SPECIES OF ALG.E. 67 



a. Without 'mucilage; filaments in irregular masses, coiled, 



tenuissimum, 282 



a. With mucilage; joints equal, rather distant . . comminutum, 282 



b. Soft, becoming gelatinous cushions (<?). 



b. " tongue-shaped, plane, irregularly expanded (d). 



b. With a firm coating (/). 



c. Fronds with a firm coating (g). 



d. Mature frond suborbicular, often perforated and expanded, 



commune, 283 



d. " " linear, straight, long; filaments parallel, 



flagelliforme, 285 



e. Globose thalli within a subspherical gelatinous mass, muscorum, 282 

 e. Globose, firm; filaments olive humifusum, 282 



e. Suborbicular, soft; filaments bluish green .... calcicola, 283 



f. Globose, firm, coating brownish; joints subspherical, 



sphcericum, 283 



/. " soft, sheath often colored and general mucus colorless, 



r up e sire, 283 



f. " not i mm in diam.; cells cylindrical, slightly constricted, 



macrosporum, 284 

 ' g. Cells of two kinds, unequal (/*). 



g. Cells uniform, regular (/'). 



h. One kind elongated, the other spherical; bluish . cccruleum, 284 



i. Fronds globose, from 2 mm to size of a cherry . pruniforme, 284 



/. " rounded or discoid, becoming hollow (/), 



j. Fronds subglobose, warty, brownish green . . verrucosum, 284 



j' Fronds suborbicular, erect, smooth, tenacious . . Alpinum, 285 



94. ANAB^NA. 



On tree trunks, near the water's edge, bluish . cupressaphila, 288 

 In brackish ditches; stratum bluish .... oscillarioides, 288 

 In sweet waters (a), 

 a. Cells 3-4yw in diameter (b). 



a. Cells 4-1 1// in diameter (c). 



b. Deep blue green; filaments curved, almost parallel, 



variabilis, 287 



b. Pale bluish, sometimes yellowish; filaments curved, usually in 



clusters stagnalis, 288 



c. Filaments curved, often coiled flos-aqua, 286 



c. Filaments straight, often coiled when young . . gigantea, 287 



