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CHAPTER, XT, 
THE ROTIFERA. 
THE Roftifera are a genus of microscopic animals belonging to 
the class Rotatoria. They owe their appellation to an organ which 
when in action has the appearance of a revolving wheel. Originally 
they were classed among the infusoria, but upon the discovery of 
FURCULARIA. 
their higher organisation they were promoted from one class into 
another, until they now occupy a place at the entrance of the class 
which we are about to consider—the crustaceans. There seems 
much reason to believe that they are a permanent form of the larva 
of the crustaceans. The bodies of the rotifers are generally fusiform, 
and are covered not with a shell, but with a very firm, transparent 
skin. In those species called wszvalves this hide is all of one piece, 
whereas the dzva/ves have a division along the ridge of the back. 
The peculiar organ which has given to the race their appellation, is 
fixed to the anterior part of the body, and consists of a lobed disc, 
which is usually furnished with vibratory cils. This organ is the 
fin or swimming apparatus, and when in motion presents the 
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