. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 23^ ACtlNlARlA The mesenteries are hexamerously arranged in 5 or 6 cycles. The mesenteries of the three first orders are perfect, though tlaose of the third order do not reach as far down on the actinopharynx as both the first. Both mesenteries in the pairs of the third cycle seem to be about equally developed. From the mesenteries of the fourth cycle the mesenteries are distinctly arranged, according to the 12 first pairs of mesenteries are sterile like those of the youngest cycle, sometimes also one p
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 23^ ACtlNlARlA The mesenteries are hexamerously arranged in 5 or 6 cycles. The mesenteries of the three first orders are perfect, though tlaose of the third order do not reach as far down on the actinopharynx as both the first. Both mesenteries in the pairs of the third cycle seem to be about equally developed. From the mesenteries of the fourth cycle the mesenteries are distinctly arranged, according to the 12 first pairs of mesenteries are sterile like those of the youngest cycle, sometimes also one part of the last cycle but one. The species is monoecious, and testes and ovaries were simultaneously developed. As far as I have observed, the mesenteries of the third cycle always have ovaries, those of the fourth cycle now ovaries, now testes, sometimes both mesenteries of this cycle are only provided with testes, sometimes the strongest mesentery of a pair has ovaries, the weakest testes. The mesenteries of the fifth cycle as a rule form testes. I have, how- ever, found specimens, in which testes are present only in a part of the mesenteries, while the others have ovaries. The testes, when found, were always numerous. Rather often testes and ovaries may be found in the same mesentery. There is thus a great variation in the distribution of the testes and the ovaries, still it seems, as if the ovaries appear on the older, the testes rather on the younger mesenteries. In the textfig. 209 I have reproduced a transversal section of a part of a mesen- tery with ovaries (ov) and testes (t). The ovaries, as well as the testes were well developed; in a specimen, one of the largest of the collection, the reproductive organs were absent. The longitudinal muscles of the mesenteries form no pennons but are ordinarily developed, the transversal muscles are distinct and the parietobasilar muscles strong, well marked and almost reach the spliincter. The basilar muscles on transverse section
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscienti, bookyear1921
