In the upper part of the bell is the stomach, with the phacelli in its interradii, and continued ventrally into the manubrium, or the proboscis. The cavity of the stomach is continued in the perradii through the four gastric ostia into the four stomach pockets, which occupy the sides of the bell and extend to the margin. Immediately below the gastric ostia, and in the bell cavity, are the suspensoria, one in each perradius. These support the floor of the stomach much as the frenula support the velarium, except that the suspensoria are placed under the shelf (to continue Conant’s figure) and not above it as are the frenula. A nerve ring, underneath the epithelium of the subumbrella, passes from near the origin of each pedalium at the margin to the origin of the peduncles of the sensory clubs, a little above the margin, giving off a branch to each club. Eight ganglia are found in the course of this nerve. The four pedal ganglia lie near the bases of the pedalia, and are hence interradial; the four radial ganglia lie near the bases of the peduncles of the clubs, and are perradial. A small nerve, radial nerve, can be traced a short distance upwards from each radial ganglion. Underlying the epithelium of the frenula and the suspensoria are ganglion cells and nerve fibers in larger numbers than elsewhere (excepting the ganglia mentioned) in the subumbrella. Otherwise, ganglion cells and nerve fibers underlie the epithelium of the subumbrella, including the inner surface of the velarium, as also do muscle fibers, except in the perradii and in the region of the nerve, where the latter become interrupted. PHYSIOLOGICAL. CHARYBDEA. _Light and Darkness_--Experiments 1-9, 10, 33, 34.--As already stated in the Introduction, a part of Conant’s experiments were performed in a photographer’s dark-room, with the animals in a deep glass jar. In the dark a fair proportion of the animals became nearly quiescent on the bottom, but upon lighting a lamp many started up immediately, while others took a longer time to come to the surface and swim. These experiments were tried a number of times and on different occasions with very similar results. Some medusæ, however, tried immediately after being brought in, seemed not to react so well upon being placed in the dark-room, nor would they become quiescent. This, probably, was due to the fact that the animals had not yet recovered from the effects of being caught and placed in new surroundings. (Experiments 1, 2, 3.)