„, . Minnesota Algae 



431. Tolypothrix ravenelii Wolle. Fresh Water Algae. Bull. Torr. Bot. 



Club. 6: 285. 1879; Fresh-Water Algae U. S. 265. pi. 180. f. 8-10. 

 1887. De Toni. Syll. Algar. 5: 542. 1907. 



Plate XIV. fig. 7- 



Plant mass thin, more or less expanded, reddish brown; filaments 15-25 

 mic. in diameter, elongate, false branches elongate; sheaths thin, 

 close, yellowish or dark-colored; trichomes often interrupted; cells equal 

 to or twice as short as their diameter; transverse walls distinct; heterocysts 

 basal or intercalary, usually single, oblong, yellowish; cell contents finely 

 granular, yellowish or reddish. 



Florida. On sandstone rock. Gainesville. December 1877. (Ravenel). 



432. Tolypothrix setchellii Collins. Some Perforating and other Algae on 



Freshwater Shells. Erythea. 5: 96. pi. 4. 1897. Collins, Holden and 

 Setchell. Phyc. Bor.-Am. Fasc. 7. no. 310. 1897. De Toni. Syll. 

 Algar. 5: 548. 1897. 

 Setchell and Gardner. Algae of Northwestern America. Univ. Calif. 

 Pub. Bot. i: 196. 1903. 



Plate XIV. fig. 8. 



Filaments 5-6 mic. in diameter, up to 7 dm. in length, scattered or ar- 

 ranged in parallel series and forming a layer, flexuous, occasionally thick- 

 ened, repeatedly branched; false branches spreading; sheaths thick, gelati- 

 Jious, refractive, colorless or yellowish; trichomes 4 mic. in diameter, con- 

 stricted at joints; cells equal to or longer than the diameter; heterocysts 

 disc-shaped; cell contents blue-green. 



Alaska. "A dwarf species.'' On C h a r a. Near Iliuliuk, Unalaska. (Law- 

 son). Connecticut. On shells. Twin Lakes, Salisbury, Litchfield County. 

 August 1897. (Setchell and Holden). 



433. Tolypothrix limbata Thuret in Bornet and Flahault. Revis. des Nos- 



toc. Ann. Sci. Nat. Bot. VII. 5: 124. 1887. De Toni. Syll. Algar. 

 5: 550. 1907. 



Setchell and Gardner. Algae of Northwestern America. Univ. Calif. 

 Pub. Bot. 1 : 196. 1903. 



Plant mass floccose-caespitose, blue-green; filaments 12-15 mic. in 

 diameter, 2-3 mm. in length, repeatedly branched; false branches erect, 

 spreading, flexuously curved; sheaths refringent, colorless, lamellose, with 

 the outer layers mucous; trichomes 6-9 mic. in diameter, constricted at 

 joints; cells equal to or a little longer than the diameter; heterocysts one 

 to two; cell contents dull blue-green. 



Washington. Growing on the side of a jar in the botanical laboratory. 

 University of Washington, Seattle. (Gardner). 



434. Tolypothrix rupestris Wolle. Fresh Water Algae. III. Bull. Torr. Bot. 



Club. 6: 185. 1877; in Rabenhorst. Die Algen Europas. no. 2573. 

 1879; Fresh-Water Algae U. S. 265. pi. 180. f. 11-13. 1887. 



