I "> 1 ZOOLOGY. 



THE SECOND SUB-DIVISION. 



OF THE ANXELIDES, OR ANNl'LATKI) ANIMALS. 

 THE VEBMES, OR WORM>. 



582. In these animals the annulated division of the 

 body becomes less and less marked ; every structure becomes 

 as it were degraded in proportion as we leave those most re- 

 sembling the articulated to those approaching the zoophytes ; 

 the limbs disappear, and the nervous system becomes less and 

 less distinct, or loses its importance, and the structures sim- 

 plify more and more. Their most remarkable feature is the 

 elongation of their bodies, and they form five distinct classes ; 

 namely, the annelides, rotatoria, turbellaria, helminthides or 

 intestinal worms,* and cestoids. 



OF THE ANNELIDES. 



583. The class is composed of worms having a multi- 

 gangular nervous system, and a vascular apparatus for the 

 circulation of the blood. 



Their bodies are always elongated, soft, and divided by cir- 

 cular folds into a great number of rings ; sometimes the head 

 is distinct, sometimes it is wanting ; and generally along the 





Fig. 438. -Nereis. 



sides of the body they have a long series of hairs in bundles, 

 supported on fleshy tubercles, taking the place of feet (Fig. 



Eutozoa. 



