LEPTOTHRIX. 319 



BEGGIATOA LEPTOMITIFORMIS, (Menegh. ) Trevis. 



Habitat, strata, and filaments, in character with the pre- 

 ceding, but trichonies stouter and usually in larger masses. 



Diameter of filaments, 1.8-2.5 /-/. 



Syn. Oscillaria Icptomitiformis, Menegh. 



Larger sulphur springs, New York and Florida. 



Plate CCYIII, figs. 6, 7, clusters of filaments, and separate 

 ones under higher magnification. 



Genus 105, LEPTOTHEIX, Kg. 



Filaments simple, very slender, articulation none or indistinct, 

 without oscillating movement. 



LEPTOTHEIX TENAX, Wolle. 



Stratum sometimes expanded, attached to submerged 

 stones, forming loosely interwoven masses, six or more 

 inches in diameter, at other times in small caespitose, pul- 

 vinate clusters on wet rocks. Filaments slender but strong, 

 tough, from one-half to six inches long ; often forming firm 

 membranes. Color of trichomes primarily light aeruginous, 

 but soon changing to a dull yellow or light brown. Articu- 

 lation rarely observed, as long as wide. Sheath close. 



Diameter of filaments, 3.5-4 yu. 



Sluggish or stagnant waters, wet slate, and other rocks, 

 from Vermont to Florida. 



Plate CCIII, figs. 1, 2, from Pennsylvania specimens, six 

 to eight inches long. Described in Bull. Tor. Botanical 

 Club, 1878, as Hypheothrix tenax. 



LEPTOTHRIX OALCICOLA, Kg. 



Stratum dull aeruginous ; filaments strongly curved and 

 closely interwoven, rather fragile ; aerial, sometimes form- 

 ing a glossy stratum, more frequently a dull, dark aerugi- 

 nous coating on old walls. 



Diameter of filaments, 2.25-3.25 //. 



Syu. Hypheothrix calcicola, Kg. ; Oscillaria calcicola, Ag. ; Leplo- 

 thrix muralis, Kg. 



Plate CCVIII, fig. 21, stratum slightly enlarged. 



LEPTOTHRIX AERTJGINEA, ( Kg. ) Kirch. 



Stratum thin, membranaceous, bright aeruginous ; fila- 



21 



