SPECIES OF ALG^E. 65 



a. Diameter of filaments 2-3^, of sheath at the base 6-y//, apex 3-4;* 



crustaceus, 263 



a. 5-7 yw ......... ambiguum, 262 



$. Surface pubescent; black; filaments 9-15^ .... Castelli, 262 



b. " " filaments 15-20^ ...... Austinii, 262 



b. Surface not pubescent (c). 



c. Diameter of filaments 15^ or less (d). 



d. Filaments brown, 12-15^, cells ^ as long as wide, 



Bornetianuni, 261 



d. bluish, 8-iOyW, cells about as long as wide hirtiilus, 261 



d. bluish, 8-1 2yu, sheath wider at base . Hofmanni, 262 



88. TOLYPOTHRIX. 



On tree trunks, surface velvety, blackish; diam. 11-14^, 



truncicola^ 266 



On wet exposed rocks (a). 



Aquatic (b). 



a. Reddish brown; filaments with dark transverse bands, 



Ravenellii, 265 



a. Red, purple and black; filaments much branched . rupestris, 265 



b. Spherical, pea-like masses, filaments bluish . sGgagropkila, 264 



b. Not spherical masses (c). 



c. Diameter of filaments 3-4/< .......... tennis, 265 



c. Diameter 10-17/1 (d). 



c. " 9-1 1//, often interrupted by inclined disc-like cells, 



muscicola, 264 



d. Impossible to separate here, distorta, 26$; pitlchrn, 2&4 C ; flaccida, 265 



89. PLECTONEMA. 



91. SIROSIPHON. 

 Aquatic; brown; cells of stems 2-rowed, in branches i-rowed, 



ocellatus, 272 

 On old wood and tree trunks; in black spots; often aggregated, 



lignicola, 273 



In soda springs, west; not fully described . . . Brandcgeei, 274 

 On damp soil or wet rocks (a). 



