Fig. 28. Segmental organ or nephridium from the 9th pair of legs of _Peripatus capensis_, shewing the external opening, the vesicle, the coiled portion and the terminal portion with internal opening (enlarged). (From a drawing by Miss Balfour.) _o.s._ External opening of segmental organ. _p.f._ Internal opening of nephridium into the body-cavity (lateral compartment). _s._ Vesicle of segmental organ. _s_{1}. Portion of segmental organ of 4th and 5th legs, corresponding to vesicle of the other nephridia. _s.c._1. First or external portion of coiled tube of nephridium, lined by columnar epithelium with small nuclei; the cells project for very different distances, giving the inner boundary of this region a ragged appearance. _s.c._2. Region No. 2 of coiled tube of nephridium, lined by small closely-packed columnar cells. _s.c._3. Region No. 3 of coiled tube of segmental organ, lined by large flat cells with large disc-shaped nuclei. _s.c._4. Region No. 4 of coiled tube of nephridium; this region is very short and lined by small columnar cells. _s.o.t._ Terminal portion of nephridium. Fig. 29. "Portion of nephridium of the hindermost leg of _Peripatus capensis_, seen in longitudinal and vertical section. The figure is given to shew the peritoneal funnel of the nephridium. Portions of the collecting sack (_s._) and other parts are also represented. (Zeiss B, Hartnack's camera.)" _p.f._ Peritoneal funnel. _s._ Vesicle. _s.c.1_, _s.c.2_, _s.c.3._ Portions of coiled tube. Fig. 30. "Section through a tracheal pit and diverging bundles of tracheal tubes" taken transversely to the long axis of the body. (Zeiss E, oc. 2.) (From a rough drawing by Prof. Balfour.) _tr._ _Tracheæ_, shewing rudimentary spiral fibre. _tr.c._ Cells resembling those lining the tracheal pits, which occur at intervals along the course of the tracheæ. _tr.s._ Tracheal stigma. _tr.p._ Tracheal pit. Fig. 31. "Sense organs and nerves attached from antenna of _Peripatus capensis_ (Zeiss, immersion 2, oc. 2.)" (From a rough drawing by Prof. Balfour.) The figure shews the arrangement of the epidermis cells round the base of the spine. The spine is seen to be continuous with the inner layer of the cuticle. Fig. 32. Section through the skin of _Peripatus capensis_; it shews the secondary papillæ covered with minute spinous tubercles and the relation of the epidermis to them. (The cuticle in the process of cutting has been torn away from the subjacent cells.) The cells of the epidermis are provided with large oval nuclei, and there is a deposit of pigment in the outer ends of the cells. The granules in the protoplasm of the inner ends of the cells are arranged in lines, so as to give a streaked appearance. (Zeiss E, oc. 2.) (From a rough drawing by Prof. Balfour.) _c._ Dermis. _cu._ Cuticle. _ep.c._ Epidermis cells. _pi._ Deposit of pigment in outer ends of epidermis cells. _s.p._ Secondary papillæ.