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HANDBOOK OF PROTOZOOLOGY 



Trinema enchelys (Ehrenberg) (Fig. 96, /). One or two 

 contractile vacuoles ; pseudopodia attenuate, radiating and long. 

 Length 30 to 100 microns, breadth 15 to 60 microns. In mosses 

 and other vegetation. 



Genus Cor3rthion Taranek. Test small, hyaline, composed 

 of small oval silicious plates; compressed; elliptical in optical 

 cross-section. Aperture subterminal, ventral or oblique; circular 

 or oval. Numerous filopodia. 



Fig. 97 a. Corythion pulchellum. X350 (After Wailes). 



b. Placocista spinosa. X200 (After Wailes). 



c. Assulina seminulum. X400 (After Wailes). 



d. Nebela collaris. X200 (After Cash). 



e. Quadrula symmetrica. X200 (After Cash). 



Corythion pulchellum Penard (Fig. 97, a). Aperture lenticu- 

 lar, cytoplasm colorless. Contractile vacuoles 2 to 3. 25 to 35 

 microns long by 15 to 20 microns broad. In mosses. 



Genus Placocista Leidy. Test ovoid, hyaline, compressed; 

 lenticular in optical cross-section, with oval or subcircular 

 silicious scales. Aperture wide, linear, with flexible undulate 

 borders. A large nucleus posterior. Often with Zoochlorellae. 

 Pseudopodia filose, branching and numerous, generally arising 

 from a protruded portion of the cytoplasm. 



Placocista spinosa (Carter) (Fig. 97, b). Margin of the 

 test with spines, either single or in pairs. Two contractile 



