CALLIDINA. 161 



caused by the rapid movement of the cilia and 

 the swift motion through the water, but repeated 

 observation undeceived me. 



The individuals of the family next under con- 

 sideration are not cased in a lorica, and are very 

 peculiar, from the form being more or less spin- 

 dle-shaped, and from their having the power of 

 sliding some portions of the body within each 

 other, like the tubes of a telesc6pe, so that it is 

 either long or short at the will of the creature. 

 This construction is very wonderful, when we 

 consider the mechanism and muscular power 

 required to effect it. Actinnrus Neptunius is the 

 most striking example of this peculiarity. The 

 genera are as follows :- 



The Cattidina elegam is found in bog- water, 



TIT 



