Subfamily Plegmosphærida, Haeckel, 1881, Prodromus, p. 455

Definition.—Liosphærida with spongy spherical shell, with or without latticed medullary shell in the centre.

Genus 25. Styptosphæra, Haeckel, 1881, Prodromus, p. 455.

Definition.—Liosphærida forming a solid sphere of spongy framework, without enclosed medullary shell, and without central cavity.

The genus Styptosphæra presents a spherical shell with smooth or rough surface (without radial spines), the whole mass of which is composed of looser or denser spongy wicker-work.

1. Styptosphæra spumacea, n. sp.

Spongy framework of the solid sphere loose, with large polygonal meshes of slightly different size, ten to twenty times as broad as the bars. Structure of the whole spongy sphere the same. Central capsule filled with crystals. Surface smooth.

Dimensions.—Diameter of the sphere 0.32, of the central capsule 0.26, meshes 0.01 to 0.02, bars 0.001.

Habitat.—North Pacific, Station 236, surface.

2. Styptosphæra spongiacea, n. sp.

Spongy framework in the central part of the solid sphere much more compact than in the peripheral part, becoming gradually looser towards the rough surface. Meshes in the centre three to five times, in the periphery fifteen to twenty times as broad as the bent bars.

Dimensions.—Diameter of the sphere 0.45, inner meshes 0.006 to 0.01, outer meshes 0.03 to 0.04, bars 0.002.

Habitat.—Central Pacific, Station 271, surface.

3. Styptosphæra stupacea, n. sp.

Spongy framework of the solid sphere rather compact, everywhere of the same structure, with roundish, nearly equal meshes, six to eight times as broad as the bars. Surface rough with prominent thorns.

Dimensions.—Diameter of the sphere 0.22, meshes 0.01 to 0.012, bars 0.0015.

Habitat.—South Pacific, Station 291, surface.

Genus 26. Plegmosphæra, Haeckel, 1881, Prodromus, p. 455.

Definition.—Liosphærida forming a hollow sphere of spongy framework, without a medullary shell in the central cavity.

The genus Plegmosphæra develops a large hollow sphere, the wall of which is composed of looser or denser spongy wicker-work. On the inner as well as on the outer face of the spongy shell-wall may be present a simple lattice-sphere from which the threads of the framework arise; but in some species these lattice-plates are quite absent.

Subgenus 1. Plegmosphærantha, Haeckel.

Definition.—Inside and outside of the spongy shell-wall smooth, closed by a lattice-plate with polygonal meshes.

1. Plegmosphæra maxima, n. sp.

Radius of the spherical shell-cavity eight to ten times as great as the thickness of the thin spongy wall. Inside and outside of the wall smooth, closed by a lattice-plate with irregular polygonal meshes. Only three or four meshes in the thickness of the wall.

Dimensions.—Diameter of the spongy sphere 0.8 to 1.0 mm., of its inner cavity 0.7 to 0.8, meshes 0.01 to 0.02, bars 0.002 to 0.003, central capsule 0.5 to 0.6, nucleus 0.1 to 0.15.

Habitat.—Central Pacific, Station 271, surface.

2. Plegmosphæra coelopila, n. sp.

Radius of the spherical shell-cavity eight to ten times as great as the thickness of the spongy wall. Inside and outside of the wall closed by a smooth lattice-plate with irregular polygonal meshes, five to ten times as broad as the bars.

Dimensions.—Diameter of the shell 0.32, of its cavity 0.26, meshes 0.01 to 0.02, bars 0.002.

Habitat.—North Atlantic, Færöe Channel, Gulf Stream, John Murray.

3. Plegmosphæra pachypila, n. sp.

Radius of the spherical shell-cavity about equal to the thickness of the spongy wall. Inside and outside of the wall closed by a smooth lattice-plate with irregular polygonal meshes, three to six times as broad as the bars.

Dimensions.—Diameter of the shell 0.24, of its cavity 0.12.

Habitat.—North Pacific, Station 250, surface.

Subgenus 2. Plegmosphærella, Haeckel.

Definition.—Inside of the spongy shell-wall closed by a smooth lattice-plate, outside rough, spongy, with prominent thorns.

4. Plegmosphæra entodictyon, n. sp.

Radius of the spherical shell-cavity half as great as the thickness of the spongy wall. Inside of the wall closed by a smooth lattice-plate, outside rough, spongy.

Dimensions.—Diameter of the shell 0.24, of its cavity 0.08.

Habitat.—South Pacific, Station 300, surface.

5. Plegmosphæra leptodictyon, n. sp.

Radius of the spongy shell-cavity six times as great as the thickness of the spongy wall. Inside of the wall closed by a smooth lattice-plate, outside rough spongy.

Dimensions.—Diameter of the shell 0.44, of its cavity 0.36.

Habitat.—Central Pacific, Station 266, surface.

Subgenus 3. Plegmosphæromma, Haeckel.

Definition.—Inside of the spongy shell-wall rough spongy, without lattice-plate, outside closed by a smooth lattice-plate.

6. Plegmosphæra exodictyon, n. sp. (Pl. , fig. 8).

Radius of the spongy shell-cavity only one-fourth as great as the thickness of the spongy shell-wall. Outside of the wall closed by a smooth lattice-plate, inside rough, spongy.

Dimensions.—Diameter of the shell 0.4, of its cavity 0.08.

Habitat.—South Atlantic, Station 325, surface.

Subgenus 4. Plegmosphærusa, Haeckel.

Definition.—Inside and outside of the spongy shell-wall rough, with spongy or spiny surface, without lattice-plate.

