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

Amphistylus neptunus, Haeckel, 1878, Atlas, pl. xvii. fig. 6.

Cortical shell thick walled, smooth, with subregular, circular, polygonally framed pores, quite as broad as the bars; ten to twelve on the half equator. Polar spines three-sided pyramidal, about as long as the half main axis, three times as broad at the base as the pores. (Much resembles Amphisphæra neptunus, p. [142], but differs from it by the prolongation of the main axis, which equals one and a half or one and a fourth the equatorial axis, and by the somewhat irregular formation of the cortical hexagonal network. Sometimes also, as in the figured specimen, the length of both polar spines is somewhat different.)

Dimensions.—Major axis of the cortical shell 0.15, minor axis 0.12; pores and bars 0.007; main axes of both ellipsoidal medullary shells 0.08 and 0.05; length of the polar spines 0.08 to 0.1, basal breadth 0.02.

Habitat.—Pacific, central area, Stations 266 to 268, depth 2700 to 2900 fathoms.

2. Stylatractus fusiformis, n. sp.

Cortical shell thick walled, smooth, with regular, simple, circular pores, quite as broad as the bars; fourteen to sixteen on the half equator. Polar spines three-sided pyramidal, half as long as the main axis, as broad at the base as the inner medullary shell. (Resembles very nearly Xiphatractus armadillo, Pl. [17], fig. 11, but differs in the regular form and equal length of the polar spines.)

Dimensions.—Major axis 0.17, minor axis 0.13; pores and bars 0.007; main axes of both ellipsoidal medullary shells 0.09 and 0.05; length of the polar spines 0.08, basal breadth 0.04.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, at various depths.

3. Stylatractus compactus, n. sp. (Pl. [17], fig. 4).

Cortical shell thick walled, smooth, with subregular, circular, double-contoured pores, smaller than the bars; sixteen to eighteen on the half equator. The thickness of the shell-wall equals the radius of the inner medullary shell. Polar spines short, three-sided pyramidal; their length and basal thickness variable, but commonly equal to the diameter of the inner medullary shell.