HOLOTRICHA 613 



Genus Cryptochilidium Schouteden. Ellipsoid; with rounded an- 

 terior end, posterior end pointed in profile; highly compressed; uni- 

 form and close ciliation; cytostome near middle; one or more longer 

 cilia at posterior end; contractile vacuole posterior; macronucleus 

 round; a micro nucleus; commensal. 



C. echini (Maupas) (Fig. 290, b). 70-140m long; in the gut of Echi- 

 nus lividus. 



Genus Eurychilum Andre. Elongate ellipsoid; anterior end some- 

 what narrowed; cilia short; dense ciliation not in rows; contractile 

 vacuole terminal; macronucleus band-form; cytostome about 2/5 

 from anterior end and toward right, with a strong undulating mem- 

 brane on left; no cytopharynx; actively swimming. One species. 



E. actiniae A. (Fig. 290, c). About 155^ long; in gastro vascular 

 cavity of Sagartia parasitica. 



Genus Monochilum Schewiakoff. Ovoid to ellipsoid; medium 

 large; uniform and dense ciliation in rows; oblong cytostome left of 

 median line, in about 1/4 the body length from anterior end; short 

 cytopharynx conical, with an undulating membrane; contractile 

 vacuole near middle; in fresh water. 



M. frontatum S. (Fig. 290, d). Anterior end broader; ventrally 

 flattened, dorsally somewhat convex; macronucleus ellipsoid; a 

 micro nucleus ; feeds on algae; 80m by 30/x. 



Genus Dichilum Schewiakoff. Similar to Monochilum; but mem- 

 brane on both edges of the cytostome; in fresh or salt water. 



D. cuneiforme S. (Fig. 290, e). Ellipsoid; cytostome about 1/5 the 

 body length from anterior end; right membrane larger than left; 

 small cytopharynx; macronucleus ellipsoid; about 40^ by 24/i; in 

 fresh water. 



Genus Loxocephalus Eberhard. Ovoid to cyhndrical; sometimes 

 compressed; crescentic cytostome on slightly flattened area near 

 anterior end, with 2 membranes; often a zone of cilia around body; 

 usually 1 (or more) long caudal cilium; endoplasm granulated, yel- 

 lowish to dark brown; macronucleus ovoid; a single contractile 

 vacuole; in fresh or brackish water. Many species. 



L. plagius (Stokes) (Fig. 290, /). 50-65m long; nearly cylindrical; 

 15-16 ciliary rows; endoplasm usually darkly colored; in fresh water 

 among decaying vegetation. 



Genus Balanonema Kahl. Similar to Loxocephalus; but with plug- 

 like ends; cytostome diflftcult to see; a caudal cilium; macronucleus 

 oval; contractile-vacuole; ciliation uniform or broken in the middle 

 zone ; fresh water. 



B. biceps (Penard) (Fig. 290. g). Ellipsoid; no cilia in the middle 



