SPIROTRICHA, HYPOTRICHA 841 



E. eurystomus Wrzesniowski (Fig. 357, h). Elongated ellipsoid; 

 length 100-195/*; average dimensions 138/* by 78/*; 9 f rontal-ventrals ; 

 no aboral ridges, but 7 rows of bristles ; peristome wide, deep ; peri- 

 stomal depression sigmoid; membranellae forming sigmoid curve; 

 end of cytopharynx far to left and anterior to the fifth anal cirrus; 

 post-pharyngeal sac; macronucleus 3-shaped; micronucleus near 

 flattened anterior corner of macronucleus; fresh and brackish water. 

 Division and conjugation (Turner, 1930); neuromotor system (Tur- 

 ner, 1933; Hammond, 1937; Hammond and Kofoid, 1937). 



E. woodruffi Gaw (Fig. 357, i). Oval; length 120-165/*; average 

 dimensions 140/1 by 90/*; 9 f rontal-ventrals ; aboral surface often 

 with 8 low ridges; peristome wide, with a small peristomal plate; end 

 of cytopharynx almost below the median ridge; 4th ridge between 

 anal cirri often extends to anterior end of body; post-pharyngeal sac; 

 macronucleus consistently T-shaped; micronucleus anterior-right; 

 brackish (with salinity 2.30 parts of salt per 1000) and fresh water 

 (Gaw, 1939). 



E. aediculatus Pierson (Fig. 357, j). Elliptical; length 110-165/*; 

 average dimensions 132/* by 84/*; 9 f rontal-ventrals ; aboral surface 

 usually without ridges, but with about 6 rows of bristles; peristome 

 narrow; peristomal plate long triangular, drawn out posteriorly; a 

 niche midway on the right border of peristome; anal cirri often form 

 a straight transverse line; 4th ridge between anals may reach anterior 

 end of body; macronucleus C-shape with a flattened part in the left- 

 anterior region; micronucleus some distance from macronucleus at 

 anterior-left region; post-pharyngeal sac; fresh and brackish (salin- 

 ity 2.30 parts of salt per 1000) water. 



E. plumipes Stokes. Similar to E. eurystomus. About 125/* long; 

 fresh water. 



E. carinatus S. (Fig. 358, a). About 70/* by 50/*; fresh water. 



E. charon (Miiller) (Fig. 358, b). 70-90/* long; salt water. 



Genus Euplotidium Noland. Cylindrical; 9 f rontal-ventrals in 2 

 rows toward right; 5 anals; a groove extends backward from oral 

 region to ventral side, in which the left-most anal cirrus lies; peri- 

 stome opened widely at anterior end, but covered posteriorly by a 

 transparent, curved, flap-like membrane; adoral zone made up of 

 about 80 membranellae; longitudinal ridges (carinae), 3 dorsal and 

 2 lateral; a row of protrichocysts under each carina; a broad zone 

 of protrichocysts in antero-dorsal region; cytoplasm densely granu- 

 lated; salt water. One species (Noland, 1937). 



E. agitatum N. (Fig. 358, c, d). 65-95/* long; erratic movement 

 rapid; observed in half-dead sponges in Florida. 



