HOLOTRICHA 779 



Genus Ancistrospira Chatton and Lwoff. Ciliation meridional to 

 spiral; peristome right spiral; commensal. 



A. veneris C. and L. 50-60/z by 22-28^; ovoid, anterior end 

 pointed; ciliary rows meridional; thigmotactic field on the left side, 

 sharply marked from body ciliation; on the gills of Venus fasciata. 



Genus Boveria Stevens (Tiarella Cheissin). Conical; cytostome 

 at posterior end; peristome spiral posteriorly; macronucleus oval, 

 in anterior half; a micronucleus; contractile vacuole posterior; ecto- 

 commensal on gills of various marine animals such as Teredo, Bankia, 

 Tellina, Capsa and Holothuria. Several species. 



B. teredinidi Pickard (Fig. 330, c). 27-173/i by 12-3 1m; on gills of 

 Teredo navalis; California (Pickard, 1927). 



Genus Plagiospira Issel. Conical; anterior end attenuated; peri- 

 stome runs spirally from middle of body to cytostome, with long 

 cilia ; marcronucleus oval, anterior; a micronucleus; contractile vacu- 

 ole near middle of body; somewhat spirally arranged striae widely 

 apart on right side; commensal. 



P. crinita I. (Fig. 330, d). 32-58ju by 18-34^; in Cardita calyculata 

 and Loripes lacteus. 



Family 4 Hysterocinetidae Diesing 



Inclusion of this family in the present suborder is provisional, since 

 its affinity to other forms is not yet clear. Beers (1938) who placed 

 it in Hymenostomata, in agreement with Cheissin (1931), states that 

 the nutrition is in part saprozoic, and that the organisms are in the 

 process of acquiring the saprozoic and astomatous condition. 



Genus Hysterocineta Diesing (Ladopsis Cheissen). Elongate; 

 flattened; flexible, an inverted V- or U-shaped sucker conspicuously 

 present in antero- ventral margin; ciliation uniform; cytostome and 

 cytopharynx at the posterior end; an undulating membrane along 

 peristome which borders the posterior margin of body; macronucleus 

 elongate; a micronucleus; contractile vacuole posterior; in the intes- 

 tine of gastropods and oligochaetes. 4 species. Taxonomy (Jarocki, 

 1934; Beers, 1938; Raabe, 1949). 



H. eiseniae Beers (Fig. 330, e). 190-210/x by 35-40/x; cytostome 

 not functional; endoplasm with small granules; macronucleus 45-50^ 

 long; sucker inverted V, about 25-30;u long; in the intestine of Ei- 

 senia lonnbergi (Beers, 1938). 



Genus Ptychostomum Stein (Lada Vejdovsky). Sucker circular or 

 ovoid; macronucleus ovoid or reniform, not elongate; in oligochaetes. 

 Several species. Taxonomy (Studitsky, 1932; Raabe, 1949). 



