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



in Figure 6 on Plate III. The writer was unable to observe 

 them long enough to determine whether the process was one of 

 longitudinal division, which to the writer's knowledge is unde- 

 scribed for this species, or of conjugation. 

 Length 63)u; breadth 46/i. 



Family MicrothoracidcB. 



Cinetochilum margaritaceum (Ehrenberg). 



In December, this organism was common in algae from 

 Station G. It was not found again until late in March when it 

 was abundant in sediment at Station L, at the opposite end of 

 the larger pond. 



Length 24/x. 



Family ParamaecidcB. 



Paramaecium bursaria (Ehrenberg). 



This species was infrequent on alga-covered poplar roots 

 (Station D) and among dead Oedogonium filaments (Station H), 

 from November to the end of February. All the individuals 

 were colored bright green by numerous Zoochlorellce. 



Length 122-153ai. 



Paramaecium caudatum Ehrenberg. 



This well-known species, usually found in hay infusions, 

 was most common in those parts of Mirror Lake made foul by 

 decaying organic matter. It was common in newly collected 

 material, but soon became abundant in a culture when the 

 growth of bacteria was at its height. It was taken in the black 

 sediment at Station B throughout the fall. During January, 

 February and March it was abundant on alga-covered poplar 

 roots, (Station D), and in algae at Station G, H, and E. 



Length 320-352iu; diameter SO/x. 



Family PleuronemidcB. 



Lembadion buUinum (Muller). 



This form was common during November among dead 

 Oedogonium filaments (Station H). One individual was taken 

 in December and another in January among algae from the 

 submerged stones at Station G. 



Length 128^- 



