384 BIOLOGY OF THE PROTOZOA 



5. Frontonia (Fig. 168, C), ellipsoidal; elongate mouth with 



furrow running posteriorly. 



6. Lo.rocephalus (Fig. 168, F), mouth in anterior half; with 



caudal spine. 



7. Uronenia, with caudal cirrus; mouth with marginal mem- 



brane. 



8. Placus, with caudal cirrus; membrane cross-striped, plaid- 



like. 



9. Colpoflojms, body kidney-shape, with caudal bristle. 



10. Plagiopyla, peristomial furrow very narrow and transverse. 



11. Tillina, spheroidal with posterior, pigmented, dorsal lobe. 



12. Colpoda, body distincth' kidney-shape; oral region deeply 



insunk. 



13. ColjiidiiDu, elongate; dorsal side arched, oral region shallow. 



14. Chasmaiastoina, elongate; dorsal side flat, oral region shallow. 

 (See Key for additional genera.) 



Family 3. Microthoracidse, Wrzesniowsky.— These forms are small 

 for the most jmrt anfl frequently of peculiar shape— lens, sickle, 

 triangle, etc. The body is compressed except in the cases of 

 Boverla and Plagiospira and accessory bristles are frequent. The 

 main genera are: 



1. Ancisirum, with a tuft of anterior anchoring cilia. 



2. Boveria, with short peristome; body cylindrical. 



3. CinetockUuin, body lens-shape, obliquely truncate posteriorly. 



4. Drepanomonas, body crescentic or sickle-form. 



5. Microthorax (Fig. 170, A), mouth small, posterior in position. 



6. Plagiospira, peristome long and spirally wound. 



7. Ptychostomum , form triangular. 



Family 4. Pleuronemidse, l^iitschli. — Forms with general clothing 

 of long cilia with a tendency to longer and more powerful cilia in 

 the anterior region. The main characteristic is the presence of one 

 or more powerful undulating membranes which may be folded into 

 the peristome on the left anterior side. The typical genera are: 



1. Blepharostoma, with one pseudo-membrane (close set cilia). 



2. Calyptotricha, tube or jelly-dwelling; no long anterior cilia. 



3. CycUdium (Fig. 169, p. 385), narrow peristome; one balloon- 



like membrane; with caudal filament. 



4. Cyrtiilophosis, tube- or jelly-dwelling; anterior tuft of long 



cilia. 



5. Leinbadion (Fig. 77, p. 149), peristome very broad; three 



undulating meml)ranes; with or without caudal filament. 



6. LcDihvs (Fig. 170, T'), two pseudomembranes; with caudal 



filament. 



7. Plciirocoptes, ectoparasitic on hydroids; no caudal filament 



and without balloon-like membrane. 



8. Plenronema (Fig. 169, C), no caudal filament; with one 



balloon-like membrane. 



