IX. EARTHWORMS, LEECHES, AND SEAWORMS 



Branch VIII. — Annulata (annulus, ring) 



Annulata. — With very few exceptions the members of 

 this branch have their bodies divided externally into a 

 number of rings which represent a division of the internal 

 parts into a series of segments. The segmented worms 

 are widely distributed. They are found on land, in fresh 

 water, and in the sea. 



Example of the Branch — the Earthworm 



External features. — The body is long and cylindrical, 

 bluntly pointed at one end and rounded and flattened at 

 the other. The bluntly pointed end of its body which 

 bears the mouth is known as the anterior end. The opposite 

 end of the body is known as the posterior end. At the an- 

 terior end of the body is a small lobe which overhangs 

 the mouth and is called the prostomium, or "lip." A 

 short distance back of the anterior end is a swollen ring, 

 or band, called the ditellum. It is furnished with glands 

 for secreting mucus to form the egg capsules. If a 

 worm be carefully watched, it will be found that a certain 

 side of the body is always held uppermost and away from 

 the ground. This is called the dorsal side. The side of 

 the body in contact with the ground is called the ventral 

 side. Moreover, the body is plainly divided into rings, or 

 segments. The segments seem to be marked off by super- 



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