Feb., 1920] The Protozoa of Mirror Lake 105 



Acanthocystis sp.? 



Several individuals were taken on December 3 among 

 floating algae from Station C. These agreed perfectly with 

 Leidy's figures of Acanthocystis sp.? (1879; PI. 43, Fig. 8). 



Diameter 32ju. , 



Diplophrys archeri Barker. 



Early in March one colony was observed among dead 

 Oedogonium filaments from Station H. It was ruby red in color 

 with colorless pseudopodia. The animal moved steadily across 

 the field. 



Diameter 48iLi. 



Class Mastigophora. 



SUBCLASS FLAGELLIDIA. 

 Order Monadida. 



Family Heteromonadidce. 



Monas fluida Dujardin. 



An individual was taken on October 24 in green sediment on 

 the leaves at Station A. It contained numerous refractive 

 bodies and it was very metabolic. 



Length of the extended form 36/i. 



Anthophysa vegetans Muller. 



One colony of eight individuals occurred in floating Spiro- 

 gyra (Station C) late in October. This species was not seen 

 again until late in March when it was abundant in algae at 

 Station G. The colonies were 48/x in diameter. 



Streptomonas cordata (Perty). 



This species was common during December in alga-covered 

 poplar roots (Station D) and among algae growing at the point 

 at which the spring water enters the larger pond (Station E). 



Length 15ju. 



