species is similar to Peripanartus atractus, Pl. 40, fig. 7, but is without the superficial spines and the equatorial girdle-like envelope of the latter.)
Dimensions.—Total length of the shell 0.25 to 0.3; greatest breadth (in the equator of the proximal chambers) 0.08 to 0.1; pores of the proximal chambers 0.008 to 0.012, pores of the distal chambers half their size, bars 0.002 to 0.006.
Habitat.—North Pacific, Station 237, surface.
9. Panartus profundissimus, Haeckel.
Both proximal chambers nearly ellipsoidal, with irregular, polygonal pores, six to eight times as broad as the bars; four to five pores on the half meridian, eight to nine on the half equator of each chamber. Both distal chambers hemispherical, with a very delicate irregular network. Medullary shells spherical; surface of the shell smooth.
Dimensions.—Total length of the shell 0.15; greatest breadth in the equator of the proximal chambers 0.08; pores of the proximal chambers 0.015, bars 0.002.
Habitat.—Philippine Sea, depth 3300 fathoms, Ehrenberg; Station 213, depth 2050 fathoms.
Subgenus 3. Panartoma, Haeckel.
Definition.—Surface of the cortical shell thorny, covered with scattered spines. All its four chambers exhibit the same form and structure.
10. Panartus quadriceps, n. sp.
All four chambers of the cortical shell of the same form, size, and structure, kidney-shaped, twice as broad as long. Pores rather regular, circular, with hexagonal frames, twice to three times as broad as the bars; six to seven pores on the half meridian, ten to twelve on the half equator of each chamber. Surface spiny; from the corners of the hexagonal frames (between every three pores) arise short radial spines. Both medullary shells spherical, the outer one-third as broad as the constriction of the cortical shell. (All the four chambers of this species have the same form as the two proximal chambers of Peripanartus amphiconus, Pl. 40, fig. 5.)
Dimensions.—Main axis of the cortical shell 0.24, equatorial axis 0.08; meshes 0.01, bars 0.003 to 0.005; length of the spines 0.01 to 0.02.
Habitat.—Pacific, central area, Station 274, depth 2750 fathoms.
11. Panartus quadrijugus, n. sp.
All four chambers of the cortical shell of the same form and size, kidney-shaped, twice as broad as long. Pores irregular, roundish, twice to three times as broad as the bars; a circle of larger pores at the base of both distal chambers; six to eight pores on the half meridian, twelve to
