40 Proceedings of the Ohio State Academy of Science. 



This society is not found in exposed situations, it occupies 

 small, shallow pools in the open margin of the shrub zone. In 

 several very shallow, open basins in a Typha latifolia tussock, 

 excepting a scanty growth of Algae, the dominant and only 

 dearly visible plant was Utricularia minor. 



3. Wollfiella floridana society. 



This plant is indigenous to sub-tropic regions and is found 

 in swamps and pools of stagnant water often associated with 

 Ricciocarpus natans. It was reported from Florida as early as 

 1877, later in 1896 it was found in a swamp in southeastern Mis- 

 souri and up to the time (1906) of its discovery by Dr. W. A. 

 Kellerman in the pool in Cranberry Island, the Missouri station 

 was its farthest north. It forms an almost pure society in a small 

 basin about 12-18 inches deep in the Bog meadow near the thicket 

 border. Here it forms so copius a growth that the surface is 

 filled with clusters of the small filamentous fronds. During the 

 winter the plants sink to the bottom to rise again in the warm 

 days of April. 



' 4. Nostoc sp. society. 



Several small, narrow pools, mere depressions in the 

 'Sphagnum cover, situated at the margin of the wooded belt and 

 shaded by a border of Typha latifolia and lined with Sphagnum 

 and Oxycoccus macrocarpus stems, contain a copious growth of 

 Nostoc glomeratum and N. pruniforme. These pools were almost 

 without standing water, September 23, 1910, and the Nostoc had 

 collected thickly over the Sphagnum and the Oxycoccus leaves 

 and stems on the sides and bottom of the pool. They had evi- 

 dently been in this condition for several days as the exposed 

 Nostoc nodules were soft and decaying; only those still sub- 

 merged were firm to the touch and dark green. 



5. Riccia fluitans society. 



Many of the small, shallow depressions in the bog meadow 

 at the edge of the thicket have during some years, as 191 1, an 

 almost pure growth of Riccia fluitans. 



