SPIROTRICHA, HETEROTRICHA 



641 



C. medusula P. (Fig. 302, /). 150^ by 130m; fresh and brackish 

 water. Several varieties. 



Fig. 302. a, Metopvs es, X260 (Kahl); b, M. striatus, X220 (Kahl); 

 c, M.fuscus, Xl50 (Kahl); d, M. circumlabens, x370 (Powers^; e, Spiro- 

 rhynchus verrucostis, X360 (Kirby); f, Caenomorpha medusula, X200 

 (Blochmann); g, Blepharisma lateritium, Xl60 (Penard); h, B. persici- 

 num, X290 (Penard); i, B. steini, X340 (Penard); j, Protocrxizia piger- 

 rinia, X390 (Faria, da Cunha and Pinto); k, Phacodinium vietschnicoffi,, 

 X270 (Kahl). 



Family 3 Spirostomidae Kent. 



Genus Spirostomum Ehrenberg. Elongated; cylindrical; some- 

 what compressed; ectoplasm with highly developed mj^onemes which 

 are arranged lengthwise independent of ciliary rows, hence highly 

 contractile; yellowish to brown; excretory vacuole terminal large, 

 with a long dorsal canal; macro nucleus either ovoid or chain form; 

 cilia short; rows longitudinal; caudal cilia are thigmotactic, secrete 



