SPIROTRICHA, HYPOTRICHA 839 



into 2-8 parts; fresh or salt water. Morphology and physiology 

 (Weyer, 1930). 



G. muscorum Kahl (Fig. 356, k). 130-200^ long; macronucleus in 

 8 parts; fresh water in vegetation. 



Genus Stylonychia Ehrenberg. Ovoid to reniform; not flexible; 

 ventral surface flat, dorsal surface convex; 8 frontals; 5 ventrals; 

 5 anals; marginals; 3 caudals; with short dorsal bristles; fresh or salt 

 water. Many species. 



S. mytilus (Muller) (Fig. 357, a). 100-30(V long; fresh, brackish 

 and salt water. Encystment (von Brand, 1923). 



S. pustulata E. (Figs. 93; 357, b). About 150/j, long; fresh water. 

 Cytology (Hall, 1931) ; division and reorganization (Summers, 1935). 



S. putrina Stokes (Fig. 357, c). 125-150/x long; fresh water. 



S. notophora S. (Fig. 357, d). About 125^ long; standing water. 



Genus Onychodromus Stein. Not flexible; somewhat rectangular; 

 anterior end truncate, posterior end rounded; ventral surface flat, 

 dorsal surface convex; peristome broadly triangular in ventral view; 

 3 frontals; 3 rows of cirri parallel to the right edge of peristome; 5-6 

 anals; marginals uninterrupted; 4-8 macronuclei; contractile vacu- 

 ole; fresh water. One species. 



0. grandis S. (Fig. 357, e). 100-300^ long. 



Genus Onychodromopsis Stokes. Similar to Onychodromus; but 

 flexible; 6 frontals of which the anterior three are the largest; fresh 

 water. One species. 



O.flexilis S. (Fig. 357,/). 90-125/z long; standing pond water. 



Family 2 Euplotidae Claus 



Genus Euplotes Ehrenberg. Inflexible body ovoid; ventral surface 

 flattened, dorsal surface convex; longitudinally ridged; peristome 

 broadly triangular; frontal part of adoral zone lies in flat furrow; 9 

 or more frontal- ventrals; 5 anals; 4 scattered caudals; macronucleus 

 band-like; a micronucleus; contractile vacuole posterior; fresh or 

 salt water. Many species. Comparative morphology (Pierson, 1943). 



E. patella (Muller) (Fig. 357, g). Subcircular to elliptical; average 

 dimensions 91^ by 52^; 9 f rontal-ventrals ; aboral surface with 6 pro- 

 minent ridges with rows of bristles embedded in rosettes of granules; 

 peristome narrow; peristomal plate small triangle; macronucleus 

 simple C-form band; micronucleus near anterior-left end; membra- 

 nellae straight; posterior end of cytopharynx anterior to, and to left 

 of, the fifth anal cirrus; post-pharyngeal sac; fresh and brackish 

 water. Doubles and amicronucleates (Kimball, 1941) ; mating types 

 (p. 194). 



