PERITRICHIDA 397 



Genus Gerda Claparede and Lachmann. Body elongated 

 and cylindrical, highly contractile. Cytostome at the anterior 

 end; adoral zone spiral, leading into the cytostome. Macro- 

 nucleus band-form. A contractile vacuole. No stalk; not 

 firmly attached. 



Gerda vernalis Stokes (Fig. 170, e). In shallow freshwater 

 ponds in early spring. About 250 microns long when extended. 



Genus Scyphidia Dujardin. Somewhat similar to Gerda. 

 Posterior end drawn out and suctorial in function. Stalk is 

 non-contractile. Attached. Fresh water. Several species. 



Scyphidia constricta Stokes (Fig. 170,/). Pond water, often 

 attached in clusters of 2 to 4 to Nais. Body about 55 microns 

 long. 



Genus Glossatella Butschli. Non-contractile stalk rudi- 

 mentary. An enormously large undulating membrane around 

 the peristomal margin. Often attached to Triton larvae. 



Glossatella tintinnahuliini (Kent) (Fig. 170, g). On the epi- 

 dermis and gills of the young Triton. Body about 40 microns 

 long. 



Genus Rhabdostyla Kent. Solitary with non-contractile 

 stalk. Attached to aquatic animals. Fresh or salt water. 

 Several species. 



Rhabdostyla vernalis Stokes (Fig. 170, h). Attached to Cy- 

 pris and Cyclops in the pools in early spring. Body about 50 

 microns long. 



Genus Astylozoon Engelmann. Without stalk, two pos- 

 terior setae. Free-swimming. Rare. 



Astylozoon fallax Engelmann (Fig. 170, i). Fresh water. 

 Body about 70 to 100 microns long. 



Genus Hastatella Erlanger. With several conical projec- 

 tions. Free-swimming. Fresh water. Two species. 



Hastatella aesculacantha Jarocki and Jakubowska (Fig. 

 170, j). In stagnant water. Extended body 30 to 52 microns 

 long by 24 to 40 microns wide. 



Genus Cothurnia Ehrenberg. Vorticella-like body in pseu- 

 dochitinoid lorica which is attached directly, or by a short stalk, 

 to submerged objects. Salt or fresh water. 



Cothurnia crystallina Ehrenberg (Fig. 170, k). Fresh or salt 

 water. Lorica 70 to 200 microns in length. 



