EDMONDSON — PROTOZOA OF IOWA. 103 



Length, 120-160 microns. (Fig. 163, PI. XXII.) 

 This is the rarest of the four species of the genus thus far ob- 

 served in this state. It has been found in pond water, associated 

 with other members of the family, in Cedar county. In manner 

 of reproduction, movement, etc., it resembles other species of the 

 genus. 



Family, EUPLOTID^. 



EUPLOTES Ehrenberg. 



Persistent in shape, inflexible, oval, ventral surface flattened, 

 dorsal surface convex and longitudinally furrowed. From six to 

 eight styles about the front border, a few scattered ventral ones, 

 five anal styles and usually four large setae on the posterior margin. 

 Peristome extending backward to or beyond the middle of the 

 body. Nucleus band-like, curved. Contractile vesicle in the 

 , posterior region and lateral. 



EUPLOTES CHARON Mlill. 



Body a little longer than broad, the dorsal surface conspicu- 

 ously ribbed. Seven frontal styles and three ventral. Peristome 

 extending beyond the middle of the body. 



Length, 80 microns. (Fig. 172, PI. XXIV.) 



The plate figure represents a dorsal view showing the ribbed 

 surface. This form can usually be distinguished from the more 

 common species, Euplotes patella, by the shorter oval body and the 

 greater number of frontal styles. 



Found in fresh water. 



Euplotes patella Ehr. 



Body elongate-oval, evenly rounded posteriorly, truncate or 

 rounded anteriorly. Usually six frontal and two or three scat- 

 tered ventral styles. Of the four setae on the posterior margin, 

 two are usually somewhat lateral in position. 



Peristome broad, extending nearly to the middle of the body. 

 Nucleus band-like, curved, following the contour of the body. 

 Contractile vesicle posterior and lateral. 



Length, 150 microns. (Fig. 173, PI. XXIV.) 



This is the most common species of the genus to be found in 

 this state and one in which individual variation is shown to a re- 

 markable degree. Frequently the setae of the posterior border, 



