202 



The Ohio Naturalist. 



[Vol. XI, No. 1, 



In the deeper water it is a pure Nclumbo lutea family; in the shal- 

 lower, the other plants, especially Potamogeton pectinatus and the 

 variety are quite abundant. There is some evidence of vertical 

 zonation or layering ; in the deeper water the Nelumbo leaves float 

 on the surface; and in the shallower rise 12 inches above the 

 surface. 



Fig. I. View of the vegetation from the S. E. side of the island in 

 belt transect a-a', showing formation I, II and III ; and societies i, 2, 3, 

 4, 5, 6 and 7 of map. 



2. Nelumbo-Polygonum society. 

 Facies. 

 Nelumbo lutea. Polygonum emersum. 



Secondary species. 



Ceratophyllum demersum. 

 Spirogyra sp. 

 Lemna minor. 

 Cladophora sp. 

 Spirodela polyrhyza. 



Brachythecium rivulare. 

 Riccia fluitans. 

 Riccia sp. 



Ilysanthes gratioloides. 

 Sium cicutaefolium. 



This society fonns a dense zone 60 feet broad, and extends 

 from water S inches deep to a wholly emersed surface. 35 feet 

 of the zone covers a mud flat which is submerged at the normal 

 water level. The Polygonum has advanced into the Nelumbo, 



