CILIATA 



155 



Bursaria ; the cell is a half ellipse, something like a common twin 

 tobacco-pouch when closed : a deep depression thus occupies the 

 whole ventral surface, and opens by a wide slit extending along 

 the anterior end. The peristomial area occupies the dorsal side 

 of the pocket so formed, and the mouth is in the hinder left- 

 hand corner. Blepharisma sp. is parasitic in the Heliozoon 

 Baphidiophrys viridis (Fig. 20, 1, p. 74). 



Among Oligotrichaceae, Halteria, common among the debris 

 at the bottom of pools in woods containing dead leaves, is 

 remarkable for an equatorial girdle of very long fine setae, and 



Fig. 58. Caenomorpha uniserialis. crh, Zone of cirrhi ; c.t, cilia of tail ; c.v, contractile 

 vacuole ; c.w, ciliary wreath ; g, granular aggregate ; m, zone of membranellae ; 

 JY, meganucleus ; n, micronucleus ; oe, pharynx ; t, tail-spine ; t 1 , accessory 

 spine; u.m, undulating membrane ; v, vacuole; z, precaudal process. (After 

 Levander.) 



for its rapid erratic darting movements, alternating with a 

 graceful bird-like hover. The Tintinnidae are mostly marine, 

 pelagic, with the general look of a stalkless Vorticella ; some 

 have a latticed chitinous shell. 1 



Among Peritrichaceae, Vorticella (Fig. 60) and its allies have 

 long been known as Bell- animalcules to every student of pond-life. 

 The body has indeed the form of an inverted bell, closed at its 

 mouth by the " peristome," or oral disc ; this is a short, inverted 



1 Torquatella typica, described by Lankester as possessing a continuous undu- 

 lating membrane for its peristomial wreath, is identified by Biitschli as a Strom- 

 bidium, possessing exceptionally large membranellae. 





