Medusae of the world . of the floor of the subumbrella begin to develop when the medusa hasacquired 8 radial tubes; they first appear near the region of the periphery of the stomach. Zygodactyla (?) crassa A. Agassiz. Zygodactyla crassa, AfiAssiz, A., 1865, North Amer. Acal., p. 106, figs. 157, crassa, Haeckel, 1879, Syst. der Medusen, p. 232. Adult medusa.—Bell hemispherical in form and about 300 mm. in diameter. About 350long, marginal tentacles, more massive than in Z. grcenlandica. Only about 32 radial tubes. —ZYGODACTYLA, ZYGOCANNA. 337 Velum well developed. Diam
Medusae of the world . of the floor of the subumbrella begin to develop when the medusa hasacquired 8 radial tubes; they first appear near the region of the periphery of the stomach. Zygodactyla (?) crassa A. Agassiz. Zygodactyla crassa, AfiAssiz, A., 1865, North Amer. Acal., p. 106, figs. 157, crassa, Haeckel, 1879, Syst. der Medusen, p. 232. Adult medusa.—Bell hemispherical in form and about 300 mm. in diameter. About 350long, marginal tentacles, more massive than in Z. grcenlandica. Only about 32 radial tubes. —ZYGODACTYLA, ZYGOCANNA. 337 Velum well developed. Diameter of stomach about four-sevenths as great as that of stomach-walls are not capable of much extension and the mouth does not protrude beyondvelar opening. Mouth surrounded by crenulated and folded lips, which are as numerous asthe radial-canals. Gonads of very large size, occupying the whole lengths of the radial-canalsfrom periphery of stomach to bell-margin. They are complexly folded and hang down into. Fig. 194.—Oral view of Zygodactyla crassa, after A. Agassiz, North American Acalepha?. the bell-cavity. Papillae upon the subumbrella( ?) Bases of tentacles colored with a faintgreenish-blue tinge. Gonads slightly yellowish-green. Color of male gonads pinkish. This medusa was found by A. Agassiz in Massachusetts Bay, at Nahant, but has notbeen observed since. Is it a variety of Z. granlandica ? Genus ZYGOCANNA Haeckel, 1879, sens. ampl. Z\gocanna+ Zxgocannota, Haeckel, 1879, Syst. der Medusen, pp. 214, (in part), Eschscholtz, 1829, Syst. der Acalephen, p. 118. The type species is Zygocanna pleuronola, described by Peron and Lesueur from the north-ern coast of Australia under the name JEquovea pleuronota. GENERIC CHARACTERS. ./Equoridae with forked or branching radial-canals, which arise at equal intervals from theperiphery of the stomach. With 8 or more lips. Manubrium without a peduncle. Develop-ment unknown. Haeckel distinguishes Zygocanna with
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectcnidari, bookyear1910
