IOWA ACADEMY OF SCIENCE 
69 
KEY TO THE FAMILIES. 
Thallus branched. 
Without large barrel shaped resting spores.... I. Cladophoraceae 
With large barrel shaped asexual spores .II. Pithophoraceae 
Thallus unbranched III. Sphaeropleaceae 
Family I. 
Cladophoraceae. 
1 . Cladophora . 
KEY TO THE SPECIES. 
At first attached as tufts, afterwards floating as mats. 
Cell membrane smooth, articulations more or less swollen. ...... .C. fracta 
Filaments thin, long, sparingly branched, green C. fracta gossypina 
Filaments shorter, much branched, in brownish or nearly black masses 
C. fracta rigidua 
Cell membrane delicately plicate striate. .C. crispata 
Tufts permanently attached, branches not connate at the base . . C. glomerata 
2-4 inches long, branches somewhat scattered, ultimate cells penicillate 
fascicles C. glomerata rivularis 
Barely one inch long, corymbosely fasciculate, erect . . C. glomerata pumila 
86. C. fracta Kuetz. 
Iowa City. Hobby. 
Ames. Bessey. 
West Okoboji. Common. Shimek. 
Arbor Lake. Grinnell. Fink. 
Eagle Grove. Jenning’s Pond. Buchanan. 
Eagle Grove. Railroad Pond. Buchanan. 
Ames, near Ontario. Buchanan. 
87. C. fracta var. gossypina Rabenh. 
West Okoboji. Shimek. 
88. C. fracta var. rigidula Rabenh. 
Grinnell. Arbor Lake. Fink. 
89. C. crispata Kuetz. 
Iowa City. Hobby. 
Fayette. Quiet water of Volga. Fink. 
Grinnell. Fink. 
90. C. glomerata Kuetz. 
Iowa City. Hobby. 
Ames. Common in streams. Bessey. 
West Okoboji. Common. Shimek. 
North Gar Lake. On weeds. Buchanan. 
Fayette. Common in Volga. Fink. 
91. C. glomerata var. rivularis Rabenh. 
Fayette. Volga, quiet waters. Fink. 
92. C. glomerata var. pumila Bail. 
Fayette. Volga, quiet waters. Fink. 
