Page:Scientific results HMS Challenger vol 18 part 1.djvu/546

338 spherical, about one-third as broad as the cortical, with simple circular pores. The connection between the two shells is only made by two simple opposite beams, lying in the equatorial axis.

Dimensions.—Middle spheroidal part of the cortical shell 0.14 to 0.16; polar tubes 0.15 to 0.2 or longer, 0.03 broad; pores and bars of the former 0.007, of the latter 0.003. Medullary shell 0.04, pores 0.006, bars 0.003.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Pipetta salpinx, n. sp.

Cortical shell ellipsoidal, sharply separated from the cylindrical polar tubes, which reach about the same length (or more). Network regular, with circular pores, three times as broad as the bars, without hexagonal frames, fourteen to fifteen on the half equator. Pores of the polar tubes smaller, arranged in eight to ten longitudinal rows. Medullary shell spherical, one-fourth as broad as the cortical, connected with it by a circle of four to six radial beams, lying in the equatorial plane. Differs from Pipettella prismatica (Pl. 39, fig. 6) in the possession of a medullary shell and the absence of the tube edges.

Dimensions.—Main axis of the ellipsoid 0.14, equatorial axis 0.12, pores 0.01, bars 0.003; length of the tubes 0.15 or more, breadth 0.03. Medullary shell 0.03, pores 0.002, bars 0.001.

Habitat.—Pacific, central area, Stations 265 to 268, depth 2700 to 2900 fathoms.

4. Pipetta conus, n. sp.

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing over at both poles into the conical tubes, which attain only half its length. Network irregular, with roundish or subcircular pores, twice to three times as broad as the bars, twelve to sixteen on the half equator. Medullary shell spherical, one-fourth as broad as the cortical. (Differs from the foregoing species in the short conical tubes and the irregular reticulation.)

Dimensions.—Middle part of the cortical shell 0.16 long, 0.13 broad; tubes 0.09 long, 0.05 on the base broad; pores 0.005 to 0.01, bars 0.003. Medullary shell 0.04.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

Definition.— with simple ellipsoidal cortical shell and double medullary shell, with two hollow fenestrated tubes opposite on both poles of the main axis.

The genus Pipettaria differs from the foregoing Pipetta only in the duplication of the medullary shell; as in this, the tubular prolongations of the main axis of the cortical shell may be either conical (with closed apex) or cylindrical (with apical opening?).