Chapter 34 



Order 1 Holotricha Stein (continued) 



Suborder 4 Hymenostomata Hickson 

 Cytostome not connected with peristome. 



.Family 1 Frontoniidae 

 Cytostome at end or bottom of peristome 



Peristome sickle-form, ciliated slit; sunk at right angles to body sur- 

 face Family 2 Ophryoglenidae (p. 555) 



Peristome long, begins at anterior end of body 



Peristome with a one-layered membrane which forms a pocket 

 surrounding cytostome on right edge and a row of cilia or 



membrane on left Family 3 Pleuronematidae (p. 555) 



Peristome otherwise 



Peristome with 2 one-layered membranes; no distinct ecto- 



plasmic pocket around cytostome 



Family 4 Cohnilembidae (p. 558) 



Peristome furrow either covered densely with cilia, besides an 

 undulating membrane on right edge, or with only a thick 



undulating membrane on the right edge 



Family 5 Philasteridae (p. 559) 



Family 1 Frontoniidae Kahl 



Genus Frontonia Ehrenberg. Ovoid to ellipsoid; anterior end 

 more broadly rounded than posterior end; flattened; oral groove 

 lies in anterior third on more or less flattened ventral surface, to 

 right of median line; lancet-like with pointed anterior and trun- 

 cate posterior end; left edge more curved than right edge, and 

 posteriorly becomes a prominent ectoplasmic lip ; cytostome with 

 a complex organization (on left edge a large undulating mem- 

 brane composed of 3 layers, each being made up of 4 rows of cilia; 

 on right, semi-membranous groups of cilia; 3 outer rows of cilia 

 form the postoral suture; along this suture ectoplasm is discon- 

 tinuous so that large food matter is taken in; wdth a small triangu- 

 lar ciliated field posterior to cytostome and left of suture); 

 cytopharynx with numerous strong fibrils; ciliary rows close and 

 uniform; ectoplasm with numerous fusiform trichocysts; macro- 

 nucleus oval; 1 to many micronuclei; 1-2 contractile vacuoles, 

 with collecting canals and an external pore; fresh or salt water. 

 Many species. 



547 



