Subgenus 2. Clathropyrgus, Haeckel, 1881, Prodromus, p. 439.
Definition.—Shell with four or more annular strictures, and five or more joints.
4. Artopilium trifenestra, n. sp. (Pl. 75, fig. 7).
Shell tower-shaped, nearly cylindrical, with nine deep strictures. The ten joints are of different lengths and breadths. The third and fourth joints are the longest, twice as long as the first, fifth, sixth, eighth, and ninth joints. The third, seventh, and tenth joints are the broadest, and nearly twice as broad as the second and ninth joints. The mouth of the last joint is dilated. The second joint bears three divergent ribs, and the third joint (as prolongations of these) three broad, triangular, lattice-wings, and between the latter three large, ovate openings or windows, recalling those in Clathrocanium (Pl. 64). Cephalis subspherical, with a pyramidal horn of twice the length. Pores subregular, circular, hexagonally framed.
Dimensions.—Length of the shell (with ten joints) 0.28, of the first and ninth joints 0.02, of the third and fourth joints 0.04; breadth of the third and seventh joints 0.08, of the second and ninth joints 0.04.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
5. Artopilium trigonopterum, n. sp.
Shell in the upper half campanulate-conical, in the lower half cylindrical, with seven internal septa. The four middle joints are equal in length, each about twice as long as each of the two first and of the two last joints. Cephalis hemispherical, with a conical horn of the same length. Along the first three joints arise three broad, triangular, lattice-wings. Pores small, regular, hexagonal, in the wings and the two first joints circular. The five lower joints are of equal breadth.
Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1. Length of the four middle joints, each about 0.034, of the two first and the two last, each 0.017.
Habitat.—South Pacific, Station 300, depth 1375 fathoms.
6. Artopilium cornutella, n. sp.
Shell slenderly conical, without external strictures, but with twelve to fifteen internal annular septa. All thirteen to sixteen joints are nearly equal or slightly different in length, but increase gradually in breadth. Along the whole shell arise three narrow, divergent lattice-wings, increasing in height towards the wide open mouth. Pores subregular, square, in three to four transverse rows on each joint, half as large in the three wings as in the joints. Cephalis small, subspherical, with a conical horn of twice the length. (In the specimen described the axis of the slender cone was straight, in another incomplete specimen curved; this may perhaps be a separate species, Artopilium curvatum.)
