762 PROTOZOOLOGY 



on right and 3 membranellae on left; ectoplasmic ridge on right bor- 

 der of mouth; ciliation uniform; 30-40 ciliary meridians; 7 postoral 

 meridians; macro nucleus rounded; a micro nucleus; a contractile 

 vacuole; with or without 1 or more caudal bristles; fresh water. 



G. scintillans E. (Fig. 324, g, h). Ovate with rounded ends; 45-75 ix 

 long; U-shaped cytostome, about one-fourth the body length, ob- 

 lique; ectoplasmic flange and 3 membranellae conspicuous; a con- 

 tractile vacuole in posterior one-third; macronucleus oval, central; 

 a micronucleus ; bacteria-feeder; in fresh water. Bacteria-free culture 

 (Kidder, 1941); division (Kidder and Diller, 1934) 



Genus Colpidium Stein. Elongate reniform; ciliary meridians 

 variable in number, but typically one postoral meridian; small tri- 

 angular cytostome one-fourth from anterior end toward right side; 

 a small ectoplasmic flange along right border of cytostome which 

 shows an undulating membrane on right and 3 membranellae on left; 

 rounded macronucleus; a micronucleus; a contractile vacuole; fresh 

 or salt water or parasitic. 



C. colpoda (Ehrenberg) (Tillina helia Stokes) (Figs. 10, c; 324, 

 i, j). Elongate reniform; 90-1 50m long; cytostome about one- 

 tenth the body length ; 55-60 ciliary meridians; preoral suture curved 

 to left; macronucleus oval, central; a micronucleus; fresh water. 

 Bacteria-free culture (Kidder, 1941); division (Kidder and Diller, 

 1934); effect of food bacteria on division (Burbank, 1942). 



C. campylum (Stokes) (Fig. 324, k). Elongate reniform; 27-30 

 ciliary meridians; preoral suture curved to right; 50-70 m long; in 

 fresh and brackish water. Division (Kidder and Diller, 1934). 



C. striatum S. Similar to the last species; contractile vacuole 

 further posterior; 50^ long; in standing water. 



C. echini (Russo) (Fig. 324, I) . In the intestinal caeca of Strongylo- 

 centrotus lividus; 37-64(55)/* by 21-28(25)/*; 24 longitudinal ciliary 

 rows; cytostome at anterior third (Powers, 1933). 



Genus Paraglaucoma Kahl. Somewhat similar to Glaucoma; but 

 without perioral ectoplasmic ridge; a membrane on right ridge of 

 the cytostome; anterior end drawn out to a point in profile, posterior 

 end rounded; a stiff posterior bristle; a contractile vacuole; rapid 

 zig-zag movement. One species. 



P. rostrata K. (Fig. 324, m). 60-80ix long; in fresh water (often in 

 dead rotiferan body); California, Wisconsin (Kahl). 



Genus Malacophrys Kahl. Ellipsoid or cylindrical; plastic; cilia 

 uniformly close-set in longitudinal rows; slit-like cytostome at an- 

 terior extremity ; in fresh water. 



M. rotans K. (Fig. 324, n). Oval; close and dense ciliation; spheri- 



