(67) 

 under the microscope do not show a brancVi of the nerve rins of 

 the lobe passinr upward to the nerve ran^lion. Sections also 

 fail to show this condition which is very necessary to Master- 

 man's comparison of the nervous system of Balanot;lo ssus and the 

 Actinotro cha. ■Fitcr-D frcm i ae nerve ring do, however, pasa 

 en tc ventral surface of the collar region. 



Numerous fibers which Masterman speaks o f as passiu_, down 

 on to the ventral collar wall are massed in the Actinotrocha 

 Species, E. , into tv© definite thickenini;:s v^ich are seen in 

 nr. 44. (c) and 7ic. 40. These thickenings o -^ tl:e nervous tis- 

 sue gradually a,pi.roach one anotner as v/e trace the sections 

 backv;ara aiid come to run alon^. the same line as do the two ven- 

 tral muscle tracts of the collar, but before the line of inser- 

 tion o-f tne ventral tentacles is reactied, these tii ickeniui^s are 

 lost in the subepidermal nervous tissue, 



I ftave not been able, to make out eitner in sections or in 

 surface mounts any definite nervous tract nmnivKv; from the col- 

 lar nerve rin^. alon^j the ventral re^^ion of ti^e trimk, althoupi 

 as I have said before, there is a subepidermal network of ner- 

 vous tissue throui-,;hout the wall. It will be r erne rrbe red, how- 

 ever, thiat above I have described two loni_^itudiXial dorso-lat- 

 eral tracts of muscle fibers and there are quite numerous longi- 

 tudinal muscle fibers in t.-e vcr^tral v;all of t r.e trunk. There 



