V 



CHAPTER VII 



THE WORM GROUP 



65. The Worm Group. — Here are found several distinct 

 groups of animals that in advanced text-books of zoology 

 are treated separately. The word "worm " is an old term 

 which properly describes such animals as the earthworm, 

 sea worm, leech, tapeworm, flat worm, and a few others. 

 The word " worm ' cannot be correctly used for such 

 larvae of insects as the " apple tree worm " or " currant 

 worm." 



The worm group is divided into two classes — those 

 whose body is composed of numerous segments (seg'ments) 

 or rings, such as the earthworm, the sea worm, and the 

 leech ; and those whose body is not segmented, such as 

 the tapeworm and flat worm. The first class comprises 

 the true worms, which are known as Annelida (a-nel'I-da). 

 The second class, the unsegmented worms, have no single 

 technical name, and are not believed by scientists to be 

 true worms. They comprise a number of worm-like ani- 

 mals which have hardly any features in common. Here 

 are found the fresh water planarians, the parasitic tape- 

 worms, liver flukes, and numerous round worms, of which 

 the hair worm is an example. 



The planarian worm is one of the simplest of these un- 

 segmented worms. It is found under stones submerged 

 in stagnant water and in streams. It is frequently 

 brought into the laboratory and lives easily in aquaria. 



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