Page:Scientific results HMS Challenger vol 18 part 1.djvu/346

138 Polar spines three-sided pyramidal, about as long as the axis of the outer sphere, one-fourth as broad as its radius. (Similar to Xiphosphæra vesta, Pl. 14, fig. 6.)

Dimensions.—Diameter of the outer shell 0.15, pores 0.008 to 0.015, bars 0.003; inner shell 0.05; polar spines 0.12 long, 0.02 broad.

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

Definition.— with two concentric lattice-spheres and two free spines, of different size or form.

The genus Sphærostylus differs from Stylosphæra in the different size or form of the two polar spines, and therefore has the same relation to it that Xiphostylus bears to Xiphosphæra.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without thorns.

1. Sphærostylus liostylus, Haeckel.

Stylosphæra liostylus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 2.

Cortical shell thin walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular, circular, twice as broad as the bars; ten to twelve on the half equator. Polar spines cylindrical, as broad as one pore, with conical apex; the minor spine about as long as the axis of the outer shell, the major three to four times as long.

Dimensions.—Diameter of the outer sphere 0.12, pores 0.12, bars 0.006; diameter of the inner sphere 0.04; length of the major polar spine 0.3 to 0.4, of the minor 0.1 to 0.15, breadth 0.012.

Habitat.—Fossil in the Barbados rocks.

2. Sphærostylus flexuosus, Haeckel.

Stylosphæra flexuosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 5.

Cortical shell thick walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular circular, of the same breadth as the bars; eight to ten on the half equator. Polar spines cylindrical, S-like curved, irregular; the minor scarcely as long as the axis of the outer sphere, the major two to three times as long. (In the figure of Ehrenberg the spines are broken off; I have found them myself constantly irregular and of unequal length, sometimes with conical apex.)