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



Holosticha vernalis Stokes. 



This form was abundant from the latter part of January- 

 through March among algae in the bowl of the spring (Station 

 J), in those on the submerged stone at Station G and among the 

 algae scraped from posts at Stations I and I'. 



Length 112-160At. . 



Family Euplotidce. 



Euplotes charon (Miiller). 



One individual was taken among floating algae at Station C,. 

 in October. 



Length SOm; breadth 62/^. 



Euplotes variabilis Stokes. 



One individual of this species occurred in sediment on the 

 leaves at Station A during October. 

 Length 220^; breadth 128/1. 



Aspidisca costata (Dujardin). 



This species ranks with Coleps Hirtus in its wide distribution 

 and frequency in Mirror Lake. It was common throughout 

 the period of study in every station where algae grew, except 

 in the bowl of the spring and at its entrance into the larger 

 pond. Immature stages were invariably present in the col- 

 lections. 



Length 38/z. 



Order Peritrichida. 



Family Vorticellidce. 



Vorticella alba Fromentel. 



This species was abundant in sediment from Station B 

 during November ; it was not taken again until late in February 

 and then among alga-covered poplar roots (Station D). 



Length of zooid 48-64/x. 



Vorticella microstoma Ehrenberg. 



But one individual of this species was taken, among alga- 

 covered poplar roots (Station D), on January 8. 

 Length of zooid 62/i. 



