Definition.—On each side of the ring-plane three pairs of large annular meshes; no middle zygomatic ring is developed between the two tympanic transverse rings (superior orbital and inferior maxillary ring).
1. Amphispyris thorax, n. sp. (Pl. [88], fig. 4).
Shell thorax-shaped, as long as broad, with a deep sternal incision and two slight transverse strictures. On each side of the ring-plane three pairs of large, irregular, annular holes of nearly equal size, the middle holes nearly half as broad as the shell. No zygomatic bars between the orbital and maxillary bars. Lateral lattice-girdle narrow, with few small roundish meshes.
Dimensions.—Shell 0.17 long, 0.17 broad, ring 0.06 long.
Habitat.—Central Pacific, Station 270, depth 2925 fathoms.
2. Amphispyris quadrigemina, n. sp. (Pl. [88], fig. 6).
Shell shaped like the "corpora quadrigemina cerebralia," with two deep crossed strictures, a coronal transverse stricture and a sagittal sternal stricture. On each side of the ring plane three pairs of large, irregular, annular, double holes, the middle holes larger than the upper and lower holes, and about one-fourth as long as the shell. No zygomatic bars between the orbital and maxillary bars. Lateral lattice-girdle broad, with numerous small meshes.
Dimensions.—Shell 0.13 long, 0.16 broad, ring 0.07 long.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
3. Amphispyris reticulata, Haeckel.