I82 



AN' INTRODUCTION TO ZOOLOGY. 



The class Annelida are worms with segmented 

 bodies, a highly- developed nervous system, and a 

 vascular system. 



The sub-class Ch^topoda are remarkable for their 



Wf^ 



Pig. 47. Fig. 48. 



Fig. 47.— A group of tubes of one of the tubicolous -worms, Sei^pula con- 

 (ortupHcata, showing heart and gill. filaments of one worm. 

 Fig. 48 o and b.— Shell-like tubes of Sjjirortis. 



appendages, called cirri or parapodia. The order 

 Polychceta have tentacles and tree-like gills {brancMai) ; 

 Polygordius, the larval form of which has been re- 

 ferred to on p. 179, is considered to be allied to them. 

 The sub-order Eirantia are free-swimming forms. 

 The Spa-mouse is. fairly common ; it is a creature not 

 much like a worm in shape, covered with long pur- 



