Page:Scientific results HMS Challenger vol 18 part 2.djvu/734

1610 bars of the network, and bears in its distal half four cruciate verticils, each composed of four crossed and curved horizontal branches.

Dimensions.—Diameter of the sphere 1 to 2, length of the bars 0.08 to 0.09, breadth 0.002.

Habitat.—Mediterranean (Messina), surface.

8. Sagoscena fragilis, n. sp.

Pyramids very irregular, with four to eight sides, of different form and unequal size; crowned at the top with a single, slender, radial spine, of the same thickness as the slender bars of the network; the latter as well as the former are smooth, without lateral branches.

Dimensions.—Diameter of the sphere 1.0 to 2.0, length of the bars 0.1 to 0.2, breadth 0.001 to 0.002.

Habitat.—Cosmopolitan; Atlantic, Pacific, surface.

Definition.— with a delicate spherical shell, the thin wall of which is composed of a simple lattice-plate and covered with numerous pyramidal elevations; each pyramid bears on its top one or more radial spines, and has an internal axial rod in its radial axis.

The genus Sagenoscena differs from the preceding closely allied Sagoscena in the possession of an internal radial axial rod, which arises in the centre of the base of each pyramid, and is prolonged usually over its apex into a free, radial, apical spine. The distal end of the latter is usually armed with a bunch of terminal teeth or bristles. In the similar Sagoscena the internal cavity of the pyramids is simple, without axial rod.

1. Sagenoscena stellata, n. sp. (Pl. 108, fig. 3).

Pyramids rather regular, usually six-sided (intermingled with single five-sided and four-sided forms); their axial rod and its prolongation, the radial apical spine, three to four times as thick as the slender edges of the pyramid. The distal end of the apical spine bears an elegant star of numerous radially divergent terminal branches, each of which is armed with a spinulate terminal knob.

Dimensions.—Diameter of the sphere 3.5 to 4.0, length of the net bars 0.3, breadth 0.003; length of the radial spines 0.2, breadth 0.012.

Habitat.—South Atlantic, Station 318, depth 2040 fathoms.

2. Sagenoscena ornata, n. sp. (Pl. 108, fig. 4).

Pyramids rather regular, usually six-sided (intermingled with single five-sided and seven-sided forms); their axial rod and apical spine spindle-shaped, two to four times as thick as the smooth bars