4r»4 



ZOOLOGY 



tent 



-,-<r ^ 



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. 

 Connected with the rectum is a nar- 

 row accujii of variable length, which 

 opens into the beginning of the rec- 

 tum. Two tuft-like groups of rectal 

 glands occurclose to the anal opening. 

 The nervous system (Fig. 389) 

 differs considerably from that of 



m 



dors retr- 



7i^h- 



ISS u 



dors, retr- 



ttd-- 



n.co- 



\ — reel 



m 



m 



w 



Fig. 388.— Dissection of the internal organs 

 of Sipunculus nudus. dovB. veir. 

 dorsal retractor muscles of the intro- 

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

 accompanying the nerve-cord ; n. co. 

 nerve-cord ; ne)>k. nephridium ; ces. 

 oesophagus ; reel, rectum ; tcnl. tenta- 

 cular fold. (After Vogt and Jung.) 



Fxo. 3SU. — Anterior part of the nervous system 

 of Sipunculus nudus. can. o. ceb. cere- 

 bral organ ; romx. (..-, oesophagal connective ; 

 n.'iiin. ret. nerves to retractor muscles ; n. spl, 

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

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

 24, main mass (.if braiu. (After Ward.) 



