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MANUAL OF ELEMENTARY ZOOLOGY 



youngest segments being at the front end and the old ones 

 dropping off, whereas in the earthworm the youngest seg- 

 ments are those at the hind end and the animal does not 

 shed its segments. 



The earthworm is adapted to a burrowing habit and a 

 vegetarian diet. Many marine worms, how- 

 ever, while they resemble the earthworm in 

 most respects, lead a free and predaceous existence. Of 



10 ,2?f 



Fig. 148. — A transverse section through Nereis cultrifer, slightly 

 simplified. The parapodia are shown in perspective. Magnified. 

 — From Shipley and MacBride. 



1, Cuticle ; 2, epidermis ; 3, circular muscles ; 4, longitudinal muscles ; 5, oblique 

 muscles forming a partition ; 6, somatic layer of peritoneal epithelium ; 7, ccelom ; 

 8, splanchnic layer of epithelium ; 9, cavity of intestine ; 10, dorsal blood 

 vessel ; n, ventral blood vessel ; 12, ventral nerve cord ; 13, nephridium 

 in section; 14, ova; 15, notopodium ; 16, neuropodium ; 17, dorsal cirrus; 

 18, ventral cirrus ; 19, sets ; 20, aciculum with muscles at inner end. 



these, Nereis cultrifer, common under stones on the south 

 coast of England, where it is known as the Red Cat and is 

 used as bait, is a good example. The body of this worm is 

 about six inches in length, of a greenish colour, roughly 

 cylindrical, tapering towards the hinder end, and divided 

 into about eighty segments. Like the earthworm, it is 

 covered with a thin cuticle and provided with setae, but the 

 setas are longer and much more numerous than in the 

 earthworm, and are borne on movable limbs or parapodia, 

 of which a pair is placed on each segment. A parapodium 



