r6tifers. 



223 



or to Myriophyllum, and are often visible to the un- 

 aided eye as grayish little balls. 



2. Stephan6ceros (Fig. 155). 

 The body of this, the most beautiful of all the Rotifera 

 is somewhat spin'dle-shaped, and ends in a long, flexi- 

 ble, tail-like foot which is attached to some submerged 

 object. It has its characteristic fea- 

 ture in the five long, slightly curved 

 arms arranged in a row about the edge 

 of the front border, these arms being 

 held aloft, and forming a beautiful 

 object for the microscopist, but an 

 effectual trap for wandering Infusoria, 

 which are attracted or drawn into it 

 by some means not easy to make out, 

 but probably by ciliary action difficult 

 to observe. 



The front of the body is like a deep 

 open funnel leading down to the pre- 

 oral aperture, to the mastax, and to 

 the stomach. The ordinary ciliary 

 disk is absent, being replaced by the 

 beautiful arms, but around the lower 

 inside border of the funnel-like front there are 

 many fine cilia that produce the currents in the 

 water by which the living food is drawn to the trap. 

 These cilia are exceedingly fine and difficult to see 

 even with a high-power objective. 



The sheath is usually colorless and transparent but 

 with considerable firmness. It often surrounds the 

 body up to the origin of the arms. 



When a small animal once enters the cage formed 

 by th.ese arms, beautiful objects as they are, it seldom 



Fig. 155- 

 Stephan6ceros. 



