Habitat.—Central Pacific, Station 270, depth 2925 fathoms.
Subgenus 2. Spirocyrtoma, Haeckel.
Definition.—Shell ovate, or nearly spindle-shaped, more or less tapering towards the narrower, somewhat constricted mouth.
3. Spirocyrtis holospira, n. sp. (Pl. [76], fig. 16).
Shell subovate, twice as long as broad, without external strictures, but with an internal regularly descending spiral septum, which separates seven to nine broad joints of nearly equal lengths; the first and second joints together are conical, and about as long as each of the following joints. Cephalis small, hemispherical, with a thick pyramidal horn of the same length. The fifth joint is the broadest, the truncate mouth is slightly constricted (in the specimen figured it is broken off). Pores regular, circular, quincuncial.
Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1; length of each joint, about 0.03.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
4. Spirocyrtis hemispira, n. sp.
Shell slender, nearly spindle-shaped, three times as long as broad, without external strictures, but with ten to eleven internal septa. The five or six upper of these are perfectly separate, complete parallel rings; the five or six lower are spirally connected. The eleven or twelve joints gradually taper in length and breadth, from the broadest middle towards the two constricted ends of the shell. The middle (fifth or sixth) joint is the broadest, and is three to four times as broad as the constricted mouth. Cephalis small, hemispherical, with a conical horn of the same length. Pores regular, circular, hexagonally framed.
Dimensions.—Length of the shell (with twelve joints) 0.25, breadth 0.09; length of the middle joint 0.03.