Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 HTDEOZOA— SCYPnOMEDUS.'E. 253 The form of the gastrovascvxlar apparatus exhilnts considerable differences, which in the Dlscophora may be considered as modifica- tions of the Ephyra tj-pe. The flat disc of the Ephjjra, which is split into eight pairs of lobes, contains a central gastric cavity into which the canal of the short, wide, four-cornered manu- brium leads. From this central cavity there diverge eight canal- like peripheral diverticula (radial pouches), between whic
Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 HTDEOZOA— SCYPnOMEDUS.'E. 253 The form of the gastrovascvxlar apparatus exhilnts considerable differences, which in the Dlscophora may be considered as modifica- tions of the Ephyra tj-pe. The flat disc of the Ephjjra, which is split into eight pairs of lobes, contains a central gastric cavity into which the canal of the short, wide, four-cornered manu- brium leads. From this central cavity there diverge eight canal- like peripheral diverticula (radial pouches), between which there are 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 Pelagia and Fig. 196. Section through the olfactory pit, the sense-organ (marginal body) and its nerve centre, of Aurelia aurifa. S, Olfactory pit; X, lobe of the umbrella covering the sense organ; P, eye spot; Ot, otolith of the auditory sac; Z, cells after solution of the otoliths ; £n, entoderm; Ec, ectoderm with the underlj'ing layer of nerve fibrillar, 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 transfoi-med 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 {^Aiorelia, Rhizostovia).
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