DROP IV. 



THE animalcules comprised under the class Ro- 

 tatoria are of a higher organization than those 

 already mentioned ; the body is of a more 

 definite form (not changing its shape, or dividing 

 spontaneously, as is the case with many of the 

 Polyffastrica), having but one digestive cell, in the 

 form of a tubular alimentary canal, being pro- 

 vided with a rotatory organ, and in general a 

 single foot, or process, by which it clings to sub- 

 stances in the water. Of the cilia, and their 



