Page:Scientific results HMS Challenger vol 18 part 2.djvu/765

Rh the bars of which bear on the outside bunches of similar tridentate anchor-threads. At each nodal point arises a simple, smooth, radial spine, which bears at the distal end a verticil of three or four small, curved, terminal branches.

Dimensions.—Diameter of the inner shell 0.2 to 0.3, of the outer 1.5 to 2.0.

Habitat.—Antarctic Ocean, Stations 154 to 157, depth 1300 to 1975 fathoms.

3. Cannosphæra pacifica, n. sp. (Pl. 112, fig. 4).

Internal shell mammillate, with one hundred to one hundred and twenty radial rods, which are studded with cruciate verticils of tridentate anchor-threads. External shell with irregular, mostly hexagonal meshes, the bars of which bear on the outside and on the inside bunches of similar tridentate anchor-threads. At each nodal point arises a simple, thorny, radial spine, which bears at the distal end an elegant verticil of fifteen to twenty flatly expanded, thin, terminal branches.

Dimensions.—Diameter of the inner shell 0.25 to 0.35, of the outer 2.0 to 2.5.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

Definition.— with a latticed internal shell.

The genus Cœlacantha comprises those Cannosphærida in which the inner shell is formed by a fenestrated flint-plate, and exhibits numerous pores between the prominent bases of the radial beams.

1. Cœlacantha anchorata, R. Hertwig.

Cœlacantha anchorata, R. Hertwig, 1879, Organism. d. Radiol., p. 92, Taf. ix. fig. 2.

Internal shell slightly mammillate, with thirty to forty radial rods, which are densely studded with verticils of tridentate anchor-threads. External shell with irregular, mostly pentagonal meshes, the bars of which bear the same verticils, each composed of three thin, tridentate anchor-threads. At each nodal point arises a slender radial spine, which bears six verticils, each composed of three to five lateral branches.

Dimensions.—Diameter of the inner shell 0.5, of the outer 3.0.

Habitat.—Mediterranean, Messina (R. Hertwig), surface.

2. Cœlacantha mammillata, n. sp.

Internal shell strongly mammillate, with sixty to eighty radial rods, which are densely studded with cruciate verticils of quadridentate anchor-threads. External shell with irregular, mostly