HOLOTRICHA 565 



A. veneris C. et L. 50-60^ by 22-28;u; ovoid; anterior end point- 

 ed; ciliary rows meridional; thigmotactie field on left side, 

 sharply marked from body ciliation ; on gills of Ve7ius fasciata. 



Genus Boveria Stevens (Tiarella Cheissin). Conical; cytostome 

 at posterior end; peristome spiral posteriorly; macronucleus oval, 

 in anterior half; a micronucleus; contractile vacuole posterior; 

 ectocommensal on gills of various marine animals such as Teredo, 

 Bankia, Tellina, Capsa and Holothuria. Several species. 



B. teredinidi Pickard (Fig. 256, d). 27-173m by 12-31/^; on gills 

 on Teredo navalis; California. 



Genus Plagiospira Issel. Conical; anterior end attenuated; 

 peristome runs spirally from middle of body to cytostome, with 

 long cilia; macronucleus oval, anterior; a micronucleus; contrac- 

 tile vacuole near middle of body; somewhat spirally arranged 

 striae widely apart on right side; commensal. 



P. crinita I. (Fig. 256, e). 32-58/i by 18-34ai; in Cardita calycu- 

 lata and Loripes lacteus. 



Genus Hemispeira Fabre-Domergue. Nearly spherical; flat- 

 tened; longitudinal non-ciliated furrow on ventral surface, which 

 encircles thigmotactie posterior cilia; 4-5 cross-furrows of cilia; 

 a huge adoral membrane at anterior end; macronucleus, micro- 

 nucleus large; contractile vacuole, anterior-right; commensal. 



H. asteriasi F.-D. (Fig. 256,/). 20-30^ long; ectocommensal on 

 Asierias gracilis. 



Genus Hemispeiropsis Konig. Oval; body surface not cihated, 

 except the aboral end which bears 1-2 cross-rows of cilia and thig- 

 motactie cilia; adoral membrane double; macronucleus large, 

 spherical, with an imbedded micronucleus; contractile vacuole 

 central; ectocommensal. 



H. comatulae K. About 23-27^ long, excluding membrane; on 

 Comatula mediterranea. 



Family 4 Sphenophryidae Chatton et Lwoff 



Genus Sphenophrya Chatton et Lwoff. Triangular to crescen- 

 tic; in mature state, basal rows of cilia distinct on a broad side, 

 converging toward middle, from which budding takes place side- 

 wise; in gills of mussels. 



S. dosiniae C. et L. 120/x by 15-20ju; fijied to interfilamental 

 space of gills of Dosinia exoleta. 



