Page:Scientific results HMS Challenger vol 18 part 1.djvu/718

510 2. Stylodictya multispina, Haeckel.

Stylodictya multispina, Haeckel, 1862, Monogr. d. Radiol., p. 496, Taf. xxix. fig. 5.

Stylodictya forbesii, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 160, Taf. xxiii. fig. 6.

All rings of the disk concentric, circular, of equal breadth. Pores regular, circular, two and a half to three on the breadth of each ring. Eight to twelve radial beams beginning from the central chamber, others from the inner rings. Commonly from the third or fourth ring arise twenty-four to thirty (sometimes forty or more) piercing beams, which are prolonged at the margin into bristle-shaped radial spines, as long as the breadth of two to four rings.

Dimensions.—Diameter of the disk (with seven rings) 0.2; breadth of each ring 0.013; pores 0.004.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface and various depths.

3. Stylodictya hastata, Ehrenberg.

Stylodictya hastata, Ehrenberg, 1873, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 257; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, Taf. xxiii. fig. 5.

Stylodictya gracilis, Bury, 1862, Polycystins of Barbados, pl. ii. fig. 1.

All rings of the disk concentric, circular, of equal breadth. Pores regular, circular, very small, two on the breadth of each ring. Eight to twelve marginal spines very large, spear-shaped, sulcated, pyramidal, nearly as long as the diameter of the disk, with a thin pedicle at the base, above this as thick as the breadth of one ring.

Dimensions.—Diameter of the disk (with five rings) 0.13; breadth of each ring 0.012; pores 0.003.

Habitat.—Fossil in the rocks of Barbados.

4. Stylodictya stellata, Bailey.

Stylodictya stellata, Bailey, 1856, Amer. Journ., vol. xxii. p. 6, pl. i. fig. 20.

Stylodictya stellata, Haeckel, 1862, Monogr. d. Radiol., p. 499.

All rings of the disk concentric, circular, of equal breadth. Pores regular, circular, very small, two on the breadth of each ring. Marginal spines fourteen (probably variable in number, twelve to sixteen), very thick and short, conical; their length seems to be equal to their basal breadth and to the breadth of one ring. Related to Stylochlamydium?

Dimensions.—Diameter of the disk (with five rings) 0.11; breadth of each ring 0.01; pores 0.003.

Habitat.—North Pacific, depths of the Kamtschatka Sea, Bailey; Station 241, depth 2300 fathoms.

5. Stylodictya arachnia, Haeckel.

Stylodictya arachnia, Haeckel, 1862, Monogr. d. Radiol., p. 497.

Stylocyclia arachnia, J. Müller, 1856, p. 492; Abhandl. d. k. Akad. d. Wiss. Berlin, 1858, p. 41, Taf. i. figs. 8, 9.

All rings of the disk concentric, circular, or polygonal; their breadth increases from the centre towards the periphery, so that the fourth or fifth ring is twice as broad as the second. Pores