Page:Scientific results HMS Challenger vol 18 part 1.djvu/803

Rh 2. Spongasteriscus clavatus, n. sp.

Arms at equal distances, forming a regular, rectangular cross, club-shaped, about as long as the diameter of the central disk, and at their rounded distal end one and a third times as long as broad, at their narrow base only one third as broad. In the centre five to six concentric rings.

Dimensions.—Radius of the arms 0.13, distal breadth 0.06, basal breadth 0.02.

Habitat.—Pacific, central area. Station 271, surface.

3. Spongasteriscus mucronatus, n. sp.

Arms at equal distances, forming a regular, rectangular cross, club-shaped, three times as long as the radius of the central disk, in the distal half nearly circular, three to four times as broad as at the narrow base. The rounded distal end armed with a strong pyramidal spine. In the centre no concentric rings. (Similar to Stauralastrum rhopalophorum, Pl. 45, fig. 1, but quite spongy.)

Dimensions.—Radius of the arms 0.12, basal breadth 0.03, distal breadth 0.02.

Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.

4. Spongasteriscus furcatus, n. sp.

Arms at equal distances, forming a regular, rectangular cross, in the distal third forked; both fork branches half as long as the basal undivided part of the arm, which is twice as long as broad. Distal ends of the eight branches blunt, rounded. In the central disk no concentric rings.

Dimensions.—Radius of the arms 0.12, basal breadth 0.03; distal breadth of the branches 0.02.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

5. Spongasteriscus armatus, n. sp.

Arms at equal distances, forming a rectangular, regular cross, in the distal half forked; both fork branches of the same length as the basal undivided part of the arm, which is nearly square. Distal ends of the eight branches armed with a strong pyramidal spine. In the central disk no concentric rings. (Similar to Dicranastrum cornutum, Pl. 45, fig. 2, but quite spongy.)

Dimensions.—Radius of the arms 0.18, basal breadth 0.03, distal breadth 0.015.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Definition.—Cross formed by the four arms, bilateral or irregular, with the arms at different distances.