236 Minnesota Algae 



patches of a blackish green color on stones in the swiftest currents of 

 Roaring Brook, Cheshire. May 1894. (Setchell). New Jersey. Swamps; 

 Morris Pond, Morris. (Wolle). Maryland. Garrett County. (Wolle). 



Genus DIPLOCOLON Naegelii in Itzigsohn. 

 Phykologische Studien. Part i. 160. 1857. 



Plant mass gelatinous, terrestrial; colonies irregular in shape, constrict- 

 ed, somewhat club-shaped; filaments several, contorted within a common 

 tegument, branched; false branches solitary or in pairs, usually arising be- 

 tween two heterocysts, but rarely in the immediate region of the hetero- 

 cj'sts; trichomes single within the sheath. 



437. Diplocolon heppii Naegeli in Itzigsohn. Phykologische Studien. Nova 



Acta Acad. Leopold-Carolin. der Nat. 26: Part i. 160. pi. 11. (excl 



f. 8-12). 1857. Bornet and Flahault. Revis. des Nostoc. Ann. Sci, 



Nat. Bot. VII. s: 129. 1887. De Toni. Syll. Syll. Algar. 5: 561. 1907 



Wolle. Fresh-Water Algae. II. Bull. Torn Bot. Club. 6: 139. 1877; Fresh 



Water Algae. U. S. 260. pi. 195. f. 1-9. 1887. (S c y t o n e ma heppii 



CNaeg.) Wolle). Setchell. Notes on Cyanophyceae. — II. Erythea. 4: 193. 



1896. 



Plate XIV. fig. II. 



Plant mass caespitose, grumous-gelatinous, brownish becoming black; 

 colonies club-shaped, gelatinous, irregularly dilated, up to i mm. m thick- 

 ness, yellowish brown; common tegument lamellose, yellowish brown; 

 filaments 20-28 mic. in diameter, repeatedly branched within the common 

 tegument, flexuously curved and densely interwoven; trichomes constricted 

 at joints; cells and heterocysts 6-10 mic. in diameter, somewhat spherical; 

 cell contents blue-green. 



New York. Forming a blackish brown gelatinous stratum upon rocks. 

 Niagara Falls. (Wolle). Florida. On old wood. March 1878. (Wolle). 



Family IV. STIGONEMACEAE 



Filaments free, rarely laterally aggregated, scattered, frequently 

 branched; sheaths thick, firm, often irregular; trichomes consisting of one 

 or several rows of cells, with heterocysts; heterocysts often lateral, some- 

 times intercalary; reproduction by means of vegetative division, hormo- 

 gones and gonidia. 



I Sheaths distinct, definite. 

 I Filaments free 



(i) Trichomes consisting of one row of cells 



A Branches of two kinds, the one cylindrical, the other flagelliform; 

 heterocysts terminal or lateral Mastigocoleus 



B Branches unilateral, usually tapering at the apex; heterocysts in- 

 tercalary Hapalosiphon 



