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 u. 

 Infusions containing animal matter. 



FIG. 490. Saprophilus agitatus. X 390. (After Stokes.) 



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



anterior extremity obliquely truncate. . . Trichoda Miiller. 

 Representative species Trichoda pur a Ehrenberg 1838. 



Length 40 M- 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 ;.' .:**'.- "* : "-'v . 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 A*. Still water, with aquatic plants. 



FIG. 492. Dallasia frontata. X 335- (After Conn.) 



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. -"". 7 '. . 81 



8 1 (82) Body ovate, slightly 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 

 Cyclidiwn but not so numerous. 



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



