HOLOTRICHA 765 



cytostome more or less toward right side, with 2 outer membranes; 

 ciliary furrows horseshoe-shaped; in fresh or salt water. 



P. sociale (Penard) (Fig. 325, h). Anterior hall more flattened; 

 ventral side concave; cytostome in the anterior third; yellowish and 

 granulated; 30-50/x long; sapropelic in fresh and brackish water. 



Genus Saprophilus Stokes. Ovoid or pyriform; compressed, cy- 

 tostome in anterior 1/4-1/3 near right edge, with two membranes; 

 macro nucleus spherical; contractile vacuole posterior; in fresh water. 



S. agitatus S. (Fig. 325, i). Ellipsoid; ends bluntly pointed; com- 

 pressed; plastic; close striation; about 4G> long; in fresh water in 

 decomposing animal matter such as Gammarus. 



S. muscorum Kahl (Fig. 325, j). Cytostome large, with a large 

 membrane; trichocysts; contractile vacuole with a distinct canal; 

 body about 35ju long; in fresh water. 



Genus Cinetochilum Perty. Oval to ellipsoid; highly flattened; 

 cilia 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 3^1 caudal cilia; macro nucleus spherical, central; contractile 

 vacuole terminal; in fresh or salt water. Neuroneme system (Gelei, 

 1940). 



C. margaritaceum P. (Fig. 325, k). 15-45/x long; in fresh and 

 brackish water. 



Genus Dexiotrichides Kahl (Dexiotricha 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. 326, 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. 326, b). 25-28m long; in infusion of leaves. 



Genus Urocentrum Nitzsch. Short cocoon-shaped, constricted 

 in 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; cytopharynx with a stiff ectoplasmic membrane which sepa- 

 rates two undulating membranes; macronucleus horseshoe-shaped, 



