98 Minnesota Algae 



This plant is very near typical P. 1 a m i n o s u m. The points of 

 difference are that the iilaments are slightly greater in diameter, the apex 

 is almost invariably sharply bent, and the transverse walls may or may 

 not be marked by granules. Sometimes the entire cell contents are gran- 

 ular. 



194. Phormidium tenue (Meneghini) Gomont. Monogr. Oscill. 189. pi. 4. f. 

 23-2S. 1893. De Toni. Syll. Algar. 5: 227. 1907. 

 Wolle. Fresh-Water Algae. VI. Bull. Torr. Bot. Club. 9: 25. 1882. 

 (Oscillatoria detersa Stitz.); Fresh-Water Algae. U. S. 310. 1887. 

 Bennett. Plants of Rhode Island. 115. 1888. Tilden. American Algae. 

 Cent. 11. no. 182. 1896; Observations on some West American Thermal 

 Algae. Bot. Gaz. 25: 100. pi. 9. f. 17. 1898. Collins, Holden and Setchell. 

 Phyc. Bor.-Am. Fasc. 13. no. 606. 1899. Bessey, Pound and Clements. 

 Additions to the Reported Flora of the State. Bot. Surv. Nebraska. 5: 13. 

 1901. Setchell and Gardner. Algae of Northwestern America. Univ. 

 Calif. Pub. Bot. i: 185. 1903. West. West Indian Freshwater Algae. 

 Journ. of Bot. 42: 292. 1904. Brown. Algal Periodicity in certain Ponds 

 and Streams. Bull. Torr. Bot. Club. 35: 248. 1908. Buchanan. Notes on 

 the Algae of Iowa. Proc. Iowa Acad. Sci. 14: 13. 1908. 



Plate IV. fig. 63-65. 



Plant mass thin, membranaceous, expanded, pale blue-green; filaments 

 elongate, somewhat straight, densely entangled; sheaths thin, finally dif- 

 fluent into a fibrous mucus; trichomes 1-2 mic. in diameter, straight, slight- 

 ly constricted at joints; apex of trichome not capitate, at first straight, 

 afterwards becoming tapering and bent; apical cell acute-conical; calyptra 

 none; cells 2.5-5 mic. in length; transverse walls usually indistinct; cell 

 contents homogeneous, pale blue-green. 



Alaska. In various situations, submerged and emergent, in fresh water. 

 Walls of Amaknak Cave, Amaknak Island; Bay of Unalaska. (Setchell and 

 I.awson). Massachusetts. In fresh water. Naushon Island. August 1895. 

 (Nott). Rhode Island. Roger Williams Park. (Bennett). New York. 

 Stagnant waters. Rochester. (Wolle). Virginia. In a pool in Luray 

 Cave, 260 feet below the surface. (Seipt). Indiana. Edge of pond. Near 

 Bloomington. May, June 1907. (Brown). Iowa. Frequent. Fayette. 



(Fink). On pots in greenhouse; in pond. Ames; in pond among decaying 

 rushes, bottom of the margin of the slough. Eagle Grove. (Buchanan). 

 Nebraska. On boards of mill-dam. Milford. (Bessey). Wyoming. Around 

 edges of spring, not covered by water, but water flows in little streams 

 through and around it. Mixed with P. 1 a m i n o s u m. Temperature of 

 water 33° C. Lower Geyser Basin, Yellowstone National Park. June 

 1896. (Tilden). Washington. Coupeville, Oak Harbor, Whidbey Island; 

 Seattle. (Gardner). West Indies. Near Bridigetown; Bay Estate; Graeme 

 Hall Swamp. Barbados. (Howard). 



195. Phormidium valderianum (Delponte) Gomont. Monogr. Oscill. 187. pi. 

 4. f. 20. 1893. De Toni. Syll. Algar. 5: 223. 1907. 



Hariot. Algues du Golfe de Californie recueillies par M. Diguet. Journ. 

 de Bot. 9: 169. 1895. Setchell. Notes on some Cyanophyceae of New 



