534 PROTOZOOLOGY 



with a small tooth on left margin; no cytopharynx; macronucleus 

 spherical; 2 contractile vacuoles; in fresh water. Many species. 

 M. simulans Kahl (Fig. 243, h). 30-35^1 long; decaying plant 

 infusion, also in moss. 



Family 3 Trimyemidae Kahl 



Genus Trimyema Lackey {Sciadostoma Kahl). Ovoid, more or 

 less flattened; anterior end bluntly pointed, posterior end similar 

 or rounded; with a long caudal cilium; cilia on 3-4 spiral rows 

 which are usually located in the anterior half of body; round cyto- 

 stome near anterior end with a small cytopharynx; spherical 

 macronucleus central with a small micronucleus ; one contractile 

 vacuole; active swimmer; fresh or salt water. 



T. compressum L. (Fig. 243, i). About 65/x by 35/i; 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 trun- 

 cate, posterior region drawn out to a rounded end, with a group 

 of longer cilia; spiral ciliation; beginning at right posterior end 

 the central ciliary row runs over ridge to left and then reaches the 

 cytostome; other rows are parallel to the above; cytostome in 

 anterior 1/4, with cytopharynx; ellipsoid macronucleus nearly 

 central; contractile vacuole terminal; fresh water, sapropelic. 



S. caudata K. (Fig. 243, j). 80-100m long. 



Family 5 Trichospiridae Kahl 



Genus Trichospira Roux. Body cylindrical; posterior end 

 rounded, anterior end conical in profile, where the cytostome sur- 

 rounded by 2 spiral rows of ciUa, 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; macronucleus oval, with a micronucleus; 

 contractile vacuole posterior; fresh water, sapropelic. 



T. inversa (Claparede et Lachmann) (Fig. 243, k). 70-100^ 

 long. 



Family 6 Plagiopylidae Schewiakoff 



Genus Plagiopyla Stein. Peristome a broad ventrally opened 

 groove from which body ciliation begins; peristomal cilia short, 



