. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. STYLASTERIDAE 17 whatever here or anywhere else to call the tentacles capitate; they are formed quite like the thread- like tentacles in the athecate hydroids. - Further, the gasterozooid shows in its finer structure no difference from what has been described in Stylaster (Ewtylaster) gemmas- a ecus. In the present species it is also broken up at the base into a circle of columns, the number of which seems mostly to be about 6. — The structure of the dactylozooid also agrees with that in the other northern species of Stylast
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. STYLASTERIDAE 17 whatever here or anywhere else to call the tentacles capitate; they are formed quite like the thread- like tentacles in the athecate hydroids. - Further, the gasterozooid shows in its finer structure no difference from what has been described in Stylaster (Ewtylaster) gemmas- a ecus. In the present species it is also broken up at the base into a circle of columns, the number of which seems mostly to be about 6. — The structure of the dactylozooid also agrees with that in the other northern species of Stylaster; but the dactylozooids are somewhat larger in Stylaster norvegicits than in the previous species. The large cnidocysts are found in extremely small numbers in the stolons. Whilst the preceding species was only represented by specimens Text-fig. D. Diagrammatic me- not very well-preserved, the opportunity was taken to obtain fresh material dian section trough the cycle- system of Stylaster {Allopora) nor- of Stylaster norvegicits from the Trondhjem Fjord, in the outer part of vegktis. d = dactylozooid, gt = which the species is fairly common in suitable localities. Both male and . gas 1 J = gasterostyle, gw = free part female colonies could be examined and even if most of the questions of the body-wall of the gastero- • -ii zooid. concerning the development of the gonophores must still remain un- answered, yet the investigation contributes a good deal to the understanding of the nature of the gonophore in Stylaster. The sexual cells are already present in the youngest developmental stage of the male gono- phore which was found (PI. IV fig. 35) so that their origin cannot be settled. The gono- phore shows clearly, that Hicksou (1891 p. 384) was wrong in maintaining, that "the spermarium is covered by a double sheath of very thin etcoderm and endoderm". Neither at this stage or later can anything be seen in the numerous gonophores examined (PI. IV, fig. 37), which
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