740 PROTOZOOLOGY 



usually located in the anterior half of body; round cytostome near 

 anterior end with a small cytopharynx; spherical macro nucleus cen- 

 tral with a small micronucleus; one contractile vacuole; active swim- 

 mer; fresh or salt water. 



T. compressum L. (Fig. 314, i). About 65/i by 35/t; Lackey found it 

 in Imhoff tank; fresh and salt water (Kahl). Klein (1930) studied its 

 silverline system. 



Family 4 Spirozonidae Kahl 



Genus Spirozona Kahl. Short spindle-form; anterior end truncate, 

 posterior region drawn out to a rounded end, with a group of longer 

 cilia; spiral ciliation; beginning near right posterior third the central 

 ciliary row runs over ridge to left and then reaches the cytostome; 

 other rows are parallel to it; cytostome in anterior 1/4, with cyto- 

 pharynx; ellipsoid macro nucleus nearly central; contractile vacuole 

 terminal; fresh water, sapropelic. 



S. caudata K. (Fig. 314, j). 80-100/* long. 



Family 5 Trichospiridae Kahl 



Genus Trichospira Roux. Body cylindrical; posterior end rounded, 

 anterior end conical in profile, where the cytostome surrounded by 2 

 spiral rows of cilia, is located; a special ciliary band beginning in the 

 cytostomal region runs down on ventral side, turns spirally to left 

 and circles partially posterior region of body; ciliary rows parallel to 

 it; macro nucleus oval, with a micronucleus; contractile vacuole pos- 

 terior; fresh water, sapropelic. 



T. inversa (Claparede and Lachmann) (Fig. 314, k). 70-100/z long. 



Family 6 Plagiopylidae Schewiakoff 



Genus Plagiopyla Stein. Peristome a broad ventrally opened groove 

 from which body ciliation begins; peristomal cilia short, except a 

 zone of longer cilia at anterior end; cytostome near median line at the 

 end of the peristome; cytopharynx long; a peculiar 'stripe band' lo- 

 cated on dorsal surface has usually its origin in the peristomal 

 groove, after taking an anterior course for a short distance, curves 

 back and runs down posteriorly near right edge and terminates about 

 1/3 the body length from posterior end; macro nucleus rounded; a 

 micronucleus; contractile vacuole terminal; free-living or endozoic. 



P. nasuta S. (Fig. 315, a). Ovoid; tapering anteriorly; peristome at 

 right angles or slightly oblique to the edge; trichocysts at right an- 

 gles to body surface; macro nucleus round to irregular in shape; body 

 about 100/x (80-180/*) long; sapropelic in brackish water. Lynch 



