107 





CLASS III. ROTIFERA. 



THESE are animals so minute as to be appre- 

 ciable only by the microscope ; but affording, by 

 their crystalline transparency, the elegance of 

 their forms, the complexity of their internal struc- 

 ture, their beautiful ciliary wheels, and their lively 

 motions, peculiarly interesting objects of study 

 under that instrument. The great majority of 

 the forms are found only in fresh water, very few 

 indeed being recognised as marine : but these 

 exhibit considerable diversity. The most con- 

 spicuous character of the Class is that the front 

 parts are set with one or more circles of cilia, 

 which, waving in regular succession and perfect 

 order, present the appearance, to the eye, of one 

 or more wheels revolving rapidly, as if by the 

 power of machinery. 



Localities, &c. Synchceta swims at large through 

 the water, never resting; it is self-luminous, and 

 is one of the causes of the phosphorescence of the 

 sea. Brachionus Mulleri and Pterodina dypeata 

 occur in the brackish water at the mouths of rivers. 

 The other marine species may often be detected by 

 searching with a pocket-lens the glass sides of a 

 well-stocked Aquarium. 



Authorities. Ehrenberg's "Die Infusions-thier- 

 chen " is the standard authority for nomenclature 