7. Plegmosphæra leptoplegma, n. sp.

Radius of the spherical shell-cavity half as great as the thickness of the loose spongy shell-wall. Inside and outside of the wall rough spongy, not closed by a lattice-plate. Meshes ten to twenty times as broad as the bars.

Dimensions.—Diameter of the shell 0.3, of its cavity 0.088.

Habitat.—North Atlantic, Station 253, surface.

8. Plegmosphæra pachyplegma, n. sp.

Radius of the spherical shell-cavity about equal to the thickness of the dark and dense spongy shell-wall. Inside and outside of the wall rough spongy, not closed by a lattice-plate. Meshes three to five times as broad as the bars.

Dimensions.—Diameter of the shell 0.2, of its cavity 0.1.

Habitat.—Central Pacific, Station 270, surface.

Genus 27. Spongoplegma, Haeckel, 1881, Prodromus, p. 455.

Definition.—Liosphærida forming a sphere of spongy framework, which encloses in the centre one single latticed medullary shell.

The genus Spongoplegma may be regarded as a Carposphæra, in which the simple latticed cortical shell is represented by an irregular spongy framework, immediately enclosing the simple latticed medullary shell.

1. Spongoplegma antarcticum, n. sp.

Cortical shell with loose spongy framework and rough surface, four to six times as broad as the enclosed simple medullary shell. Pores of the latter regular circular, twice as broad as the bars. From its surface arise numerous (forty to fifty or more) short radial beams, which become forked and compose, by communication of lateral branches, the spongy cortical shell.

Dimensions.—Diameter of the spongy cortical shell 0.2 to 0.3 of the latticed medullary shell 0.05 to 0.06.

Habitat.—Antarctic Ocean, in large number, together with Cromyosphæra antarctica; in the Diatom ooze of Station 157 (depth 1950 fathoms).

Genus 28. Spongodictyon, Haeckel, 1862, Monogr. d. Radiol., p. 459.

Definition.—Liosphærida forming a sphere of spongy framework, which encloses in the centre a double latticed concentric medullary shell.

The genus Spongodictyon can be regarded as a Thecosphæra, in which the simple latticed cortical shell is represented by an irregular spongy framework, which immediately encloses the double latticed medullary shell. Sometimes this latter appears triple, the inner surface of the spongy cortical shell forming a smooth spherical lattice-plate, separated by an interval from the double medullary shell.

Subgenus 1. Dictyoplegma, Haeckel, 1862, Monogr. d. Radiol, p. 458.

Definition.—Spongy cortical shell enveloping immediately the double medullary shell.

1. Spongodictyon spongiosum, Haeckel.

Dictyosoma spongiosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 31, Taf. ii. figs. 9-11.

Dictyoplegma spongiosum, Haeckel, 1862, Monogr. d. Radiol., p. 458.

Spongy framework of the cortical shell loose, with large, polygonal roundish meshes, on an average as large as the double medullary shell, which is immediately enveloped by it. Both concentric medullary shells with subregular roundish pores, twice as broad as the bars.

Dimensions.—Diameter of the cortical shell 0.2 to 0.3 or more; of the outer medullary shell 0.03, inner 0.01.

Habitat.—Mediterranean (French south coast, surface), J. Müller.

2. Spongodictyon cavernosum, n. sp.

Spongy framework of the cortical shell rather compact in the inner part, which immediately envelops the double medullary shell; very loose, with large caverns in the outer part, caverns of the surface larger than the medullary shell. Both medullary shells with regular circular pores, three times as broad as the bars.

Dimensions.—Diameter of the cortical shell 0.3 to 0.4, outer medullary shell 0.1, inner 0.03.

Habitat.—Tropical Atlantic, Station 338, surface.

Subgenus 2. Spongodictyoma, Haeckel.

Definition.—Spongy cortical shell on the inner surface with a smooth lattice-plate (or third medullary shell), which is connected by radial beams with the inner double medullary shell.

3. Spongodictyon trigonizon, Haeckel.

Spongodictyon trigonizon, Haeckel, 1862, Monogr. d. Radiol., p. 459, Taf. xxvi. figs. 4-6.

Dictyosoma trigonizon, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 841.

Spongy framework of the cortical shell very loose, with very large, for the most part triangular meshes, which are two to six times as large as the enclosed double medullary shell. From the surface of the latter arise numerous radial beams, which are connected by a spherical lattice-plate, forming the smooth inner surface of the spongy sphere (or a third medullary shell). The structure of the framework reminds one of the Phæodarium Sagena (Pl. ). Pores of both medullary shells regular circular, twice as broad as the bars.

Dimensions.—Diameter of the cortical shell 0.5 to 1.15, outer medullary 0.05, inner 0.035.

Habitat.—Mediterranean, Messina, surface.

4. Spongodictyon arcadophoron, n. sp.

Spongy framework of the cortical shell in the inner part very loose, in the outer part more compact; outer meshes scarcely as large as the inner medullary shell (or only half as large), inner meshes two to four times as large. From the surface of the double medullary shell arise numerous radial beams, which are forked at equal distances from the centre; the fork branches are curved and united together by dichotomous branches, like elegant arcades; and these arcades form together the large polygonal meshes on the inside of the cortical shell (or a third medullary shell). Both medullary shells with regular circular pores, of the same breadth as the bars.

Dimensions.—Diameter of the cortical shell 0.2, outer medullary shell 0.04, inner 0.02.

Habitat.—Tropical Atlantic, Station 349, surface.