Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 HYDROZOA—SCYPHOMEDTTSJE. 253 The form of the gastrovascular apparatus exhibits considerable differences, which in the Discophora may be considered as modifica- tions of the Ephyra type. The fiat disc of the Ephyru, which is split into eight pairs of lobes, contains a central gastric cavity into which the canal of the short, wide, four-cornered manu- oriuni leads. From this central cavity there diverge eight canal- like peripheral diverticula (radial pouches), between which there .-in- fo
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 HYDROZOA—SCYPHOMEDTTSJE. 253 The form of the gastrovascular apparatus exhibits considerable differences, which in the Discophora may be considered as modifica- tions of the Ephyra type. The fiat disc of the Ephyru, which is split into eight pairs of lobes, contains a central gastric cavity into which the canal of the short, wide, four-cornered manu- oriuni leads. From this central cavity there diverge eight canal- like peripheral diverticula (radial pouches), between which there .-in- formed sooner or later in the vascular lamella the same number of short intermediate canals (intermediate pouches). The radial and intermediate canals sometimes become enlarged, as in Pelai/ia and - FIG. 100. Section through the olfactory pit, the sense-organ (marginal body) and its nerve centre, of Aun-lia uiirlta. If, Olfactory pit; L, lobe of the umbrella covering the sense organ; P, eye spot; Of, otolith of the auditory sac; Z, cells after solution of the otoliths ; En, entoderm; EC, ectoderm with the underlying layer of nerve fibrilla?, F. Chrysaora, so as to form unusually broad gastric pouches separated by thin septa and without any communication with each other at the periphery. Sometimes, however, they become transformed into narrow vessels, between which, in the broad intervening septa, there is secondarily developed during the subsequent growth by a separa- tion of the two layers of the vascular-lamella, a rich network of anastomosing canals, and near the edge of the disc a circular canal (J nrrJia, ItJiizostoma).
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