SPIROTRICHA, OLIGOTRICHA 597 



and wide; macroniicleus elongate; a single micronucleus; 2 or 

 more contractile vacuoles; in horse and anthropoid apes. 



Genus Cycloposthium Bundle. Large, elongate barrel-shaped; 

 cytostome in center of a retractile conical elevation at anterior 

 end; adoral zone conspicuous; an open ring-zone of membranellae 

 near posterior end on both dorsal and ventral sides; pellicle 

 ridged; skeleton club-shaped; several contractile vacuoles in a 

 row along band-form macronucleus; in caecum and colon of 

 horse. Many species. 



C. hipalmatum (Fiorentini) (Fig. 270, c). 80-127/x by 35-57/z. 



C. dentiferum Gassovsky (Fig. 270, d). 140-222^ by 80-1 10^. 



Genus Spirodinium Fiorentini. Elongate, more or less fusiform; 

 adoral zone at anterior end; zone making at least one complete 

 spiral near anterior end; posterior zone only half-spiral; in caecum 

 and colon of horse. One species. 



S. equi F. (Fig. 270, e). 77-180^ by 30-74ai; widely distributed. 



Genus Triadinium Fiorentini. More or less helmet-shaped; 

 compressed; adoral zone at anterior end; 2 posterior (ventral 

 and dorsal) zones; with or without a caudal projection; in caecum 

 and colon of horse. 



T. caudatum F. (Fig. 270, /). 59-86/x by 50-68/^. 



T. galea Gassovsky. 59-78/i by dO-QO/i. 



T. viinimum G. (Fig. 270, g). 35-58^ by 30-40/^. 



Genus Tetratoxum Gassovsky. Slightly compressed; 2 anterior 

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



T. imifasciculatum (Fiorentini) (Fig. 270, h). 104-168/i by 

 62-100^; widely distributed. 



T. escavatum Hsiung. 95-1 35^ by 55-90At. 



T. parvum H. 67-98m by 39-52^. 



Genus Tripalmaria Gassovsky {Tricaudalia Buisson). Adoral 

 zone at anterior end; 2 dorsal and 1 ventro-posterior zones in 

 tuft-form; macronucleus inverted U-shape; in colon of horse. 



T. dogieli G. (Fig. 271, a). 77-123m by 47-62/i. 



Genus Cochliatoxum Gassovsky. Adoral zone near anterior 

 end; 3 additional zones, I antero-dorsal, 1 postero-dorsal and 1 

 postero-ventral; macronucleus with curved anterior end; in colon 

 of horse. One species. 



C. periachtum G. (Fig. 271, b). 210-370/x by 130-210/i. 



Genus Ditoxum Gassovsky. Large adoral zone near anterior 

 end; 2 dorsal (anterior and posterior) zones; macronucleus curved 

 club-shaped; in colon of horse. 



