The Animalcules, continued. 



135 



lost its tenant. I tried the experiment of mounting 

 it in balsam, which answered perfectly. The object 

 is now before me, under a high magnifying power. 

 It stands like a tower, its front battlements showing 

 well, and those farthest from the eye appearing in 

 distant perspective. The round bricks, by mutual 

 pressure have assumed the hexagonal form, giving an 

 ornamental appearance to the little edifice. 



The second tribe of rotifers, namely, those which 



No. 21. Philodina. 



frequently attach themselves by the foot, but which 

 are able to swim, has been represented by the com- 

 mon wheel-animalcule. The rotifer represented in 

 No. 21, pliilodina, is another example. Its method 

 of walking is similar to that practised by the 

 common rotifer; and, like it, this rotifer can 

 draw itself into a globular and rather uninterest- 

 ing form when at rest, and disinclined for wheel- 

 exercise. 



The third tribe are pretty little animals, often 

 possessing a cuirass or carapace of hard material, 



