2 7 8 



FRESH-WATER BIOLOGY 



65 (62) No zones of strong cilia about the body 66 



66 (67) Mouth covering the whole oblique anterior end. Body usually oval 



or purse-shaped Leucophrys Ehrenberg. 



Representative species Leucophrys patula Ehrenberg 1838. 



Body oval; pharynx tubular, curved. Nucleus band- 

 like, central. Contractile, vacuole posterior. Length 200 /*. 

 Among algae. 



FIG. 486. Leucophrys patula. X 150. (After Kent.) 



67 (66) Mouth at some distance from the anterior end. 



68 (69) 



68 



Body ellipsoidal, ciliation regular, mouth a crescent-shaped or spiral 

 slit leading into a pharynx. . . . Ophryoglena Ehrenberg. 

 Representative species Ophryoglena atra Ehrenberg 1838. 



Body with posterior extremity pointed. Endoplasm usually 

 opaque, with a dark blue pigment spot in" the anterior region. 

 Nucleus round, posterior; contractile vacuole central. Length 125 

 to 1 50 p. Stagnant water. 



FIG. 487. Ophryoglena atra. cv, contractile "vacuole; macn, macronucleus. 

 X 200. (After Kent.) 



69 (68) Body laterally compressed, ovate, with the dorsal surface rounded. 



Mouth one-third of the distance from the anterior end, with 

 a few, long, fine cilia on its superior wall or roof. 



Colpoda Miiller. 

 Representative species Colpoda campyla Stokes 1886. 



Length of body 55 M - Standing water with dead 

 leaves. 



FIG. 488. Colpoda campyla. X 600. (After Conn.) 



70 (61) With one or more undulating membranes 71 



71 (76) One membrane present 72 



72 (75) Mouth not terminal 73 



73 (74) Body not flexible; mouth lateral, triangular, following a small peri- 



stome and with an undulating membrane in front. Body 



similar to Colpoda, but less compressed. . Colpidium Stein. 



Representative species Colpidium striatum Stokes 1886. 



Body twice as long as broad, striated longitudinally, an- 

 terior extremity curved ventrally. Nucleus subcentral; 

 contractile vacuole posterior, often leaving several small 

 vacuoles after contraction. Length 50 /* Infusions. 



FIG. 489. Colpidium striatum. X SOQ. (After Edmondson.) 



