Habitat.—Pacific, central area, Station 270, depth 2925 fathoms.
2. Zygartus chrysalis, n. sp. (Pl. [40], fig. 13).
Inner cortical shell composed of six to twenty (commonly eight to twelve) chambers of different size and form. Both proximal chambers nearly hemispherical, with spiny surface and subregular, circular pores, three to four times as broad as the bars. All following chambers cap-like, tapering towards both poles, with more irregular, roundish pores, with a circle of ten to twelve larger square pores at the base. Middle cortical shell with smaller roundish pores. Outer cortical shell with larger polygonal, quite irregular pores. Both medullary shells lenticular. Polar tubes conical or cylindrical with conical apex, of very variable length, sometimes not longer than one internal chamber, at other times twice to four times as long (in the figured specimen not fully developed, as also a part of the shells). Differs from Zygocampe chrysalis only by the production of polar tubes.
Dimensions.—Length of the six-chambered inner cortical shell 0.25, of the middle 0.3, of the outer 0.35; greatest breadth of the first 0.07, of the second 0.11, of the third 0.14; other measures the same as in Zygocampe chrysalis; length of the tubes 0.05 to 0.12 or more.
Habitat.—Pacific, central area, Stations 270 to 274, depth 2350 to 2925 fathoms.
Suborder V. DISCOIDEA, Haeckel (Pls. [31]-[38], [41]-[48]).
Discida vel Discoidea, Haeckel, 1862, Monogr. d. Radiol., pp. 56, 476.
Discoida, Discoidea, Discida, Haeckel, 1878, Protistenreich, p. 103.
Definition.—Spumellaria with discoidal or lenticular central capsule (often with radial prolongations, rarely allomorphic); with discoidal or lenticular fenestrated siliceous shell (often with radial spines or fenestrated arms, rarely allomorphic). Growth reduced or diminished in the direction of one dimensive axis.