CILIATE PROTOZOA (INFUSORIA) 



289 



154 (155) 



Body elongate-oval, with five to eight frontal styles; ventral setae 

 usually arranged in two or more rows, the inner rows having 

 but few setae. Anal styles five or six, two of which are near 

 the posterior border Plciirotricha Stein. 



Representative species. . . Pleurolrichalanceolata¥j\\vQr\hcTg\9>T,^. 



Somewhat resembling Stylonychia but without caudal setae and 

 with anal styles arranged in two groups. Nuclei two in number, 

 one in front of the apex of the peristome. Length 250 m- Among 

 algae. 



Fig. 525. Pleurotriclia lanceolate. X112. (After Edmondson.) 



155 (154) 



Body somewhat rectangular in outline with slightly rounded ends. 

 Three or four obHque rows of ventral setae running from 

 left to right, and three rows parallel to the peristome Ijorder. 

 Anal styles five or six. Border ciha uninterrupted. 



Onychodromiis Stein. 



Representative species Onychodromiis grandis Stein 1859. 



Body not flexible. Frontal styles from sixteen to 

 twenty-eight, in three rows. Anal styles from five to 

 seven. Nuclei usually four. Length 100 to 300 ti. 

 Onychodromopsis flexilis Stokes differs from Stein's form 

 in having a soft, flexible body. 



Fig. 526. Onychodromus grandis. x 125. (After Conn.) 



156 (153) Ventral setae in one obHque row. Body elongate-oval. Five or 

 six frontal styles and as many anal. Peristome triangular, 

 curved, with an undulating membrane. 



Gastrostyla Engelmann. 

 Representative species. . . . Gastrostyla steinii Engelmann i86-\ 



Body evenly rounded at each extremity. Three very 



large frontal styles near the border. Anal styles five, 



^ ==^^ i^ ^" obHque row, not projecting beyond the border. 



Nuclei four. Contractile vacuole near the middle of the 



v>\N body on the left side. Length 250 m- Fresh water. 



Fig. 527. Gastrostyla steinii. X 125. (.\fter Edmondson.) 



157(132) Ventral cilia few, not in rows 158 



158(165) Not produced posteriorly into a tail-hke process 15Q 



159 (162) Body flexible 160 



160 (161) Border cilia uninterrupted. Narrow, elliptical, rounded^ at both 



ends. Five ventral setae and five anal styles. No caudal 

 bristles. Inner right wall of peristome bent toward outer 



left wall Oxytricha Ehrenberg. 



Representative species. . . . Oxytricha pell ioftelld MiJUleT lySe. 



^^^^^^^^^'^'^'^^'^^^^'r^ Marginal setae set well in on the ventral surface. 



■-■o'^-Q-; .' -^^b^/ .Anal styles arising near the iiosterior lK)rdcr and vx- 



'" '^^*^<^^ tending' nearly their entire length beyond it. Nuclei 



*i;^tf^^!^^P two. Contractile vacuole on the left side. Length So 



^^'^ii^iic--''^ \im\ j.^^ jQQ ^ Common in infusions and fresh water. 



Fig. 528. Oxytricha peUionella. X 335. Opisthotricha Kent resembles Oxytri<h<i in general 



(After Conn.) characteristics but has three caudal setae. 



