Habitat.—North Atlantic, west of Madeira, Station 354, depth 1675 fathoms.
2. Concharium nucula, n. sp. (Pl. [123], fig. 3).
Shell pear-shaped, with costate surface. Oral face somewhat truncated, broader than the aboral face. Its longitudinal diameter about one-fifth longer than the two other diameters. Borders of the two valves ovate, smooth, about as broad as the pores. In the half frontal perimeter of the shell twenty-two to twenty-four pores, in the half sagittal perimeter eighteen to twenty, in the half equator sixteen to eighteen. Pores irregularly roundish, three to four times as broad as the bars. The pores are so disposed in meridional rows that the crests between the rows converge towards the two poles of the sagittal axis.
Dimensions.—Length of the shell 0.2, height 0.18, breadth 0.16.
Habitat.—South Atlantic (west of Tristan da Cunha), Station 332, depth 2200 fathoms.
3. Concharium diatomeum, n. sp. (Pl. [123], fig. 1).
Shell nearly spherical, slightly lenticular, somewhat compressed in dorso-ventral direction; the sagittal diameter therefore somewhat shorter than the two others. Borders of the two hemispherical valves nearly circular, quite smooth, about as broad as the length of the largest pores. In the half frontal perimeter of the shell forty-four to fifty pores; in the half sagittal perimeter twenty to twenty-four; in the half equator thirty to thirty-three. Pores different in form and size; the marginal pores small, nearly circular; the dorsal and ventral pores oblongish-hexagonal, twice as long as broad, about four to six times as long as the bars, regularly arranged in transverse rows.
Dimensions.—Length of the shell 0.22, height 0.21, breadth 0.2.
Habitat.—Tropical Atlantic, near Sierra Leone, Station 348, depth 2450 fathoms.
4. Concharium bacillarium, n. sp. (Pl. [123], fig. 4).