SPECIES OF ALG^E. 69 



c. Filaments 4yu in diameter, curved; substratum whitish, 



inundata, 303 

 c. Filaments 3-3.5 in diam., slightly curved . . . cataracta, 302 



c. Filaments 7-8 in diam. (d\ 



d. Cells finely punctate; on rocks ruprestre, 300 



d. Cells not punctate, joints somewhat contracted; moist ground, Fla. 



subtorulosa, 300 



e. More or less radiating; apices obtuse . Juliana, $Q>\\ Retzii, 302 



f. Filaments straight, sheathed, 5-9/f diam vulgaris, 300 



/. slightly curved or flexuose; with sheath 40-80/4 diam., 



pallida, 298 

 /. " forming a purple stratum, long, waving, S-g^i diam., 



tinctoria, 301 



g. In alpine lakes or marshes cincinnata, 296 



g. Not alpine (h). 



h. Tufted on stones; filaments 40-45 to 50-60/4 diam. . Wollei, 297 

 h. In a stratum or floating singly (/). 



/. Filaments i2-i8/* diam obscura, 298 



/. " 7-9. 5 diam., matted; wet marsh bottoms, 



phormidium, 299 

 i. " 5~7 diam. (j). 



j. Stratum thin, paper-like, substratum, pallid, of empty sheaths, 



papyrina, 302 

 j. " membranous, mucous, filaments yellowish, 



inter rupta, 302 



102. SYMPLOCA. 



Stratum dull green or blackish; filaments 4-67* diam. 



Friesiana, 304 

 Stratum bluish green; filaments 3-4^, lucifuga, y>$', fuscescens, 304 



103. MICROCOLEUS. 



On rocks or moist earth (a). 

 Aquatic (b). 



a. Diameter of filaments 3^ to 4^/4 anguiformis, 306 



a. " 5~6/< terrestris, 305 



a. " " " i2/f Ravenellii, 307 



a. " " " 10-13/4; in a thin membrane amorpha, 304 



b. Stratum cushion-like, large, 6-8 in. or more in diam., 



pulvinatus, 305 



