204 Minnesota Algae 



of cells which are quadrate or slightly longer than broad in the lower por- 

 tion and shortened to one-third as long as broad in the upper part; cells 

 0-16 mic. in length; heterocysts basal and intercalary, the former being 

 spherical or nearly so, while the latter are elongated and rectangular; 

 cell contents finely granular, blue-green. 



Washington. In ponds of fresh water, near Seattle. (Kincaid). 



377. Microchaete grisea Thuret. Essai Class. Nostochinees. 7. 1875. Bornet 



and Flahault. Revis. des Nostoc. Ann. Sci. Nat. Bot. VII. 5: 85. 1887. 



De Toni. Syll. Algar. 5 : 485. 1907. 

 Collins. Notes on New England Marine Algae IV. Bull. Torr. Bot. 

 Club. 11: 130. 1884. Collins, Holden and Setchell. Phyc. Bor.-Am. Fasc. 

 4. no. 158. 1896. Collins. Preliminary Lists of New England Plants. V. 

 Marine Algae. Rhodora. 2: 42. 1900; Phycological Notes of the late Isaac 

 Holden. — II. Rhodora. 7: 223. 1905. 



Plate X. fig. 12. 



Plant mass densely caespitose, tomentose, orbicular, dull green, be- 

 coming violet when dried; filaments 6-7 mic. in diameter, i mm. in length, 

 curved at the bulbous base, soon becoming erect, densely crowded; sheaths 

 thin, close, continuous, colorless; trichomes 5-6 mic. in diameter; cells 

 shorter than their diameter; heterocysts basal, hemispherical. 



Ceuiada. Forming patches on Fucus evanescens. Malpeque, 

 Prince Edward Island. (Faull). Maine. On Zostera marina Goose 

 Creek, Cape Rosier. July 1895. (Collins). Massachusetts. On an old 

 pecten shell in company with Calothrix Crustacea. West Falmouth. 

 (Collins). Connecticut. On stranded stump. Seaside Park. November. 

 (Holden). 



378. Microchaete vitiensis Askenasy in Bornet and Flahault. Tableau 



synopt. des Nostochacees filamenteuses heterocystees. 22. 1885. 

 Bornet and Flahault. Revis. des Nostoc. Ann. Sci. Nat. Bot. VII. 

 5: 85. 1887. De Toni. Syll. Algar. S: 485. 197. 

 Lemmermann. Algenfl. Sandwich.-Inseln. Bot. Jahrb. 34: 624. 1905. 



Plant mass loosely caespitose, tomentose^ short; filaments 7-9 mic. 

 in diameter, scarcely attaining i mm. in length, curved and slightly thick- 

 ened at the base, above slightly tapering, erect, flexuous; sheaths thin, 

 close, colorless; trichomes 5-6 mic. in diameter; cells a little shorter than 

 their diameter; heterocysts basal. 



Hawaii. Growing on Liagora coarctata. Laysan. 1896-1897. 

 (Schauinsland). 



Genus HORMOTHAMNION Grunow. 

 Reise d. Freg. Novara. 31. 1867. 



Plant mass formed from filaments growing together in a longitudinal 

 manner, sometimes developing as an expanded layer, sometimes erect, 

 filiform, torn and branched, not surrounded by a common gelatinous tegu- 

 ment; sheaths membranaceous, thin, often diffluent, colorless; trichomes 



