SPIROTRICHA, HYPOTRICHA 



669 



Genus Tachysoma Stokes {Actinotricha Cohn). Flexible; frontals 

 8-10, of which anterior three are usually the largest; 5 ventrals 

 scattered; 5 anals; marginals at some distance from lateral borders, 

 interrupted posteriorly; fresh or salt water. 



T. parvistyla S. (Fig. 314, e). 10 frontals scattered; about 63^ long; 

 in shallow freshwater pools. 



Fig. 314. a, Oxytrichafallax, X230 (Stein); b, 0. bifaria, Xl80 (Stokes); 

 c, 0. ludibunda, x400 (Stokes); d, 0. setigera, X870 (Stokes); e, Tachj- 

 soma parvistyla, X490 (Stokes); f, Urosoma caudata, X250 (Stokes); 

 g, Amphisiella thiophaga, X380 (Kahl); h, Eschaneustyla brachytona, 

 X240 (Stokes); i, Gonostomum strenuum, Xl60 (Engelmann); '],Hemi- 

 cycliostyla sphagni, XlOO (Stokes); k, 1, Cladotricha koltzowii (k, Xl70; 

 1, X300) (Kahl). 



Genus Urosoma Kowalewski. Similar to Oxytricha; but posterior 

 portion drawn out and much narrowed; fresh water. 



U. caudata (Stokes) (Fig. 314,/). 200-250/i long; pond water. 



