. Fig. 7. Nervous system. A, sagittal section; B, frontal section. 6, ganglion; c, gonad; c/), collar pore; /, stomach; pn, pre-oral nerve ; pn^, nerve plexus in ventral wall of proboscis; In, post-oral nerve; In^, nerve to pharj'nx; /n,, nerve to post-oral lamella; In^, nerve to ventral body wall; iig, nerve to gonad; dn, nerve to dorsal body wall; na, nerve to arms; r, rectum. glandular region of the ventral wall. This pre-oral nerve plexus does not extend to the anterior tip of the proboscis, so that Masterman's description of its course is incorrect. From the dorsal side o
. Fig. 7. Nervous system. A, sagittal section; B, frontal section. 6, ganglion; c, gonad; c/), collar pore; /, stomach; pn, pre-oral nerve ; pn^, nerve plexus in ventral wall of proboscis; In, post-oral nerve; In^, nerve to pharj'nx; /n,, nerve to post-oral lamella; In^, nerve to ventral body wall; iig, nerve to gonad; dn, nerve to dorsal body wall; na, nerve to arms; r, rectum. glandular region of the ventral wall. This pre-oral nerve plexus does not extend to the anterior tip of the proboscis, so that Masterman's description of its course is incorrect. From the dorsal side of the ganglion arise the nerves to the arms; from the posterior end, a pair of post-oral nerves and a median nerve which runs in the dorsal wall of the trunk. This median nerve gives off a pair of small branches which enter the ducts of the gonads. The post-oral nerves, homologous with the "post-oral ring" of Masterman, proceed backwards on either side, and at the base of the collar pores each divides into three branches which enter the pharynx, post-oral lamella and body wall respectively. PI. XXXVI11, figs. I to 8 are transverse sections which show the course of the main nerve
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscientificexpedition
