376 PROTOZOOLOGY 



G.fluvialis D. (Fig. 175, a). Test spherical to subspherical ; smooth 

 or sparsely covered with siliceous particles; yellowish cytoplasm 

 fills the test; aperture not seen; a large nucleus and numerous con- 

 tractile vacuoles; filopodia long, often enveloping test; 90-250/i 

 long; on aquatic plants, in moss or soil. 



G. ovoidea (Rhumbler) (Fig. 175, 6). In salt water. 



G. nigricans (Penard) (Fig. 175, c). Test large, circular in cross- 

 section; a single nucleus; 220-400)U long; in pond water among vege- 

 tation. 



Genus Microgromia Hertwig and Lesser, Test small, hyaline, 

 spherical or pyriform, not compressed; aperture terminal, circular; 

 filopodia long straight or anastomosing, arising from a peduncle; a 

 single nucleus and contractile vacuole; solitary or grouped. 



M. socialis (Archer) (Fig. 175, d). Cytoplasm bluish; contractile 

 vacuole near aperture; filopodia arise from a peduncle, attenuate, 

 branching, anastomosing; often numerous individuals are grouped; 

 multiplication by fission and also by swarmers; 25-35^ in diameter; 

 among vegetation in fresh water. 



Genus Microcometes Cienkowski. Body globular, enclosed within 

 a transparent, deUcate, light yellowish and pliable envelope with 

 3-5 apertures, through which long branching filopodia extend; body 

 protoplasm occupies about 1/2 the space of envelope; 1-2 contrac- 

 tile vacuoles; fresh water. 



M. paludosa C. (Fig. 175, e). About lQ-17f^ in diameter; fresh 

 water among algae. 



Genus Artodiscus Penard. Body globular, plastic; covered by 

 envelope containing small grains of various kinds; nucleus eccentric; 

 a few pseudopodia extend through pores of the envelope; movement 

 very rapid ; fresh water. 



A. saltans P. (Fig. 175,/). 18-23/1 in diameter; fresh water. 



Genus Lieberkiihnia Claparede and Lachmann. Test ovoidal or 

 spherical, with or without attached foreign particles; aperture 

 usually single, lateral or subterminal; one or more nuclei; many con- 

 tractile vacuoles; pseudopodia formed from a long peduncle, reticu- 

 late, often enveloping test; fresh or salt water. 



L. wagneri C. and L. (Fig. 176, a). Spheroidal; aperture subtermi- 

 nal, oblique, flexible; cytoplasm slightly yellowish, fills the test; 

 80-150 vesicular nuclei; many contractile vacuoles; pseudopodia 

 long, anastomosing; 60-160/x long; nuclei Q/j, in diameter; among 

 algae in fresh and salt water. 



