36 INTRODUCTION TO THE PROTOZOA 



extend from a row of papillae along left rim of peristome, 

 and an adoral cilium arises from each papilla. 



Cyathodinium 



Family ISOTRICHIDAE 



Mouth terminal or subterminal. Pharynx ciliated, with 

 longitudinal striations in its wall. Somatic ciliation com- 

 plete and practically uniform. 



Dasytriclia 

 Isotricha 



Family PARAISOTRICHIDAE 



Mouth subterminal, opening just posterior to concretion 

 vacuole. Somatic ciliation complete, with an anterior tuft 

 of longer cilia. 



Paraisotricha 



Family BALANTIDIIDAE 



Somatic ciliation complete, with cilia arranged in approx- 

 imately longitudinal rows. Peristome a pouch with a tri- 

 angular opening, thru which the short adoral band of mem- 

 branelles is not easily seen from the outside. Numerous 

 long fibrils extend into the endoplasm from the basal gran- 

 ules of cilia and membranelles. Concretion vacuole absent. 



Balantidium 



Order HYMENOSTOMORIDA 



Adoral cilia fused in membranes, the number, size and arrangement 

 of which vary in different genera. 



Family OPHRYOGLENIDAE 



With a ciliated vestibule (peristome), an invagination of the 

 body wall, and a pharynx which opens into the vestibule. A 

 retractile body ("body of Lieberkiihn", "watch-glass body") 

 lies just to the left of the vestibule. Reproduction takes 

 place within a cyst. The resultant young ciliates (tomites) 

 leave the cyst, develop into trophic therontes and then into 

 large trophonts which encyst. 



Ichthyophthirius 



