INFUSORIA, OR FRESH-WATER ANIMALCULES. 31 



produces an appearance of a rotatory motion, like that 

 of a wheel on its axis; and this resemblance is so 

 striking, that the name Botifera, or wheel-bearing ani- 

 malcules, is given to the Infusoria possessing this char- 

 acter; which are also further distinguished, by a more 

 highly endowed organisation than the other species. 

 The Infusoria are therefore arranged by Ehrenberg in 

 two classes, which are respectively designated POLYGAS- 

 TRIA, and ROTIFERA. 



