362 PROTOZOOLOGY 



S. fockei G. (Fig. 164, /). Diameter about 30ju; often colonial; 

 in swamps. 



Family 5 Heterophryidae Poche 



Genus Heterophrys Archer. Spherical; mucilaginous envelope 

 thick, with numerous radial, chitinous spicules which project 

 beyond periphery; nucleus eccentric; axial filaments originate in 

 a central granule; fresh or salt water. 



H. myriopoda A. (Fig. 164, g). Nucleus eccentric; cytoplasm 

 loaded with spherical algae, living probably as symbionts; con- 

 tractile vacuoles indistinct; 50-80^ in diameter; in pools and 

 marshes; and also among marine algae. 



H. glahrescens Penard. Spherical; gelatinous envelope poorly 

 developed; chitinous needles indistinct; pseudopodia very long; 

 11-15m in diameter; fresh water. 



Family 6 Clathrellidae Poche 



Genus Clathrella Penard. Envelope distinct, polygonal; surface 

 with uniform alveoli with interalveolar portion extending out; 

 envelope appears to be continuous, but in reality formed by a 

 series of cup-like bodies; contractile vacuole large; voluminous 

 nucleus eccentric; filopodia straight, rarely bifurcated, arising 

 between "cups." 



C. foreli P. (Fig. 165, a). Envelope about 40-55/x in diameter; 

 fresh water. 



Family 7 Acanthocystidae Glaus 



Genus Acanthocystis Carter. Spherical; siliceous scales, ar- 

 ranged tangentially and radiating siliceous spines with pointed 

 or bifurcated ends; nucleus and endoplasm eccentric; a distinct 

 central granule in which the axial filaments originate. Several 

 species. 



A. aculeata Hertwig et Lesser (Fig. 165, b). Tangential scales 

 stout and pointed; spines curved and nail-headed; cytoplasm 

 greyish; a single contractile vacuole; diameter 35-40^; spines 

 about 1/3 the body diameter; in fresh water. 



Genus Pompholyxophrys Archer. Spherical; outer mucilaginous 

 envelope with minute colorless spherical granules arranged in 

 concentric layers; nucleus eccentric; contractile vacuoles; pseudo- 

 podia long, straight, acicular; fresh water. 



P. punicea A. (Fig. 165, c). Body colorless or reddish, with 



