LEPTOTHRIX. 321 



LEPTOTHRIX TINCTORIA, Kg. 



Fasciculate-caespitose, about 6 mm (I inch) long-, deep 

 amethyst, or purple-green ; trichomes rigid, equal, distinctly 

 articulate, pale steel blue ; articulations as long as broad ; 

 sheath close, colorless. 



Diameter of filaments, 1.75-2.25. 

 Attached to submerged plants. 



Syu. Hyplieoihrix tinctoria, ( Ag. ) Rab. ; Calothrix tinctoria, 

 (Persoon) Ag. 



Plate CCVIII, fig. 16, a usual appearance. 



LEPTOTHRIX RIGIDULA, Ag. 



Stratum composed, usually, of segregate or subapproxi- 

 rnate clusters; light, dilute aeruginous. Filaments fiexu- 

 ously curved, articulate or homogeneous. 



Diameter of trichomes, 1.25-1.75 yw; length, 100-130 ^. 



Syn. Leptomitus divergens, Kg. ; Hygrocrocis rigidula. Kg. 



In stagnant, or sluggish waters, parasitic on aquatic plants. 

 Plate CCVIII, fig. 15. 



LEPTOTHRIX LAMINOSA, Kg. 



Stratum often broadly expanded, membranaceous lamel- 

 lose, on the surface aeruginous or olivaceous, below faded 

 yellowish or colorless. Trichomes flexuously curved, inter- 

 woven, and sometimes spirally coiled, homogeneous or arti- 

 culate ; articles subequal. 



Diameter, 1.75-2/v. 



Syn. Oscillaria laminosa, Ag. ; Hypheothrix laminosa, Rab. ; Oscil- 

 laria labyrinthiformis, Ag. 

 Stagnant waters, ponds and ditches. 



Plate CCVIII, fig. 17, a specimen with filaments gently 

 curved ; fig. 18, filaments coiled. 



LEPTOTHRIX BULLOSA, Wolle. 



Thallus subspherical, gregarious, dilute straw color or 

 yellowish white. Filaments simple, in part densely inter- 

 woven into very tough globular, or oval, hollow bodies, 4-8 

 mm in diameter. Trichomes pale aeruginous, often faded 

 and contracted. 



Diameter 1.5-2. /* ; sheath about twice as wide. 



In shallow, sluggish waters, Susquehanna River, Harris- 

 burg, Penna. 



