260 FRESH- WATER ALG^J OF THE UNITED STATES. 



Adhering to the wet sides of a wooded gutter, leading 

 water from a spring, Aiken, South Carolina. Transcribed 

 from Wood's Contribution to Fresh- water Algre. The correct- 

 ness of "articles seven times longer than the diameter, " may be 

 questioned. 



SCYTONEMA DUBIUM, Wood. 



Evidently a Hapalosiphon. 



SCYTONEMA AUSTINII, Wood. 



See Symphyosiphon. 



SCYTONEMA NAEGELII. 



Described by Wood, and doubtfully referred to this 

 species, is most likely a Plectonema, Thur. 



SCYTONEMA HEPPII, (Naeg.) Wolle. 



Stratum gelatinous, blackish-brown ; filaments somewhat 

 flexuously curved, densely intricate ; internal trichome pale 

 or dull aeruginous, with age brownish, moiiiliform, irregular 

 in thickness, measuring 8-13 yw ; here and there interrupted ; 

 articulations equal, to one -half as long as wide. Sheath 

 wide, distinctly laniellose, golden yellow or colorless, 

 smooth ; heterocysts depressed globose at base of branchlets 

 or more rarely interstitial, brownish yellow, usually single. 



Propagation by rnacrogonidia, which slide out of older 

 or ruptured filaments, , increasing in size, dividing and 

 redividing until finally they reproduce the young forms. 



Diameter of sheath, 20-25 yw. 



Syn. Diplocolon Heppii, Naeg. 



The reasons for forming a new genus to receive this species 

 appear insufficient ; it is really a Scytonema. 



Unlike the European form found on rocks and stones, 

 the present form was collected from old wood, Florida, 

 March, 1878. 



Plate CXCV, figs. 1-4, plants in vegetative condition ; 

 fig. 5, a broken filament, the macrospores escaping out of it, 

 gradually developing and multiplying; figs. 6, 7, repro- 

 ducing plants ; figs. 8, 9, young conditions. 



Genus 87, SYMPHYOSIPHON. 



Trichomes as in Scytonema, but agglutinated in erect wick- 

 like bundles, or forming more or less extended strata with even 

 or pulvinate surfaces. 



