9. _Reproductive Organs._ The sexes are separate in Charybdea. In both sexes the reproductive organs consist of four pairs of long leaf-like bodies, each leaf attached along one edge to the wall of the subumbrella in an interradius (see Fig. 1, _r_), and hanging free in the stomach pockets. From this position in the stomach pockets it is evident that the reproductive organs are endodermal. The lines of attachment of each pair is just internal to the longitudinal vascular lamella that fuses the outer and inner walls of the stomach pockets together in the interradius (_ivl_), and the reproductive organs are therefore structures belonging to the subumbrella. It is interesting to note how careful examination of the medusan organization takes away from the importance of the outer cup, the exumbrella, and adds to that of the inner, the subumbrella. We have seen that the phacelli and the sensory clubs, from whose position it would be supposed that they belonged to the exumbrella, are organs of the subumbrella, and that there is no muscle-tissue in the exumbrella; we find now that the reproductive organs belong to the subumbrella, and it will be shown later that the tentacles, like the sensory clubs, are structures of the subumbrella also. To the exumbrella are left only the functions of support and covering. The mature reproductive organs extend very nearly throughout the entire vertical length of the bell, and are therefore found in the series of cross-sections in all but the uppermost and lowermost (Figs. 7-15 _r_). The organs consist of germ cells within, covered by an epithelium of columnar cells that shows here and there nettle cells. The ova are found with different amounts of yolk, according to age, surrounding a large nucleus almost devoid of chromatin and an intensely staining nucleolus. In young ova there appears very plainly in every case at least one small deeply staining body inside the nucleus, which very much resembles the nucleolus. These are probably so-called yolk nuclei, and while I have not made a special study of the ovogenesis, I infer that the constant presence of at least one, points to an origin of the ovum from a syncytium (of at any rate two cells), similar to that which has been recently shown by Doflein (’96) to occur in the formation of eggs in Tubularia. In the nearly mature ovary each ovum is surrounded by a layer of gelatine, which comes from the gelatinous sheet that enters the leaf-like ovary for its support along its line of attachment just internally to the interradial septum. It seems as if the ova, arising in the epithelium on the surface, pushed their way into the gelatine inside and there completed their development entirely surrounded by a slight investment of gelatine, which grows thinner around each ovum as it increases in size. In males the testes always show a similar division into compartments by gelatinous meshes, the compartments thus mapped out