PHYLUM ANNULATA 



lent 



part or rectum, is a narrow groove. Twisted round the posterior 



part is a long narrow ccccum, which 

 opens into the beginning of the 

 rectum. Two groups of /-rrfal 

 glands occur close to the anal 

 opening. 



The nervous system ( Fig. 355) 

 differs considerably from that of 

 the rest of the Anmilata. There 

 is a relatively small bilobed cere- 

 bral ganglion situated on the dorsal 

 aspect just behind the tentacular 

 circlet, to which it gives off on 

 each side several pairs of nerves. 



m.n.co 



7Z'. CO- 



dors.retr- 



-oes 



dors, 



n.co- 



\ 



-reel 



FIG. 354. Dissection of the internal organs 

 of Sipunculus nudus. dors, ret i: 

 dorsal retractor muscles of the intro- 

 vert ; int. intestine ; m. n. co. muscles 

 accompanying the nerve cord ; n. co. 

 nerve cord; tic ph. iiephridium ; ces. 

 cesophagus ; reft, rectum ; it ,it. tenta- 

 cular fold. (After Vogt and Jung.) 



ca.n.0. ceb 



FIG. 355. Anterior part of the nervous system 

 of Sipunculus nudus. can. o. o'<, cere- 

 bral organ; corns. . irsophagal connective; 

 ii.'Hti'. i-it, nerves to retractor muscles : //. *jil. 

 splanchnic nerves ; n. tfi, 1-lt, nerves to ten- 

 tacular fold ; /, //, nerves from ventral cord, 

 (After Ward.) 



