83 



the body-wall, this division is in free communication wilh the remainder of the cavity round the 

 posterior wall ol the oviduct (figs. 121, 122). At the ventral ends of the oviducts, the mesenteries 

 of tliese organs originate from near the middle of the median mesentery (fig. 122). The ovarian 

 mesenteries are continued as far as at the extreme dorsal ends of the ovaries (fig. 123), which 

 along the greater part of their course are not siipported by mesenteries (figs. 124, 125). In zooids 

 in which ripe eggs are not being produced, the ovary and oviduct lie in the same straight Hne. 

 This is seen in fig. 33, in which the right ovary is shewn, on the far side of the large dorsal 

 vesseL The wall of the epidermic recess into which the oviduct opens is seen as an ovoid mass 

 of cells which carries the pigmented oviduct to some little distance from the level of the median 

 part of the dorsal body-wall. In zooids containing ripe eggs, the dorsal part of the ovary may 

 be considerably bent, as shewn in fig. 139 (PI. XI). 



The relations of the ovaries and oviducts of C. dodecalophus are essentially similar to 

 those füund in C. levinseni. Fig. 42 shews an old ovary, bent in the way just referred to in 

 the other species. The ovarian mesenteries are shewn, in frontal sections, in figs. 152 — 156, 

 while fig. 157 demonstrates the absence of the mesenteries in the more ventral parts of the 

 ovaries. Fig. 1 5 i illustrates the position of the mesenteries as .seen in an obliquely longitudinal 

 section, which passes mostly through the right .side of the animal, but also shews some of the 

 organs of the left side. The edge of the right oviduct [ovd. /-.) is just cut, while the right 

 ovarian mesenteiy [ov. m. r.) carries a distinct blood-vessel which joins the right ovary in one 

 of the neighbouring sections. The left ovarian mesentery {ov. iii. /.) is cut near its dorsal end, 

 where it forms a bridge passing from the bod)--wall to the median mesentery, and thus isolates 

 a section of the third body-cavity. The external openings of the oviducts in C. dodecalopJuis 

 are situated in epidermic recesses, as in C. levinseni. 



In C. gracilis I do not find any epidermic recesses connected with the external apertures 

 of the oviducts. These apertures are situated very close together (PI. \T, fig. 61) on a part 

 of the dorsal swelling of the metasome which is very prominent in some specimens (PI. III, 

 fig. 22). The pigmented oviduct extends completely up to the level of the epidermis (figs. 

 45 — 51) and opens on the convex surface of the dorsal swelling. The relations of the ovarian 

 mesenteries are essentially the .same as those of the other species, with the exception of the 

 fact that the median dorsal mesentery of the body is incomplete in C. gracilis.^ and the ovarian 

 mesenteries join the part of it which persists, namely that which is attached to the pharynx. 

 The mesentery here carries a large and very conspicuous vascular space (figs. 45, 68) and it 

 is easy to demonstrate that this gives off a conspicuous blood-vessel which runs in the ovarian 

 mesentery to the dorsal part of the ovary. Evidence to this effect is not wanting in the other 

 species, but I have seen it most conclusively in C. gracilis. One important function of the 

 ovarian mesenterv is thus to carrv the nutritive blood-vessel of the or^an. That vessel havingf 

 found its way to the ovary there is no further use for the mesentery, which accordingly 

 disappears in the ventral part of the ovary. 



It is not easy to account for the universal occurrence of the pigment of the oviducts. 

 I have, in Section \TI (p. 27), called attention to the suggestion of M'Intosh that this substance 

 may have something to do with phosphorescence ; and I have mentioned the re.semblance which 



