1918] Yocum: The Neuromotor Apparatus of Euplotes Patella 339 



ventral surface is feebly denticulated. Cirri similar to the above 

 species. Length, 78-96 microns. 



Euplotes worcesteri Griffin. Body oval, anterior end rounded, pos- 

 terior end bluntly pointed; dorsal surface much curved and usually 

 characterized by eight rows of sensory bristles; ventral surface flat- 

 tened, cytostome broad, containing forty-five to seventy membranelles 

 while the pharynx contains twenty to thirtj" membranelles. Ten cirri 

 anterior to the five anal cirri and from two to five marginal cirri. 

 Length, 72-93 microns. 



Euplotes vannus 0. F. M. Closely resembles E. ivorcesteri in 

 general structure. Usually the pharynx of E. vannus is shorter than 

 that of E. ivorcesteri. The most important difference is that the pos- 

 terior end of the macronucleus of E. vannus is recurved op itself and 

 slightly enlarged. 



Euplotes patella has an elliptical cuirass, somewhat truncated 

 anteriorly with a projecting lip extending anteriorly from the cyto- 

 stomal field. The dorsal side is convex, w^hile the ventral side is con- 

 cave, markedly so in the anterior part. A series of membranelles 

 extends along the left side of the wide triangular cytostome and into 

 the pharynx posteriorly, while anteriorly it is continued around the 

 anterior end dorsal to the lip, to the right anterior corner of the cyto- 

 stomal field. The right anterior ventral field bears nine styliform 

 cirri, six of which according to Kent (1881) are termed frontal cirri, 

 while the other three are the abdominal or ventral cirri. Five heavy 

 anal cirri extend backward over the posterior margin of the body from 

 the posterior ends of five parallel ventral grooves which begin near the 

 middle of the body to the right of the cytostome and extend back to 

 within twenty to twenty-five microns of the posterior end of the body. 

 There are four caudal cirri, the two to the right being fimbricated 

 (pi. 14, fig. 4). 



The dorsal surface is marked by eleven parallel equidistant rows 

 of granules arranged in rosettes (pi. 14, fig. 7). The macronucleus is 

 roughly C-shaped with the open side of the C to the right {mac., fig. 

 A). The micronucleus is a small spherical body lying in an indenta- 

 tion on the anterior left side of the macronucleus {mic, fig. A). The 

 single contractile vacuole lies just anterior to the anal cirri (c. v., 

 fig. A). 



While Euplotes is of widespread occurrence, little literature is 

 found which indicates an intensive study of the animals belonging to 

 the genus. As has been mentioned Ehrenberg (1838) gave a brief 



