388 Ciliophora 



Only two genera have been assigned to the family: Pediostomum Kahl (104) and 

 Peritromus Stein (104, 214; Fig. 7. 31, D, E). 



Family 10. Plagiotomidae. This group includes parasites of oligochaetes 

 and other invertebrates and various vertebrates. The body is densely 

 ciliated, the band of membranelles (Fig. 7. 32, A, B, L, M) is well de- 

 veloped, and an undulating membrane lies at the right margin of the 

 peristome (Fig. 7. 32, L). A ciliated cytoproct has been described in 

 Nyctotherus (Fig. 7. 32, C). 



Three genera have been referred to the family. Nyctotherus Leidy (75, 81, 179, 214; 

 Fig. 7. 32, A-C, F-H, L, M) is represented by intestinal parasites of vertebrates and 

 invertebrates. Paranyctotherus Sandon (187; Fig. 7. 32, I-K), erected for a ciliate from 

 a South African clawed toad, is similar to Nyctotherus but shows a row of mem- 

 branelles along the right margin of the peristome. Plagiotoma Dujardin (84, 166; Fig. 

 7. 31, F) includes parasites of coelomic cavities in earthworms. 



Family 11. Reichenowellidae. This family was erected by Kahl (104) for 

 Reichenowella Kahl (Fig. 7. 32, E) and Balantidioides Penard (Fig. 7. 32, 

 D). These ciliates are said to differ from other Heterotrichina in the pres- 

 ence of a slit-like mouth, usually closed and not easily detected, and in the 

 lack of a definite oral pit. A band of membranelles is present, but no 

 undulating membrane. 



Family 12. Spirostomidae. Some of these are elongated, with more or 

 less contractile bodies; certain others are dorso-ventrally flattened to 

 some extent. A long band of membranelles (Fig. 7. 33, L, M), or a homolo- 

 gous double row of cilia, extends to the cytostome. An undulating mem- 

 brane, sometimes fairly short, or a corresponding row of cilia extends 

 along the right margin of the peristome. The peristome may be rather 

 straight or may show some degree of spiral torsion. In at least certain 

 species, bands of trichocysts alternate with rows of cilia (214). 



The following genera have been assigned to the family: BlepJiarisma Perty (104, 

 192; Fig. 7. 33, G, I), Gruberia Kahl (13, 104; Fig. 7. 33, F), Parablephnrisma Kahl 

 (104, 214; Fig. 7. 33, L), Phacodinium Prowazek (104), Protocrucia da Cunha (214; 

 Fig. 7. 33, H), PseudobJepharisina Kahl (104), Spirostomina Gruber (104), and Spiro- 

 stomum Ehrbg. (9, 104, 214; Fig. 7. 33, A-C, M). 



Family 13. Stentoridae. The zone of membranelles tends to extend 

 around the anterior pole of the body, and in some cases the peristome 

 itself has shifted to the pole (Fig. 7. 33, D, J, K). The undulating mem- 

 brane has disappeared. Somatic ciliation is relatively uniform, with the 

 cilia arranged in longitudinal or slightly spiral rows. 



The Stentoridae, represented in both fresh and salt water, include the following 

 genera: CUmacostomum Stein (104; Fig. 7. 33, K), Fabrea Henneguy (104, 113, 214; 

 Fig. 7. 33, E), and Stentor Oken (104, 214; Fig. 7. 33, D, J). 



