Feb., 1920] The Protozoa of Mirror Lake 95 



of the former were Epistylis fiavicans, Stylonychia mytilus, and 

 Urocentrum turbo. The flagellates Ckilomonas paramaecium, 

 Trachelomonas volvocina and Peranema trichopJiorum were 

 plentiful. Several species of Diffliigia were taken; these 

 multiplied rapidly in the laboratory. 



STATION D. 



Alga-covered roots in clear water well lighted much of the time. 



Station D was on the north shore of the larger pond just 

 east of the spring. The shore is steep and the water is about 

 a foot and a half deep. It was quiet and clear, and the sun 

 shone here all the afternoon. The temperature of the water 

 never became lower than one degree centigrade, due to the 

 proximity of this station to the spring. A white poplar {Populus 

 alba Linnaeus) overhangs the lake here and its roots extend 

 into the water. These were thickly covered by algae (largely 

 Oedogonium), which harbored many Protozoa. Arcella vulgaris, 

 Raphidiophrys pallida, Acanthocystis sp. and Amoeba radiosa 

 were the most plentiful rhizopods; Cyclidium glaucoma, Coleps 

 hirtus, Paramaecium caudatum, and Lionotus fasciola represented 

 the ciliates well; some few flagellates were taken, but they were 

 not plentiful. 



STATION E. 



Sand and algae in clear, fresh, slowly running water, well 

 exposed to light. 



Station E was located at the point where the water from 

 the spring entered the larger pond. The water was about 

 two inches deep, clear, fresh, and always in motion. Ice never 

 formed here, because of the uniformity in temperature of the 

 spring water, which varied between six degrees and twelve 

 degrees centigrade. This locality was never shaded from the 

 sun. Large boulders covered the shore, and below the water 

 line these were covered by a scanty growth of algae (mostly 

 Spirogyra). Collections were made here in two different ways: 

 algae were scraped from the rocks, and some of the sand was 

 taken with a pipette. This station was an ideal habitat for- 

 rhizopods. Throughout the period of study, the following 

 were common : Amoeba Umax, Amoeba radiosa, and Actinophrys 

 sol. A number of others were taken, but they were infrequent 

 in collections. A few ciliates occurred, but their number was 



