Page:Scientific results HMS Challenger vol 18 part 1.djvu/969

Rh triangular; their base occupies about the middle third of each spine; the proximal side of each wing is the shortest, truncated or concave.

Dimensions.—Length of the spines 0.4 to 0.5, greatest breadth (diagonal of the middle leaf-cross) 0.08 to 0.12.

Habitat.—North Pacific, Stations 253 to 256, surface.

10. Xiphacantha platyptera, n. sp.

Spines four-winged, nearly prismatic in the basal and distal parts. Apex truncated. Base with small wing-cross. Four apophyses wing-shaped, very broad and thin, extremely delicate, of irregular quadrangular or nearly rhomboidal form; their base occupies the middle half of the length of the spines (second and third quarter). Very variable in form. Often the edges of the wing-apophyses of the neighbouring spines seem to meet.

Dimensions.—Length of the spines 0.2 to 0.3, greatest breadth (diagonal of the leaf-cross) 0.06 to 0.08.

Habitat.—Pacific, widely distributed, Stations 239, 253, 272, 288, &c., surface.

11. Xiphacantha ciliata, n. sp. (Pl. 129, figs. 4, 5).

Spines four-winged, prismatic in the basal and the distal third. Apex pyramidal, short. Base with large leaf-cross. Four apophyses wing-shaped, nearly semicircular, with dentated edges and rough spinulate or porous faces; their base occupies the middle third of the length of each spine.

Dimensions.—Length of the spines 0.2 to 0.3, greatest breadth (diagonal of the apophysial cross) 0.08 to 0.12.

Habitat.—Tropical Atlantic, Stations 342 to 352, surface.

12. Xiphacantha alata, Haeckel.

Xiphacantha alata, Haeckel, 1862, Monogr. d. Radiol., p. 388.

Acanthometra alata, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 48, Taf. ix. figs. 1-3.

Spines four-winged, prismatic in the basal quarter, more slender in the distal half. Apex simple pyramidal. Base with small wing-cross. Four apophyses wing-shaped, nearly semicircular, with denticulated edges (and often also with spinulate faces); their base occupies the second quarter of the length of each spine.

Dimensions.—Length of the spines 0.3 to 0.4, greatest breadth (diagonal of the apophysial cross) 0.05 to 0.06.

Habitat.—Mediterranean (Nice), Müller, (Portofino), Haeckel.

Definition.— with four branched (but not latticed) apophyses on each radial spine, opposite in pairs in the form of a cross.