286 FRESH-WATER BIOLOGY 



122 (123) Equatorial region of the body bearing a circle of long, fine bristles. 



Body spheroidal with a spiral wreath of strong cilia about 

 the anterior border. Mouth anterior, marginal. 



H alter ia Dujardin. 

 Representative species Halteria grandinella Mliller 1 786. 



Nucleus round, central, with contractile vacuole near. Moving by a 

 rotary motion accompanied by sudden leaps. Length 25 M. Common 

 in pond water. 



FIG. 514. Halteria grandinella. cv, contractile vacuole; macn, macronucleus. 

 X 400. (After Kent.) 



123 (122) Without long, fine bristles, otherwise very similar to Halteria. 



Strombidium Claparede and Lachmann. 

 Representative species. . Strombidium claparedii Kent 1882. 



Body somewhat elongate, tapering posteriorly. Length 80 n. Pond 

 water. 



FIG. 515. Strombidium claparedii. cv, contractile vacuole; n, nucleus. X 100. 

 (After Kent.) 



124(121) Body in a lorica 125 



125 (126) Lorica mucilaginous, attached to some support. Body ovate to 

 pyriform, attached in the lorica by a pedicel. Mouth ante- 

 rior, surrounded by a wreath of long cilia. 



Tintinnidium Kent. 

 Representative species. . Tintinnidium fluviatilis Stein 1867. 



The lorica has an uneven surface, frequently with incorporated foreign 

 particles. Body sometimes attached to the bottom, sometimes to the side 

 of the lorica. Length of lorica 125 n. Attached to aquatic plants. 



FlG. 516. Tintinnidium ftuviatilis. X 200. (After Entz.) 



126 (125) Lorica chitinous; otherwise as Tintinnidium. . . Tintinnus Fol. 



127 (2) Body not uniformly covered with cilia 128 



128 (169) Cilia setae-like, usually limited to the ventral surface. Dorsal 



surface sometimes with bristles. Body flattened. 



Order Hypotricha . . 129 



129 (130) Ventral side uniformly ciliate, except sternum; a group of stronger 



cilia behind peristome and near posterior end. 



Trichogaster Sterki. 



130 (129) Ventral surface not uniformly ciliate 131 



131 (166) Many border cilia 132 



T 3 2 ( I 57) Ventral cilia numerous, in rows 133 



*33 ( I S 2 ) Ventral cilia bristle-like 134 



134 (143) Usually more than two rows of ventral cilia 135 



135 (140) Five or more rows of ventral cilia 136 



