at the base; trichomes 7-8 mic. in diameter 



C. fusca 

 E Filaments 5-15 mic. in diameter, sometimes thicker at the base; 

 trichomes 3.5-5.5 mic. in diameter 



C. sandwicensis 

 F Filaments 15-16 mic. in diameter at base; sheaths thick, lamellose, 

 finally becoming brownish black; cells very short 



C. breviarticulata 

 G Filaments 15-18 mic. in diameter; sheaths wide, often truncate, 

 almost colorless; trichomes 7-9 mic. in diameter 



C. violacea 

 H Filaments 18-24 mic. in diameter; sheaths thick, gelatinous, lamel- 

 lose, finally ocreate C. adscendens 



(2) Plants living in warm or hot water 



A Filaments 8-10 mic. in diameter; sheaths somewhat thick, uni- 

 form, transparent, sometimes yellowish at base; heterocysts 

 basal, rarely intercalary C. thermalis 



B Filaments 8-10 mic. in diameter; sheaths close, ocreate, trans- 

 parent, becoming yellowish brown; heterocysts basal and in- 

 tercalary, spherical or quadrate C. calida 



C Filaments lo-ii mic. in diameter; sheaths close, thick, lamellose, 

 ocreate, transparent and yellowish C. kuntzei 



(3) Plants living on stones and wood 



A Filaments 9-10 mic. in diameter; sheaths narrow, close, uniform, 

 colorless; trichomes 6-7 mic. in diameter C. braunii 



B Filaments 10-12 mic. in diameter; sheaths thick, close, uniform 

 or ocreate, yellowish brown C. parietina 



C Filaments 12-13 mic. in diameter; sheaths thin, close, uniform, 

 colorless or yellowish C. castellii 



