138 Minnesota Algae 



Norwich. (Setchell). Pennsylvania. On stones in rapid water; in sphag- 

 num swamps. (Wolle). 



264. Hydrocoleus ravenelii Wolle. Bull. Torr. Bot. Club. 6: 183. 1877. De 



Toni. Syll. Algar. 5: 322. 1907. 



Plate V. fig. 64-65. 



Plant mass dark violet or blue-green; filaments 15 mic. in diameter, 

 those containing two or more trichomes proportionately wider; sheaths 

 of younger plants close and colorless, those of older plants thicker and 

 firmer, golden brown in color, lamellose, with ends usually empty and 

 sharply pointed; trichomes 12 mic. in diameter, of equal thickness, solitary 

 or two or three somewhat twisted together in a common sheath; cells 

 somewhat equal, or two or three times shorter than the diameter; cell 

 contents blue-green changing to golden brown or chestnut. 



Texas. Pasture grounds. Houston. (Ravenel). 



265. Hydrocoleus heterotrichus Kuetzing. Gomont. Monogr. Oscill. 80. 



pi. 13. f. 3, 4. 1893. De Toni. Syll. Algar. 5: 320. 1907. 

 Wolle. Fresh Water Algae. Bull. Tbrr. Bot. Club. 6: 283. 1879; Fresh- 

 Water. U. S. 307. pi. 205. f. 2-5. 1887. 



Plate V. fig. 66. 



Plant mass about 5 mm. in height, caespitose, blackish; filaments ad- 

 nate, short, in basal portion trunk-like, broadening out towards the apex, 

 then divided and repeatedly branched; false branches more or less widely 

 diverging, flexuous; sheaths somewhat close, somewhat mucous, irregu- 

 lar and roughened in outline, broadened out in middle portion of filament, 

 gradually tapering towards the apex, pointed, open or closed, transversely 

 wrinkled; trichomes 16-19 mic. in diameter, many within the sheath, closely 

 aggregated, straight or spirally tangled and twisted, sometimes solitary, 

 not constricted at joints; apex of trichome very slightly tapering, scarcely 

 capitate, truncate; cells 3.4-4.S mic. in length; cell contents finely granular. 



Pennsylvania. In swamp. Near Bethlehem. (Wolle). 



Genus HYPHEOTHRIX Kuetzing. Phyc. Gen. 229. 1843. 



Plants living on moist earth or dripping rocks; filaments prostrate, 

 commonly slightly branched, woven into a more or less compact mass; 

 sometimes hardened with calcium carbonate; sheaths always colorless. 



I Filaments very much twisted, scarcely flexible, ruptured if disentangled. 



1 Plant mass thin, somewhat gelatinous, papery-membranaceous, very 



hard when dry, not encrusted with calcium carbonate; sheaths 

 firm; trichomes 1-1.7 mic. in diameter, usually one or two within 

 the sheath H. calcicola 



2 Plant mass flocculent, waving, light fawn-colored; filaments i. 2-1.8 



mic. in diameter; sheaths inconspicuous; transverse walls not visible 



H. hinnulea 



