File:Medusae of the world (1910) (14801787953).jpg

Identifier: medusaeofworld02mayo (find matches)
Title: Medusae of the world
Year: 1910 (1910s)
Authors: Mayor, Alfred Goldsborough, 1868-1922 Mayer, Alfred Goldsborough, 1868-1922
Subjects: Jellyfishes Cnidaria
Publisher: Washington, D.C., Carnegie institution of Washington
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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stem and each branchare annulated with 3 to 6 ringsabove the point of origin oteach branch or ramulation. The hydrothecx are cam-panulate, quite large, delicate,and elongate. They are nearlyconical, with slightly bulgingsides. The rims are delicatelynotched with very small, blunt,shallow teeth. These hydro-thecae are borne upon quitelong pedicels, usually ringedthroughout with about 8 to 15rings, and tapering from theirpoint of origin to base ofhydrotheca. The reproductive calyclesarise from relatively short pedi-cels in the axils of the stems.They are ovate to conical, withsmooth outer surface and withthe terminal aperture at theextremity of a crater-like pro-jection. About 10 to 15 me-dusa-buds are seen developingat one and the sametimeineachcalycle. The calycles break offvery readily, and on this accountare rarely seen in preserved orroughly handled specimens.When set free, the medusa has Fig. 134.—Obelia longissima, after Hincks, in British Hydroid Zoophytes. 20 to 24 tentacles.
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256 MEDUS/E OF THE WORLD. This hydroid is abundant on the Atlantic coasts of Europe and in America north of theCarolinas. It has been found by Saemundsson at Iceland, and by Hartlaub off the Pacificcoast of Chile and in the Straits of Magellan. Clarke records it from Alaska. Billard, 1904 (Annal. Sci. Nat., Ser. 8, Zool., tome 20), finds that at St. Vaast, on thenorthwest coast of France, there are two varieties of O. longissima; a large form in deep water,and a smaller variety along the shore; in which latter the indentations of the margin are greatlyreduced so as to be all but indistinguishable. This common Obeli a may be at once recognized by its long, flexible, black, thread-like,main stems, and its delicate alternate branches, all tapering from base to summit. The maturemedusa can not be distinguished from that of other species of Obeha. Obelia chinensis Marktanner-Turneretscher.Obelia chinensis, Marktanner-Turneretscher, 1890, Ann. Hofmuseum Wien, Bd. 5, p. 210, taf. 3, fign. 6,

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