Page:Scientific results HMS Challenger vol 18 part 1.djvu/404

196 Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.03; cortical pores 0.012, bars 0.003; length of the six spines 0.08, breadth 0.03.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

14. Hexacontium hexaconicum, n. sp.

Cortical shell spiny, thick walled. Pores regular circular, of the same breadth as the bars, ten to twelve on the radius; between them long bristle-shaped by-spines, half as long as the six main spines. Radial proportion of the three spheres = 1 : 3 : 9. Six main spines conical, as long as the radius of the outer shell, four times as broad at the base as one pore.

Dimensions.—Diameter of the outer shell 0.18, middle 0.06, inner 0.02; cortical pores and bars 0.005; length of the spines 0.1, basal breadth 0.02.

Habitat.—Antarctic Sea, Station 157, depth 1950 fathoms.

15. Hexacontium asteracanthion, Haeckel.

Haliomma asteracanthion, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 816.

Actinomma asteracanthion, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiii. figs. 5, 6.

Cortical shell thin walled, spiny; its pores circular, without hexagonal frame (as a rule very regular, but in other specimens more or less irregular), often very variable in size, three to six times as broad as the bars, commonly seven to eight on the radius. Radial proportion of the three spheres = 1 : 2 : 4, or sometimes 1 : 3 : 8. Pores of the two inner shells also circular, but much smaller; those of the middle shell about half as broad, those of the inner shell one-fourth to one-sixth as broad as the pores of the outer shell. Six radial spines strong, three-sided prismatic, about as long as (or somewhat longer than) the radius of the outer shell, as broad as one of its large meshes. Accessory spines very numerous and very thin, bristle-like, usually half as long as the six main spines. (For the variability of this common species compare my Monograph, p. 442.)

Dimensions.—Diameter of the outer shell 0.1 to 0.12, of the middle 0.04 to 0.06, of the inner 0.02 to 0.03; cortical pores 0.005 to 0.01; length of the six spines 0.06 to 0.08.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth, without radial by-spines or papillæ (other than the six main spines).

16. Hexacontium axophænum, n. sp.

Cortical shell thin walled, smooth. Pores irregular polygonal, three to nine times as broad as the bars; seven to ten on the radius. Radial proportion of the three spheres = 1 : 3 : 8. Both