490 PROTOZOOLOGY 



posterior; often with zoochlorellae; filo podia branching and man}', 

 generally arising from a protruded portion of cytoplasm; fresh 

 water. 



P. spinosa (Carter) (Fig. 207, b). Margin of test with spines, 

 either singly or in pairs; 116-174/z by 70-100^; in sphagnum. 



Genus Assulina Ehrenberg. Test colorless or brown; ovoid; with 

 elliptical scales, arranged in diagonal rows; aperture oval, terminal 

 bordered by a thin chitinous dentate membrane; nucleus posterior; 

 contractile vacuoles; filo podia divergent, sometimes branching; fresh 

 water. 



A. seminulum (E.) (Fig. 207, c). Body does not fill the test; with 

 numerous food particles; pseudo podia few, straight, divergent, 

 slender, seldom branched; 60-150/x by 50-75^; in sphagnum. 



Genus Nebela Leidy. Test thin, ovate or pyriform; with circular 

 or oval platelets of uniform or various sizes; highly irregular; endo- 

 plasm with oil globules; nucleus posterior; body does not fill the 

 test, and is connected with the latter by many ectoplasmic strands 

 at fundus end; pseudo podia blunt, rarely branched; fresh water. 

 Numerous species. Taxonomy (Jung, 1942a). 



N. collaris (Ehrenberg) (Fig. 207, d). Test pyriform, fundus obtuse 

 in profile; aperture without any notch; endoplasm with chlorophyl- 

 lous food particles; pseudopodia digitate, short, usually 3-6 in num- 

 ber: about 130m by 85-90/*: in marshes among sphagnum. Feeding 

 habit, binary fission and plasmogamy (MacKinlay, 1936). 



Genus Quadrula Schulze. Test pyriform, hemispherical, or dis- 

 coidal; with quadrangular siliceous or calcareous platelets, arranged 

 generally in oblique series, not overlapping; a single nucleus; body 

 and pseudopodia similar to those of Difflugia; fresh water. 



Q. symmetrica (Wallich) (Fig. 207, e). Compressed, smaller plate- 

 lets near aperture; cytoplasm very clear, with chlorophyllous gran- 

 ules; 3-5 pseudopodia digitate; nucleus posterior; 80-140/z by 40- 

 96/*; in sphagnum. 



Genus Sphenoderia Schlumberger. Test globular or oval, some- 

 times slightly compressed; hyaline, membranous, with a short broad 

 neck, and a wide elliptical aperture; scales circular, oval, or hexag- 

 onal, arranged in alternating series; cytoplasm colorless; 1-2 con- 

 tractile vacuoles; filo podia, fine, branching; fresh water. 



S. lenta S. (Fig. 207, /). Hyaline test ovoid or globular; scales cir- 

 cular or broadly oval; aperture terminal, surrounded by a thin chi- 

 tinous collar, one side inclined inwards; nucleus large; cytoplasm 

 colorless; 2 contractile vacuoles; 30-64/* by 20-46/*; aperture 10-22/* 

 in diameter. 



