Page:Scientific results HMS Challenger vol 18 part 1.djvu/439

Rh circular, three times as broad as the bars (four to five on the radius). The two shells connected by about forty radial beams. At each nodal-point of the outer shell arises one bristle-shaped radial spine, twice as long as the diameter of one hexagonal mesh.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; pores of the outer 0.012, of the inner 0.006; length of the spines 0.025.

Habitat.—Central Pacific, Station 266, surface.

3. Haliomma favosum, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, with regular, circular, hexagonally framed pores, twice as broad as the bars; eight to ten on the radius. Medullary shell with simple, circular pores, of the same breadth as the bars. At each nodal-point of the outer shell arises a short triangular spine three times as long as one pore.

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; pores of the former 0.01, of the latter 0.005; bars 0.005; length of the spines 0.015.

Habitat.—Central Pacific, Station 271 to 274, surface.

4. Haliomma regulare, n. sp.

Cortical shell thin walled, nearly twice as broad as the medullary shell, and connected with it by forty to sixty thin radial beams. Both shells of the same perfectly regular structure, with an identical number of regular, circular pores, which are hexagonally framed, four times as broad as the bars, nine to eleven on the radius. The outer pores are twice as broad as the inner, exactly corresponding pores. Between every three pores of the outer surface (in each corner of the cortical hexagon) arises one short three-sided pyramidal spine, twice as long as the diameter of one pore.

Dimensions.—Diameter of the outer shell 0.2, of the inner 0.11; pores of the former 0.018, of the latter 0.009; length of the spines 0.04.

Habitat.—South Atlantic (Tristan da Cunha), Station 332, depth 2200 fathoms.

5. Haliomma melitomma, n. sp. (Pl. 20, fig. 4).

Melitomma formosum, Haeckel, 1879, Atlas, ''loc. cit.''

Cortical shell thick walled, two and a half times as broad as the medullary shell, with regular pores of very elegant structure, twice as broad as the bars; eight to ten on the radius. The inner opening of each pore is simple, circular, the outer regular, six-lobed; corresponding to the six lobes are six short conical spines, which arise from the six corners of the regular hexagonal frames separating the pores. Pores of the medullary shell simple, circular, of the same breadth as the bars. The two shells connected only by six radial beams (in three dimensive axes).

Dimensions.—Diameter of the outer shell 0.17, of the inner 0.07; pores of the former 0.012, of the latter 0.004; length of the spines 0.005 to 0.01.

Habitat.—Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.