Chapter 38 

 Order 2 Spirotricha Butschli 



With free cilia only; exceptionally with small groups of cirrus-like pro- 

 jections in addition to cilia 

 Uniformly ciliated; in Peritromidae dorsal surface without or with a 

 few cilia; in Licnophoridae cilia only on edge of attaching disk; 



peristome usually extended; peristomal field mostly ciliated 



Suborder 1 Heterotricha 



Ciliation much reduced or none at all 



Rounded in cross-section; cilia usually much reduced; adoral zone 



encloses a non-ciliated peristomal field in spiral form 



Suborder 2 Oligotricha (p. 652) 



Compressed; carapaced; peristomal zone reduced to 8 membranellae 



which lie in an oval hollow. .Suborder 3 Ctenostomata (p. 665) 



Cirri only, on ventral side; dorsal side usually with rows of short bristles . . 



Suborder 4 Hypotricha (p. 668) 



Suborder 1 Heterotricha Stein 



Body ciliation complete and uniformly the same 



Peristome sunk in a funnel-like hollow at anterior end, thus mostly 



covered Family 1 Bursariidae (p. 637) 



Peristome lies almost completely free, leading to a short and narrow 



oral funnel (absent in one family) 

 Peristome in anterior region 



A narrow non-ciliated zone on right of adoral zone; usually an 



undulating membrane or ciliary row to right of this non-ciliated 



zone and anterior to cytostome; a small peristomal field between 



the membrane and adoral zone 



Adoral zone extends diagonally to posterior-right on ventral 



surface; highly developed forms, with a long zone twisting 



spirally around body Family 2 Metopidae (p. 640) 



Adoral zone parallel to body axis on flat ventral surface, turns 

 somewhat to right in front of cytostome; oral funnel dis- 

 tinct; typically an undulating membrane or a double ciliated 



furrow in front of cytostome 



Family 3 Spirostomidae (p. 641) 



Without the non-ciliated zone; a large peristomal field with a half 

 or completely spiral adoral zone 

 Peristomal field not ciliated; with a large undulating membrane 



on its right edge Family 4 Condylostomidae (p. 645) 



Peristomal field ciliated; without undulating membrane 



Peristomal field not drawn out in 2 wings; free-swimming or 



secretes gelatinous lorica 



Family 5 Stentoridae (p. 645) 



Peristomal field drawn out into 2 wings; with flask-shaped, thin 

 pseudochitinuous lorica .. Family 6 Folliculinidae (p. 647) 



636 



