164 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Family Oxytrichid^e. 



Peristome somewhat indistinct. Cilia limited to a few on the ventral 

 surface, usually arranged in rows or groups. Anal and frontal styles 

 present. 



Genus Urostyla Ehr. 



Body flexible, elongated oval, flattened ventrally, convex dorsally. 

 Peristome acutely triangular. Three or more frontal styles; several rows 

 of ventral styles; from 5 to 12 anal styles, set in an oblique row; an 

 uninterrupted border of marginal setae. Macronucleus single or multiple. 

 Contractile vacuole single, located near the end of the peristome on the 

 left-hand border. 



Urostyla grandis Ehr. 



Body ovate, variable in form, from three to four times as long as broad. 

 Peristome field narrowly triangular, about one-third the length of the 

 body, its reflected border ciliated. Numerous frontal styles between the 

 reflected border of the peristome and the right-hand margin of the body; 

 several slender anal styles, obliquely set; numerous rows of ventral cilia. 

 Usually two macronuclei, each with its attached micronucleus. 



Found in infusions of hay and leaves. 



Lengths given vary from 250 to 410 microns. Length of type speci- 

 men, 250 microns. (Fig. 48, plate XLIV.) 



Genus Uroleptus Ehr. 



Body narrow, greatly elongated, persistent in form but highly flexible. 

 Anterior extremity rounded, posterior extremity prolonged into a tail- 

 like projection. Three or four frontal styles; usually two median longi- 

 tudinal rows of ventral setaa; no anal styles; marginal setae well set in on 

 the ventral surface. Contractile vacuole located near the posterior end of 

 the peristome. 



Uroleptus agilis Ehr. 



Body greatly elongated, four to five times as long as broad, widest 

 centrally, rounded anteriorly, prolonged posteriorly into a narrow, tail- 

 like prolongation, which sometimes curves toward the right. Peristome 

 narrowly triangular, about one-fifth the length of the body. Four frontal 

 styles; two median rows of ventral styles, additional ventral styles some- 

 times produced ; marginal series of setae complete, somewhat longer in the 

 posterior region. Macronuclei ovate, two in number. Contractile vacuole 

 located anterior to the middle of the left-hand border. 



Length given varies from 83 to 250 microns. Length of type sped* 

 men, 180 microns. (Fig. 40, plate XLII.) 



Genus Onychodromus Stein. 



Body nearly rectangular, extremities more or less rounded. Peristome 

 broadly triangular, extending to the middle of the body. Three rows of 

 frontal styles, parallel to the peristome and located between its reflected 

 border and the right-hand margin of the body; three or four rows of 

 ventral styles; an uninterrupted series of marginal setae; five or six anal 

 styles. Usually four macronuclei with attached micronuclei. Contractile 

 vacuole single, located on the left-hand side, near the posterior angle of 

 the peristome. 



