Haeckel’s treatment of the Cubomedusæ in his “System” (’79) in the Challenger Report (’81) is much more lucid than Claus’s; but the extended scope of his work and the imperfect preservation of his material prevented a detailed investigation, and for a more complete and readily intelligible account of the structure of the Cubomedusæ a larger number of figures is desirable.
In the foregoing facts lies whatever excuse is necessary for repeating in the present paper much that has already seen print in one form or another.
Part I: SYSTEMATIC.
It seems advisable first of all to establish the systematic position of the two newly found species, Charybdea Xaymacana and Tripedalia cystophora. Haeckel’s classification, as given in his “System der Medusen,” is an excellent one and will be followed in this case. One of the new species, however, will not classify under either of Haeckel’s two families, so that for it a new family has been formed and named the Tripedalidæ. In showing the systematic position of the two new forms, an outline of Haeckel’s classification will be given, so far as it concerns our species, together with the additions that have been made necessary.
Cubomedusæ (Haeckel, 1877).
Characteristics: Acraspeda with four perradial sensory clubs which contain an auditory club with endodermal otolith sac and one or several eyes. Four interradial tentacles or groups of tentacles. Stomach with four wide perradial rectangular pockets, which are separated by four long and narrow interradial septa, or cathammal plates. Gonads in four pairs, leaf-shaped, attached along one edge to the four interradial septa. They belong to the subumbrella, and are developed from the endoderm of the stomach pockets, so that they project freely into the spaces of the pockets.
Family I: Charybdea (Gegenbaur, 1856).
Cubomedusæ with four simple interradial tentacles; without marginal lobes in the velarium, but with eight marginal pockets; without pocket arms in the four stomach pockets.