As Wilson pointed out in his notes, these facts have a close bearing upon the question of the origin of the velarium. Sixteen marginal pockets are found in both Chiropsalmus and Tripedalia, and all of them extend into the velarium. It is not unnatural to suppose that these belong to sixteen marginal lobes, and that these lobes have fused together to form the velarium. In the Chirodropus figured by Haeckel (Taf. XXVI) in his “System” gelatinous lobe-like thickenings are shown in the velarium, corresponding to the sixteen marginal pockets. In Tripedalia no special gelatinous thickenings are found, but the arrangement of the marginal pockets is the same as that of the Chirodropidæ, and perhaps I ought, when treating of the systematic relations of Tripedalia (p. 5, Fam. III), to have recognized the analogy to the extent of saying that marginal lobes may not be completely absent from the velarium of Tripedalia. At any rate the gelatinous lobes in the case of Chirodropus on the one hand, and on the other hand the sinuous outline of the margin still mapped out by the lamella in Chirodropus, Chiropsalmus and Tripedalia, are certainly very suggestive of an ancestral Cubomedusa in which there was no velarium, but sixteen free marginal lobes instead. Two more indications favor slightly the same view. In both Charybdea and Tripedalia a small notch is seen in the edge of the velarium in the perradius (Fig. 44). Its constancy suggests that it may not be a chance or meaningless feature. The second point is the small size of the two marginal pockets adjoining the perradius. These are in the position of the ephyra lobes of the Discomedusæ, which always lie on either side of each sensory club, and which do not keep pace with the other marginal lobes in development. In the Rhizostome jelly-fish especially they are found much smaller than the other lobes, as will be seen by a glance at such figures as Haeckel’s for Lychnorhiza (System, Taf. XXXIV Fig. 2), or for Archirhiza (Taf. XXXVI, Fig. 5), or Hesse’s figure of the margin of Rhizostoma Cuvieri (’95, Taf. XXII, Fig. 22). The resemblance between such margins and that of Tripedalia (Fig. 44), with its simple, unbranched velar canals, is very suggestive. On the other hand it must be remembered that in considering the vascular lamellæ of the internal system we found the indication pointing rather more to Hydromedusan affinities than to any other. Charybdea throws no light on the question, since it has no marginal lobes on the velarium and the marginal pockets end strictly at the margin, so that the only diverticula of the gastro-vascular system in the velarium are the velar canals.