History of British animals - University of Guam Marine Laboratory

Actinea. RADIATA. ACALEPHA. 497ACALEPHA.I. Sect.— Fixed ;the base, opposite the mouth, adhering toother bodies.A. Tentacula surrounding uninterruptedly the oral disc.Actinea.Mammaria.AA. Tentacula on the margin of the oral disc disposed in tufts.Lucernaria.II. Sect.— Free ;the base oppositethe mouth ineapableof adheringto other bodies.A. Body closed oppositethe mouth.a. Bodv strengthened internally by a cartilaginous plate-Velella.aa.Body destitute of an internal cartilaginous plate.b. A mouth in the centre of the oral disc.bb.c. Destitute of lateral cavities.Eulimena.cc.Geryonia.With four lateral cavities, or ovaries.Cyanea.Destitute of a mouth in the centre.Ithizostoma.Cassiopea.AA. Body open at both extwnities.Beroe.Pleurobrachia.Gen. XVI. ACTINEA.—Base with the disc capableof shiftingplace ; mouth terminal, retractile ;tentacula numerous.41. A. equina.— Body smooth, finely wrinkled transversely;margin of the disc with a row of tubercles.A. equina,Linn. Syst.i. 1088— Hydra disciflora, tentaculis retractilibus,extimo disci margine tuberculato. Gaertner^ Phil. Trans. 1761, t. i.f. 5. Dicqemare, Phil. Trans. 1773, 364. t. xvi. f. 1—A. hemisphaerica,Penn. Brit. Zool iv. 50.— A. mesembryanthemum, Turt. Brit. Fauna,131.—A. rufa, Steivarfs El. i. 393— Common, adhering to rocks.Body, when contracted, hemispherical, red or brown, smooth ;base blackish-grey,with unequal, tubercular, diverging ridges, the margin with a purplering; tentacula numerous, lengthened, of the colour of the body, or variegatedexterior to which, there is a ; ringof about twenty purple tubercles ;the margin of the mouth is slightly tinged with purple.VOL. I. I i