8 Minnesota Algae 



ilies which occur as shapeless bunches; sheaths of medium thickness, hya- 

 line, very slightly lamellose, often pale yellow or orange in color, almost 

 opaque; cells 2-4 mic. in diameter; cell contents pale bluish gray or bluish 

 green, sometimes yellowish. 



Massachusetts. On walls of greenhouse. Botanic Garden. Cambridge. 

 January 1899. (Collins). Montana. In hot springs. Lo Lo Hot Springs. 

 Lo Lo. September 1898. (Griffiths). Wyoming. On rocks near vent of 

 geyser. Sometimes heated. Norris Geyser Basin. June 1896. In overflow 

 from spring, temperature 41" C. Frying Pan Basin, July 1896. Yellowstone 

 National Park. (Tilden). Forming a green coating on floor of overflow 

 channel. Temperature 49° C. Constant Geyser, Norris Geyser Basin; in 

 acid waters. Green Spring, between Norris Geyser Basin and Beaver Lake. 

 Yellowstone National Park. 1897. (Weed). 



Dr. Setchell is undoubtedly right in placing the Yellowstone specimens 

 in the genus Pleurocapsa. (See P. c a 1 d a r i a.) 



10. Chroococcus decorticans A. Braun. Betracht. ueber die Erschein. Ver- 



jung. in der Natur. 194. 1851. De Toni. Syll. Algar. 5: 18. 1907. 



WoUe. Fresh Water Algae. III. Bull. Torr. Bot. Club. 6: 181. 1877. 



Plants 6-1 1 mic. in diameter, single or associated in families of two or 

 four; sheaths distinct, lamellose, finally irregularly peeling off; cell wall 

 solid, colorless; cell contents blue-green. 



Pennsylvania. Submerged timbers. (Wolle). 



11. Chroococcus refractus Wood. Contr. Hist. Fresh- Water Algae North 



America. 11. pi. 5. f. 5. 1872. De Toni. Syll. Algar. 5:20. 1907. 

 Buchanan. Notes on the Algae of Iowa. Proc. Iowa Acad. Sci. 14: 10. 

 T908. 



Plants 5 mic. in diameter, mostly subquadrate, very often triangular, 

 rarely multiangular, closely associated in solid families; families often lobed; 

 sheaths thin, scarcely perceptible, transparent; cell contents finely granular, 

 brownish, olive-green, or yellowish, highly refractive. 



Pennsylvania. Growing abundantly on wet rocks along the Reading 

 Railroad between Manayunk and the Flat Rock tunnel. (Wood). Iowa. 

 Ames. 1884. (Bessey). 



12. Chroococcus helveticus Naegeli. Gatt. Einz. Alg. 46. pi. i. 1849. De Toni. 



Syll. Algar. 5: 17. 1907. 



Lagerheim. Ueber einige Algen aus Cuba, Jamaica und Puerto-Rico. 

 Bot. Notiser. 199. 1887. 



Plants 4-7.5 i"ic., rarely 9 mic. in diameter, spherical, associated in fam- 

 ilies of two, four or eight; sheaths spherical, gelatinous, scarcely visible; 

 cell wall very thin, colorless; cell contents homogeneous or somewhat gran- 

 ular, blue-green or greenish, pale or yellowish in color. 



West Indies. On Utricularia in stagnant water. Near Fajardo. 

 Porto Rico. April 1885. (Sintenis). 



