Page:Scientific results HMS Challenger vol 18 part 1.djvu/654

4. Heliodiscus glyphodon, n. sp. (Pl. 35, fig. 2).

Heliosestrum glyphodon, Haeckel, 1881, Prodromus et Atlas (pl. xxxv. fig. 2).

Disk with smooth surface, four times as broad as the medullary shell. Pores subregular, circular; seven to eight on the radius. Marginal spines ten to twelve, equilateral triangular, flat, deeply furrowed, twice as long as broad, and as long as the radius of the disk.

Dimensions.—Diameter of the disk 0.14, of the medullary shell 0.035; length of the radial spines 0.07, basal breadth 0.035.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

5. Heliodiscus helianthus, Haeckel.

Haliomma helianthus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxvii. fig. 1.

Disk with smooth surface, five times as broad as the medullary shell. Pores regular, oblong, disposed regularly in sixty to eighty radial series; fourteen to sixteen on the radius. Marginal spines sixty to eighty, conical, about as long as the diameter of the medullary shell, twice as broad as one pore.

Dimensions.—Diameter of the disk 0.2, of the medullary shell 0.04; length of the radial spines 0.04, basal breadth 0.005.

Habitat.—Fossil in Barbados.

6. Heliodiscus sol, Haeckel.

Haliomma sol, Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 52. Heliodiscus sol, Haeckel, 1862, Monogr. d. Radiol., p. 438.

Disk with smooth surface, four times as broad as the medullary shell. Pores irregular, roundish; eight to ten on the radius. Marginal spines twenty to thirty, conical, the largest as long as the radius of the medullary shell, their bases widely distant. (The species from Barbados figured by Ehrenberg, 1875, as Haliomma sol, appertains to Heliosestrum solare.)

Dimensions.—Diameter of the disk 0.2, of the medullary shell 0.05; length of the radial spines 0.02 to 0.025, basal breadth 0.01.

Habitat.—Fossil in Tertiary rocks of Greece (Ægina), Ehrenberg.

7 Heliodiscus siculus, Stöhr.

Heliodiscus siculus, Stöhr, 1880, Palæontogr., vol. xxvi. p. 89, Taf. i. fig. 14.

Disk with smooth surface, three times as broad as the medullary shell. Pores irregular roundish; seven to eight on the radius. Marginal spines forty to fifty, conical, very irregular, the largest as long as the radius of the medullary shell, their bases coming in contact.

Dimensions.—Diameter of the disk 0.13 to 0.15, of the medullary shell 0.04 to 0.05; length of the radial spines 0.02 to 0.03, basal breadth 0.002 to 0.006.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr), Caltanisetta (Teuscher).