1. Tetrapyle circularis, n. sp. (Pl. 9, fig. 8).
Cortical shell rough, without radial spines. Lateral girdle circular, therefore the longitudinal axis is equal to the transverse. Four gates kidney-shaped, twice as broad as high. In each half wing of the transverse girdle six to seven longitudinal rows of irregular, roundish pores.
Dimensions.—Medullary shell 0.05 long, 0.04 broad; cortical shell 0.15 long and broad; gates 0.04 high, 0.08 broad.
Habitat.—Pacific, central area, Station 263, surface.
2. Tetrapyle circopyle, n. sp.
Cortical shell smooth, without radial spines. Lateral girdle elliptical, one and a half times as long as broad. Four gates nearly circular. On each half wing of the transverse girdle four to five rows of subregular, circular pores. (Similar to Tetrapyle pleuracantha, Pl. 9, fig. 9, but without lateral spines.)
Dimensions.—Medullary shell 0.04 long, 0.03 broad; cortical shell 0.16 long, 0.11 broad; gates 0.05 high and broad.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.
3. Tetrapyle quadriloba, Haeckel.
Cortical shell thorny, without regular, radial spines. Lateral girdle elliptical, one and a half times as long as broad. Four gates nearly circular. On each half wing of the transverse girdle three to four rows of irregular, roundish pores.
Dimensions.—Medullary shell 0.06 long, 0.04 broad; cortical shell 0.16 long, 0.1 broad; diameter of the gates 0.05.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian Ocean, Pacific, surface.
4. Tetrapyle nephropyle, n. sp.
Cortical shell thorny, without radial spines. Lateral girdle elliptical, one and a third times as long as broad. Four gates kidney-shaped, nearly twice as broad as high, with two prominent polar spines on the poles of the longitudinal axis of the medullary shell. On each half wing of the transverse girdle three to four longitudinal rows of large roundish pores.
Dimensions.—Medullary shell 0.06 long, 0.04 broad; cortical shell 0.24 long, 0.18 broad; gates 0.05 high, 0.08 broad.
Habitat.—Pacific, central area, Station 271, depth 2425 fathoms.
