144 Minnesota Algae 



becoming darker in color; sheaths close, delicate, colorless; trichomas 2.3- 

 2.8 mic. in diameter, slightly curved, loosely entangled; cells a little short- 

 er than the diameter; transverse walls distinct, slightly granulated; cell 

 contents pale becoming darker. 



Arctic Regions. Marshy spots on land, 82° 27' N. (Dickie). 



278. Hypheothrix pallida Kuetzing. Spec. Algar. 893. 1849. De Toni. 



Syll. Algar. 5: 339. 1907. 



Wolle. Fresh Water Algae. III. Bull. Torr. Bot. Club. 6: 182. 1877; 

 Fresh- Water Algae U. S. 298. pi. 202. f. 26-31. 1887. (L. pallida (Naeg.) 

 Wolle). Wolle and Martindale. Algae. Britton's Catalogue of Plants 

 found in New Jersey. Geol. Surv. N. J. 2: 608. 1889. 



Plant mass membranaceous, firm, somewhat smooth, pale rose or 

 dark red in color; filaments 40-80 mic. (?Wolle) in diameter; sheaths very 

 ■vvide, at first homogeneous, finally becoming lamellose and fibrillose; trich- 

 omes S.6-8.3 mic. in diameter, rather straight or sightly curved, some- 

 what parallel or sometimes flexuously curved and interwoven; cells some- 

 what quadrate, here and there slightly swollen; cell contents faded or yel- 

 lowish brown. 



New Jersey. Forming reddish-brown stratum on dry ground. (Austin). 

 On wet soil and old meadow grounds. (Wolle). 



Genus SYMPLOCASTRUM Gomont. Monogr. Oscill. 52. 1893. 



Plants terrestrial or living on damp rocks; filaments twisted and en- 

 tangled, ascending from a prostrate base, agglutinated together in erect 

 fascicles; sheaths colorless. 



I Plant mass blue-green; trichomes 1.4-2 mic. in diameter, constricted 



at the joints; cells shorter than the diameter S. fragile 



II Plant mass flesh-colored or reddish; trichomes 1.6-2 mic. in diameter; 



cells usually longer than the diameter S. rubrum 



III Plant mass gray or yellowish; trichomes 1.9-2.3 mic. in diameter; 



cells longer than the diameter S. cuspidatum 



IV Plant mass blackish, olive or lead-colored; trichomes 3-6 mic. in 



diameter; cells somewhat quadrate or longer than the diameter 



S. friesii 



279. Sjrmplocastrum fragile (Kuetzing). De Toni. Syll. Algar. S: 347. 1907. 



Gomont Monogr. Oscill. 52. pi. 8. f. 13, 14. 1893. (Schizothrix 

 fragilis (Kg.) Gom.). 



Collins, Holden and Setchell. Phyc. Bor.-Am. Fasc. 3. no. 104. 189S. 

 Setchell. Notes on some Cyanophyceae of New England. Bull. Torr. Bot. 

 Club. 22: 429. 1895. 



Plate VI. fig. 5- 



Plant mass up to i mm. in thickness, pannose, tomentose, olive or 

 blue-green; filaments flexuous, entangled, more or less, parallel, finally be- 

 coming united into short, erect fascicles; sheaths irregular in outline, some- 



