Shell very thin walled, rough, with regular circular, hexagonally framed pores, six times as broad as the bars, eight to ten on the quadrant; in the corner of each hexagon a small bristle. In the central point of the shell are united about twelve (?) thin and straight radial beams, which are forked, with dichotomous branches; the distal ends of the branches are inserted in the corners of the hexagons on the inside of the shell.
Dimensions.—Diameter of the shell 0.15, pores 0.02, bars 0.003.
Habitat.—Central Pacific, Station 271, surface.
Genus 17. Ethmosphæra,[[28]] Haeckel, 1862, Monogr. d. Radiol., p. 349.
Definition.—Liosphærida with one single latticed sphere, with simple shell-cavity; with shell-pores which are prolonged on the outside in centrifugal, conical, or cylindrical tubuli.
The genus Ethmosphæra differs from the simple Cenosphæra, its ancestral form, by the peculiar formation of the shell-pores; in all observed species of the genus these are quite regular, of nearly equal size and form; their base in the spherical shell-face is hexagonal, but on the outside prolonged into centrifugal, external, radial tubuli, which are either conical or cylindrical (in the latter case both openings of the tubes being equal, in the former the outer opening being smaller than the inner). The solitary Ethmosphæra corresponds to the social Siphonosphæra; but in the former the formation of the shell and of its tubuli is quite regular, in the latter more or less irregular.
Subgenus 1. Ethmosphærella, Haeckel.
Definition.—Tubuli conical, their outer opening smaller than the inner.
1. Ethmosphæra siphonophora, Haeckel.
Ethmosphæra siphonophora, Haeckel, 1862, Monogr. d. Radiol., p. 350, Taf. xi. fig. 1.