HOLOTRICHA 557 



Genus Cyclidium Mliller. Small (15-60^ long); ovoid; usually 

 with refractile pellicle; with a caudal bristle; peristome near right 

 side; on its right edge occurs a membrane which forms a pocket 

 around cytostomal groove and on its left edge either free cilia or 

 a membrane which unites with that on right; no semicircular 

 swelling on left of oral region; round macronucleus with a micro- 

 nucleus; contractile vacuole posterior; fresh or salt water. Numer- 

 ous species. 



C. litomesum Stokes (Fig. 253, g). About 40)Li long; dorsal sur- 

 face slightly convex with a depression in middle; ventral surface 

 more or less concave; cilia long; in fresh water. 



Genus Cristigera Roux. Similar to Cyclidium; much com- 

 pressed; with a postoral depression; peristome closer to mid- ven- 

 tral line; fresh or salt water. Several species. 



C. -phoenix Penard (Fig. 253, h). 37-45At long; fresh water. 



C. media Kahl (Fig. 253, i). 45-50/i long; in salt water. 



Genus Ctedoctema Stokes. Similar to Cyclidium in body form; 

 peristome nearer median Une, diagonally right to left; right peri- 

 stomal ridge with a sail-like membrane which surrounds the cyto- 

 stome at its posterior end; trichocysts throughout; fresh water. 



C. acanthocrypta S. (Fig. 254, a). Ovoid; anterior end truncate; 

 macronucleus round, anterior; about 35/^ long; in fresh water 

 among vegetation. 



Genus Calyptotricha Philhps. Somewhat resembles Pleuronema 

 or Cyclidium; but dwelling in a lorica which is opened at both 

 ends; with zoochlorellae; fresh w^ater. 



C. pleuronemoides P. (Fig. 254, h). Lorica about 85ai high; body 

 about 50 fjL long; Kellicott's (1885) form is more elongated; in 

 fresh water. 



Genus Histiobalantium Stokes. Ovoid; ventral side flattened; 

 ciliation uniform ; long stiff cilia distributed over the entire body 

 surface; peristome deep; both anterior and posterior regions with 

 a well-developed membrane, connected with the undulating 

 membrane ; macronucleus in 2 parts ; 1-2 micronuclei ; several con- 

 tractile vacuoles distributed; fresh water. 



H. nutans (Claparede et Lachmann) (Fig. 254, c). 70-1 10^ long. 



H. semisetatum Noland (Fig. 254, d). Elongate ellipsoid; pos- 

 terior end bluntly rounded; macronucleus spherical; longer setae 

 on posterior half only; contractile vacuoles on dorsal side; 126- 

 205^1 long; salt water; Florida. 



