236 HANDBOOK OF PROTOZOOLOGY 



aperture terminal, of various shape. Granulated cytoplasm 

 does not fill the test. A single nucleus, large; one or two con- 

 tractile vacuoles. Length 60 to 120 microns; projections 8 to 

 10 microns long. Among aquatic plants. 



Genus Clypeolina Penard. Test ovoid, compressed, formed 

 of a double envelope; the outer envelope is composed of two 

 valves with scales and particles; the inner envelope a mem- 

 branous sac. Filopodia long, often branched. 



Clypeolina marginata Penard (Fig. 94, d). The outer test- 

 valves yellow to dark brown; lenticular in cross-section. Aper- 

 ture terminal, wide. The endoplasm contains numerous small 

 globules. A single nucleus; a contractile vacuole. Length 80 

 to 150 microns. Among aquatic plants in ponds and marshes. 



Family 3 Difflugiidae Taranek 



Genus Difflugia Leclerc. Test variable in shape, but 

 generally circular in cross-section; composed of cemented 

 quartz-sand, diatoms and other foreign bodies. Aperture 

 terminal. Often with Zoochlorellae. The cytoplasmic body 

 almost fills the test. A single nucleus and numerous contractile 

 vacuoles. Pseudopodia several, cylindrical, simple or branching; 

 end rounded or pointed. Numerous species occur in fresh 

 water, peat, woodland soil and meadows. 



Difflugia oblonga Ehrenberg { = D. pyriformis Perty) (Fig. 

 95, a). Test pyriform, flask-shaped, or ovoid; neck variable in 

 length. Fundus rounded with occasionally one to three conical 

 processes. Aperture terminal, typically circular. Test composed 

 of angular sand-grains and diatoms. The cytoplasm contains 

 chlorophyllous bodies and is therefore bright green in color. 

 Length 100 to 300 microns, width 50 to 100 microns. In the 

 ooze of freshwater ponds, ditches and bogs. Also in moist soil. 

 Several varieties. 



Difflugia urceolata Carter (Fig. 95, 6). A large ovoid, rotund 

 test, with a short neck and a rim around the aperture. Length 

 200 to 230 microns, breadth 150 to 200 microns. In ditches, 

 ponds, sphagnous swamps, etc. 



Difflugia arcula Leidy (Fig. 95, c). Test hemispherical, 

 base slightly concave, but not invaginated; aperture triangular, 

 central, trilobed. Test yellowish with scattered sand-grains 



