TESTACEA 



483 



the ooze of fresh water ponds, ditches and bogs; also in moist soil. 

 Several varieties. 



D. urceolata Carter (Fig. 204, b). A large ovoid, rotund test, with 

 a short neck and a rim around aperture; 200-230^ by 150-200^: 

 in ditches, ponds, sphagnous swamps, etc. 



Fig. 204. a, Difflugia oblonga, X130 (Cash); b, D. urceolata, X130 

 (Leidy); c, d, D. arcula, X170 (Leidy); e, D. lobostoma, X130 (Leidy); 

 f, D. constricta, X200 (Cash); g, Centropyxis aculeata, X200 (Cash); 

 h, Campuscus cornutus, X170 (Leidy); i, Cucurbitella mespiliformis, 

 X200 (Wailes). 



D. arcula Leidy (Fig. 204, c, d). Test hemispherical, base slightly 

 concave, but not invaginated ; aperture triangular, central, trilobed ; 

 test yellowish with scattered sand-grains or diatoms; diameter 

 100-140ju; in sphagnous swamp, moss, soil, etc. 



D. lobostoma L. (Fig. 204, e). Test ovoid to subspherical; aperture 

 terminal; with 3-6 lobes; test usually composed of sand-grains, 

 rarely with diatoms; endoplasm colorless or greenish; diameter 

 80-120ju; in fresh water. Sexual fusion and life cycle (Goette, 1916). 



D. constricta (Ehrenberg) (Fig. 204, /). Test laterally ovoid, 

 fundus more or less prolonged obliquely upward, rounded, and sim- 

 ple or provided with spines; soil forms generally spineless; aperture 

 antero -inferior, large, circular or oval and its edge inverted; test 

 composed of quartz grains; colorless to brown; cytoplasm colorless; 

 80-340/1 long; in the ooze of ponds and in soil. 



