494 



ZOOLOGY 



lent 



f& 



back from the mouth towards the posterior end, and then bending 



sharply round to run forwards to the 

 anus, the two limbs being twisted 

 spirally round one another. Run- 

 ning along the inner surface of the 

 entire length of the alimentary canal, 

 with the exception of the terminal 

 part or rectum, is a narrow groove. 



oes ^° nn ected with the rectum is a nar- 

 row cwcum of variable length, which 

 opens into the beginning of the rec- 

 tum. Two tuft-like groups of rectal 

 glands occur close to the anal opening. 

 The nervous system (Fig. 389) 



-red differs considerably from that of 



dors retr - 



neph- 



dors, retr- 



inl- 



n.co- 



tr'- 



Fio. 388. — Dissection'of the internal organs 

 of Sipunculus nudus. dor*, retr. 

 dorsal retractor muscles of the intro- 

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

 accompanying the nerve-cord ; n. co. 

 nerve-cord ; ne/th. nephridium ; eet. 

 oasophagus ; rtct. rectum ; tent, tenta- 

 cular fold. (After Vogt and J ung. ) 



PlO. 889. — Anterior part of the nervous system 

 <>f Sipunculus nudus. can. o. cab. cere- 

 bral organ ; corns, «, oesophagal connective ; 

 n.mu. ret. nerves to retractor muscles ; n. »j>l, 

 splanchnic nerves ; n. ta. 1-U, nerves to ten- 

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

 24, main mass of brain. (After Ward.) 



