Myxophyceae 147 



^- 



2 Plant mass strongly encrusted with calcium carbonate, stony; fila- 



ments slender, simple in basal portions, fasciculately branched 

 above; trichomes 1.4-3 mic. in diameter; cells somewhat quadrate 

 or longer than the diameter I. fasciculata 



3 Plant mass cushion-shaped or crustaceous, not hardened with calcium 



carbonate; filaments forming trunk at base, very much branched 

 in upper portions; trichomes 1-1.5 mic. in diameter; cells longer 

 than the diameter I. lacustris 



4 Plant mass somewhat hemispherical, plano-convex; filaments more 



or less branched, growing in tufts; cells two or three times longer 

 than broad I. austini 



II Plant mass forming penicillate fascicles, floating. 



1 Plant mass submerged, attached; filaments very long; trichomes 



1.4-2.4 mic. in diameter, constricted at joints 



I. tinctoria 



2 Plant mass submerged, epiphytic on other algae; trichomes 3-6 mic. 



in diameter, usually constricted at joints I- simmonsiae 



3 Plant mass submerged, attached; filaments very long; trichomes 



6 mic. in diameter, constricted at joints I. mexicana 



III Filaments solitary, growing in gelatinous mass formed by other 



algae; trichomes 1.5-2 mic. in diameter, not constricted at joints 



I. hawaiensis 



283. Inactis pulvinata Kuetzing. Tab. Phyc. i: 44. pi. yy. f. 3. 1845-1849. 



Gomont. Monogr. Oscill. 36. 1893. (Schizothrix pulvinata 

 Gom.). De Toni. Syll. Algar. 5: 350. 1907. 



Plate VI. fig. 11-13. 



Plant mass cushion-shaped or crustaceous, stony, hardened with cal- 

 cium carbonate, uneven or mammillate, blue-green on the outer surface, 

 zonate within; filaments straight, rigid, parallel, coalesced or closely 

 crowded, moderately branched; false branches entirely appressed; sheaths 

 papery, with pointed apex; trichomes 1-2 mic. in diameter, constricted 

 at joints, more or less numerous within the sheath; cells somewhat quad- 

 rate or twice as long as broad; cell contents pale blue-green. 



North America. In cataracts. (Anderson). 



284. Inactis fasciculata (Naegeli) Grunow in Rabenhorst. Fl. Eur. Algar. 



2: 160. 1865. Gomont. Monogr. Oscill. 36. pi. 6. f. 1-3. 1893. (Schi- 

 zothrix fasciculata Gom.). De Toni. Syll. Algar. 5: 351. 

 1907. 



Murray. Calcareous Pebbles formed by Algae. Phyc. Mem. Part III. 

 74. pi. 19. 1895. Setchell. Notes on Cyanophyceae. — I. Erythea. 4: 89. 

 1896. Pennhallow. Note on Calcareous Algae from Michigan. Bot. Gaz. 

 21: 215. 1896. MacMillan. Minnesota Plant Life. 41. 1899. Tilden. 



American Algae. Cent. VI. no. 585. 1902. Powell. Observations on some 

 Calcareous Pebbles. Minn. Bot. Studies. 3: 75. pi. 16. f. 8, 9; pi. 17. f. 1-5. 

 1903- 



