FLAGELLATE PROTOZOA (MASTIGOPHORA) 257 



III (no) Two flagella, unequal 112 



112(113) Body with spiral ridges Tropidoscyphus Stem. 



113 (112) Body without spiral ridges 114 



114 (115) Trailing flagellum very prominent, curving around the anterior 



end Anisoncma Dujardin. 



Representative species. . . . Anisonema acinus V>\i]diX<\\\\ i?>^i . 



ys'^^'-^r'^-^^.^^ Body wider posteriorly, flattened ventrally; anterior vi- 



fii^~^ ■ -'^^^vv^^ bratile flagellum short. Mouth near the base of the an- 



^^jggliaS^r"^-''^^- terior flagellum. Length 25 m. Among diatoms. Common. 



Fig. 414. Anisonema acinus. X scxd. Jhe genus Metanema Klebs resembles Anisonema but is 



(After Conn.) flexible. 



115(114) Trailing flagellum not prominent 116 



116 (117) Primary flagellum carried obliquely forward, vibratile only at its 

 end. Body ovate or angular with dorsal side concave. 



No protrusile pharynx Notosolenus Stokes. 



Representative species . . Notosolenus orbicularis Stokes 1884. 



Body with a broad, shallow, dorsal concavity; the ventral surface convex. 

 Movements somewhat eccentric, the convex surface usually directed down- 

 ward. Nucleus to the left of the center of the body. Contractile vacuole 

 near the anterior end. Length 10 to 12 /i. Bottom of shallow ponds. 



Fig. 415. Notosolenus orbicularis. X looo. (After Conn.) 



117 (116) Primary flagellum not carried obliquely forward; pharynx pro- 

 trusile. A strong furrow on the ventral surface. 



Entosiphon Stein. 

 Representative species. . . Entosiphon sukatus Stein 1S78. 



Body oval, flattened; anterior border oblique, with a concavity at the 

 bottom of which is the mouth leading into a long tubular phar>'nx. 

 Nucleus posterior. Contractile vacuole anterior. Length 22 ti. Pond 

 water, among aquatic plants. 



Fig. 416. Entosiphon sukatus. X 500. (.\fter Conn. 



118(2) With protoplasmic collars. . . Subclass Choanoflagellata . . 119 

 119(122) Not forming colonies 120 



