Page:Scientific results HMS Challenger vol 18 part 1.djvu/482

274 it therefore exhibits the same relation to the latter that Spongodrymus bears to Spongiomma.

1. Spongothamnus furcatus, n. sp.

Spongy sphere twice as broad as its inner cavity, with very delicate bars, and irregular, dense framework. From the surface arise one hundred and fifty to one hundred and eighty thin, forked, bristle-shaped spines, half as long as the radius; both fork branches one-third as long as the basal or simple part.

Dimensions.—Diameter of the sphere 0.3, of its inner cavity 0.15; length of the spines 0.08.

Habitat.—North Pacific, Station 241, surface.

2. Spongothamnus scoparius, n. sp.

Spongy sphere four times as broad as its inner cavity, with thick bars and rather loose framework. From the surface arise sixty to eighty broom-shaped radial spines, as long as the radius, each in the basal half simple, in the distal half with six to twelve irregularly ramified branches (similar to the spines of Cromyodrymus abietinus, Pl. 30, fig. 6).

Dimensions.—Diameter of the sphere 0.4, of the inner cavity 0.1; length of the spines 0.2.

Habitat.—Central Pacific, Station 271, surface.

Definition.— with a single, spherical, latticed medullary shell, immediately enveloped by the spongy framework of the cortical shell; on the surface of the latter are numerous radial spines.

The genus Spongopila is a Spongoplegma with radial spines. On the other hand it may be derived either from Elaphococcus, by communication of the branched spines, or from Arachnosphæra, by development of spongy branches between the concentric spheres.

1. Spongopila dichotoma, n. sp.

Medullary shell with regular, hexagonal meshes, six times as broad as the bars. From each nodal-point (between every three meshes) arises a bristle-shaped radial spine, which is dichotomously branched. By communication of the neighbouring branches the loose spongy framework of the spherical cortical shell is formed, which is four times as broad as the medullary shell. On the surface occur very numerous bristle-shaped radial spines, as long as the diameter of the medullary shell. (May be derived from Elaphococcus.)

Dimensions.—Diameter of the spongy cortical shell 0.3, of the medullary shell 0.08.

Habitat.—Tropical Atlantic, Station 347, surface.