ANATOMY AND DEVELOPMENT OP PERIPATUS CAPENSIS. 229 



oesophageal ganglia, where another pair of nerves are given 

 off to the jaws, (PI. XVITI, fig. 22/ n) may be regarded as the 

 anterior ganglion of the ventral cords. There are, therefore, 

 according to the above reckoning, nineteen pairs of ganglia 

 connected with the ventral cords. 



The ventral cords are placed each in the lateral compart- 

 ments of the body cavity, immediately within the longitudinal 

 layer of muscles. 



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 be- 

 tween each pair of feet (PI. XIX, 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 novae zealandite, and probably also in P. 

 capensis, 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. XIX, fig. 26 g co). 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. XV, fig. 8). Behind the generative aper- 

 ture the two cords bend upwards, and, as is shown 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 



VOL. XXIII. NEW SER. Q 



