Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
Subfamily 2. Sethophænida, Haeckel, 1881, Prodromus, p. 433.
Definition.—Anthocyrtida with the basal mouth of the shell fenestrated (vel Dicyrtida multiradiata clausa).
Genus 570. Sethophæna,[[187]] Haeckel, 1881, Prodromus, p. 433.
Definition.—Sethophænida (vel Dicyrtida multiradiata clausa) with lateral apophyses. Cephalis with a horn.
The genus Sethophæna and the following Clistophæna form together the small subfamily of Sethophænida, comprising those Dicyrtida in which the thorax bears numerous radial appendages (four to six or more), and the mouth is closed by a lattice-plate. In Sethophæna the apophyses are lateral wings, as in Micromelissa, from which it may be derived by development of secondary wings, interpolated between the three primary wings.
1. Sethophæna tetraptera, n. sp.
Shell smooth, with deep collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 9. Cephalis subspherical, without horn. Thorax ovate, with rounded hemispherical base, and subregular, hexagonal pores. From its upper half (below the collar stricture) arise four divergent, conical, straight wings, of half the length, opposite in pairs in two meridional planes, perpendicular to one another (compare Tetralacorys, Pl. [65], figs. 4, 5).
Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.09 broad.
Habitat.—South Pacific, Station 300, depth 1375 fathoms.