CILIATE PROTOZOA (INFUSORIA) 



287 



(137) Peristome with an undulating membrane, body flexible. Three or 

 more frontal styles. Five to twelve anal styles in an oblique 

 row extending to the left. Peristome an elongated triangle. 



Urostyla Ehrenberg. 

 Representative species Urostyla trichogaster Stokes 1885. 



Ventral surface with closely approximated rows 

 of fine cilia. Anal styles ten or twelve in number. 

 Nucleus single, according to Stokes. Contractile 

 vacuole single, to the left of the peristome. 

 Length 250 to 300 /* Vegetable infusions. 

 Hemiciplostyla Stokes agrees with Urostyla, but 

 has no anal styles. 



X 1 50- (After Conn found two nuclei in his form and states that 

 it may be a variety of Urostyla grandis Ehrenberg. 



FIG. 517. Urostyla trichogaster. 

 Conn.) 



137 ( J 3 6 ) Peristome without an undulating membrane 138 



138 (139) Elongate, rounded at both extremities, not flexible; five nearly 



straight rows of ventral cilia. Peristome on the right-hand 

 margin, extending back of the middle, with a row of long 

 cilia or membranellae. Nuclei four to six in number. 



Homostyla Conn. 

 Representative species Homostyla elliptica Conn 1905. 



FIG. 518. Homostyla elliptica. X 325. (After Conn.) 



139 (138) Kidney-shaped, with six oblique rows of ventral cilia, the posterior 

 row the stronger. No frontal, ventral, or anal styles. Border 

 cilia forming a complete row around the periphery. Peri- 

 stome reaching to the middle of the body. External para- 

 sites on Hydra. . ....... . . . . . Kerona Ehrenberg. 



Representative species. ..... Kerona pediculus Miiller 1786. 



FIG. 519. Kerona pediculus. x 250. (After Stein.) 



140 (135) Less than five rows of ventral cilia 141 



141 (142) 



Body elongated anteriorly into a neck; rounded behind, very con- 

 tractile. Peristome narrow, extending to or beyond the 

 middle. Membranellae long. Two or three oblique rows 

 of ventral setae. No frontal or anal styles. 



Stichotricha Perty. 



Representative species Stichotricha secunda Perty 1849. 



Marginal setae long and slender. Nuclei two, with 

 the contractile vacuole between. Often a mucilaginous 

 sheath is secreted by the animal, from which it may 

 project the anterior half of the body or may entirely 

 vacate it and swim freely in water. Length about 

 200 p. Among sphagnum. 



FIG. 520. Stichotricha secunda. X 235. (After Conn.) 



