. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. ACTINIARIA 159 v/ere developed, on the other side two mesen- teries of the 4th order were lacking. In the specimen from Ikamiut the number was 55 (6 + 6 + 12 + 24 + 7 — compare the table). The arrangement of the mesenteries thus seems commonly to be deca- merous, though it may happen to be hexame- Fig. 165 rous. All mesenteries were perfect in the lar- ger specimens, in the smaller specimens the last cycle was not connected with the actinopharynx. The number of mesenteries seems sometimes to he a little smaller than that of
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. ACTINIARIA 159 v/ere developed, on the other side two mesen- teries of the 4th order were lacking. In the specimen from Ikamiut the number was 55 (6 + 6 + 12 + 24 + 7 — compare the table). The arrangement of the mesenteries thus seems commonly to be deca- merous, though it may happen to be hexame- Fig. 165 rous. All mesenteries were perfect in the lar- ger specimens, in the smaller specimens the last cycle was not connected with the actinopharynx. The number of mesenteries seems sometimes to he a little smaller than that of the tentac- les, which indicates that also here the mesen- teries grow from the basis upwards, a rule, which perhaps holds good for all Cribrinids. The longitudinal muscles of the mesenteries recall those of Urticina, and the pennons appear as bands, a little but deeply folded. The parie- tobasilar muscles are well developed, though not as strong as in Urticina. The uppermost part is. Fig. 168 Fig. 169 Fig. 167 Textfigs. 165—169. Cribrinopsis siniilis. Transverse sections of sphincters (figs. 165, 166), of tentacles (figs. 167 —168 and oral disc (fig. 169). (Figs. 165, 167, spec, from Finmark; fig. 166 spec, from Kola, Chewanna; fig. 169 spec, from Corea strait). rather narrow, and the muscles end before reaching the region of the sphincter. The basilar muscles are well developed and discoverable to the naked eye. Oral stomata are present, sometimes also marginal stomata, the latter, however, occur anytliing but regularly. All mesenteries are fertile, only on the directive mesen- teries they are often lacking (compare the table p. i6o). The species is dioecious. Remarks. In this specimen I have never found any embryos in the coelenteric cavity. The most closely examined specimens were however male. A specimen was a double animal, each specimen had two pairs of directive mesenteries symmetrically arranged, perpendictdarly to the div-iding plane. The small fragments of the
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscienti, bookyear1921
