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

2. Cromyatractus tetralepas, n. sp.

Proportion of the main axes of the four concentric shells about = 1 : 2 : 4 : 6. Network of the two medullary shells regular, with small circular pores, little larger than the bars. Network of the two cortical shells irregular, with much larger polygonal pores, three to nine times as broad as the thin bars. (Somewhat similar to Cromyatractus ceparius, Pl. [15], fig. 4.) Surface of the outermost shell smooth or a little thorny. Polar spines cylindrical, very large, twice to three times as long as the main axis of the outermost shell, about as broad as the innermost shell, with conical apex; smooth or a little thorny.

Dimensions.—Main axes of the four shells—(A) 0.03, (B) 0.05, (C) 0.13, (D) 0.18; equatorial axes of them—(A) 0.2, (B) 0.45, (C) 0.11, (D) 0.14; pores of the two medullary shells 0.004 and 0.006, of both cortical shells 0.01 to 0.03, bars 0.003.

Habitat.—Indian Ocean, Zanzibar, Pullen, 2200 fathoms.

3. Cromyatractus tetracelyphus, n. sp. (Pl. [15], figs. 1, 1a).

Proportion of the main axes of the four concentric shells about = 1 : 3 : 10 : 11. Network of the two spherical medullary shells (fig. 1a) regular, with small circular pores, twice as broad as the bars. Network of the inner cortical shell regular with circular, hexagonally-framed pores, twice as broad as the bars. From every corner of the hexagons (between three pores) arises a very thin, hair-like, short radial spinule. These spinules communicate with one another by tangential branches (at equal distances from the inner cortical shell), and form thereby an outer, delicate cortical network, with large polygonal meshes and very thin bars. Polar spines very strong, pyramidal, with prominent edges, as long as the main radius of the cortical shell, and half as broad at the base.

Dimensions.—Main axes of the four shells—(A) 0.02, (B) 0.06, (C) 0.2, (D) 0.22; equatorial axes of them—(A) 0.02, (B) 0.06, (C) 0.13, (D) 0.15; pores of the four shells—(A) 0.002, (B) 0.004, (C) 0.008, (D) 0.02; bars 0.001 to 0.003; length of the polar spines 0.1, basal breadth 0.05.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

Subgenus 2. Caryatractus, Haeckel.

Definition.—Shell composed of two medullary shells and three or more cortical shells.