T 



Chapter 36 

 Order 1 Holotricha Stein (continued) 



Suborder 5 Thigmotricha Chatton and Lwoff 



HE 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 appearing 

 heterogeneous, Chatton and Lwoff hold that there is a phylogenetic 

 unity among them, which has been brought about by the degenera- 

 tive 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; peristome 



small Family 2 Thigmophryidae (p. 624) 



Long cilia only on posterior margin where cytostome is located; 



sucker at anterior end Family 3 Hysterocinetidae (p. 624) 



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

 rudimentary 



Cytostome with conspicuous peristome bearing long cilia 



Family 4 Ancistrumidae (p. 626) 



Cytostome rudimentary Family 5 Sphenophryidae (p. 628) 



With tentacular attaching organella . . . Family 6 Hypocomidae (p. 629) 



Family 1 Conchophthiridae Reichenow 



Genus Conchophthirus Stein. Oval to ellipsoid; flattened; right 

 margin concave at cytostomal region, left margin convex; ventral 

 surface somewhat flattened, dorsal surface convex; cytostome on 

 right sidie near middle in a depression with an undulating membrane; 

 macronucleus; micro nucleus; contractile vacuole opens through a 

 canal to right side ; in the mantle cavity and gills of various mussels, 

 Kidder made careful studies of several species. 



C. anodontae (Ehrenberg) (Figs. 63; 294, a). Ovoid; cytostome 

 in anterior third, wdth an overhanging projection in front; cyto- 

 pharynx, surrounded by circular fibrils, continues down as a fine, 

 distensible tubule, to near the macronucleus; with peristomal bas- 

 ket; ciliary grooves originate in a wide ventral suture near anterior 

 end; anterior region filled with refractile granules; macronucleus 

 posterior; contractile vacuole between nuclei and peristome, with 

 a slit-like aperture (Fig. 27); 65-125m by 47-86m; in the mantle 



623 



