Myxophyceae 141 



Wolle. Fresh-Water Algae U. S. 320. pi. 208. f. 13. 1887. (L e p t o t h r i x 

 herbacea Kg.). 



Plant mass thin, somewhat cushion-shaped, mucous, bright green, 

 more or less faded underneath; filaments 1.8-2.2 mic. in diameter, very 

 slender, slightly flexuously curved, entangled; sheaths very close, color- 

 less; cells here and there distinct. 



South Carolina. Very abundant on the wood-work around the artesian 

 well. Charleston. (Wolle). 



270. Hypheothrix tenax Wolle. Fresh Water Algae. Bull. Torr. Bot. Club. 



6: 282. 1879; Fresh-Water Algae. U. S. 319. pi. 203. f. 2. 1887. 



(Leptothrix tenax Wolle). De Toni. Syll. Algar. 5: 329. 



1907. 

 Plant mass sometimes expanded, forming loosely interwoven masses 

 i.S dm. or more in diameter, at other times forming small, caespitose, 

 cushion-shaped clusters; filaments 3.5-4 mic. in diameter, slender but strong 

 and tough, often forming firm membranes; sheaths colorless, firm, close; 

 transverse walls not always visible; cells about as long as wide; cell con- 

 tents primarily light blue-green, soon changing to dull yellow or light 

 brown. 



Pennsylvania. On stones in stagnant water. (Wolle). 



271. Hypheothrix bullosa Wolle. Fresh Water Algae. III. Bull. Torr. Bot. 



Club. 6: 182. 1877; Fresh-Water Algae U. S. 321. pi. 208. f. 19. 



1887. (Leptothrix bullosa Wolle). De Toni. Syll. Algar. 



5: 329'. 1907. 



Plant mass 4-8 mm. in diameter, somewhat spherical or oval, hollow, 



tough, gregarious, dilute straw color or yellowish white; filaments 4-6 



mic. in diameter, unbranched, densely interwoven; sheaths colorless; trich- 



omes i.S-2 mic. in diameter; cell contents pale blue-green, often faded 



and contracted. 



Pennsylvania. Shallow, sluggish water, Susquehanna River, Harris- 

 burgh. (Wolle). 



272. Hypheothrix turicensis Naegeli in Kuetzing. Spec. Algar. 269. 1849. 



De Toni. Syll. Algar. 5: 333. 1907. 



Wolle. Fresh Water Algae. III. Bull. Torr. Bot. Club. 6: 182. 1877. 



Plant mass compact, leathery, irregularly roughened, brick-colored, 

 v/ithin faded or dull green; filaments up to 7.5 mic. in diameter; sheaths 

 wide, membranaceous, firm, homogeneous, colorless, very smooth, taper- 

 ing at apex; trichomes 3.2-4 mic. in diameter, thick, flexuously curved, here 

 and there interrupted; cells a little shorter than the diameter; transverse 

 vifalls sometimes indistinct; cell contents sometimes granular, dark or 

 pale blue-green. 



Pennsylvania. Moist rocks. (Wolle). 



273. Hypheothrix aikenensis Wolle. Fresh Water Algae. III. Bull. Torr. 



Bot. Club. 6: 182. 1877. De Toni. Syll. Algar. 5: 329. i907- 

 Plant mass more or less expanded, olive green; filaments 8-1 1 mic. 



