56 
IOWA ACADEMY OF SCIENCE 
19. A. cycadacearum. Reinke. 
Filaments curved, spores 16-18u A. circinalis 
Occurring as the cause of the nodular thickenings on the roots of the 
Cycas revoluta wherever grown. 
Ames. Greenhouse. Buchanan. 
20. A. flos-aquae. Breb. 
One of the most common (together with the next) of the constituents 
of the plankton of many of our lakes at some seasons of the year. Oc- 
curs frequently in the sloughs in the northern part of the state also. 
Eagle Grove, Jenning’s Pond. 1904. Buchanan. 
Eagle Grove, Pond near Boone River. Buchanan. 
Eagle Grove, Slough. 1904. Buchanan. 
Collected some eight or ten times under similar conditions to 
the above. 
21. A. circinalis. Rabenh. 
Very common in the lakes. 
East Okoboji Lake. October. 1904. Buchanan. 
Upper Gar Lake. October. 1904. Buchanan. 
3. Cylindrospermum. 
KEY TO THE SPECIES. 
(It is impossible to give a key to the species that occur in Iowa, inasmuch 
as only one has come to the notice of the writer, and the names that have been 
used by other writers may mean any one of several species, at least as recog- 
nized by Bomet and Flahault) . 
22. C. limnicola Kg. 
Iowa City. Hobby. 
Ames. Soil on pots in greenhouse. Buchanan. 
23. C. comatum Wood. 
Grinnell. Frequent on wet soil along brooks. Fink. 
2 If.. C. macrospermum Kg. 
Iowa City. Hobby. 
Family III. 
Oscillatoriaceae. 
KEY TO THE SUBFAMILIES. 
I. Several trichomes included in a single sheath Vaginarieae 
II. Single trichome in a sheath Lyngbyeae 
Subfamily I. 
Vaginarieae. 
1. Microcoleus. 
25. M. vaginatus (Vauch) Comont. (M. terrestris Kg.) 
Grinnell. Damp Ground. Fink. 
Ames. On flower pots in greenhouse. Buchanan. 
