EXPLANATION OP PLATES X AND XI. 



shown. The oral papilla (or. pap.) and slime-j^land (si. gl!) are also 

 visible. 

 Figs. 2 — 4 drawn with Zeiss's camera, obj. C, oc. 2. 



Fig. 5. — Portion of transverse section through the middle rej?ion of tlie 

 body of an embryo of Peripatus capensis of Stage G (removed from 

 uterus 16th December). The section passes through the anterior part of a 

 pair of legs. The details are filled in on the left-hand side of the drawing. 

 The section passes through a ventral organ (v. o.), with which the nerve-cords 

 are connected by a cellular process, a persistent trace of the original complete 

 continuity between these two structures. The anterior of the two large pedal 

 nerves is shown (nerve), leaving the cord as it immediately passes forwards out 

 of the plane of the section ; the continuity between it and the neuro-muscular 

 network (rieuro-nnisc), which will eventually develop into the nerves and 

 muscles of the foot, and between it and the circularly disposed network from 

 which tlie circular muscles (circ. muse.) of the body wall will develop, could 

 not be shown in this figure. The walls of the alimentary canal are very thin. 

 h. lat. marks the lateral compartment of the vascular body cavity (space 

 formed in parietal mesoderm of early stages), h. app. The vascular body cavity 

 of the appendage. Drawn on the table, Zeiss's new camera C, oc. 2. 



Fig. 6. — A diagram of the ventral portion of the third somite at Stage r. 

 The vertical lines indicate the planes of the sections Figs. 37, 38, 39 of 

 Part III. 



Ftg. 7. — Diagram of the ventral portion (nephridium) of third somite at 

 birth. The hinder part of the tube of the preceding stage has elongated 

 backwards to form the long tubular salivary gland (sal. gl.). 



Figs. 8 — 13 are all from embryos just before birth (removed from uterus 

 19tli April). They were all drawn on tiie table with a Zeiss's new camera, 

 obj. C, 00. 2. 



Figs. 8 and 9. Transverse sections through the same structure, along the 

 lines marked 8 and 9 in the preceding diagram (Fig. 7). The vesicle 

 (/. s, V. 3) has thick, much vacuolated walls, and is placed dorsal to 

 the tubular part (/. s. t. 3). In Fig. 9, the small portion connecting 

 the vesicle and tube is shown closely applied to the dorsal wall of the 

 salivary gland. 

 Fig. 10. Portion of a transverse section through the region of the third 

 leg of P. capensis just before birth. The section passes through 

 the opening of the nephridium, and what I take to be the rudiment of 

 the crural gland (crur. gl.). The whole nephridium is shown in the 

 section. In the actual section the internal vesicle was somewhat more 

 collapsed than in the figure. The funnel and internal vesicle I take 

 to be homologous with the similarly named structures of the posterior 

 nephridia. 



