278 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- 

 ■rfSfg.-.-^^.l.-^vs like, central. Contractile vacuole posterior. Length 200 ^i. 



, ^ ^te^E3~-Ji^^.;B^ Among algae. 



^■tS^>'-/--V-'-l:3i2^?^S?£ifi^^ Fig. 486. Leucophrys patula. X 150. (After Kent.) 



67 (66) Mouth at some distance from the anterior end 68 



68 (69) Body ellipsoidal, ciliation regular, mouth a crescent-shaped or spiral 



slit leading into a pharynx. . . Ophryoglena Ehrenberg. 

 Representative species Ophryoglena atra Ehrenberg 1838. 



fBody 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 

 tois°M. 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 53 m. Standing water with dead 



SP>»A->'-> vSiS-JS^^^^fc leaves. 



Fig. 48S. 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. 



^*'SJS!Wj^ji((i^^_ Body twice as long as broad, striated longitudinally, an- 



terior extremity curved ventrally. Nucleus subcentral; 

 . ., _ contractile vacuole posterior, often leaving several small 



V«' " ss? „ ^^ vacuoles after contraction. Length 50 n. Infusions. 



Fig. 489. Colpidium striatum. X Soo. (After Edmondson.^ 



