Genus 410. Clathrocircus,[[29]] Haeckel, 1881, Prodromus, p. 447.
Definition.—Semantida with a variable number of pores on the apical and the basal part of the ring, symmetrically arranged, without typical basal feet.
The genus Clathrocircus comprises those Semantida in which the sagittal ring bears not only basal pores (as in the three preceding genera) but also apical pores (on the opposite pole of the main axis), or a variable number of pores along the whole ring. All these pores are symmetrically arranged in pairs. In the simplest form there are only two apical pores opposite to four basal pores, whilst in the highest state of development the whole ring bears two complete circles of pores. At both poles of the transverse axis two large lateral gates remain open. If these become closed by lattice-work, Clathrocircus passes over into Dictyospyris.
1. Clathrocircus hexaporus, n. sp.
Sagittal ring circular, smooth, with three pairs of pores (one apical and two basal). The two apical pores are triangular with two lateral spines, and correspond to the two mitral gates of the Tympanida. The four basal pores form a hexagonal basal plate, with six lateral spines, and correspond to the four basal pores of Semantrum; the two jugular are pear-shaped, and half as broad as the two triangular cardinal pores.
Dimensions.—Height of the sagittal ring 0.08, breadth 0.06.
Habitat.—Cosmopolitan; Atlantic, Pacific, many Stations, surface.
2. Clathrocircus octoporus, n. sp.
Sagittal ring elliptical, smooth, with four pairs of pores (two apical and two basal). The four apical pores are of nearly equal size, subcircular, and form a regular cross around the apical pole. The four basal pores are ovate, and form a quadrangular plate, armed with marginal thorns; the two jugular pores are somewhat smaller than the two cardinal pores.
Dimensions.—Height of the sagittal ring 0.11, breadth 0.08.