File:Medusae of the world (1910) (14595309018).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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canals. They are slightly sinuous, being somewhat longer thanthe parts of the radial-canals upon which they are situated. Ova in female large and prom-inent. The genital organs and bell are pink in color. This medusa was found at Nahant,Massachusetts, in ;une. It has not been seen since A. Agassiz studied it in 1862 and 1864. Mitrocoma megalota.Halopsis nicgalotis, Maas, 1893, Ergeb. der Plankton Expedition, Bd. 2, K. c., p. 57, taf. 6, fign. 3-6. Bell flat, shield-shaped, with firm gelatinous substance, 40 mm. wide, 5 mm. high. About100 very contractile tentacles. These are lash-like, tapering, with large, swollen, hollow, basalbulbs, and only about one-eighth as long as bell-radius. About 800 veryshort, solid cirri,arising from bell-margin between the tentacles. 8 adradial lithocyst-pouches,similar in struc-ture to those of Mitrocoma anncc. These lithocysts are very elongate, open pouches, and lieupon the subumbrella side of the margin at the base of the velum. Each pouch contains a
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Fig. 155.—Mitrocoma cruciata (Halopsis cruciata), after A. Agassiz, in North American Acalephae.Fig. 156.—Mitrocoma megalota, after Maas, in Ergeb. Plankton Expedition. number of ectodermal concretions. There are no ocelli. Velum very narrow, its muscles weaklydeveloped. There are 4 narrow radial-canals and a simple, slender circular vessel. Thelarge stomach is quadratic at base, a radial-canal arising from each of the 4 corners. Themouth is at the extremity of a short neck and is surrounded by 4 large, folded, crenated lips.The gonads are swollen, linear, and lie upon the outer thirds of the 4 radial-canals. Eachgonad is developed upon both sides of its radial-canal, leaving the middle line of the canalfree. Found by the Plankton expedition off northwest coast of Scotland in July. Mitrocoma discoidea Torrey. Mitrocoma discoidea, Torrey, 1909, University of California Publications, Zool., vol. 6, p. 17, fig. 4. Bell flatter than a hemisphere, 45 mm. wide. 180 to 240 short tentacle

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