336 PROTOZOOLOGY 



rounded triangular in cross-section; aperture circular, oblique, 

 with a thin transparent discoid collar; nucleus large; 1 or more 

 contractile vacuoles; body does not fill the test; fresh water. 



C. cornutus L. (Fig. 153, h). Test pale-yellow, retort-form; with 

 a covering of small sand particles; triangular in cross-section; a 

 single nucleus and contractile vacuole; filopodia straight; 110- 

 140m long; aperture 24-28m in diameter; in the ooze of mountain 

 lakes. 



Genus Cucurbitella Penard. Test ovoid with sand grains, not 

 compressed; aperture terminal, circular, surrounded by a 4-lobed 

 annular collar; cytoplasm grayish, with zoochlorellae; nucleus 

 large; 1 to many contractile vacuoles; pseudopodia numerous, 

 digitate; fresh water. 



C. mespiliformis P. (Fig. 153, i). 115-140/1 long; diameter 80- 

 105yu; in the ooze or on vegetation in ponds and ditches. 



Genus Plagiopyxis Penard. Test subcircular in front view; 

 ovoid in profile; aperture linear or lunate; cytoplasm gray, with 

 a single nucleus and a contractile vacuole; fresh water. 



P. callida P. (Fig. 154, a). Test gray, yellowish, or brown; large 

 nucleus vesicular; pseudopodia numerous, radiating, short, 

 pointed or palmate; diameter 55-135/z; in vegetation. 



Genus Pontigulasia Rhumbler. Test similar to that of Difflugia, 

 but with a constriction of neck and internally a diaphragm made 

 of the same substances as those of the test. 



P. vas (Leidy) (Fig. 154, b). Round or ovoid test; constriction 

 deep and well-marked; with sand-grains and other particles; 

 aperture terminal; 125-170/i long; fresh water ponds. 



Genus Phryganella Penard. Test spheroidal or ovoid, with 

 sand-grains and minute diatom shells; aperture terminal, round; 

 pseudopodia drawn out to a point; fresh water. 



P. acropodia (Hertwig et Lesser) (Fig. 154, 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 en- 

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



Genus BuUinula 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. 



BandicaF. (Fig. 154, d). Test dark brown; 120-250/t in diameter. 



