Planarians. 



59 



FIG. 35. 



CLASS I. Tnrbellaria. The simplest worms 

 with which we are acquainted are found on the sea- 

 shore, under or adhe- 

 rent to stones, or else 

 in fresh water pools, 

 as small ciliated, flat- 

 tened soft bodies, 

 which glide with a 

 slug-like motion over 

 wet surfaces, or swim 

 by the vibrations of 

 their cilia. These 

 Turbellarians (so cal- 

 led from the commo- 

 tion produced by their 

 cilia in the water 

 around them) have a 

 mouth placed gene- 

 rally beneath, not at 

 the anterior extremity, 

 and the part of the 

 digestive canal imme- 

 diately within the 

 mouth is protrusible 

 as a kind of proboscis. 

 This contains, in some 

 of the larger forms, a ?'&**** 

 spine or dart, which 



is used as a weapon of offence, and being supplied 

 with poison from a little poison-gland at its base, acts 

 as a formidable weapon against the minute creatures 

 upon which these animals feed. The digestive canal 



common Turbelia- 



