Echinoidea of the Swedish South Echinoidea of the Swedish South Polar Expedition echinoideaofswed00mort Year: 1910 Bd. VI: 4) THE ECIIINOIDEA. hand it is not probable that tridentate pedicellaria; will occur, in view of the fact that this form of pedicellarue has not been found either in any of the related genera, Notocidaris, Rhynchocidaris, Austrocidaris and Eurocidaris. The spicules of the tube-feet are of the usual shape and arranged in the usual manner, so as to leave a bare space for the tentacle nerve. The walls of the in- testine contain more or less numerous, small, irregular, more
Echinoidea of the Swedish South Echinoidea of the Swedish South Polar Expedition echinoideaofswed00mort Year: 1910 Bd. VI: 4) THE ECIIINOIDEA. hand it is not probable that tridentate pedicellaria; will occur, in view of the fact that this form of pedicellarue has not been found either in any of the related genera, Notocidaris, Rhynchocidaris, Austrocidaris and Eurocidaris. The spicules of the tube-feet are of the usual shape and arranged in the usual manner, so as to leave a bare space for the tentacle nerve. The walls of the in- testine contain more or less numerous, small, irregular, more or less elliptical cal- careous corpuscles (Fig. 2). The organs of Stewart do not seem to contain any spicules. The genital organs contain only very few spicules, mainly of the same shape as those of the intestine. As might be expected from the size of the female genital opening, the eggs are very large, ca. mm. diameter, and rather few in number. It may be con- cluded with certainty that this species has not pelagic larva;. Probably it will also prove to have some sort of care of the brood. I have, however, been unable to find the young on any of the available specimens. The colour is dark purple, viz. the secondary spines and the test, which latter is covered by a thick skin in which the chromatophores are found. The radioles are white, with a faint tint of violet at the base, and stand out very beautifully from the dark ground-colour of the test. It is, however, rather seldom that the natural colour of the radioles is seen. Generally the radioles are covered by a profusion of foreign organisms: sponges, a Bryozoan (of the genus Alcyonidium), which wholly invests the radioles in a thick layer of its soft matter (PI. 1) or a small, white bivalve Mollusc (PI. II) which proves to be viviparous; this fact accounts for the enormous numbers occur- ring on some specimens, the young ones taking their place on the same host as the parents. According to Mr. H. LvNGE it belongs to
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