CILIATE PROTOZOA (INFUSORIA) 



279 



74 (73) 



Body very flexible and changeable in shape. Ovate, covered with 

 fine cilia, with a long bristle extending from the posterior 

 border. Mouth ventral with a vibratile and retractile hood- 

 like velum .... Saprophilus Stokes. 



Representative species Saprophilus agitatus Stokes 1887. 



Body twice as long as broad, compressed, obliquely truncate in front; 

 cilia very short and fine. Body longitudinally striate. Nucleus sub- 

 central. Contractile vacuole posterior. Length of body 35 to 45 11. 

 Infusions containing animal matter. 



Fig. 490. Saprophilus agitatus. X 3go. (After Stokes.) 



75 (72) Mouth terminal with a delicate membrane. Body ovate, elastic; 



anterior extremity obliquely truncate. . Trichoda Miiller. 



Representative species. . . Trichoda pura Ehrenberg 1838. 



Length 40 ^. Often found abundantly in old infusions of pond 

 water. Swift moving, usually rolling on its long axis. 



Fig. 491. Trichoda pura. macn, macronucleus. X 400, (After Kent.) 



76 (71) Two membranes present 77 



77 (78) Body elongated, rounded in front, contracting into a tail behind. 



One side somewhat flattened, the other convex. Mouth 



triangular, near the anterior end. . . Dallasia Stokes. 



Representative species Dallasia frontata Stokes 1886. 



Body five times as long as broad, ventral 

 surface convex, dorsal slightly concave; taper- 

 ing posteriorly to a retractile tail-like prolonga- 

 tion. Anterior extremity narrow. Mouth 

 obliquely placed on the ventral surface. Length 

 150 /x. Still water, with aquatic plants. 



Fig. 492. Dallasia frontata. X 335. (After Conn.) 



ffi?--'' 



78 (77) Body not contracting into a tail 79 



79 (84) With a long, posterior bristle 80 



80 (83) Without a spiral row of long cilia 81 



81 (82) Body ovate, sHghtly compressed, broader behind; ventral surface 

 straight, dorsal surface curved. Mouth near or anterior 

 to the middle, with an extensile membrane. Cilia densely 

 arranged in a furrow in front of the mouth. 



Uronema Dujardin. 

 Representative species Uronema marinum Dujardin 1841. 



The cilia are exceedingly vibratile, their movements being ir- 

 regular and independent. Nucleus central. Contractile vacu- 

 ole posterior. Length 30 n. Fresh water, often associated with 

 Cyclidium but not so numerous. 



Fig. 493. Uronema marinum. X 400. (After Kent.) 



