ANNULATA 



95 



Branch IX. ANNULATA 



The Annelidas include the highest and most special- 

 ized Worms. They have many segments, spines, or 

 suckers for locomotion, a supra-esophageal brain, a 

 ventral chain of ganglia, and usually a closed blood sys- 

 tem. 



There are two principal classes : Chcetopoda, or bristle- 

 footed worms ; and Hirudinea, or leeches. The former 



FIG. 51. Marine Worm (Cirratulus grandis}, with extended cirri. Atlantic. 



class includes the earthworms {Liimbricus and Allolobo- 

 phora), the sandworm (Nereis), and the lobworm (Areni- 

 cola). 



The earthworm develops from eggs laid, several in a 

 capsule, in the earth or near refuse heaps, under boards 



