SPECIES OF ALGJE. 6l 



71. SIROGONIUM. 



One species ......... ..... '..-.. sticticuni, 22 J 



72. ZYGNEMA. 



, Color soon becoming dark purple; filaments 20-25 A* m diam., 



purpureiini, 224 



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

 a. Filaments with gelatinous sheath; cells 25/4 wide, anomalum, 224 

 a. cells 40-44;* wide, crassum, 224 



a. " without sheath (b). 



b. Spore membrane smooth (c). 



b. " " punctate or granulate (d). 



x. Diameter of filaments 20-22 jj. ...... . leiospennum, 222 



,c. -u " " 26-30// ........ insigne, 223 



Y/. Diameter of filaments 10-36/4, very variable . . . stellium, 223 



t d. SS-S /^? ........ cruciatum, 224 



73. ZYGOGONIUM. 



Diameter of filaments zojj. or less (a). 



" " " more than 20^1 (c). 



a. Diameter of filaments 15-18^ ........ Agardhii^ 226 



.^. Spore spherical . .. . .......... decussatum, 262 



^. " compressed ellipsoid, twice as long as wide . Ralfsii 227 

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



pectinatiuti, 225 

 . " not constricted .(</).. 

 .//. Filaments 30-33^ in diameter ........ aquale, 226 



//. 22-24/4 - 4< ....... parvulum, 227 



74. MOUGEOTIA. 



Filaments 20-25/4 in diameter (a). 



" less than 20;^ in diameter (^). 



a. Spore spherical, diameter about 40 jw .... sphcerocarpa, 227 

 #. " " " " 45/t ..... divarecata, 228 

 A Filaments 15-18;* in diameter ...... Minnesotensis, 228 



b. " io-i4yw " 4< (^). 



r. Spore spherical, 25-30^ in diameter ..... delicatula^ 228 

 . " oval, radiately corrugated, yellowish-brown glyptosperma, 229 

 ur. " " coarsely granular, dark brown . . . verrucosu-s, 229 



