824 PROTOZOOLOGY 



ton club-shaped; several contractile vacuoles in a row along band- 

 form macronucleus; in the caecum and colon of horse. Many species 

 (Hsiung, 1930). Cytology (Strelkow, 1929, 1932). 



C. bipalmatum (Fiorentini) (Fig. 351, c). 80-127/* by 35-57 /*. Con- 

 jugation (Dogiel, 1925). 



C. dentiferum Gassovsky (Fig. 351, d). 140-222/* by 80-110/*. 



Genus Spirodinium Fiorentini. Elongate, more or less fusiform; 

 adoral zone at anterior end; anterior ciliary zone encircles the body 

 at least once; a posterior ciliary arch, only 1/2 spiral; a dorsal cavity 

 of unknown function (Davis, 1941), lined with stiff rods; in the colon 

 and caecum of the horse. Species (Hsiung, 1930, 1935). 



S. equi F. (Fig. 351, e). 82-196/x by 46-108/*; widely distributed. 

 Morphology (Hsiung, 1935a; Davis, 1941); division (Davis, 1941). 



Genus Triadinium Fiorentini. More or less helmet-shaped; com- 

 pressed; adoral zone at anterior end; 2 posterior (ventral and dorsal) 

 zones; with or without a caudal projection; in the caecum and colon 

 of horse. Species (Hsiung, 1935). 



T. caudatum F. (Fig. 351,/). 59-86/* by 50-68/*. 



T. galea Gassovsky. 59-78/1 by 50-60/*. 



T. minimum G. (Fig. 351, g). 35-58/* by 30-40/z. 



Genus Tetratoxum Gassovsky. Slightly compressed; 2 anterior 

 and 2 posterior zones of membranellae ; in the colon of horse. Species 

 (Hsiung, 1930). 



T. unifasciculatum (Fiorentini) (Fig. 351, h). 88-186/* by 60-108/*; 

 widely distributed. Morphology and micronuclear division (Davis, 

 1941a). 



T. escavatum Hsiung. 95-135/x by 55-90/*. 



T. parvum H. 67-98/* by 39-52/*. 



Genus Tripalmaria Gassovsky (Tricaudalia Buisson). Adoral zone 

 at anterior end; 2 dorsal and 1 ventral-posterior zones in tuft-form; 

 macronucleus inverted U-shape; in the colon of horse. Cytology 

 (Strelkow, 1932). 



T. dogieli G. (Fig. 352, a). 77-123/* by 47-62/* (Hsiung, 1930). 



Genus Triplumaria Hoare. Adoral zone; 2 dorsal and 1 ventral 

 cirrose tufts (caudals); skeleton, composed of polygonal plates ar- 

 ranged in a single layer, surrounds the body except the dorsal sur- 

 face; dorsal groove supported by rod-like skeleton; macronucleus 

 elongate sausage-form, with a micronucleus attached to its dorsal 

 surface near middle; about 6 contractile vacuoles arranged in line 

 along dorsal surface of body; in the intestine of Indian rhinoceros 

 (Hoare, 1937). 



T. hamertoni H. 129-207/* long, 65-82/* thick, 4-39/* broad; endo- 



