FLAGELLATE PROTOZOA (MASTIGOPHORA) 255 



99 (100) Resembling Sphenomonas, but without ridges; flagella two, unequal. 



Clostonema Stokes. 

 Representative species Clostonema socialis Stokes 1886. 



Body fusiform, with a short, rounded posterior prolongation. Primary flagel- 

 lum as long as the body; secondary, about one-fourth as long. A long, pha- 

 ryngeal passage present. Length about 20 . In standing water. 



FIG. 407. Clostonema socialis. x 600. (After Stokes.) 



100 (99) Resembling Clostonema, but with a single flagellum. 



Menoidium Perty. 

 Representative species. 



Menoidium pellucidum Perty 1852. 



Body lunate, obliquely truncated at the anterior extremity. Pos- 

 terior end rounded. The short side of the body thin and sharp, the 

 long side rounded. Flagellum equalling the body in length. One or 

 more amylaceous corpuscles usually present. Length 40 to 60 M. 

 Fresh water. 



FIG. 408. Menoidium pellucidum. X 500. (After Senn.) 



101 (88) Body rigid or plastic, usually symmetrical; one or two dissimilar 



flagella deeply sunk in the body. Nutrition holozoic. 



Family PERANEMIDAE . . 102 



102 (109) Body plastic 103 



103 (108) One flagellum 104 



104 (105) Oval, flattened, very flexible; distinct pharynx and rod-like organ 



back of the mouth . Peranema Dujardin. 



Representative species. 



Peranema trichophorum Ehrenberg 1838. 



Cuticle finely marked spirally. Flagellum very long, vibratile at the tip 

 only. Nucleus central. 



FIG. 409. Peranema trichophorum. X 250. (After Conn.) 



Conn reports a number of undetermined forms which bear considerable 

 resemblance to the above species and should, without doubt, be assigned 

 to the genus Peranema. 



105 (104) Flask-shaped; neck-like anterior end with elongated pharynx and 

 rod-like organ 106 



