494 



ZOOLOGY 



SECT. 



m 



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 cwcum of variable length, which 

 opens into the beginning of the rec- 

 turn. Two tuft-like groups of rectal 

 glands occur close to the anal opening. 

 The nervous system (Fig. 389) 

 rccl differs considerably from that of 



.o. ceb 



oes 



V\<-. :;>s. Dissection of the intcmal 



>f Sipunculus nudus. dors. retr. 

 dorsal retractor muscles of the intm- 

 vort ; int. intestine; /. n. ro. musrlcs 

 accompanying the nerve-cord ; n. co. 

 nerve-cord; ncph. nephridiuin ; o?a. 

 o'Miphagus: n.rl. rectum; (cut. tent;i- 

 cular fold. (After \'ogt and Jung.) 



FIG. 389. Anterior part of the nervous system 

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

 bral (D-gaii ; anus. (-, o:sophagal connective ; 

 n.mu. ret. nerves to retractor muscles ; n. x/>l. 

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

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

 _'!, main mass of brain. (After Ward.) 



