854 PROTOZOOLOGY 



E. fugitans Kellicott. 50-60/* long; attached to Sida in early spring. 



E. cambari K. (Fig. 362, d, e). About 50 ^ long; attached to the 

 gills of Cambarus. 



E. niagarae (Fig. 362, /). Expanded body about 16G> long; peri- 

 stomal ring prominent; flat cap makes a slight angle with the ring; 

 bandform macronucleus transverse to long axis, in the anterior 

 third; gullet with ciliated wall; 40-50 in a colony; attached to the 

 antennae and body surface of crayfish (Kellicott, 1883) or to painted 

 and snapping turtles (Bishop and Jahn, 1941). 



Genus Rhabdostyla Kent. Similar to Epistylis; but solitary with 

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

 water. Numerous species (Nenninger, 1948). 



R. vernalis Stokes (Fig. 362, g). About 50/x 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 (Nenninger, 1948). 



0. annulata S. (Fig. 362, h). Body about 23^ long; fresh water. 



Genus Campanella Goldfuss. Similar to Epistylis; but adoral 

 double zone turns 4-6 times; fresh water. 



C. umbellaria (Linnaeus) (Fig. 362, i). Colony may reach several 

 millimeters in height; individuals 130-250/* 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. Taxonomy (Nenninger). 



P. vernale Stokes (Fig. 362, j). Solitary or few together; 70-85/z 

 long; fresh water among algae. 



P. urceolatum S. (Fig. 362, k). About 90/x long; fresh water on 

 plants. 



Genus Opercularia Stein. Individuals similar to Pyxidium; but 

 short stalk dichotomous; peristome border like a band. 



O. stenostoma S. (Fig. 362, 1). When extended, up to 125/x long; at- 

 tached to Asellus aquaticus and others. 



O. plicatilis Stokes (Fig. 362, m). About 254/x long; colony 1.25- 

 2.5 mm. high; pond water. 



Genus Operculariella Stammer. Fixed stalk, branched, short and 

 rigid; peristome small, without border, smooth; without disk or 

 frontal cilia; vestibule large (Stammer, 1948). 



0. parasitica S. (Fig. 362, n). 100-1 10/u long; barrel-shaped; peri- 

 stome opening only 1/4 the body breadth; macronucleus about 30^ 



