420 OHIO BIOLOGICAL SURVEY 



rigid, not metabolic; two flagella, the anterior about as long as 

 the body, the posterior considerably longer; pellicula smooth or 

 striate in longitudinal spirals; principal vacuole with accessory 

 contractile vacuole; nucleus on right side of body; movement in 

 a slow creeping or a quick jerking manner. 



Habitat, fresh water and marine. 



Distribution, cosmopolitan. 



TABLE OF SPECIES. 



A' Length not more than 2 times diameter. 



Bi Elongately oval; primary flagellum approximately as 



long as body 1- A. ovale 



B- Broadly oval; primary flagellum 2 times length of 



body. • • • • • . 2. A. emarginatum 



A- Length nearly 3 times or more than 3 times the diameter. 

 Bi Length 25-60m. 



C^ Pointed anteriorly; length 25-40/x. , . 3. A. acinus 



C2 Broadest anteriorly; length 60^^. . . 4. A. truncatum 

 B2 Length 11m.; broadly fusiform .... 5. A. pusillum 



*1. A. ovale Klel:s (Fig. 10. PI. XXV). 



Oval, rigid, emarginate anteriorly ; periplast smooth ; primary 

 flagellum about as long as body; secondary flagellum about II/2 

 times as long as body. 



L. 11^. D. 7/x. 



Distribution, Europe and North America. Standing water. 



Gambler, 0. (McElroy Farm). 



Var latum Klebs with L. 12/i, D. 10/., broad and emargmate 



posteriorly. 



2. A. emarginatum Stokes (Fig. 11, PI. XXV). 



Broadly oval, rigid, emarginate anteriorly; periplast smooth; 

 primary flagellum about 2 times length of body ; secondary flagel- 

 lum about 21/2 times length of body. 



L. IV D.(?). 



Distribution, North America. Standing water with Myrio- 

 phijUum, etc. 



*3. A. acinus Duj. (Fig. 12, PI. XXV). 



Oval, rigid, noticeably flattened; periplast smooth or weakly 

 striate; left side of ventral furrow prominent, thickened ante- 

 riorly; primary flagellum as long as body; secondary flagellum 

 about 2 times length of body. 



