TESTACEA 



385 



typically circular; test composed of angular sand-grains, diatoms; 

 bright green with chlorophyllous bodies; 60-580ju by 40-240^; in 

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

 Several varieties. 



D. urceolata Carter ^Fig. 180, b). A large ovoid, rotund test, with 

 a short neck and a rim around aperture; 200-230/i by 1 50-200/1 ; 

 in ditches, ponds, sphagnous swamps, etc. 



Fig. 180. a, Difflugia oblonga, Xl30 (Cash); b, D. urceolata, Xl30 

 (Leidy); c, d, D. arcula, Xl70 (Leidy); e, D. lohostoma, Xl30 (Leidy); 

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

 h, Campuscus cornutus, Xl70 (Leidy); i, Cucurhitella mespiliformis, 

 X200 (Wailes). 



D. arcula Leidy (Fig. 180, c, d). Test hemispherical, base slightly 

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

 test yellowish with scattered sand-grains or diatoms; diameter 

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



D. lohostoma L. (Fig. 180, 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 

 80-1 20)u; in fresh water. 



D. constrida (Ehrenberg) (Fig. 180, /). Test laterally ovoid, 

 fundus more cr less prclonged 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 



