PERITRICHA 687 



E. fugitans Kellicott (Fig. 322, d). 50-60^ long; attached to Sida 

 in early spring. 



E. cambari K. (Fig. 322, e,j). About 50m long; attached to the gills 

 of Cambarus. 



Genus Rhabdostyla Kent. Similar to Epistylis; but solitary with 

 a non-contractile stalk ; attached to aquatic animals in fresh or salt 

 water. Numerous species. 



R. vernalis Stokes (Fig. 322, g). About 50^ long; attached to Cy- 

 clops and Cypris in pools in early spring. 



Genus Opisthostyla Stokes. Similar to Rhabdostyla; but stalk long, 

 is bent at its point of attachment to submerged object, and acts like 

 a spring; fresh or salt water. 



0. annulata S. (Fig. 322, h). Body about 23^ long; fresh water. 



Genus Campanella Goldfuss. Similar to Epistylis; but adoral 

 double zone turns 4-6 times ; fresh water. 



C. umhellaria (Linnaeus) (Fig. 322, i). Colony may reach several 

 millimeters in height; individuals 130-250ai long (Kent). 



Genus Pyxidium Kent. Stalk simple, not branching; peristome 

 even when fully opened, not constricted from the body proper; 

 frontal disk small, oblique, supported by style-like slender process 

 arising from peristome ; attached to freshwater animals and in vege- 

 tation. 



P. vernale Stokes (Fig. 322, j). Solitary or few together; 70-85/x 

 long; fresh Avater among algae. 



P. urceolatum S. (Fig. 322, A-). About 90^ long; fresh water on 

 plants. 



Genus Opercularia Stein. Individuals similar to Pyxidium; but 

 short stalk dichotomous; peristome border like a band, 



0. sienostoma S. (Fig. 322, I). When extended up to 125^ long; at- 

 tached to Asellus aquaticus and others. 



0. plicatilis Stokes (Fig. 322, w, n). About 254^ long; colony 1.25- 

 2.5 mm. high; pond water. 



Family 5 Vorticellidae Fromental 



Genus Vorticella Linnaeus. Inverted bell-form; colorless, yellow- 

 ish, or greenish ; peristome more or less outwardly extended ; pellicle 

 sometimes annulated; with a contractile stalk, macronucleus band- 

 form; micronucleus; 1-2 contractile vacuoles; solitary; in fresh or 

 salt water, attached to submerged objects. Noland and Finley (1931) 

 gave a taxonomic consideration of the genus. Numerous species. 



V. campanula Ehrenberg (Fig. 323, a-c). Usually in groups; endo- 

 plasm filled with refractile reserve granules; vestibule very large 



