. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 210 ACTINIARIA In the specimens i, 3, 4, 5 I have found solitary typical nematocysts in the actinopharynx. They were a httle larger (29—38 X 2,5 11) than usual. Whether these nematocysts belong to the actinopharynx or are sticking to it, I cannot with certainty decide, in specimen 5 I observed only a few typical nematocysts in the maceration preparations, in the other specimens the nematocysts, put down in the table, were, how- ever, numerous. The mesogloeal, longitudinal muscles of the tentacles on transverse sections show
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 210 ACTINIARIA In the specimens i, 3, 4, 5 I have found solitary typical nematocysts in the actinopharynx. They were a httle larger (29—38 X 2,5 11) than usual. Whether these nematocysts belong to the actinopharynx or are sticking to it, I cannot with certainty decide, in specimen 5 I observed only a few typical nematocysts in the maceration preparations, in the other specimens the nematocysts, put down in the table, were, how- ever, numerous. The mesogloeal, longitudinal muscles of the tentacles on transverse sections show meshes of ordinary size, which are situated now in the middle of the mesogloea, now nearer to the endoderm. In the textfig. 198 I have reproduced a transverse section of a tentacle: the muscles are weaker on the outer side than on the inner one. The radial mus- cles of the oral disc recall the longitud- inal muscles of the tentacles. They are the best developed in the specimens i and 5 (textiig. 199). They are distinctly interrupted at the insertions of the me- senteries. The number of mesenteries varies. In one half of specimen i with 96 tentacles I counted 54 pairs of mesenteries (27 pairs sterile and as many fertile), in spe- cimen 2 with 90 tentacles the pairs of mesenteries were 94 (22 on one side and 25 on the other, sterile and as many fer- tile), in specimen 4 with 62 tentacles pro- bably 90 pairs of mesenteries half of which sterile, in the specimen 5 with 86 tentacles 86 (18 pairs on one side and 25 on the other, sterile and as many fertile). As we see, the arrangement of the mesenteries was different on both sides of the directive plane. In one half of specimen i the mesenteries of the first to the third cycles were perfect, among the mesenteries of the fourth cycle three pairs reached the actinopharynx, six pairs consisted of a per- fect and an imperfect mesentery and three pairs were imperfect like the mesenteries of the fifth and sixth orders. In specimen 4 ther
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscienti, bookyear1921
