. Outlines of zoology. Zoology. 156 CCELENTERA. Examples :— Phtfuiilaria and Sertiilaria have sessile gonophores. Campamda7'ia geniculata liberates the meclusoid Obelia geniciilata. {b) HydrocoralliriDS.—Colonial forms which suggest the Hydractiniaa in their polymorphism and division of labour, but are distinguished by their power of taking up lime, and so forming "; The colonies are complex and divergent, the medusoid persons are probably sessile gonophores, but a simple male medusoid has been described. Millepora^ Sty last er. [c] Trachymedusie.—These exist only in the medus
. Outlines of zoology. Zoology. 156 CCELENTERA. Examples :— Phtfuiilaria and Sertiilaria have sessile gonophores. Campamda7'ia geniculata liberates the meclusoid Obelia geniciilata. {b) HydrocoralliriDS.—Colonial forms which suggest the Hydractiniaa in their polymorphism and division of labour, but are distinguished by their power of taking up lime, and so forming "; The colonies are complex and divergent, the medusoid persons are probably sessile gonophores, but a simple male medusoid has been described. Millepora^ Sty last er. [c] Trachymedusie.—These exist only in the medusoid form, and are divided into two groups, Tracho- medusce and Narcomedusce, accord- ing to the position of the gonads. Geryonia^ Car7narma^ Cuniiia^ Aeginopsis, 2. Order Siphonophorce.—Free swimming colonies of modified medusoid persons {medusomes}, with much division of labour. Physalia (Portugese Man-of-War), Diphyes^ I'ek/Ia, Forpita. B. Class ScYPHOzoA. There are two types—polypoid and medusoid—veiy rarely occur- ring in one Ufe history. The gastric cavity has partitions with gastric or mesenteric filaments, and there is an ectodermic gullet. The mesoglcea generally contains migrant cells. The reproductive cells are endo- dermic. I, Sub-class ScyphomedusDe, or Acraspeda— Jelly fish with gastric fila- ments, sub-genital pits, and no velum— (i.) Lucernarice. — Sessile forms. Luteriiaria. (2.) DiscomedusDs.—Active forms, often with complicated life his- tory. Aio'elia^ Pe- lagia, Cya^iea, Rhizo- stoma. (3.) ConomedusLie.—Forms with broad pseudu-veluni, and other peculiar features. Charybdea. (4.) Peromedusce. — Forms with four tentaculocysts only. Fig. 49.—Diagram of a gymnoblastic HydromedusK. (After Allman. ) gut ca-\'Uy ; ectoderm; hydra like the same, «, Stem ; />, root; c d, endoderni (dark); J\ horny perisarc ; g " person " (hydranth); contracted ; h, hypostome bearing mouth ; ^, like reproductive bud (sporosac);
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
