Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, First Part: Porulosa (Spumellaria and Acantharia) / Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII

by Ernst Haeckel

Dictyastrum triactis, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 306.

Arms rectilinear, four times as long as broad, with parallel edges, pointed at the distal end, with a short terminal spine. Diameter of the circular central disk equal to double the breadth of the arms.

Dimensions.—Radius of each arm 0.2, breadth 0.04.

Habitat.—Pacific, Philippine Sea, Station 206, depth 2100 fathoms.

7. Dictyastrum aculeatum, n. sp.

Arms lanceolate, three times as long as broad, twice as broad in the middle as at either end, with thorny surface and numerous conical terminal spines, one very large in the radius. Central disk triangular, about as broad as the arms. (Resembles Rhopalastrum arcticum, Pl. [43], fig. 6, but differs by the equal angles and the triangular disk.)

Dimensions.—Radius of each arm 0.2, breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 228. Rhopalastrum,[^[267]] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Porodiscida with three simple undivided, chambered arms, without a patagium; triangular shell bilateral, one odd arm opposite to the odd angle between two paired arms.