XX Mil INTRODUCTION. 



Generally there is extreme difficulty ill making out the 

 details of the system in the marine forms. In Meinbrani- 

 pora membranacea Nitsche has only detected mere rudi- 

 ments of nerve-trunks, on the surface of the ganglion. 

 Ehlers has done the same in Hypophordla. In Loxo- 

 soma Salensky has traced various filaments to the tactile 

 organs on the sides of the body*; whilst Nitsche has 

 described three nerve-trunks as given off on the op- 

 posite sides of the ganglion in Pedicellina, which soon 

 divide and supply the tentacles (Woodcut, fig. xi.). 

 Two of smaller size were also observed passing from the 



Fig. xi. 



Ganglion or Nervous centre, 

 nt. Nerve-trunks, gc. Ganglionic cells. 



anal surface towards the reproductive organs. The gan- 

 glion itself consists of a solid membranous envelope, 

 inclosing a mass in the outer region of which no struc- 

 ture is distinguishable, but which is made up towards 

 the centre of large cells with granular contents and a 

 nucleusf. 



* " tudes sur lea Bryozooires Entoproctes," Ann. d. Sc. Nat. G e se>. Zool. 

 vol. v. (1877), Article no. 3, pis. xii.-xv. 



t Nitsche, " Ueber die Anatomic von Pcdicdlina cchinata" Sara, Zeitsch. 

 f. wisscnsch. Zool. xx. Heft 1, p. 28. 



