CILIATE PROTOZOA (INFUSORIA) 



279 



74 (73) Body very flexible and changeable in shape. Ovate, covered with 

 fine ciUa, with a long bristle extending from the posterior 

 border. Mouth ventral with a vibratile and retractile hood- 

 like velum Saprophilus Stokes. 



Representative species Saprophilus agilatus 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 n. 

 Infusions containing animal matter. 



Fig. 490. Saprophilus agilalus. 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. (.^fter 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 froutata Stokes 1886. 



Body five times as long as broad, ventral 

 surface convex, dorsal slightly concave: taper- 

 ,^„^^ ing posteriorly to a retractile tail-like prolonga- 

 ^^^^^.-^ >^ ^-^J^ tion. Anterior extremity narrow. Mouth 



^ll^\ ^ .,__ jM^'~~ obliquely placed on the ventral surface. Length 



'*'^' " '^ 150 M- 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 81 



81 (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. 



Uroncma Dujardin. 

 Representative species Uroncma marinum Dujardin 1841. 



The cilia are exceedingly vibratile, their movements being ir- 

 regular and independent. Nucleus central. Contractile vacu- 

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

 Cyclidium but not so numerous. 



Fig. 493. Uroncma marinum. X 400- (After Kent.) 



