282 



FRESH-WATER BIOLOGY 



96 (95) Like Pleuronema but with a shorter peristome and one or more long 



posterior bristles Cyclidium Ehrenberg. 



Representative species. . . . Cyclidium glaucoma Ehrenberg 1838. 



Cilia long and rigid, in longitudinal rows. Nucleus central; 

 contractile vacuole posterior. Length 20 >i. Very abundant in 

 stagnant water. 



Fig. 501. Cyclidium glaucoma. X 625. (After Edmondson.) 



97 (92) Without an oral membrane. Body ovate; mouth ventral at the 



posterior end of a longitudinal groove which bears on its 

 right-hand border a row of large, arcuately curved setose 

 cUia diminishing in length toward the mouth. A long 

 bristle extending from the posterior end of the body. 



Ctedoctema Stokes. 

 Representative species. . . . Ctedoctema acanthocrypta Stokes 1884. 



Often very abundant among fresh-water algae. 

 Trichocysts are numerous and very stout. Length 

 of body 2$ n. 



Fig. 502. Ctedoctema acanthocrypta. X 875. (After Stokes.) 



98 (89) With a lorica or gelatinous sheath. 



99 



99 (100) Enclosed in a lorica. Animal similar to Pleuronema. Lorica oblong- 

 ovate, hyaline, with tapering extremities, the terminal aper- 

 tures about half as wide as the center of the sheath. Animal 

 very active within the lorica. . . Calyptotricha Phillips. 

 Representative species. . Calyptotricha inhaesa Stokes 1885. 



Kellicott reports this species from Ontario. Length of lorica 180 to 200 /i. 

 Enclosed animal 30 m* Attached laterally to algae. 



Fig. 503. Calyptotricha inhaesa. X 100. (After Kellicott.) 



100 (99) Enclosed in a gelatinous sheath to which the animal is not attached. 

 Body ovate; mouth ventral, at the end of a groove on the 

 margin of which is a series of strong cilia. A tuft of long, 

 curved cQia extends from the anterior extremity. 



Cyrtolophosis Stokes. 

 Representative species. . . . Cyrtolophosis mticicola Stokes 1885. 

 A strange form not uncommon among algae. When the animal 

 comes to rest, a transparent, sticky substance seems to be exuded 

 from the body which becomes granular, due to excreta, bacteria 

 and other foreign bodies which adhere to it. When disturbed 

 the animal glides out of its covering and another is constructed. 

 A temporary colony may be built up by the adherence of several 

 gelatinous sheaths. Length of body 25 n. 



Fig. S04. Cyrtolophosis mucicola. X 875. (After Stokes.) 





--:?i^ 



101 (88) Mouth at the posterior end of the body 103 



