Ciliophora 349 



Fig. 7. 8. A. Orlhodon hamatus Gruber, 90-260/ri (after Kahl). B. Chilo- 

 dontopsis muscorum Kahl, 65-80yn (after K.). C, D. Transverse and longitu- 

 dinal sections showing circumpharyngeal trichites of Nassula aurea Ehrbg., 

 xloOO and x240 (after Wetzel). E. Nassula gracilis Kahl, x360 (after K.). 

 F, G. Paia7iassula microstoma (Claparede and Lachmann) Kahl; ventral view 

 of preoral suture and cytostome (F), x600; pharyngeal apparatus, macro- 

 nucleus, contractile vacuole, trichocysts (G), x450 (after Noland). H. Meta- 

 cystis elongata Kahl, without lorica, xOOO approx. (after K.). I, J. Pelatractus 

 constractus Wang and Nie; extended specimen (I) showing macronucleus and 

 catial extending posteriorly from contractile vacuole, xlyO; contracted speci- 

 men (J), schematic (after W. & N.). K. Vasicola parvula Kahl, 30-50;a, spec- 

 imen in lorica (after K.). 



The family includes the following genera: Buxtonella Jameson (94, 175; Fig. 7. 9, 

 \, B), Collinella Chatton and Perard (33; Fig. 7. 9, C, D), Nicollella Chatton and 

 Perard (33; Fig. 7. 9, E-G), and Pycnothrix Schubotz (33; Fig. 7. 9, H). 



Family 14. Spathidiidae. These prostomatous ciliates have a slit-like 

 cytostome generally lying in a non-ciliated ridge (Fig. 7. 10, B-D). In 

 some genera, this ridge is continued posteriorly and spirally for some 

 distance (Fig. 7. 10, H; 11, B, C). In others, the ridge does not extend 



