SPECIES OF ALG^. 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, t,o\\ Retzii, 302 



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



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



pallida, 298 

 /. " forming a purple stratum, long, waving, 8-9 yu diam., 



tinctoria, 301 

 g. In alpine lakes or marshes cincinnata, 296- 



g. Not alpine {K). ^ 



h. Tufted on stones; filaments 40-45 to 50-60/1 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 

 /. " 5-7 diam. (y). 



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



papyrina, 302 

 / " membranous, mucous, filaments yellowish, 



interrupta, 302 



102. SYMPLOCA. 



§ Stratum dull green or blackish; filaments 4-6/1 diam. 



Friesiana, 304 

 § Stratum bluish green; filaments 3-4/1, lucifuga, 7,oy, fuscescens, 304 



103. MICROCOLEUS. 



§ On rocks or moist earth {a). 



§ Aquatic (b). 



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



a. " " " 5-6/< . . terrestris, 305 



a. " " " 12/1 . .... . Ravenellii, 307 



a. " " " io-13/i; in a thin membrane amorpha, 304 



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



pulvinatus, 305 



