276 



Minnesota Algae 



Plate XVIII. fig. 17. 



Forming extended strata either on surface of calcareous matrix, giving 

 it a pinkish brown or pale bl^ie-green tinge, or in layers throughout the 

 matrix; filaments 9-12.5 mic. in diameter, prostrate, not rigid; false branches 

 appressed; sheaths rather thin, not lamellose, hyaline; trichomes up to 

 10 mic. in diameter, for the most part constricted at joints in lower por- 

 tions, tapering to a hair point; cells in lower portion of filament equal m 

 length to their diameter, shorter in upper portions; heterocysts basal, spheri- 

 cal or depressed, equal to or a little smaller than the diameter of the fila- 

 ment. 



Minnesota. Together with Chaetophora calcarea, Lyngbya 

 martensiana calcarea and L. n an a, forming the lime encrusta- 

 tion which covers sides of wooden tank. Minneapolis. October 1895. (Til- 

 den). 



504. Dichothrix baueriana (Grunow) Bornet and Flahault. Revis. des Nos- 

 toc. VII. 3: 375. 1886. De Toni. Syll. Algar. 5: 640. 1907. 

 WoUe. Fresh Water Algae. Bull. Torr. Bot. Club. 6: 284. 1879. (S c h i- 

 zosiphon bauerianum Grun.). Setchell. Notes on Cyanophyceae. 

 — I. Erythea. 4: 88. 1896. Collins, Holden and Setchell. Phyc. Bor.-Am. 

 Fasc. 5. no. 216. 1896. Setchell and Gardner. Algae of Northwestern 



America. Univ. Calif. Pub. Bot. i: 198. 1903. Collins, Holden and Setch- 

 ell. Phyc. Bor.-Am. Fasc. 24. no. 1169. 1904. 



Plate XVIII. fig. 18. 



Filaments 15 mic. in diameter (in ultimate branches), caespitose-penicil- 

 late or forming a widely expanded layer up to a centimeter in thickness, 

 flexuous; sheaths close, gelatinous, soft, uniform, transparent or yellowish; 

 trichomes 5-9 mic. in diameter, constricted at joints, gradually tapering into 

 a long hair; cells shorter than or equal to their diameter; cell contents 

 green or brown; heterocysts somewhat spherical or hemispherical. 



Alaska. On dripping rocks or stones in running or quiet water. Near 

 Iliuliuk, Unalaska. (Setchell and Lawson). Orca. (Jepson). Rhode 



Island. Forming an uninterrupted coating on submerged limestone rocks in 

 quiet water. Lime Rock. October 1894. (Osterhout). On stones at border of 

 lily pond. Newport. Connecticut. Round Pond, Lantern Hill, Ledyard; on 

 stones about edges of lake, Lake Whitney, in Hamden, near New Haven. 

 (Setchell). Florida. On submerged wood. (Smith). Washington. 



Whatcom. (Gardner). West Indies. On rocks, littoral. Porto Rico. May 

 1903. (Howe). "The present specimens appear to be the first recorded from 

 a strictly marine station." — Collins. 



505. Dichothrix olivacea (Hooker) Bornet and Flahault. Revis. des Nostoc. 



Ann. Sci. Nat. Bot. VII. 3: 375- 1886. De Toni. Syll. Algar. 5: 



639. 1907. 

 Maz6 and Schramm. Essai Class. Algues Guadeloupe. 36. 1877. (C a 1 o- 

 thrix submarina Crouan). Murray. Catalogue of the Marine Algae 

 of the West Indian Region. Journ. of Bot. 27: 261. 1889. 



