Definition.—Staurosphærida with two concentric lattice-spheres and four crossed simple spines which are disposed in two different pairs, two opposite being larger than the other two.
The genus Staurolonchidium has arisen from Staurolonche by the stronger growth of the two opposite spines, the other two remaining stationary; both spines of each pair equal.
1. Staurolonchidium artioscelides, n. sp.
Cortical shell thin walled, with smooth surface, three times as broad as the medullary shell. Pores regular, circular, hexagonally framed, twice as broad as the bars; eight to ten on the quadrant. Four radial spines three-sided pyramidal, as broad as one mesh; two opposite larger spines three times as long as the two smaller, which are about equal to the radius.
Dimensions.—Diameter of the cortical shell 0.16, medullary shell 0.05; pores of the former 0.012, bars 0.006; length of the major spines 0.24, minor 0.08.
Habitat.—Central Pacific, Station 265, surface.
2. Staurolonchidium perspicuum, Haeckel.
Haliomma perspicuum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxix. fig. 1.
Cortical shell thin walled, covered with small conical by-spines, five times as broad as the medullary shell. Pores regular, circular, eight times as broad as the bars; three to four on the quadrant. Four radial spines three-sided pyramidal, scarcely one-third as broad as one mesh; two opposite larger spines four times as long as the two smaller, which are about equal to half the radius.
Dimensions.—Diameter of the cortical shell 0.12, medullary shell 0.025; pores of the former 0.03, bars 0.004; length of the major spines 0.12, minor 0.03.