BRANCH VERMES. 



BRANCH VERMES (ver'mez). 

 WORMS, ETC. 



This branch includes animals presenting the most di- 

 verse peculiarities, and hence is difficult of precise defini- 

 tion. The body, however, is bilateral, and either entire, 

 or divided into segments by transverse rings. Lateral 

 appendages may be present, but are never jointed. Rep- 

 resentatives are found on land, in water, both salt and 

 fresh, and as parasites on members of nearly every branch 

 of the Animal Kingdom. Though several classes have 

 been defined, we shall consider only the more important. 



CLASS PLATYHELMINTHES (plat I el mm'thez). 



The so-called FLAT WORMS have the body depressed 

 and more or less elongated. Some representatives are 

 free ; others are parasitic. 



ORDER DENDROCCELA (den dro se'la). 



FIG. 34. 



0- 



The Planarians (pla na'ri anz) are the 

 most common free Platyhelminthes, and 

 are found in abundance gliding over the 

 rocks of slowly running streams. If one of 

 these animals be placed in a tumbler of 

 water, its singular motions and peculiar 

 structure can be observed. In the form most 

 likely to be captured, there will be noticed 

 a pair of dark dots, the eyes,' on the an- 

 terior portion of the body, which is more or 

 less diamond-shaped when the animal is 

 stretched to its utmost. The mouth will be 

 seen on the lower surface, placed far back and leading 



Pla nn'n a tm-'va. 



Planarian Worm. 



0, Mouth. E, Eye. 



