110 The Ohio Journal of Science [Vol. XX, No. 4, 



congregate in those parts of the pond hghted by the sun. The 

 water in the hghted part of the pond was of a bright green 

 color, while in the shaded parts, a green tinge was scarcely 

 noticeable. On days when the sky was overcast with clouds 

 the cells settled to the bottom and formed a thick green sediment 

 on the leaves. After a heavy rain and wind storm on October 

 29, these organisms were not found. Carteria multifilis 

 was present in floating Spirogyra in the larger pond (Station C) 

 during October; its numbers were not nearly so great, 

 however, as in the smaller pond. 

 Diameter 9-lo/x. 



Order Diniferida. 



Family Peridinidce. 



Peridinium quadridens Stein. 



One individual was taken in algae from a submerged stone 

 at Station G on December 18, and another in sediment from 

 Station L in March. The environments were very similar 

 at these places. 



Length 40-43^. 



Peridinium tabulatum Ehrenberg. 



This organism was common in sediment from Stations 

 H and F until on December 7 a sudden drop in the temperature 

 caused ice to form on the lake. It was taken again at the same 

 place after thawing, but only rarely. 



Length 40/i. 



Gonyaulax polyhedra Stein. 



Not until March did this form appear in collections. It was 

 common in algae from posts (Stations I and I'), in filaments 

 of Oedogonium (Station H), and in algae from a stone (Station 

 G). 



Length 34-48/x. 



Glenodinium cinctum Ehrenberg. 



One individual was taken in March in algae scraped from 

 the submerged stone at Station G. The eye spot was unusually 

 large. 



Diameter BOju. 



