. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. HTDBOZOA— 253 The form of the gastrovascular apparatus exhibits considerable differences, which in the Dlscophora may be considered as modifica- tions of the E'fhyra type. The flat disc of the Epliyra, which is split into eight pairs of lobes, contains a central gastric cavity into which the canal of the short, wide, four-cornered manu- briuin leads. From this central cavity there diverge eight canal- like peripheral diverticula (radial pouches), between which there are forme
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. HTDBOZOA— 253 The form of the gastrovascular apparatus exhibits considerable differences, which in the Dlscophora may be considered as modifica- tions of the E'fhyra type. The flat disc of the Epliyra, which is split into eight pairs of lobes, contains a central gastric cavity into which the canal of the short, wide, four-cornered manu- briuin 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 sometimes become enlarged, as in Pelagia and. Z FIG. 196. Section through the olfactory pit, the sen?e-organ (marginal body) and its nerve centre, of Aurelia aurita. K, 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 (Aurelia, Rhizostomci).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Claus, Carl, 1835-1899; Sedgwick, Adam, 1854-1913; Sinclair, F. G. (Frederick Granville), b. 1858. London, Swan Sonnenschein & co.
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