Page:Scientific results HMS Challenger vol 18 part 2.djvu/737

Rh partly pierced by a hole. The peculiar network of a complete specimen, observed by me at Portofino in 1880, was so similar to that of Spongodictyon trigonizon, described above (p. 91), and figured in 1862 in my Monograph, that I am doubtful if the two forms are not identical, the two medullary shells of the latter being accidentally entangled in the framework. (Compare p. 1602.)

Dimensions.—Diameter of the sphere 1.1 to 1.5, length of the bars 0.1 to 0.2, breadth 0.002.

Habitat.—Mediterranean (Messina, Portofino), surface.

Definition.—Sagosphærida with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework, and bears on the nodal points of its surface radial spines.

The genus Sagmidium differs from the preceding Sagmarium in the development of radial spines on the surface of the spongy hollow sphere. It bears therefore the same relation to the latter as Sagosphæra does to Sagena, and may be derived either from Sagmarium by the formation of radial spines, or from Sagosphæra by development of the spongy envelope.

1. Sagmidium unicorne, n. sp.

Radial spines simple, straight, smooth, a single one at each nodal point of the surface of the spongy sphere, bearing on its distal end a spinulate knob, or a bunch of numerous radial bristles. (Similar to Sagenoscena penicillata, Pl. 108, fig. 10.) Bars of the spongy framework smooth.

Dimensions.—Diameter of the sphere 3.0 to 3.5, length of the bars 0.15 to 0.2, breadth 0.003 to 0.006.

Habitat.—Antarctic Ocean, Station 256, surface.

2. Sagmidium tricorne, n. sp.

Radial spines simple, smooth, usually three divergent united at each nodal point of the surface (sometimes two or four instead of three). Each spine bears on its distal end three short divergent conical teeth. (Similar to the terminal teeth of Sagoscena tentorium, Pl. 108, fig. 6.) Bars of the spongy framework smooth.

Dimensions.—Diameter of the sphere 1.6 to 2.4, length of the bars 0.06 to 0.09, breadth 0.001 to 0.002.

Habitat.—Central Pacific, Stations 263 to 268, surface.

3. Sagmidium crucicorne, n. sp. (Pl. 108, fig. 9).

Radial spines slender, verticillate, three or four divergent arising from each nodal point of the surface. Each spine bears three to six cruciate verticils of lateral branches; each verticil being