702 PROTOZOOLOGY 



highly flattened; anterior end elevated at one side where cytostome 

 and cytopharynx with 10 rods are located. 



Genus Enchelydium Kahl. Somewhat similar to Spathidium; but 

 oral ridge forms a swollen ring with trichocysts; the ridge circular or 

 elongated in cross-section; when swimming, the organisms appear 

 as if cytostome is opened; with dorsal bristle; fresh water. 



E. fusidens K. (Fig. 299, g). Cylindrical, contractile; cilia dense 

 and rather long; macronucleus reniform, often appears as composed 

 of 2 spherical parts; contractile vacuole terminal; oral ring with 

 spindle-like trichocysts; food vacuoles not seen; extended body 110m 

 long; contracted 75m; sapropelic. 



Genus Homalozoon Stokes. Elongate; cilia conspicuous on flat- 

 tened right side; left side swollen or keeled; fresh water. 



H. vermiculare (S.) (Fig. 299, h). Extended body 450-850m long; 

 vermiform; macronucleus band form; contractile vacuoles about 30 

 or more in a row; standing fresh water. 



Genus Cranotheridium Schewiakoff. Spathidium-like organisms; 

 anterior end obliquely truncate, near the extended side of which is 

 located the cytostome; cytopharynx surrounded by a group of 

 trichites; fresh water. 



C. taeniatum S. (Fig. 299, i). Anterior end flattened; with a group 

 of trichites; macronucleus long band-form; with many micro nuclei; 

 contractile vacuole terminal; ciliation and striation close; colorless; 

 movement slow; about 170m long; fresh water. 



Genus Penardiella Kahl. Ellipsoid, somewhat compressed; oral 

 ridge slightly oblique; a girdle with trichocysts encircling the body; 

 fresh water. 



P. crassa (Penard) (Fig. 299, j). Elongate ellipsoid, flattened; tri- 

 chocysts in posterior portion of girdle are longer and those in the 

 dorsal region are fewer in number and shorter; macronucleus sau- 

 sage-form; contractile vacuole posterior, in front of the girdle; body 

 160m by 50m; sapropelic. 



Genus Perispira Stein. Ovoid or cylindrical; oral ridge turns 

 right-spirally down to posterior end. 



P. ovum S. (Fig. 299, k). Oval; starved individuals 30-60m by 20- 

 45m, well-fed forms 65-120m by 50-1 10m; spiral ridge one complete 

 turn; cytostome in the anterior end of the ridge, with a number of 

 delicate trichites; ovoid to elongate macronucleus; a micronucleus; a 

 terminal contractile vacuole; in fresh water (Dewey and Kidder, 

 1940). The ciliate was cultured bacteria-free by feeding on sterile 

 Euglena gracilis. 



P. strephosoma Stokes (Fig. 299, /). Oval to cylindrical; about 85m 

 long; standing water with sphagnum. 



