66 



A HALF-HOUR WITH THE 



The wheel-animalcules abound in our ponds and 

 nvers, and sometimes occur in great numbers in 

 ^he aquarium. They are very varied in their 

 forms, and some of them possess great beauty. 

 Several of them are fixed, forming on the outside 

 of their bodies a little case or tube, in which they 

 dwell. 



