PLATE 50. Fig. 19. "A, B, C, D, E, F, G." Seven transverse sections illustrating the structure of the supra-oesophageal ganglia. (Zeiss A, Hartnack's camera.) _a._ Dorso-lateral horn of white matter. _b._ Ventro-lateral horn of white matter. _c._ Postero-dorsal lobe of white matter. _d._ Ventral protuberance of brain. _e._ Central lobe of white matter. _o.p._ Optic ganglion. "A. Section through anterior portions of ganglia close to the origin of the antennary nerve. B. Section a little in front of the point where the two ganglia unite. C. Section close to anterior junction of two ganglia. D. Section through origin of optic nerve on the right side. E. Section shewing origin of the optic nerve on the left side. F. Section through the dorso-median lobe of white matter. G. Section near the termination of the dorsal tongue of ganglion cells." PLATE 51. Fig. 20. Portion of a transverse section through the hinder part of _Peripatus capensis_ (male). The section passes through a leg, and shews the opening of the segmental organ (_o.s._), and of a crural gland, _o.f.g._, and the forward continuation of the enlarged crural gland of the 17th leg (_f.gl._). (Zeiss a a, Hartnack's camera.) _a.g._ accessory gland of male (modified crural gland of last leg). C. Cutis. _cl._ Claw. _cu._ Cuticle. _ep._ Epidermis. _f.gl._ Crural gland. _h._ Cells in lateral compartment of body-cavity. _o.f.g._ Orifice of accessory foot gland. _o.s._ Opening of segmental organ. P. Three spinous pads on ventral surface of foot. _pr._ Prostate. R.M. Retractor muscle of claw. _s._ Vesicle of nephridium. _s.c.i._ Region No. 1 of coiled part of nephridium. _sl.g._ Tubule of slime gland. _s.o.t._ Terminal portion of nephridium. _st._ Stomach. _st.e._ Epithelium of stomach. _v.c._ Ventral nerve-cord. _v.d._ Vas deferens. Fig. 21. "Longitudinal vertical section through the supra-oesophageal ganglion and oesophageal commissures of _Peripatus capensis_. (Zeiss a a, Hartnack.)" _at._ Antenna. _e._ Central lobe of white matter. _j._ Part of jaw. _s.g._ Salivary gland. Fig. 22: drawn by Miss Balfour. Brain and anterior part of the ventral nerve-cords of _Peripatus capensis_ enlarged and viewed from the ventral surface. The paired appendages (_d_) of the ventral surface of the brain are seen, and the pair of sympathetic nerves (_sy_{1}) arising from the ventral surface of the hinder part. From the commencement of the oesophageal commissures (_oes.co._) pass off on each side a pair of nerves to the jaws (_j.n._). 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 papillæ a pair of large nerves on each side (_or.n._).