Dimensions.—Diameter of the shell 1.5 to 2.0, of its wall 0.3 to 0.4; length of the radial tubes 0.2 to 0.3, basal breadth 0.015.
Habitat.—North Pacific, Station 237, surface.
2. Auloplegma spongiosum, n. sp. (Pl. [111], fig. 9).
Radial tubes slender, straight, cylindro-conical, studded irregularly with lateral branches, which are short, simple, slightly curved, partly verticillate in the distal third, and ending with a small spinulate knob. The length of the radial tubes is about twice as great as the radial diameter of the spongy framework, which forms the wall of the spherical shell, and is composed of thorny or verticillate cylindrical tubes.
Dimensions.—Diameter of the shell 3.2, of its wall 0.1; length of the radial tubes 0.24, breadth 0.01.
Habitat.—North Pacific, Station 231, surface.
Genus 686. Aulophacus,[[305]] n. gen.
Definition.—Aulosphærida with triangular meshes in the network, the tangential tubes of which form a simple, lenticular, biconvex lattice-shell, with shortened vertical main axis. Radial tubes arise at its nodal points.
The genus Aulophacus differs from the common Aulosphæra, its ancestral form, only in the lenticular compression of the spherical lattice-shell, the vertical axis of which is considerably shortened. It exhibits therefore to the latter the same relation as Cenodiscus does to Cenosphæra among the Sphæroidea. The contrary condition is shown in the following genus Aulatractus, in which the vertical axis is prolonged. In the two species of Aulophacus observed the radial spines exhibit a remarkable peculiarity, being longer on the circular periphery of the lens, shorter on both its faces, and shortest in the vertical main axis.
1. Aulophacus lenticularis, n. sp. (Pl. [111], fig. 5a).