HOLOTRICHA 615 



*S. muscorum Kahl (Fig. 290, j). Cytostome large, with a large 

 membrane; trichocysts; contractile vacuole with a distinct canal; 

 body about 35iu long; in fresh water. 



Genus Cinetochilum Perty. Oval to ellipsoid; highly flattened; 

 ciha on flat ventral surface only; cytostome right of median line in 

 posterior half, with a membrane on both edges which form a 

 pocket; oblique non-ciliated postoral field leads to left posterior end; 

 with 3-4 caudal cilia; macro nucleus spherical, central; contractile 

 vacuole terminal; in fresh or salt water. 



C. margaritaceum P. (Fig. 290, k). 15-45^ long; in fresh and 

 brackish water. 



Genus Dexiotrichides Kahl (Deziotricha Stokes). Reniform; com- 

 pressed; cytostome near middle, with two membranes; long cilia 

 sparse; a special oblique row of cilia; a single caudal cilium; contrac- 

 tile vacuole terminal; spheroidal macro nucleus anterior; a micro- 

 nucleus; in fresh water. One species. 



D. centralis (Stokes) (Fig. 291, a). About 30-45/i long; in decaying 

 vegetable matter. 



Genus Cyrtolophosis Stokes. Ovoid or ellipsoid; with a mucilagi- 

 nous envelope in which it lives, but from which it emerges freely; 

 cytostome near anterior end with a pocket-forming membrane; on 

 right side a short row of special stiff cilia, bent ventrally; sparse 

 ciliation spiral to posterior-left; spherical macro nucleus central; a 

 contractile vacuole; in fresh water. 



C. mucicola S. (Fig. 291, 6). 25-28^ long; in infusion of leaves. 



Genus Urocentrum Nitzsch. Short cocoon-shaped, constricted be- 

 hind the middle; ventral surface flat; 2 broad girdles of cilia; fused 

 cilia at posterior end; with a zone of short cilia in the constricted 

 area; cy to pharynx with a stiff ectoplasmic membrane which sepa- 

 rates 2 undulating membranes (on left) and ciliated zone (on right) ; 

 macro nucleus, horseshoe-shape, posterior; a micro nucleus; contrac- 

 tile vacuole terminal, with 8 long canals which reach the middle of 

 body; in fresh water. 



U. turbo (Miiller) (Fig. 291, c). 50-80^ long. Kidder and Diller 

 (1934) studied its fission. 



Genus Urozona Schewiakoff. Ovoid, both ends broadly rounded; 

 a distinct constriction in the ciliated middle region; ciliary band 

 composed of 5-6 rows of cilia, directed anteriorly and arranged longi- 

 tudinally; cytostome with a membrane; rounded macro nucleus and a 

 micronucleus posterior ; contractie vacuole subterminal ;in freshwater. 



U. butschlii S. (Fig. 291, d). 20-25^ long (Kahl); 30-40^ (Schewi- 

 akoff) ; in stagnant water. 



