The smaller velar canals, a pair in each perradius, seem to have in the males some function in connection with the storing of matured spermatozoa. In specimens with ripe testes they are very often found crowded to distension with spermatozoa, while the other velar canals may or may not contain them, and generally do not. The epithelium lining them is, like that of the others, composed of columnar cells higher on the wall turned toward the bell cavity than on that turned towards the exterior, but otherwise not specially differentiated. I searched in vain for any trace of opening by which the spermatozoa might gain the exterior. Fig. 29 shows another point which may be mentioned in passing, namely, that the canal of each of the three tentacles opens into the peripheral gastro-vascular system independently. The central tentacle of each group is the homologue of the single tentacle of Charybdea, and is formed in Tripedalia before the two lateral tentacles appear. Its communication with the peripheral pocket system is higher up than the openings of the lateral tentacles, so that in the section drawn the latter are just beginning to be indicated (_ct´_). It remains only to speak of the reproductive organs of Tripedalia. The sexes are separate in this form also, and ovaries and testes have the same structure as is found in other Cubomedusæ. The development of floating masses of cells in the females, however, is a feature which, so far as I know, has not been observed before. These masses, of which a small one is represented in section by Fig. 71, are apparently developed along with the eggs, and repeat the structure of the ovary to all intents the same as if they were various-sized fragments of it broken loose. They consist mostly of high, columnar epithelial cells surrounding a few central cells and showing here and there a nettle cell just as the reproductive organ does. The epithelial cells differ from those of the ovary in containing one or more large vacuoles, and this vacuolation increases as the embryos, among which the masses float, develop. The idea naturally suggests itself, therefore, that they serve for nourishing and perhaps for protecting the embryos while they are developing in the stomach pockets of the mother individual. PART III: DESCRIPTION OF SPECIAL PARTS OF THE ANATOMY. A: THE VASCULAR LAMELLÆ.