320 FRESH-WATER ALG^E OF THE UNITED STATES. 



ments irregularly intertwined ; articulation rather indistinct, 

 somewhat longer than wide. 



Diameter of filaments, 1.8-2. 25 yw. 



Syn. Hypheothrix aeruginea, Kg. 



Ponds, .springs, about basins of thermal water. 



LEPTOTHRIX HERBACEA, Kg. 



Stratum somewhat herbaceous green, not so decidedly 

 aerugmous, and not membranaceous as the last. Filaments 

 slightly flexuously curved, upright growth, caespitose, sub- 

 pulvinate ; often faded at the base, while bright green above. 

 Sheath close. The preceding differing only in the strata, 

 the one being thin smooth, membranaceous, and the other 

 more of a loose irregular upright growth. 



Diameter of filaments, like the last, 1.8-2.25 /*. 



Very abundant on the wood-work around the artesian 

 well, Charleston, South Carolina. In smaller quantity on 

 wet wood, aqueducts, etc. 



This species, so much in size and other features like the 

 last named (L. aerug.inea), may be a mere form of it. 



Plate CCVIII, fig. 13, a caespitose cluster under low 

 power, and part of a filament under high magnification. 



LEPTOTHRIX HINNULEA, Wolle. 



Stratum light fawn colored, flocculeiit caespitose, waving, 

 6 mm thick. Filaments flexible and contractile, indistinctly 

 vaginate, not articulate, 10-15 mm long; light yellow- 

 brown, or colorless. 



Diameter, 1.25-1.75 /*. 



In trenches hot waste-water from steam mills. 



Syn. Beggiatoa hinnulea, Wolle. Bull., Tor. Bot. Club, 



November, 1877. 

 Plate CCVIII, fig. 5, a flocculent cluster. 



LEPTOTHRIX CAESPITOSA, Kg. 



Caespitose, erect, aggregate ; filaments flexuously curved, 

 apices attenuated, dilute aeruginous, later brownish yellow, 

 waving, homogeneous or more rarely indistinctly articulate. 



Diameter, 2-2.75 / ; length, 125-200 yu. 



Attached to submerged wood or stones. Frequent in 

 ponds and ditches. 



Plate CCVIII, figs. 11, 12, clusters under low power and 

 parts of trichomes under higher power. 



