(116) 



wall of ihe alimentary canal. 



The nervous system of the adult is to a great extent sub- 

 epidermal. There is a nerve with a nucleated sheath extendini^ 

 alon^^ tl:c left side of the animal. Anteriorly it bends arouna 

 the anal papilla and continues as a short nerve on the ri^^ht 

 side. There is a gaii-^lion between the mouth and anus. A 

 nerve ring extends around the base of the lophophore and it 

 gives off nerves to the lophophoral organs. There is ner- 

 vous tissue in the walls o"*^ the tentacles. 



The excretory organs are pairea and each noi-hriaium con- 

 sists of a tube bent upon itself. One end opens to the exter- 

 ior while the other is continued into two funijels, one corrimun- 

 icating with the rectal and the other, with the lateral body 

 cavi ty. 



The reproductive organs arise from the lining of the caecal 

 blood vessels sjrjd the male organs develop at a different time 

 from those of the female. 



