No. 2.] FRESH-WATER PROTOZOA. 6l 



St. notophora Stokes, Fig. 259. 



St. sp. ( ?), Fig. 267. Perhaps a variety of St. mytilis. 



St. putrina Stokes, Fig. 269. 



St. my tikis Miill., Fig. 273. 



St. Ussieta C. & L., Fig. 282. 

 Euplotes Ehrbg. (Stein). 



Armored, inflexible, round to oval outline, with ven- 

 tral surface flat, and dorsal surface convex ; ribbed. Per- 

 istome large, broad, three-angled, reaching the middle of 

 the body or still further back. The right edge of the 

 peristome slightly drawn out to partly cover the peris- 

 tome. Nine or ten large cilia upon the sternum; five 

 large anal cilia and four border cilia, two of which are 

 usually at the hind end and two at the posterior left lateral 

 border. Nucleus ribbon-like on the left side, bending in 

 front and behind toward the right. Secondary nuclei 

 near the left front end of the nucleus. Contractile vacuole 

 on the right border. 



En. sp. (?), Fig. 268. 



Eu. carinata Stokes, Fig. 270. 



Eu. plumipes Stokes, Fig. 271. 



Eit. charon Miill., Fig. 272. 

 Aspidisca Ehrb'g. 



Inflexible, round or short oval in outline. Left side 

 slightly and right side strongly curved; ventral side flat, 

 dorsal side convex. Right border thickened. Adoral 

 zone not extending around the anterior end, but reaching 

 backward beyond the middle of the body. The right bor- 

 der of the peristome extends over the peristome so that it 

 is open only by a narrow opening on the left side. An- 

 terior border with a bay-like depression, or sometimes 

 drawn out into a hook-like process. Hind end of the 

 peristome border with one or more teeth from which a 

 transverse channel extends over the ventral surface in 

 front of the anus. Seven scattered ventral cilia, and com- 

 monly five anal cilia. Nucleus thread-like, sometimes 

 describing a complete circle. Contractile vacuole simple. 



Asp. costata Duj., Fig. 281. 



Asp.sp. (?),Fig. 280. 



