388 PROTOZOOLOGY 



P. acropodia (Hertwig and Lesser) (Fig. 181, c). Test circular in 

 aperture view; hemispherical in profile; yellowish or brownish, 

 semi-transparent, and covered with sand-grains and scales; in front 

 view sharply pointed pseudopodia radiating; colorless endoplasm 

 usually with chlorophyllous bodies; 30-50/i in diameter. 



Genus Bullinula Penard. Test ellipsoidal, flattened on one face, 

 with silicious plates; on the flattened surface, co -shaped aperture; 

 a single nucleus; pseudopodia digitate or spatulate, simple or 

 branched ; fresh water. 



B. indica P. (Fig. 181, d). Test dark brown; 120-250/1 in diameter. 



Genus Heleopera Leidy. Test variously colored; fundus hemi- 

 spherical, with sand-grains; surface covered with amorphous scales, 

 often overlapping; aperture truncate, narrow, elliptic notched in 

 narrow lateral view; a single nucleus; pseudopodia variable in num- 

 ber, thin digitate or branching; fresh water. Several species. 



H. petricola L. (Fig. 181, e, /). Test variable in size and color, 

 strongly compressed; fundus rough with sand-grains of various 

 sizes; aperture linear or elliptic, convex in front view; pseudopodia 

 slender, branching; 80-100^1 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 dif- 

 ferent sizes; elliptical in cross-section; pseudopodia unobserved; 135- 

 180/1 long; in sphagnum and aquatic plants. 



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

 eign bodies and collar around aperture; filo podia; fresh water. 



N. tenella P. (Fig. 181, g^). 50-55/1 long; fresh water lakes. 



Genus Frenzelina Penard. Two envelopes, outer envelope hemi- 

 spherical, 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; cytoplasm with dia- 

 toms, etc.; a nucleus and a contractile vacuole; fresh water. 



F. reniformis P. (Fig. 181, h). Outer envelope 26-30/t in diameter; 

 fresh water lakes. 



Genus Amphitrema Archer. Test ovoid, symmetrical, compressed; 

 composed of a transparent membrane, with or without adherent 

 foreign bodies; 2 apertures at opposite poles; with zoochlorellae; 

 nucleus central; 1 to several contractile vacuoles; straight filo podia, 

 sparsely branched, radiating; fresh water. Several species. 



A. flavum A. (Fig, 181, i). Test brown, cylindrical with equally 



