Page:Scientific results HMS Challenger vol 18 part 1.djvu/972

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Definition.—Apophyses of the radial spines forked, each with two divergent terminal branches, which are not parallel to the cross axes of the quadrangular spine.

8. Stauracantha stauraspis, Haeckel.

Dorataspis polyancistra, juvenis, Haeckel, 1862, Monogr. d. Radiol., p. 418, Taf. xxi. fig. 7.

Spines slender, quadrangular prismatic, with simple apex and pyramidal base (without basal leaf-cross); with four slender apophyses, which are simply forked in the outer third. Each apophysis with two recurved fork branches.

Dimensions.—Length of the spines 0.12, breadth 0.004; distance of the apophyses 0.06.

Habitat.—Mediterranean (Messina), surface.

9. Stauracantha bifurca, n. sp.

Spines stout, four-winged prismatic, with pyramidal apex and pyramidal base (without leaf-cross); in their middle with four compressed, little curved apophyses (convex on the outer, concave on the inner edge), which are simply forked at the end. Each apophysis with two short straight fork branches.

Dimensions.—Length of the spines 0.2, breadth 0.006; distance of the apophyses 0.08.

Habitat.—Central Pacific, Station 266, surface.

10. Stauracantha quadrifurca, n. sp. (Pl. 130, fig. 4).

Spines slender, four-sided prismatic, with simple apex and pyramidal base (without leaf-cross); with four slender apophyses, which are doubly forked about in their middle. Each apophysis with four short and thin terminal branches.

Dimensions.—Length of the spines 0.2, breadth 0.002; distance of the apophyses from the centre 0.08.

Habitat.—South Atlantic, Stations 325 to 330, surface.

Definition.— with four apophyses on each radial spine, opposite in pairs in cross form, and forming a lattice-plate by communicating branches.

The genus Phatnacantha has been derived from the preceding Stauracantha by concrescence of the branches of the apophyses. Therefore each spine bears a lattice-plate or a fenestrated shield. If the growing plates of the neighbouring spines