3. Litharachnium arachnodiscus, Haeckel.
Shell flatly campanulate, nearly discoidal, with convex (?) lateral outlines. Apex with three unequal cortinal pores. Nine stronger radial primary ribs complete; between them numerous secondary intercalated ribs (sixty to seventy). Margin ciliate.
Dimensions.—Shell 0.03 long, 0.1 broad (?).
Habitat.—Arctic Ocean (between Greenland and Iceland), depth 1000 fathoms (Schaffner).
4. Litharachnium epeira, n. sp. (Pl. 55, fig. 9).
Shell flatly conical or tent-shaped, with concave lateral outlines. Apex with three unequal cortinar pores. Twelve stronger radial primary ribs complete; between them numerous (twenty-four to thirty-six) thinner secondary, and very numerous (more than one hundred) tertiary ribs. Margin reflexed, like the curved brim of a hat.
Dimensions.—Shell 0.12 long, 0.27 broad.
Habitat.—Central Pacific, Station 274, surface.
Subgenus 2. Litharachnoma, Haeckel.
Definition.—Apex with four cortinar pores (two anterior jugular and two posterior cardinal pores).
5. Litharachnium discoides, n. sp.
Shell flat, funnel-shaped, nearly discoidal, with concave outlines. Apex with four unequal cortinar pores (two smaller jugular and two larger cardinal pores). Twelve strong primary or perradial ribs alternating with twelve weaker secondary or interradial ribs; between these there are twenty-four shorter tertiary or adradial ribs, and in the outer flat, discoidal, half of the shell very numerous peripheral radial ribs (more than two hundred to three hundred). Margin flat, discoidal.
Dimensions.—Shell about 0.2 long, 1.12 broad.
Habitat.—Equatorial Atlantic, Station 347, surface.
6. Litharachnium pilidium, n. sp.
Shell flat, hat-shaped, with S-shaped outlines, in the upper half convex, in the lower half concave. Apex with four equal crossed cortinar pores. Thirty primary ribs of equal size; four of them are the prolongations of the four cortinar beams, eight intercalate between these secondary,
