SPIROTRICHA, HETEROTRICHA 581 



by karyophore; endoplasm with discoid glycogenous substance, 

 especially in anterior region, hence yellowish to brown; contrac- 

 tile vacuole and cytopyge terminal; in colon of Amphibia and 

 various invertebrates. Numerous species. 



N. ovalis L. (Figs. 3; 264, a, h). Ovoid; anterior half com- 

 pressed; macronucleus elongate, at right angles to dorso-ventral 

 axis at anterior 1/3; micronucleus in front of macronucleus; dis- 

 tinct karyophore; glycogen bodies; 90-1 85^ by 62-95/^; giant 

 forms up to 360^t by 240/^; cysts 72-106ai by 58-80//; in colon of 

 cockroaches. The chromatin spherules of the macronucleus are 

 often very large (p. 35). 



N. cordiformis (Ehrenberg) (Figs. 75; 264, c). 60-200^ by 40- 

 140/^; ovoid; micronucleus behind macronucleus; no karyophore; 

 in colon of frogs and toads. Wichterman (1936) studied its life- 

 cycle in Hyla versicolor (Fig. 75). 



Family 4 Condylostomidae Kahl 



Genus Condylostoma Dujardin. Ellipsoid; anterior end trun- 

 cate, posterior end rounded or bluntly pointed; slightly flattened; 

 peristome wide at anterior end and V-shaped, peristomal field 

 not ciliated; a large membrane on right edge and adoral zone on 

 left; macronucleus moniliform; one to several contractile vacuoles 

 often with canal; cytopyge posterior; fresh or salt water. Many 

 species. 



C. vorticella (Ehrenberg) (Fig. 264, d). 100-200^ long; fresh wa- 

 ter. 



C. patens (Mtiller). 350-550^ long; salt water; Woods Hole 

 (Calkins). 



Family 5 Stentoridae Carus 



Genus Stentor Oken. When extended, trumpet-shaped or cylin- 

 drical; highly contractile; some with mucilaginous lorica; usually 

 oval to pyriform while swimming; conspicuous peristomal field 

 frontal; adoral zone encircles peristome in a spiral form, leaving a 

 narrow gap on ventral side ; the zone and field sink toward cyto- 

 stome and the former continues into cytopharynx; macronucleus 

 round, oval or elongated, in a single mass or in divided parts; con- 

 tractile vacuole anterior-left; free-swimming or attached; fresh 

 water. 



S. coeruleus Ehrenberg (Figs. 14; 264, e). Fully extended body 



