338 PROTOZOOLOGY 



sizes; aperture linear or elliptic, convex in front view; pseudopo- 

 dia slender, branching; 80-100/i long; in boggy places. 



Genus Averintzia Schouteden. Test similar to that of Heleopera, 

 but small aperture elliptical; test thickened around aperture; 

 fresh water. 



A. cyclostoma (Penard). Test dark violet, with sand-grains of 

 different sizes; elliptical in cross-section; pseudopodia unob- 

 served; 135-180/x long; in sphagnum and other aquatic plants. 



Genus Nadinella Penard. Test chitinous, thin, hyaline, with 

 foreign bodies and collar around aperture; filopodia; fresh water. 



N. tenella P. (Fig. 154, g). 50-55^1 long; fresh water lakes. 



Genus Frenzelina Penard. Two envelopes, outer envelope 

 hemispherical, thin, rigid, covered with siliceous particles; inner 

 envelope round or ovoid, drawn out at aperture, thin, hyaline and 

 covering the body closely; aperture round, through which a part 

 of body with its often branching straight filopods, extends; cyto- 

 plasm with diatoms, etc.; a nucleus and a contractile vacuole; 

 fresh water. 



F. reniformis P. (Fig. 154, h). Outer envelope 26-30/x in diame- 

 ter; fresh water lakes. 



Genus Amphitrema Archer. Test ovoid, symmetrical, com- 

 pressed; composed of a transparent membrane, with or without 

 adherent foreign bodies; 2 apertures at opposite poles; with 

 zoochlorellae; nucleus central; 1-several contractile vacuoles; 

 straight filopodia, sparsely branched, radiating; fresh water. Sev- 

 eral species. 



A.flavum A. (Fig. 154, i). Test brown, cyhndrical with equally 

 rounded ends in front view; elliptical in profile; ovoid with a small 

 central oval aperture in end-view; 45-77/x by 23-4 5m; in sphag- 

 num. 



Genus Pseudodifflugia Schlumberger. Test ovoid, usually rigid, 

 with foreign bodies; circular or elliptical in cross-section; aper- 

 ture terminal; granulated cytoplasm colorless or greyish; nucleus 

 posterior; a contractile vacuole; filopodia long, straight or branch- 

 ing; fresh water. Several species. 



P. gracilis S. (Fig. 154, j). Test yellowish or brownish; sub- 

 spherical, with sand-grains; aperture without neck; 20-65^ long. 



Genus Diaphoropodon Archer. Test ovoid, flexible, with mi- 

 nute foreign bodies and a thick covering of hyaline hair-like pro- 

 jections; pseudopodia long, filose, branching; fresh water. 



