TESTACEA 325 



gromia, Rhumbler). Thin test rigid or flexible, smooth or shghtly 

 coated with foreign bodies; spherical to elongate ellipsoid; aper- 

 ture terminal; 1 or more nuclei; contractile vacuoles; many filo- 

 podia, branching and anastomosing; cytoplasm with numerous 

 motile granules; fresh or salt water. Many species. 



G. fluvialis D. (Fig. 148, a). Test spherical to subspherical; 

 smooth or sparsely covered with siliceous particles; yellowish cy- 

 toplasm fills the test; aperture not seen; a large nucleus and nu- 

 merous contractile vacuoles; filopodia long, often enveloping 

 test; 90-250yu long; on aquatic plants, in moss or soil, 



G. ovoidea (Rhumbler) (Fig. 148, 6). In salt water. 



G. nigricans (Penard) (Fig. 148, c). Test large, circular in cross- 

 section; a single nucleus; 220-400/x long; in pond water among 

 vegetation. 



Genus Microgromia Hertwig et Lesser. Test small, hyaline, 

 spherical or pyriform, not compressed; aperture terminal, circu- 

 lar; filopodia long straight or anastomosing, arising from a pe- 

 duncle; a single nucleus and contractile vacuole; solitary or 

 grouped. 



M. socialis (Archer) (Fig. 148, d). Cytoplasm bluish; contrac- 

 tile vacuole near aperture; filopodia arise from a peduncle, at- 

 tenuate, branching, anastomosing; often numerous individuals are 

 grouped; multiplication by fission and also by swarmers; 25-35jU 

 in diameter; among vegetation in fresh water. 



Genus Microcometes Cienkowski. Body globular, enclosed 

 within a transparent, delicate, light yellowish and pliable en- 

 velope with 3-5 apertures, through which long branching filo- 

 podia extend; body protoplasm occupies about 1/2 the space of 

 envelope; 1-2 contractile vacuoles; fresh water. 



M. paludosa C. (Fig. 148, e). About 16-17^ in diameter; fresh 

 water among algae. 



Genus Artodiscus Penard. Body globular, plastic; covered by 

 envelope containing small grains of various kinds; nucleus eccen- 

 tric; a few pseudopodia extend through pores of the envelope; 

 movement very rapid; fresh water. 



A. saltans P. (Fig. 148,/). 18-23)U in diameter; fresh water. 



Genus Lieberkuhnia Claparede et Lachmann. Test ovoidal or 

 spherical, with or without attached foreign particles; aperture 

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

 contractile vacuoles; pseudopodia formed from a long peduncle, 

 reticulate, often enveloping test; fresh or salt water. 



