Subfamily Spongostylida, Haeckel, 1881, Prodromus, pp. 449, 455

Definition.—Stylosphærida with spherical spongy shell (with or without enclosed latticed medullary shells).

Genus 57. Spongolonchis, Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with a solid sphere of spongy framework, and with two opposite free radial spines.

The genus Spongolonchis differs from its probable ancestral form, Styptosphæra, by the development of two opposite radial spines situated in one axis.

1. Spongolonchis compacta, n. sp.

Spongy framework of the spherical shell very compact, with small meshes, three to four times as broad as the bars. Surface rough, but not spiny. Two polar spines pyramidal, only as long as the radius of the shell, one-third as broad at the base.

Dimensions.—Diameter of the shell 0.2; length of the spines 0.1, basal breadth 0.03.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Spongolonchis laxa, n. sp.

Spongy framework loose, with large meshes, ten to twelve times as broad as the bars. Surface spiny. Two polar spines three-sided prismatic, longer than the diameter of the shell (broken off in the observed specimen).

Dimensions.—Diameter of the shell 0.5; length of the spine 0.6 and more, breadth 0.02.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 58. Spongostylus, Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with spongy spherical cortical shell, enclosing in the centre a simple latticed medullary shell, and with two opposite free radial spines.

The genus Spongostylus may probably be derived from Spongoplegma by development of two opposite radial spines in one axis.

1. Spongostylus hastatus, n. sp.

Spongy cortical shell with compact framework, twice as broad as the enclosed medullary shell, the pores of which are regular, circular, twice as broad as the bars. Two polar spines, three times as long as the radius of the shell, in the basal two-thirds cylindrical, in the distal third compressed, two-edged, spear-shaped.

Dimensions.—Diameter of the cortical shell 0.1, medullary shell 0.05; length of the spines 0.15.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

2. Spongostylus gladiatus, Haeckel.

Stylosphæra holosphæra, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 14.

Spongy cortical shell with rather compact framework, four times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, three to four times as broad as the bars. Two polar spines sword-shaped, two-edged, as long as the shell diameter.

Dimensions.—Diameter of the cortical shell 0.24, medullary shell 0.06; length of the spines 0.25.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; Philippine Sea, depth 3300 fathoms.

3. Spongostylus serratus, n. sp.

Spongy cortical shell with lax framework, ten to twelve times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, once and a half to twice as broad as the bars. Two polar spines longer than the shell diameter (broken off in the observed specimen), three-sided prismatical, with three straight serrated edges.

Dimensions.—Diameter of the cortical shell 0.5, medullary shell 0.04; length of the spines 0.6 or more.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

Genus 59. Spongostylidium, Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with spongy spherical cortical shell, enclosing two concentric spherical latticed medullary shells, and with two opposite, free radial spines.

The genus Spongostylidium differs from Spongostylus by duplication of the latticed medullary shell, and therefore bears the same relation to it as Spongodictyon to Spongoplegma.

1. Spongostylidium streptacanthum, n. sp.

Both medullary shells spherical, with small, regular, circular pores, twice as broad as the bars (outer twice as broad as the inner). Spongy cortical shell enclosing it with dense framework, four times as broad as the outer medullary shell. Two polar spines very large, four times as long as the diameter of the outer shell; as broad as the inner medullary shell, with three dentated, spirally contorted edges. (Very similar to the common Spongosphæra streptacantha and to Hexadoridium streptacanthum, but with only two opposite spines in one axis.)

Dimensions.—Diameter of the cortical shell 0.16, of the outer medullary shell 0.04, inner 0.02; length of the spines 0.7 and more, breadth 0.02.

Habitat.—Indian Ocean, Cocos Islands, Rabbe.