Page:Scientific results HMS Challenger vol 18 part 1.djvu/373

Rh Dimensions.—Diameter of the outer shell 0.15, middle 0.13, inner 0.04; cortical pores 0.017, bars 0.003; length of the spines 0.03.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Stöhr.

5. Stauracontium sparganium, n. sp.

Cortical shell thick walled, covered with very numerous, short, conical spines, and with regular, circular pores, five times as broad as the bars; sixteen to eighteen on the quadrant. Radial proportion of the three spheres = 2 : 3 : 9. Radial main spines three-sided prismatic, as long as the radius or longer.

Dimensions.—Diameter of the outer shell 0.275, middle 0.09, inner 0.06; cortical pores 0.01, bars 0.002; length of the spines 0.15.

Habitat.—Fossil in Barbados.

Definition.—Pores irregular, of different size or form; surface smooth.

6. Stauracontium antarcticum, n. sp.

Cortical shell thin walled, smooth. Pores irregular, roundish, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 8. Radial spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.2, middle 0.05, inner 0.025; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.1.

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

Definition.—Pores irregular, of different size or form; surface covered with thorns or by-spines.

7. Stauracontium setosum, n. sp.

Cortical shell thin walled, covered with thin bristle-shaped by-spines, half as long as the radius. Pores irregular, polygonal, three to five times as broad as the bars. Proportion of the three spheres = 1 : 2 : 6. Radial main spines pyramidal, nearly as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.15, middle 0.05, inner 0.025; cortical pores 0.01 to 0.015, bars 0.003; length of the spines 0.12.

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

8. Stauracontium papillosum, n. sp.

Cortical shell thick walled, covered with short conical papillæ or by-spines. Pores irregular, roundish, two to four times as broad as the bars. Proportion of the three spheres = 1 : 3 : 12. Radial main spines conical, as long as the radius.