494 



ZOOLOGY 



SKCT. 



lent 



m.n.co 



back from the mouth towards^he 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 ccecum 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) 



dors.rctr-^it^W^l'^^rcct, differs considerably from that of 



inl- 



dors.retr- 



oes 



n.<. 



FIG. 388. Dissection of the internal organs 

 of Sipunculus nudus. Jors. rttr. 

 dorsal retractor muscles of the intro- 

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

 accompanying the nerve-cord ; n. co. 

 nerve-cord ; neph. nephridium ; o-s. 

 oesophagus ; rect. rectum ; tent, tenta- 

 cular fold. (After Vogt and Jung.) 



FKJ. 380. Anterior part of the nervous system 

 f Sipunculus nudus. can. o. ctb. cere- 

 bral organ ; coins, o;, oasophagal connective ; 

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

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

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

 L'4, main muss of brain. (After Ward.) 



