. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. Fijs;. 18. ScKjartiogeton verriUi. Section of a perfect mesentery of the first order about in the middle of ( Fisli Com.) usually not occupying half the breadth of the mesogloea and wholly separated from the endodermal muscles of the column. The sections of the sphincter of two specimens, the one taken by the U. S. Fish Conmiission, the other by the Ingolf expedition (fig. 17), show good agreement. The longitudinal muscles of the tentacles are ectodermal, at the ab
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. Fijs;. 18. ScKjartiogeton verriUi. Section of a perfect mesentery of the first order about in the middle of ( Fisli Com.) usually not occupying half the breadth of the mesogloea and wholly separated from the endodermal muscles of the column. The sections of the sphincter of two specimens, the one taken by the U. S. Fish Conmiission, the other by the Ingolf expedition (fig. 17), show good agreement. The longitudinal muscles of the tentacles are ectodermal, at the about equally developed on the outside as on tiie inside, the folds like a palissade, are of about same height as the main part of the mesogloea. The radial muscles of the oral disc agree in their appearance with the longitudinal of the tentacles, but are weaker at the insertions of the mesenteries. The ectoderm of the is rather high and contains numerous nema- tocysts, the mesogloea is of ordinarv thickness, in exjianded state of the actinopharynx thin, in the siphonoglyjths thickened. A .sectioned specimen showed the following arrangement of the mesenteries; 12 pairs of the first and second order and 6 of the third were perfect, the other 6 of the third order and those of the fourth iinjierfect. Counted from the one directive pair the ])airs of mesenteries 1, 2 and i of the thiril order were imperfect in both halves of the body. The fourth cycle of mesenteries was almost complete—the specimen had 92 tentacles. In another specimen there were also more than 12 perfect pairs. In a third. I'^i;;. 19. Sdijiirtioijetim rerrilU. Section of a directive incseiitcrv and of a mesentery of tlie third oriler at tlie lowest part of tlie actiniii)lKirvn\ (hiiiolf St. 95). individual I counted 74 tentacles Init 124 mesenteries at the l)ase. The longitudinal muscles of the mesenteries form retractors on the mesenteries of the , second and third order. The retract
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
