Page:Scientific results HMS Challenger vol 18 part 1.djvu/826

618 Dimensions.—Length of the cortical shell (or principal axis) 0.13, breadth of it (or transverse axis) 0.1, height of it (or sagittal axis) 0.07; pores 0.006, bars 0.003; medullary shell (diameter) 0.03.

Habitat.—Pacific, central area, Station 271, depth 2425 fathoms.

2. Larnacilla prometor, n. sp.

Cortical shell with rough surface and regular network; pores three times as broad as the bars; about ten on the half meridian, eight on the half equator. Proportion of the three axes = 1 : 2 : 3. Internal four gates (between transverse and lateral girdles) kidney-shaped, twice as broad as high. Medullary shell lentelliptical, of the same form as the external cortical shell, but only one third as large.

Dimensions.—Length of the cortical shell 0.15, breadth 0.1, height 0.05, pores 0.015, bars 0.005; medullary shell 0.02 to 0.05.

Habitat.—Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.

3. Larnacilla subglobosa, n. sp.

Cortical shell nearly spherical, with thorny surface and irregular network; pores roundish, twice to four times as broad as the bars; twelve to sixteen in the half circumference. Proportion of the three axes very little different = 1.3 : 1.4 : 1.5. Internal four gates elliptical, one and a half times as broad as high. Medullary shell spherical, one-fourth as broad as the cortical shell.

Dimensions.—Length of the cortical shell 0.15, breadth 0.14, height 0.13; pores 0.006 to 0.012, bars 0.003; medullary shell 0.035.

Habitat.—Pacific, central area. Station 266, depth 2750 fathoms.

4. Larnacilla medullaris, n. sp.

Cortical shell lentelliptical, with smooth surface and irregular network; pores roundish, very small, scarcely as broad as the bars; about eight to nine on the half meridian, six to seven on the half equator. Proportion of the three axes = 3 : 4 : 6. Internal four gates elliptical. Medullary shell spherical, scarcely one-third as broad as the cortical shell. (This small species may be only the medullary shell of some other Larcoid, the cortical shell of which is not yet formed.)

Dimensions.—Length of the cortical shell 0.06, breadth 0.04, height 0.03; pores and bars about 0.004; medullary shell 0.013.

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

Definition.— with a simple lentelliptical cortical shell, connected by the lateral wings of a latticed transverse girdle with the simple, spherical or lentelliptical, medullary shell. Surface armed with radial spines.