r6tifers. 215 



become temporarily adherent by means of their foot 

 and toes. The body of these free-swimming forms 

 may be soft and flexible, and without any greater pro- 

 tection than is afforded by the skin, or it may be en- 

 closed within a hard, shell-like coating. called a lorica. 

 The bodies of all sheath-building Rotifers are without 

 a lorica, the sheath or tube being a sufficient protec- 

 tion. In the other kinds the lorica is as colorless and 

 transparent as a glass box, all the creature's organs 

 being plainly visible through its walls. The front part 

 of the body, which bears the cilia or the ciliary disks, 

 and often the long tail-like prolongation of the poste- 

 rior part can be drawn within it, and the Rotifer thus 

 be shut in and protected from harm. The soft-bodied 

 forms have a similar habit of drawing in the two ex- 

 tremities, taking advantage of the hardened skin. 

 This is one of the Rotifers' characteristics. 



The long tail-like part at the posterior end of the 

 body is called the foot, and the one or two short divis- 

 ions at the free end of the foot are, of course, the toes. 

 The true tail of the Rotifer is usually a small affair, 

 which the observer must not mistake for the more im- 

 portant foot, although it is placed on the foot, and 

 sometimes near to the body. It may be represented 

 by a single short point; it may be in two parts and 

 rather conspicuous; or it liiay be entirely absent. 



The uses of the foot seem to be to act as a rudder 

 to guide the Rotifers when swimming, as they do in a 

 hurried, headlong way, and to anchor them when they 

 desire to fish for food, the toes then adhering to the 

 surface of the slide or other object, thus holding the 

 animal against the propelling power of the ciliary 

 disks. In some of the group, especially in the com- 



