[Vor. 4 
296 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
the cell into four equal segments. The margin of the minute 
cell frequently takes on an undulate appearance, due to the 
presence of an additional minor incision, but this is not 
always apparent. То add to the complex character of this 
species there ultimately appears at the juncture of the four 
segments a hole which is angular in outline and probably as- 
sists in the separation of the newly formed individuals. 
Reinsch makes no reference to this hole in his discussion of 
the species, but in the description of the plate, referring to 
fig. 1k, he says: ‘‘das Scheibchen in der Mitte mit einem vie- 
reckigen Loche versehen.’’ Figure 3, a colony of sixteen cells, 
also shows the hole at each point of connection. In the ma- 
terial from Devils Lake the central hole was always present, 
but was not as angular as shown in Reinsch’s figures. 
Order HORMOGONEALES 
Family OsctrLLATORIACEAE 
Subfamily LYNGBYEAE 
Genus ARTHROSPIRA Stizenberger 
Arthrospira Jenneri (Kuetzing) Stizenberger, Hedwigia 1: 
32. 1852. Rare. Found sparingly in two collections. 
Genus osciLLATORIA Vaucher 
Oscillatoria amphibia Agardh, Flora 10: 632. 1827. The 
most abundant and widely distributed species, being found in 
thirteen different collections. 
Oscillatoria brevis Kuetzing, Рус. Gen. 186. 1843. Found 
in seven collections. 
Oscillatoria chalybea Mertens in Juergens, Algae Aquat. 
13:4. 1822. Found but twice. 
Oscillatoria chlorina Kuetzing, Phye. Gen. 185. 1843. In a 
single towing. 
Oscillatoria geminata Meneghini, Consp. Alg. Eugan. 9. 
1837. 
Oscillatoria limosa Agardh, Disp. Alg. Suec. 35. 1812. 
This common species was found but once. 
