Dimensions.—Principal axis 0.16, transverse axis 0.15; diameter of the subspherical medullary shell 0.04.
Habitat.—South Pacific, Station 295, depth 1500 fathoms.
3. Pylonium nephropylium, n. sp.
Cortical shell thorny, without radial spines. All its three girdles elliptical, one and a third times as long as broad. Four gates kidney-shaped, nearly twice as broad as high.
Dimensions.—Principal axis 0.17, transverse axis 0.13; length of the lentelliptical medullary shell 0.04, breadth 0.03.
Habitat.—Pacific, central area, Station 273, depth 2350 fathoms.
Subgenus 2. Pylonura, Haeckel.
Definition.—Cortical shell armed with large, symmetrically disposed spines.
4. Pylonium quadricorne, n. sp. (Pl. [9], fig. 14).
Cortical shell thorny, with four strong horn-like curved spines in the lateral plane. All its three girdles elliptical, one and a third times as long as broad. Four gates kidney-shaped, twice as broad as high. (This species is a further developmental stage of Tetrapyle quadricornis, with perfect sagittal girdle.)