. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. No. 5.] VARIATION AMONG HYDROMEDUSAE. 235 primary canals, which divided the bell into approximately pen- tamerous segments, as shown in PI. Ill, Fig. 12. In another there was a very evident forking of two of the four primary canals, as shown in PI. Ill, Fig. 9 ; for while the bell was divided into hexamerous segments, the manubrium was sym- metrically tetramerous. In every one of the other five hexam- erous specimens the canals converged at the aboral pole in a perfectly symmetrical way, though the hexamerism extended to the
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. No. 5.] VARIATION AMONG HYDROMEDUSAE. 235 primary canals, which divided the bell into approximately pen- tamerous segments, as shown in PI. Ill, Fig. 12. In another there was a very evident forking of two of the four primary canals, as shown in PI. Ill, Fig. 9 ; for while the bell was divided into hexamerous segments, the manubrium was sym- metrically tetramerous. In every one of the other five hexam- erous specimens the canals converged at the aboral pole in a perfectly symmetrical way, though the hexamerism extended to the manubrium in only two specimens, and in these only. FK,. 9. —• Hexamerous specimen showing pentamerous stomach and varying size and distribution of tentacles. the basal portion or gastric pouch was strictly hexamerous. In at least two other of these hexamerous specimens the oral lobes of the manubrium were four (cf. Fig. 9). Of specimens having three and five canals there were by far the larger number, with the preponderance slightly in favor of the trimerous variety, but not sufficiently so to warrant any conclusions as to the question whether the course of variation was toward a trimerous rather than a pentamerous condition. Of those with three canals there were twenty-one specimens, while of those with five there were eighteen specimens. Of those making up the total of seventy-two specimens there were. 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 Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory
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