"_Charybdea_ is a strong and active swimmer, and presents a very beautiful appearance in its movements through the water; the quick, vigorous pulsations contrasting sharply with the sluggish contractions seen in most Scyphomedusae." It appears to be a voracious feeder. "Some of the specimens taken contained in the stomach small fish, so disproportionately large in comparison with the stomach that they lay coiled up, head overlapping tail."[355] Very little is known of the development, but it is possible that _Tamoya punctata_, which lacks gonads, phacellae, and canals in the velum, may be a young form of a species of _Charybdea_. FAM. 2. CHIRODROPIDAE.—Cubomedusae with four interradial groups of tentacles. This family is represented by the genera _Chirodropus_ from the Atlantic and _Chiropsalmus_ from the Indian Ocean and the coast of North Carolina. FAM. 3. TRIPEDALIIDAE.—Cubomedusae with four interradial groups of three tentacles. The single genus and species _Tripedalia cystophora_ has only been found in shallow water off the coast of Jamaica. Specimens of this species were kept for some time by Conant in an aquarium, and produced a number of free-swimming planulae which settled on the glass, and quickly developed into small hydras with a mouth and four tentacles. The further development of this sedentary stage is unfortunately not known. {320}ORDER II. STAUROMEDUSAE. This order contains several genera provided with an aboral stalk which usually terminates in a sucker, by means of which the animal is temporarily fixed to some foreign object. There can be little doubt that this sedentary habit is recently acquired, and the wide range of the characteristic features of the order may be accounted for as a series of adaptations to the change from a free-swimming to a sedentary habit. It is difficult to give in a few words the characters of the order, but the Stauromedusae differ from other Scyphozoa in the absence or profound modification in structure and function of the statorhabs. They are absent in _Lucernaria_ and the Depastridae, and very variable in number in _Haliclystus_. The statorhab of _Haliclystus_ terminates in a spherical knob, which is succeeded by a large annular pad or collar bearing a number of glandular cells which secrete a sticky fluid. At the base of the organ there is a rudimentary ocellus. The number is very variable, and sometimes they are abnormal in character, being "crowned with tentacles." There can be little doubt that the principal function of these organs is not sensory but adhesive, and hence they have received the names "colletocystophores" and "marginal anchors," but they are undoubtedly homologous with the statorhabs of other Scyphozoa. The tentacles are short and numerous, and are frequently mounted in groups on the summit of digitate outgrowths from the margin of the umbrella. They are capitate, except in _Tessera_, the terminal swelling containing a battery of nematocysts.