Dimensions.—Longer axis 0.15, shorter 0.12; pores 0.01 to 0.02, bars 0.002 to 0.004.
Habitat.—North Pacific, Station 253, surface.
9. Ellipsostylus hirundo, n. sp. (Pl. [13], fig. 2).
Proportion of the major axis to the minor = 4 : 3. Shell thick walled, with irregular, roundish meshes, three to five times as broad as the bars; eight to ten on the half equator. The inner aperture of every mesh is fenestrated by a delicate lamella of silex, perforated by six to eight very small circular pores. Polar spines sharp edged, more or less curved, the shorter equal to the minor axis, the longer twice as long.
Dimensions.—Longer axis 0.16, shorter 0.12; pores 0.01 to 0.02, bars 0.003 to 0.006; length of the polar spines—longer 0.24, shorter 0.12.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms; the same form also fossil in the rocks of Barbados.
Genus 128. Lithomespilus,[[167]] Haeckel, 1881, Prodromus, p. 450.
Definition.—Ellipsida with simple ellipsoidal or oviform shell, the main axis of which bears at one pole a single spine, at the other a bunch of several spines.
The genus Lithomespilus differs from the closely allied Ellipsoxiphus in the further differentiation of both poles of the main axis. One pole exhibits only a single polar spine, the other pole a group of several spines, peculiarly grouped together. It differs from the similar Sphæromespilus (Pl. [14], figs. 12, 13) in the ellipsoidal form of the shell.
1. Lithomespilus phloginus, n. sp. (Pl. [14], fig. 16).