SPIROTRICHA, HYPOTRICHA 677 



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/i long; 

 fresh water. 



E. carinatus S. (Fig. 318, a). About 70/x by 50/i; fresh water. 



E. Charon (Miiller) (Fig. 318, h). 70-90^ long; salt water. 



Genus Euplotidium Noland. Cylindrical; 9 frontal-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. 



E. agitatum N. (Fig. 318, c, d). 65-95^ long; erratic movement 

 rapid ; observed in half -dead sponges in Florida. 



Genus Certesia Fabre-Domergue. Ellipsoid; flattened; dorsal 

 surface slightly convex, ventral surface flat or concave; 5 frontals 

 at anterior border; 7 ventrals; 5 anals; no caudals; marginals small 

 in number; 4 macronuclei; salt water. One species. 



C. quadrinucleata F.-D. (Fig. 318, e). 70-100/x by about 45)u. 

 Genus Diophrys Dujardin. Peristome relatively large, often 



reaching anals; 7-9 frontal-ventrals; 5 anals; 3 strong cirri right- 

 dorsal near posterior margin; salt water. 



D. appendiculata (Ehrenberg) (Fig. 318, /). 60~100/x long; salt 

 water; Woods Hole (Calkins). 



Genus Uronychia Stein. Without frontals and ventrals; 5 anals; 



3 right-dorsal cirri (as in Diophrys); 2 left-ventral cirri near posterior 

 margin; peristome, oval with a large undulating membrane on 

 right edge; salt water. Several species. 



U. setigera Calkins (Fig. 318, g). 40/x by 25^; salt water; Woods 

 Hole. 



Family 3 Paraeuplotidae Wichterman 



Genus Paraeuplotes Wichterman. Ovoid; ventral surface slightly 

 concave, dorsal surface highly convex and bare, but with one ridge; 

 frontal and adoral zones well developed; ventral surface with a semi- 

 circular ciliary ring on the right half, posterior half of which is 



