62 Minnesota Algae 



Plate IV. fig. I. 



Plant mass expanded, floating, purple, when dried becoming lilac; 

 trichomes 2.2-5 mic. in diameter, straight, elongate, flexible, not constricted 

 at joints, when old gradually tapering at apex, obtuse, capitate; cells 4-6 

 mic. in length, subquadrate or a little longer than wide; apical cell -slightly 

 tapering, truncate; calyptra depressed conical; transverse walls frequently 

 granulated; cell contents refringent, coarsely granular. 



Massachusetts. Giving a pronounced purple color to the water of 

 Jamaica Pond. 1884. (Farlow). Jamaica Pond. (Moore, Hyams and Rich- 

 ards). Floating freely or forming scum. Jamaica Pond, Boston. (Collins). 

 Forming a floating scum. Jamaica Pond, Jamaica Plain. December 1893. 

 (Burrage). Wisconsin. Pine Lake, Waukesha County. August, October 

 1900. July 1905. (Olive). 



127. Oscillatoria agardhii Gomont. Monogr. Oscill. 225. 1893. De Toni. 



Syll. Algar. 5: 149. 1907. 

 Collins, Holden and Setchell. Phyc. Bor.-Am. Fasc. 30. no. 1451. 1908. 

 Plate IV. fig. 2. 



Plant mass widely expanded, floating, light blue-green; trichomes 4-6 

 mic. in diameter, straight throughout entire length, fragile, not constricted 

 at joints, gradually tapering towards the apex, obtuse, capitate; cells 2.S-3-5 

 mic. in length; apical cell slightly tapering, truncate; calyptra convex; trans- 

 verse walls granulated; cell contents coarsely granular, pale blue-green. 



Missouri. St. Louis. December 1906. (Hus). 



128. Oscillatoria princeps Vaucher. Hist. Conferves d'eau douce. 190. pi. 



15. f. 2. 1803. Gomont. Monogr. Oscill. 226. pi. 6. f. 9. 1903. De 

 Toni. Syll. Algar. 5: 150. 1907. 

 Harvey. Nereis Boreali-Americana. Part III. 124. 1858. Maze and 

 Schramm. Essai class. Algues Guadeloupe. 17. 1870-77. Wood. Contr. Hist. 

 Fresh- Water Algae N. A. 20. 1872. (O. imperator Wood). Farlow, 

 A.nderson and Eaton. Algae Am.-Bor. exsicc. no. 177. 1877. 

 Wittrock and Nordstedt. Algae aq. dulc. exsicc. no. 393. 1877-87. Raben- 

 horst. Algen Europas. no. 2535. 1878. Wolle. Fresh-Water Algae U. S. 

 317. pi. 207. f. 20, 22; pi. 208. f. 3, 4. 1887. Collins. Flora of Middlesex 

 County, Massachusetts. 15. 1888. Mobius. Ueber einige in Portorico 

 gesammelte Siisswasser- und Luft-Algen. Hedwigia. 27: 248. 1888. Ben- 

 nett. Plants of Rhode Island. 115. 1888. Trelease. The "Working" 

 of the Madison Lakes. Trans. Wis. Acad. Sci. Arts and Letters. 7: 125. 

 1889. Wolle and Martindale. Algae. Britton's Catalogue of Plants found 

 in New Jersey. Geol. Surv. N. J. 2: 610. i88g. Mackenzie. A preliminary 

 list of Algae collected in the neighborhood of Toronto. Proc. of Can. Inst. 

 III. 7: 270. 1890. Saunders. Protophyta-Phycophyta Flora of Nebraska. 

 21. pi. I. f. 17. 1894. Tilden. List of Fresh-water Algae collected in Min- 

 nesota during 1894. Minn. Bot. Studies, i: 235. 1895. Collins, Holden and 

 Setchell. Phyc. Bor.-Am. Fasc. i. no. 2. 1895. Tilden. Am. Alg. Cent. 

 II. no. 187. 1896; Observations on some West American Thermal Algae. 

 Bot. Gaz. 25: loi. pi. 9. f. 19. 1898; Am. Alg. Cent. III. no. 296. 1898. Col- 

 lins. Preliminary Lists of New England Plants, — V. Marine Algae. Rho- 



