[Illustration: FIG. 9.—Brain and anterior part of the ventral nerve-cords of _Peripatus capensis_ enlarged and viewed from the ventral surface. (After Balfour.) The paired appendages (_d_) of the ventral surface of the brain are seen, and the pair of sympathetic nerves (_sy_) arising from the ventral surface of the hinder part. From the commencement of the oesophageal commissures pass off on each side a pair of nerves to the jaws (_Jn_). The three anterior commissures between the ventral nerve-cords are placed close together; immediately behind them the nerve-cords are swollen, to form the ganglionic enlargements from which pass off to the oral papillae a pair of large nerves on each side (_orn_). Behind this the cords present a series of enlargements, one pair for each pair of feet, from which a pair of large nerves pass off on each side to the feet (_pn_). _atn_, Antennary nerves; _co_, commissures between ventral cords; _d_, ventral appendages of brain; _E_, eye; _en_, nerves passing outwards from ventral cord; _F.g.1_, ganglionic enlargements from which nerves to feet pass off; _jn_, nerves to jaws; _org_, ganglionic enlargement from which nerves to oral papillae pass off; _orn_, nerves to oral papillae; _pc_, posterior lobe of brain; _pn_, nerves to feet; _sy_, sympathetic nerves.] The ventral cords are placed each in the lateral compartments 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 {13}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. 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. Posteriorly the two nerve-cords nearly meet immediately in front of the generative aperture, and then, bending upwards, fall into each other dorsally to the rectum. They give off a series of nerves from their outer borders, which present throughout the trunk a fairly regular arrangement. From each ganglion two large nerves (_pn_) are given off, which, diverging somewhat from each other, pass into the feet. From the oesophageal commissures, close to their junction with the supra-oesophageal ganglia, a nerve arises on each side which passes to the jaws, and a little in front of this, apparently from the supra-oesophageal ganglion itself, a second nerve to the jaws also takes its origin.