392 



PROTOZOOLOGY 



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, 183, e). Compressed, smaller plate- 

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

 ules; 3-5 pseudopodia digitate; nucleus posterior; 80-140^1 by 40- 

 96/i; in sphagnum. 



Fig. 183. a, Trinema enchelys, X330 (Wailes); b, Placocista spinosa, 

 X200 (Wailes); c, Assulina seminulum, X400 (Wailes); d, Nebela collaris, 

 X200 (Cash); e, Quadrula symmetrica, X200 (Cash); f, Sphenoderia 

 lenta, X330 (Leidy). 



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. 183, /). 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/x by 20^6/i; aperture 10-22/x 

 in diameter. 



References 



Cash, J. 1905, 1909 The British freshwater Rhizopoda and Heliozoa. 

 Vols. 1, 2. 



and G. H. Wailes 1915, 1918 The British freshwater Rhizo- 

 poda and Heliozoa. Vols. 3, 4. 



