SPECIES OF ALG^E. 71 



/. Diameter 30^ or more (m). 

 less than $oju (n). 



m. Cells ^ to 4- as long as wide; diam. 30-45 \JL . . . princeps, 317 

 m. Cells about \ as long as wide ....... imperator, 317 



. Diameter less than 19 /^ (0). 



. " 19^ or more (/). 



o. Diameter 15^; cells YZ% as long as wide . . . percursa, 315 



o. lo-iSyu; variable ......... Frcelichii, 315 



p. Diameter 19-22/^5 cells yi% as l n as wide . . . major, 316 

 /. " 23-28/4; cells J " " " " . Bonnemasonii, 316 



105. BEGGIATOA. 



#. Diameter of filaments ii.$j4 ........ m'veum, 318 



a. i. 8-2. 5 /^ ..... leptomitiformis, 319 



I06. LEPTOTHRIX. 



In hot waste water, waving, 6 mm thick .... hinnulia, 320 

 On old wet walls; filaments strongly curved . . . calcicola, 319 

 On wet wood, herbaceous green; diam. 1.8-2.25;* . herbacea, 320 

 Aquatic, sometimes on wet rocks (a). 

 a. Forming spherical masses, light yellowish, tough, hollow, 4-8 mm 



diam ................ bullosa, 321 



a. Forming cloud-like, floating fragile masses, yellowish; filaments 



about 2fji diam ............. ochracea, 322 



a. Forming a stratum (b). 



a. Forming a tuft (e). 



b. Filaments 3^ or more in diam .......... tenax, 319 



b. " less than 3^ in diam. (c). 



c. Stratum composed of clusters, light bluish . . . rigidula, 321 



c. " more or less expanded (d). 



d. Bluish or greenish above, yellowish or colorless below, 



laminosa^ 321 



d. Bright bluish, thin, membranaceous ..... a'ruginea. 319 



e. Bluish, becoming yellowish ........ cczspitosa, 320 



e. Purple green or amethyst .......... tinctoria, 321 



Io6a. ASTEROTHRIX. 



One species ............... Creginii, 322 



