Page:Scientific results HMS Challenger vol 18 part 2.djvu/723

Rh 6. Oroscena huxleyi, n. sp. (Pl. 12, figs. 1, 1a).

Radial spines cylindrical, obliquely ascending and irregularly curved, about as long as the diameter of the shell and somewhat thicker than its thorny bars. A variable number of short, irregular, partly simple, partly forked, lateral branches arises from the spines. Meshes of the network very irregular, partly solid, partly hollow (fig. 1a*), the majority quadrangular. This species, the first observed form of Orosphærida (captured the 21st February 1873 at Station 5), was at the beginning of my observations, in 1876, and when I had no knowledge of the central capsule, erroneously regarded by me as a gigantic Sphæroid (of the Monosphærida) and therefore placed in Pl. 12. The long branched spines, afterwards observed complete in another specimen, were broken off in the specimen first figured.

Dimensions.—Diameter of the shell 2.0 to 2.5, length of the spines 2 to 3 mm., breadth 0.03.

Habitat.—North Atlantic (west of Canary Islands), Station 5, depth 2740 fathoms.

7. Oroscena darwinii, n. sp.

Radial spines cylindrical, irregularly curved and branched, about twice as long as the diameter of the shell; the branches are all again ramified and partly confluent (as in Pl. 107, fig. 1). The branches and the bars of the network are of equal breadth, smooth (not thorny as in the similar preceding species). Meshes rather subregular, quadrangular.

Dimensions.—Diameter of the shell 2.4 to 2.8, length of the spines 4 to 5 mm., breadth 0.015.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

8. Oroscena duncanii, n. sp.

? Hexactinellida dictyonina, Martin Duncan, 1881, Journ. Roy. Micr. Soc., p. 175, pl. iii. figs. 4, 6.

Radial spines cylindrical, thorny, arborescent, somewhat shorter than the diameter of the shell, with irregular ramified branches (similar to Orosphæra arborescens, Pl. 106, fig. 3). The size and ramification of the arborescent spinulate branches decrease towards the apex. The thicker branches are from two to three times as broad as the spinulate bars of the network. Meshes of the latter irregular, the majority quadrangular.

Dimensions.—Diameter of the shell 3.2, length of the spines 3.5 to 4.5, breadth 0.02 to 0.3.

Habitat.—South Atlantic, Station 318, depth 2040 fathoms; coast of Portugal, 1095 fathoms.

Definition.— with a spongy, spherical or slightly polyhedral lattice-shell, which is enveloped by a loose spongy framework and bears numerous radial spines.

The genus Oroplegma differs from the other Orosphærida in the development of an external lattice-work enveloping the internal primary shell, and produced by the union