Page:Scientific results HMS Challenger vol 18 part 1.djvu/501

Rh crests between them, their outer aperture three to four times as broad as the inner; twelve to fifteen pores on the half equator. Surface prickly.

Dimensions.—Longer axis of the ellipsoid 0.14, shorter axis 0.11; outer aperture of the pores 0.01 to 0.012, inner aperture 0.003 to 0.004.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

10. Cenellipsis oblonga, n. sp.

Proportion of the longer axis to the shorter = 2 : 1. Network of the thick wall irregular, with roundish pores of different size and form. Pores with prominent conical edges, about as broad as the bars; twenty to twenty-five on the half equator. Sometimes each pore is prolonged into a short conical tubulus.

Dimensions.—Longer axis of the ellipsoid 0.22, shorter axis 0.12; pores and bars 0.008 to 0.012.

Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.

Definition.— with simple ellipsoidal shell, without radial spines or polar tubes, but with an inner transverse axial rod, which corresponds to the shorter axis of the ellipsoid.

The genus Axellipsis differs from the simple Cenellipsis in a very peculiar character, namely, the presence of an inner siliceous bar marking the minor axis of the ellipsoidal shell. If in some forms of Druppula (e.g., Pl. 39, fig. 3) we remove the central medullary shell and prolong both beams (connecting it with the cortical shell) till they unite in the centre, we shall arrive at Axellipsis. Therefore Axellipsis may be derived in the same way from Druppula as Axoprunum is from Lithatractus, by phyletic loss of the medullary shell.

1. Axellipsis perforata, n. sp.

Proportion of the major axis of the ellipsoid to the minor = 3 : 2. Pores of the shell regular, circular, twice as broad as the bars; ten to twelve on the half equator. Surface smooth.

Dimensions.—Longer axis of the shell 0.12, shorter axis 0.08; pores 0.006, bars 0.003.

Habitat.—Central area of the Pacific, Station 266, depth 2750 fathoms.

2. Axellipsis lobata, n. sp.

Proportion of the major axis to the minor = 5 : 4. Meshes of the shell irregular, roundish, lobed, with three to six indentations (each mesh formed by the confluence of three to six, commonly