IOWA ACADEMY OF SCIENCE 
71 
98. V. germinata var. racemosa Walz. 
Iowa City. Hobby. 
Grinnell. Fink. 
Ames. Buchanan. 
Ames. Roadside puddle. Fawcett. 
99. V. terrestris Lyngb. 
Ames. Bessey. 
Fayette. Fink. 
Order VIII. 
Conjugatae. 
KEY TO THE FAMILIES. 
Thallus multicellular 
Thallus uni-cellular. 
Family I. 
Zygnemaceae. 
KEY TO THE SUBFAMILIES. 
Conjugation forming a zygospore which immediately develops a sporo- 
carp of several cells, one of which is the spore (carpospore) . The 
gametophyte is developed from this after a period of rest 
I. Mesocarpeae 
Conjugation producing a zygospore which after a period of rest develops 
directly into a new gametophyte II. Zygnemeae 
Subfamily I. 
Mesocarpeae. 
1 . Mougeotia. 
100. M. genuflexa Ag. 
Fayette. Fink. 
101. M. scalaris Hass. 
Iowa City. Hobby. 
Ames. Bessey. 
Subfamily II. 
Zygnemeae. 
KEY TO THE GENERA. 
Chlorophyll in stellate masses .1. Zygnema 
Chlorophyll in spiral bands 2. Spirogyra 
1 . Zygnema. 
KEY TO THE SPECIES. 
Zygospore in one of the conjugating cells. 
Intermediate membrane of spores smooth, 26-30 u broad . . . . Z. insigne 
.1. Zygnemaceae 
II. Desmidiaceae 
