Page:Scientific results HMS Challenger vol 18 part 1.djvu/598

390 5. Panarium tubularium, n. sp. (Pl. 40, fig. 9).

Surface of the cortical shell thorny, covered with small spines. Both proximal chambers nearly kidney-shaped, with irregular, polygonal pores, three to four times as broad as the bars; five to six pores on the half meridian, nine to ten on the half equator of each chamber. Both distal chambers nearly hemispherical, with a circle of ten to twelve large square pores at their base; the other pores much smaller, irregular, roundish. Polar tubuli prismatic, with prominent edges, nearly half as long as the main axis, only one-fourth as broad as the equatorial constriction. Pores of the tubuli very small, in longitudinal series between the edges.

Dimensions.—Total length of the shell (without tubuli) 0.18 to 0.2, greatest breadth (in the equator of the proximal chambers) 0.07 to 0.09; pores 0.003 to 0.01, bars 0.002 to 0.004; length of the polar tubuli 0.06 to 0.09, breadth of them 0.015 to 0.02.

Habitat.—Pacific, central area, Stations 270 to 272, depth 2425 to 2925 fathoms.

Definition.— with double cortical shell and double medullary shell, with two hollow fenestrated tubes, opposite on the poles of the main axis.

The genus Peripanarium differs from Panarium only in the development of an outer reticulated envelop, which mantle-like surrounds the shell and represents a second or external cortical shell. It bears therefore to Panarium the same relation as Peripanartus to Panartus, &c.

1. Peripanarium cenoconicum, n. sp.

Internal cortical shell with four kidney-shaped chambers of nearly the same form and size; their pores irregular, roundish, twice to four times as broad as the bars. External cortical shell cylindrical, hemispherical at both poles, with irregular, very small, roundish pores, only one-third to one-half as large as those of the internal. From both poles of the internal cortical shell arises a hollow conical fenestrated tube, which perforates the external. The outer free part of this slender cone equals in length the inner part or the distance between the two cortical shells, which is about equal to the length of one chamber. External surface covered with small thorns. (This species has the same appearance as Desmartus larvalis, Pl. 40, fig. 12, but has only four chambers instead of six.)

Dimensions.—Main axis (without cones) 0.23, greatest breadth 0.11; pores of the inner cortical shell 0.004 to 0.009, of the outer 0.002 to 0.003; bars of the former 0.002, of the latter 0.001; total length of the polar cones 0.05, basal thickness of them 0.03.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.