276 



FRESH-WATER BIOLOGY 



47 (46) Body flattened ventrally, convex dorsally. With a long neck and 

 usually a tail-like prolongation both of which are hyaline. 

 Mouth a slit at the base of the neck, often invisible. Nuclei 

 usually two; contractUe vacuole posterior. 



Lionotus Wrzesniowski. 

 Representative species. Lionotus wrzesniowshii Kent 1882. 



i Fig. 479. Lionotus wrzesniowshii, cv, contractile 

 vacuole. X 125. (After Kent.) 



48 (35) Mouth usually somewhat posterior, and often with a pharynx; body 



oval or kidney-shaped. . . -49 



49 (so) Body completely ciliated, cylindrical to ovate, rounded posteriorly. 



Mouth about one-third of the way from the anterior end; 



pharynx with rods. Nassula Ehrenberg. 



Representative species. Nassula ornata Ehrenberg 1838. 



Usually some shade of red or brown in color. Nucleus 

 large, spherical, posteriorly located. Contractile vacuole 

 single. Length 200 11. Among algae. 



Fig. 480. Nassula ornata. In act of feeding. X 325. 

 Conn.) 



(After 



• SI 



• S2 



• S3 



50 (49) Body not completely cihated; cilia ventral only. . . . 



51 (s6) Body flattened. . . . 



52 (ss) Mouth in the anterior half of the body. . 



53 (S4) Body with convex dorsal and flattened or slightly concave ventral 



surface. Pharynx with rods. . . Chilodon Ehrenberg. 



Representative species. . . . Chilodon citcullulus MuileT 11&6. 



o The lip-like extension prominent, a groove leading from it to the 



mouth. Nucleus oval near the inner end of the pharynx. Contractile 

 vacuoles numerous. Length 125 to 200 /i. Stagnant water and among 

 algae. 



Fig. 481. Chilodon cucullulus, cv, contractile vacuole: macn, macronucleus; 

 mic, micronucleus. X no. (After Blochmann.) 



54 (53) Body with ridges on dorsal and ventral surfaces, crenate in cross 



section, pharynx with rods Chilodonopsis Conn. 



Representative species Chilodonopsis crenvla Conn 1905. 



Fig. 482. Chilodonopsis crenula. X 335. (After Conn.) 



55 (S2) Mouth in the posterior half of the body Opisthodon Stein. 



56 (si) Body not flattened 57 



