CILIATE PROTOZOA (INFUSORIA) 283 



102 (103) Body flattened, oval, with spiral furrows. Peristome with a vi- 

 brating membrane posterior leading into the mouth. A 

 tuft of long bristles at the posterior end of the body. 



Cinetochilum Perty. 

 Representative species. 



Cinetochilum margaritaceum Ehrenberg 1838. 



Contractile vacuole posterior, opposite the mouth, with nucleus an- 

 terior to it. Length 30 M. Very common hi pond water. 



FIG. 505. Cinetochilum margaritaceum. X 500. (After Butschli.) 



103 (102) Body nearly oval, ventral surface flat, ciliated; dorsal surface 



curved, with three longitudinal grooves. Mouth posterior 

 on the left side, with a small, vibrating membrane. 



Microthorax Engelmann. 

 Representative species. . . Microthorax sulcatus Engelmann 1862. 



Associated with the preceding species. Length 40 to 60 n. 

 FIG. 506. Microthorax sulcatus. X 310. (After Kent.) 



104 (3) An adoral zone present consisting of cilia fused together into mem- 



branellae. . Order Heterotricha . . 105 



105 (120) With a uniform covering of cilia 106 



106 (115) Peristome not confined to the anterior border of the body. . 107 



107(112) Peristome a long, narrow furrow 108 



1 08 (in) With an undulating membrane 109 



109 (no) Body flattened, narrow and hook-like in front. Mouth near the 

 middle of the body at the end of the narrow peristome. 

 Membranellae on the left wall of the peristome, on the right 

 an undulating membrane. Colored. . Blepharisma Perty. 

 Representative species. . . Blepharisma lateritia Ehrenberg 1838. 



Body usually truncate behind; nucleus in the anterior half of the body. Contrac- 

 tile vacuole posterior. Color, peach-bloom. Length 1 50 n. Among aquatic plants. 



FIG. 507. Blepharisma lateritia. X 180. (After Stein.) 



