624 PROTOZOOLOGY 



cavity, gills and on non-ciliated surface of palps of Elliptio com- 

 planatus; Woods Hole. 



C. curtus Engelmann. Somewhat broader; 60-125)U by 50-90)u; 

 peristomal field smaller; cytopharynx less conspicuous, but longer; 

 ciliation dense; endoplasmic granules are more closely packed and 

 do not extend as far out toward anterior end; macro nucleus central. 

 Kidder found this ciliate in the mantle cavity of Anodonta marginata, 

 A. implicata, A. catarecta, Lampsilis radiata, L. cariosa and Alasmi- 

 donta undulata which were obtained from the freshwater lakes of 

 Massachusetts and New York. 



C. magna Kidder. Much larger; 123-204/i by 63-116m; closer cilia- 

 tion; anterior 1/3 filled with smaller granules; irregularly outlined 

 macro nucleus, 25-30m in diameter, central; 2 (or 1) micro nuclei; 

 aperture for contractile vacuole large; mantle cavity of Elliptio com- 

 planatus; Massachusetts. 



C. caryoclada K. (Fig. 294, h). Oval; extremely flattened; leaf- 

 like; cytostome small, in posterior fourth; macronucleus conspic- 

 uously branched; 2 (or 1) micronuclei; 140-250^ by 90-160m; mantle 

 cavity of the edible clam, Siliqua patula; Oregon. 



C. mytili de Morgan (Fig. 55). Reniform; 130-220^ by 76-161^; 

 peristomal groove on the right side; trichocysts conspicuous along 

 frontal margin; macronucleus oval; 2 micronuclei. Kidder (1933) 

 found the organism on the foot of the common mussel, Mytilus 

 edulis, in New York and studied its division and conjugation. 



Genus Myxophyllum Raabe. Oval or spheroid ; pellicle elastic and 

 flexible; peristome on posterior right, without undulating membrane; 

 7 macro nuclei; a micronucleus; ciliation uniform; in the slime cover- 

 ing land pulmonates. 



M. steenstrupi (Stein) (Fig. 294, c). 120^ by 100-120//; on Succinea 

 putris, etc. 



Family 2 Thigmophryidae Chatton and Lwoff 



Genus Thigmophrya Chatton and Lwoff. Elongate ; round or oblong 

 in cross section; cytostome in posterior third; contractile vacuole 

 opens in cytopharynx; on the gills or palps of lamellibranchs. 



T. macomae C. and L. Elongate ovoid; flattened; ventral surface 

 slightly concave; oral funnel opened; contractile vacuole opens at 

 the bottom of c3'topharynx ; numerous ciliary rows; about llO/i by 

 40ju; on the gills of Macoma (Tellina) halthica. 



Family 3 Hysterocinetidae Diesing 

 Inclusion of this family in the present suborder is provisional, 



