410 OHIO BIOLOGICAL SURVEY 



Var. distomata (Stokes) has the two furrows equally broad 

 and the anterior end of the cell slightly elongated. Found on the 

 surface of decaying leaves in the bottom of shallow pools. 



Var, pleurosigma (Stokes) is fusiform, similar to P. medio- 

 canellata, with the posterior end pointed, and has a length of 17ju. 

 Standing pond water with aquatic vegetation. 



2. P. angusta (Klebs) (Fig. 3, PI. XXIII). 



Elongately oval, dorsal side convex, ventral side with furrow ; 

 flagellum as long as body. 



L. 14-23/^. D, 7-14;x. 



Distribution, Europe. Pools containing much vegetation. 



Var. pusilla (Klebs) is 7/x in length and 3-4/^ in diameter; var. 

 lata (Klebs) is broadly oval with short pointed posterior end, 

 L. 22/x, D. 12-14^u 



*3. P. inflexa Klebs (Fig. 4, PI. XXIII). 



Elongately oval, flattened, broadly truncate or emarginate 

 posteriorly, pointed anteriorly; lateral margins curled inwardly; 

 flagellum as long as body. 



L. 30^. D.(?). 



Distribution, Europe and North America. Pools containing 



much vegetation. 



var. obliqua Klebs has only the left lateral margin curled 

 ventrally, while the flagellum is oblique to the longitudinal axis 



of the body during the swimming movement. 



Var. pellucida Klebs is thin, transparent, and the dorsal side 

 possesses a shallow furrow, the lateral margins curled inwardly. 

 L. 8/M, D. 8/x. 



Gambler, O. Small forms 11.5jw in length referable to the 

 var. pellucida were obtained in a small brook filled with Lynghya 

 on the McElroy Farm. 



*4. P. sinuata (Stein) (Fig. 5, PI. XXIII) . 

 Short cylindrical, pointed anteriorly and with a lateral poste- 

 rior process on each margin; flagellum IV2-2 times length of body. 

 L. 38/^. D.(?). 

 Distribution, Europe. Pools with much vegetation. 



5. P. sexlobata Klebs (Fig. 6, PI. XXIII). 



Broadly oval, pointed bluntly anteriorly, with six short but 



