. Rapporti di ricerca. Discovery (nave); spedizioni scientifiche; Ocean; Antartide; Isole Falkland. Br I Fig. 4. Willia mutabilis. Un po' più vecchie, fase in cui i due canali radiali lasciando a ciascuno dei quattro angoli dello stomaco sono ugualmente divergenti dalla direzione perradial, ciascuna di esse avente un ramo laterale.. Fig. 5. WilUamutabilis. Il canale radiale sistema di un adulto con una stomath con otto lobi. Il secondo ramo del canale radiale sistema è molto variabile in posizione; esso può staccarsi dal canale principale (Fig. 6 A, B, E) o dal primo ramo (Fig. 6 C, D). Spe
1581 x 1581 px | 26,8 x 26,8 cm | 10,5 x 10,5 inches | 150dpi
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. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. Br I Fig. 4. Willia mutabilis. A slightly older stage, in which the two radial canals leaving each of the four corners of the stomach are equally divergent from the perradial direction, each of them having one lateral branch.. Fig. 5. WilUamutabilis. The radial canal system of an adult having a stomath with eight lobes. The second branch in the radial canal system is very variable in position; it may either come off from the main canal (Fig. 6 A, B, E) or from the first branch (Fig. 6 C, D). Specimens with two branches to each of the eight main radial canals are 2-4 mm. in diameter and have about twenty-four tentacles, some of which may, however, be in a juvenile stage of development. The third branch is likewise variable and may either come off from the main canal (Fig. 6 F, H) or from the first branch (Fig. 6 G, I). There are several specimens in which some of the main canals have two branches while others have three; the number of tentacles varies in accordance herewith. Specimens with three branches to all of the eight main canals are 3-4I mm. in diameter and have about thirty-two tentacles. In the largest specimens observed within this group (4-5 mm. wide) the number of branches to the main canals varies from three to five (Fig. 5), but the maximum number of five is never seen in all of the main canals of one individual. The greatest number of canals (main canals-1-branches) reaching the umbrella-margin in specimens with eight main canals, as observed in the present material, is forty-one, and the greatest number of tentacles is likewise forty-one. In the young specimens the stomach has only four undivided perradial lobes, two radial canals coming off from the end of each lobe (Figs. 2-4). Later on the lobes become broader (Fig. 7 a), and each of them begins to bifurcate (Fig. 7 b), forming two. Please note that these images are extracted from scanned page images
