MASTIGOPHORA 33 



Key to the genera of Astasiidae here described : 



Oi Body very flexible 1. Astasia 



02 Body rigid, sickle-shaped 2. Menoidium 



1. Astasia Ehrenberg. Body spindle-shaped; very 

 plastic, with striped ciiticula: 2 species; in fresh and salt 

 water. 



A. contorta Dujardin (Fig. 38). Length .06 mm.: 

 in decaying vegetation. 



2. Menoidium Perty. Body elongate and more or 

 less bent, and rigid; cuticular stripes longitudinal: 1 

 species. 



M. pellucidum Perty. Length .08 mm.: in fresh 

 water. Fig. 33 



Family 3. PEEANEMIDAE. Astasia 



contorta 



Body usually cylindrical or ovate, plastic or rigid, ^ ^^^'' 



and covered by a striped cuticula; 1 or 2 flagella present, at the 

 base of which is a distinct mouth; no chlorophyll present: 14 

 genera. 



Key to the genera of Peranemidae here described: 



Oi Body plastic. 

 &i Body elongate, attenuated forward 1. Peranema 



62 Body bottle-shaped 2. Urceolus 



02 Body rigid ; two flagella. 



61 Pharynx not deep 3. Anisonema 



63 Pharynx very deep 4. Entosiphon 



1. Peranema Dujardin. Body tapers from behind 

 forward and very plastic, with a spirally striated cuticula 

 and a single flagellum, the tip of which vibrates when the 

 animal moves: 1 species. 



P. trichophorum (Ehrenberg) (Fig. 39). Length .08 

 mm.: in fresh water. 



2. Urceoltts Mereschkowski. Body spherical or ovate 

 with a neck from which the .flagellum emerges : 

 1 species. 



U. cyclostomus (Stein). Length .03 mm.: 

 in fresh water. 

 Pjg 39 3. Anisonema Dujardin. Body ovate and 



Peranema compressed with striated cuticula and a r. ^ • t 



•ffinhnnlinvii'm. LntOSipflOn 



(Conn). lateral gToove; 2 flagella, 1 of which trails Y^^^''^")*^ 

 behind: 3 species; in fresh and salt water. 

 A. vitreum Duj. Body transparent and with longitudinal furrows; 

 length .05 mm. 



