Ciliophora 367 



and biochemical investigations. More than twenty strains of T. pyrijormis, 

 whose history has been traced by Corliss (42c), are being maintained in 

 various laboratories. 



It is not yet certain just how many of the genera in Kahl's (102) Family Frontoniidae 

 should be transferred to the Tetrahymenidae, but the available data suggest the fol- 

 lowing list: Colpidium Stein (102; Figs. 7. 18, K; 20, L), Deltopylum Faure-Fremiet and 

 Mugard (155; Fig. 7. 19, D), Glaucoma Ehrbg. (102, 155; Fig. 7. 20, H), possibly 

 Loxocephalus Eberhard (78, 102; Fig. 7. 19, B), Paraglaucoma Kahl 3 (102, 155; Fig. 7. 

 20, J, K), and Tetrahymena Furgason (42a, 42b, 42c. 69; Figs. 7. 19, C, H; 20, A-G, I). 

 Leucophra Midler ("Leucophrys" Ehrenbcrg) is a genus of very uncertain status, and 

 as suggested by Corliss (42b), probably will become a genus dubium. Accordingly, 

 Corliss (42a) has transferred L. patula, the only remaining species of "Leucophrys," to 

 the genus Tetrahymena. In view of the similarity of this ciliate to T. vorax, this ar- 

 rangement woidd seem to be a sound one imless it can be shown that T. vorax and 

 T. patula are not congeneric with T. pyrijormis. 



Family 4. Hysterodnetidae. These are uniformly and densely ciliated, 

 dorso-ventrally flattened ciliates with a posterior cytostome. The peri- 

 stome may be merely a transverse terminal groove, along which an undu- 

 lating membrane extends into the short pharynx. An anterior non-ciliated 

 "sucker" is characteristic. These ciliates have been reported from the in- 

 testine of certain snails and fresh-water oligochaetes. 



The family includes Hysterocineta Diesing (6; Fig. 7. 21, G-I) and Ptychostomum 

 Stein (84, 181, 199; Fig. 9^ 21, F). 



Family 5. Ophryoglenidae. There is a ciliated vestibule (peristome), an 

 invagination of the body wall, and a pharynx which opens into the ves- 

 tibule. The vestibule is relatively deep in Ophryoglena, less so in Proto- 

 phryoglena, and much reduced in Ichthyophthirius (155). A spiral ridge 

 extends from the opening of the vestibule into the pharynx in Ophryo- 

 glena. According to Mugard (155), a tetrahymenal organization of the 

 oral membranes is characteristic. The membranes curve along the spiral 

 ridge before entering the pharynx in Ophryoglena but follow a less curved 

 path in Protophryoglena and almost a straight course in Ichthyophthirius. 

 In stoma togenesis, the oral membranes are derived from basal granules 

 in a number of stomatogenous rows. A refractile "body of Lieberkiihn" 

 ("watch-glass body"), usually accompanied by a mass of pigment, lies just 

 to the left of the vestibule. 



The life-cycles follow a general pattern (155). Reproduction occurs 

 within a cyst (Fig. 7. 21, A). The young ciliates ("tomites"), after excyst- 

 ment, develop into the trophic stage ("theronte") which, in free-living 

 species, grows into a large slowly swimming stage ("trophonte") with 

 much stored food. This mature stage then encysts in preparation for re- 



^ The status of the genus Paraglaucoma is rather confused at present, since Corliss 

 (1952. Proc. Soc. Protozool. 3: 3) has concluded that Paraglaucoma rostrata (the type 

 species) is congeneric with Tetrahymena pyrijormis. 



