800 PROTOZOOLOGY 



Other domestic and wild animals harbor various species of Bal- 

 antidium. 



B. duodeni Stein (Fig. 340, d). 70-80/x by 55-60^; in the intestine of 

 the frog. 



B. praenucleatum Kudo and Meglitsch (Fig. 340, e). 42-127ju long, 

 32-102/x thick, 25-80ju wide; macronucleus close to anterior end; in 

 the colon of Blatta orientalis (Kudo and Meglitsch, 1938). 



Family 2 Metopidae Kahl 



Genus Metopus Claparede and Lachmann. Body form changeable; 

 when extended oblong or fusiform; peristome conspicuous, slightly 

 spirally diagonal, beginning at the anterior end and reaching the 

 middle of body; when contracted, peristome much spirally coiled; 

 cytopharynx short; body ciliation uniform, longitudinal or in some, 

 spiral; longer cilia at ends; conspicuous contractile vacuole terminal; 

 macronucleus ovoid to elongate; fresh or salt water (sapropelic), 

 some parasitic. Numerous species. 



M. es Muller (M. sigmoides C. and L.) (Figs. 87; 342, a). 120-200^ 

 long; sapropelic. Noland's (1927) study on its conjugation has been 

 described (p. 161). 



M. striatus McMurrich (Fig. 342, b). 80-120/x long; fresh water. 



M. fuscus Kahl (Fig. 342, c). 180-300m long by 60/x wide and 40ju 

 thick ; fresh water. 



M. circumlabens Biggar (Fig. 342, d). 70-165ju by 50-75/x; in the 

 digestive tract of sea urchins, Diadema setosum and Echinometris 

 subangularis in Bermuda (Biggar, 1932; Lucas, 1934); in Centrechi- 

 nus antillarum, etc., in Tortugas (Powers, 1935); in Diadema setosum 

 and Echinometra oblonga in Japan (Uyemura, 1933). 



Genus Spirorhynchus da Cunha. Fusiform; somewhat flattened; 

 anterior end drawn out and curved toward left; posterior end also 

 drawn out; spiral peristome; cytopharynx small with an undulating 

 membrane; cilia uniformly long; contractile vacuole posterior; longi- 

 tudinally striated; body surface with closely adhering bacteria 

 (Kirby); three spherical macronuclei; micronucleus (?); in brackish 

 water (da Cunha, 1915). 



S. verrucosus da C. (Fig. 342, e). 122-140^ by 20-22^. Kirby (1934) 

 observed it in salt marsh with 3 per cent salinity; California. 



Genus Caenomorpha Perty (Gyrocoris Stein). Bell-shaped; car- 

 apaced ectoplasm in some species bears protricho cysts; strong mar- 

 ginal zone of about 8 rows of cilia; 1-2 dorsal rows of longer cilia 

 and a dense spiral field around caudal prolongation; peristome long; 

 cytostome posterior; cytopharynx directed anteriorly; a single 



