SPECIES OF ALG^. 

 71. SIROGONIUM. 



One species 



61 



sticticum, 222 



72. ZYGNEMA. 



§, Color soon becoming dark purple; filaments 20-25// in diam., 



purpureufti, 224 

 § Color green, or when in fruit yellowish or brownish (a), 

 a. Filaments with gelatinous sheath; cells 25/t wide, anomalum, 224 

 a. " " " " cells 40-44// wide, crassum, 224 



a. " without sheath (6). 



b. Spore membrane smooth {c). 



b. " " punctate or granulate {d). 

 £. Diameter of filaments 20-22/* 



c. '• " " zt-2,ofJi . 



d. Diameter of filaments 10-36/*, very variable 

 d. " " " 35-SO-W, 



ermum, 222 

 insigne, 223 

 siellium, 223 

 ci-uciatum, 2 24 



73. ZYGOGONIUM. 



§ Diameter of filaments 20/t or less (a). 



§ " " " more than 20/* (c). 



a. Diameter of filaments 15-18/* .... ... Agardhii, 226 



a. " " " i8-2o/t {b). 



b. Spore spherical . . .... ... decussatum, 262 



b. " compressed ellipsoid, twice as long as wide . Ralfsii 221 



c. Cells slightly constricted at the joints; spore punctate, 



pectinatum, 225 

 £. " not constricted {d). 



d. Filaments 30-33/t in diameter . aquale, 226 

 d. " 22-24/* " " • parvulum, 227 



74. MOUGEOTIA. 



§ Filaments 20-25/* ■'^ diameter (a). 



§ " less than 20/* in diameter (^). 



a. Spore spherical, diameter about 40/* . . 



a. " " " " 45/* . 



b. Filaments 15-18/* in diameter 



b. " 10-14/* " " W- 



c. Spore spherical, 25-30/* in diameter 

 *:. " oval, radiately corrugated, yellowish-brown ^/j^foj^frwa, 229 

 *:. " " coarsely granular, dark brown verrucosus, 229 



spharocarpa, 227 



divarecata, 228 



Minnesotensis, 228 



delicatida, 228 



