Page:Scientific results HMS Challenger vol 18 part 1.djvu/674

466 phacoid shell, seven on its radius; smaller on the equatorial ring, three on its breadth. Four marginal spines pyramidal four-sided, as long and as broad at the base as the ring.

Dimensions.—Diameter of the disk (with one ring) 0.14, of the phacoid shell 0.11, of the medullary shell 0.048.

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

4. Staurocyclia magniducis, n. sp. (Pl. 37, fig. 4).

Coccostaurus magniducis, Haeckel, 1881, MS. et Atlas (pl. xxxvii. fig. 4).

Phacoid shell twice as broad as the medullary shell, connected with it by numerous radial beams and surrounded by eight chambered rings, which are divided by one hundred to one hundred and twenty piercing radial beams into small chambers. Pores subregular, circular; ten on the radius of the phacoid shell, two on the breadth of each chamber. Margin of the disk armed with numerous bristle-shaped radial spines, as long as the breadth of the chambered girdle. Four very large crossed spines, nearly as long as the diameter of the disk, quadrangular, with four dentated edges; at the club-shaped distal end thorny, as broad as the medullary shell and three times as broad as at the narrow base. I name this splendid species in the honour of H.R.H. the Grand Duke of Saxe-Weimar, Carl Alexander, the magnanimous protector of arts and sciences, the rector magnificentissimus of the University of Jena.

Dimensions.—Diameter of the disk (with eight rings) 0.27, of the phacoid shell 0.11, of the medullary shell 0.05; length of the four crossed club-spines 0.2, basal breadth 0.02, distal breadth 0.06.

Habitat.—Indian Ocean, Ceylon, Belligemma, surface (Haeckel).

Definition.— with numerous (five or more, commonly thirty to sixty) solid radial spines on the margin of the circular disk. Medullary shell simple.

The genus Astrocyclia exhibits on the margin of the circular chambered disk a large but variable number of solid radial spines, commonly between thirty and sixty. They are the external prolongations of the inner piercing radial beams, which divide the concentric rings of the disk into chambers. All the spines lie in the equatorial plane of the disk. The genus corresponds to Stylodictya in the family Porodiscida.

1. Astrocyclia solaster, n. sp. (Pl. 36, fig. 7).

Phacoid shell two and a half times as broad as the medullary shell, surrounded by four to six regular rings of equal breadth, which are divided by thirty to forty piercing radial beams into