. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. MEDUS.'E in 1000 m. Fi^'. 1. Distribution cif Plijchogastria polaris. Q pxact Im-ality iiiikiidwn. If) clusters; in all other respects these young specimens resemble the adult, and the gonads are already visible on the eight stom- achal lobes which are all of equal size. Colour: According to sketches, made on board the '"Ingolf", St. 126, the colour of the subumbrella is a light pink, the gonads are scarlet, the stomach a deep red (PI. VI figs. 1-2). Comparison with other species
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. MEDUS.'E in 1000 m. Fi^'. 1. Distribution cif Plijchogastria polaris. Q pxact Im-ality iiiikiidwn. If) clusters; in all other respects these young specimens resemble the adult, and the gonads are already visible on the eight stom- achal lobes which are all of equal size. Colour: According to sketches, made on board the '"Ingolf", St. 126, the colour of the subumbrella is a light pink, the gonads are scarlet, the stomach a deep red (PI. VI figs. 1-2). Comparison with other species. - I quite agree with V.\NHOFFEN (1912a p. 386) that Ptychogastria antarclicn (Haeckel) difiers too much from P. â polaris to be placed in the same genus, or even in the same family. The genus is, however, really repre- .sented in the Antarctic by P. opposita VanhoflEen (1902 b), a species greatly resembling the arctic P. polaris. P. nsteroides (Haeckel) from the Adriatic Sea and the Straits of Gibraltar likewise .seems to be a true Pt/jchogastria, though there is one feature which (provided that the description is correct) presents a serious ob- stacle against its affinities to this genus: the adhesive tentacles are said to be hollow, and in Haec'KEl's figure of a transverse section (1881, PI. 7 fig. 4) the central canal is seen to be sur- rounde. 311) that Ptychogastria should be with Crossota on account of ''the arrangement of the jevera! rows of tentacles". hxPUjchogastria the tentacles are placed in distinct clusters, whereas in Crossota tlicv make an unint<'r- rujited whorl; and as previously pointed out by me (1942 p. 80) the tentacles of Crossota are not arranged in several rows or series. Thus the only point of connection supposed to exist be- tween these two genera does not hold good, and in all other re- spects they are highly different. The species of Ptychogastria con- stitute a distinct family with an isolated position within the Trachvmedusa
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
