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

Dimensions.—Radius of the arms 0.11, basal breadth 0.03, distal breadth 0.06.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; tropical zone, surface.

2. Rhopalodictyum truncatum, Ehrenberg.

Rhopalodictyum truncatum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 301.

? Dictyastrum angulatum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. viii. fig. 18.

Arms of equal size and equidistant, nearly square, with straight edges, towards the truncated end a little broader, about of the same diameter as the central triangular disk. This species is indicated by Ehrenberg only by the short diagnosis, "Radiis stellæ tribus apice truncatis." It is probably identical with his figure of Dictyastrum angulatum (loc. cit.). This latter name I have retained for the similar Porodiscid (above, p. [526]), mainly because the genera Dictyastrum and Rhopalodictyum, according to the insufficient diagnosis of Ehrenberg, seem to be identical. (Compare my Monograph, 1862, p. 466.)

Dimensions.—Radius of each arm 0.13, basal breadth 0.09, distal breadth 0.1.

Habitat.—Tropical Pacific, Philippine Sea, Station 200, depth 250 fathoms; Atlantic (Mexican Gulf Stream).

3. Rhopalodictyum subacutum, Ehrenberg.

Rhopalodictyum subacutum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 301.