886 ANATOMY AND DEVELOPMENT 



They are connected with each other, rather like the pedal 

 nerves of Chiton and the lower Prosobranchiata, by a number 

 of commissures. These commissures exhibit a fairly regular 

 arrangement from the region included between the first and the 

 last pair of true feet. There are nine or ten of them between 

 each pair of feet (PI. 52, fig. 26). They pass along the ventral 

 wall of the body, perforating the ventral mass of longitudinal 

 muscles. On their way they give off nerves which innervate 

 the skin. 



In Peripatus nova zealandia, and probably also in P. capen- 

 sis, two of these nerves, coming off from each pair of ganglia, 

 are distinguished from the remainder by the fact that they are 

 provided with numerous nerve-cells, instead of being composed 

 of nerve-fibres only, like the remaining commissures (PI. 52, fig. 

 26 g cd). In correlation with the nerves given off from them to 

 the skin the commissures are smaller in the middle than at the 

 two ends. 



Posteriorly the two nerve-cords nearly meet immediately in 

 front of the generative aperture, and between this aperture and 

 the last pair of feet there are about six commissures passing 

 between them (PI. 48, fig. 8). Behind the generative aperture 

 the two cords bend upwards, and, as is shewn in fig. 8, fall into 

 each other dorsally to the rectum. The section of the two cords 

 placed dorsally to the rectum is solely formed of nerve-fibres; 

 the nerve-cells, present elsewhere, being here absent. 



In front of the ganglion of the first foot the commissures 

 have a more dorsal situation than in the remainder of the body. 

 The median longitudinal ventral muscle here gradually thins 

 out and comes to an end, while the commissures pass imme- 

 diately below the wall of the pharynx (PI. 49, figs. 14, 15). The 

 ventral cords themselves at first approach very close to each 

 other in this region, separating again, however, to envelope be- 

 tween them the pharynx (PI. 51, fig. 22). 



There are eleven commissures in front of the first pair of legs 

 (PI. 51, fig. 22). The three foremost of these are very close 

 together, the middle one arising in a more ventral position than 

 the other two, and joining in the median ventral line a peculiar 

 mass of cells placed in contact with the oral epithelium (fig. 14). 

 It is probably an organ of special sense. 



