Chapter 35 

 Order 1 Holotricha Stein (continued) 



Suborder 5 Thigmotricha Chatton et Lwoff 



THE majority of the ciliates placed in this suborder inhabit 

 the mantle cavity of mussels. They possess thigmotactic cilia 

 with which they attach themselves to the host body. Though ap- 

 pearing heterogeneous, Chatton and Lwoff hold that there is a 

 phylogenetic unity among them, which has been brought about 

 by the degenerative influence because of the similar conditions of 

 habitat. 



Without tentacles 



Ciliation uniform; ciliary rows meridional, close; peristome does not 

 begin near the anterior end 

 Thigmotactic cilia on entire broad side; with large peristome. . . . 



Family 1 Conchophthiridae 



Thigmotactic cilia only on a small field of left broad side; peri- 

 stome small Family 2 Thigmophryidae (p. 561) 



Ciliation unequal on 2 broad sides or spirally arranged, or greatly 

 rudimentary 



Cytostome with conspicuous peristome bearing long cilia 



Family 3 Ancistrumidae (p. 562) 



Cytostome rudimentary Family 4 Sphenophryidae (p. 565) 



With tentacular attaching organella . Family 5 Hypocomidae (p. 566) 



Family 1 Conchophthiridae Reichenow 



Genus Conchophthirus Stein. Oval to elUpsoid; flattened; right 

 margin concave at cytostomal region, left margin convex; ventral 

 surface somewhat flattened, dorsal surface convex; cytostome on 

 right side near middle in a depression with an undulating mem- 

 brane; macronucleus ; micronucleus; contractile vacuole opens 

 through a canal to right side; in mantle cavity and gills of various 

 mussels. Kidder made careful studies of several species. 



C. anodontae (Ehrenberg) (Figs. 60; 255, a). Ovoid; cytostome 

 on dorsal surface in anterior third, with an overhanging projec- 

 tion in front; cytopharynx, surrounded by circular fibrils, con- 

 tinues down as a fine, distensible tubule, to behind the macronu- 

 cleus; with peristomal basket; cihary grooves originate in a wide 

 ventral suture near anterior end; anterior region filled with re- 



560 



