Subfamily Caryommida, Haeckel

Arachnosphærida, Haeckel, 1862, Monogr. d. Radiol., p. 354; Prodromus, 1881, p. 454.

Definition.—Astrosphærida with five or more concentric spherical lattice-shells.

Genus 107. Caryomma, n. gen.

Definition.—Arachnosphærida with five to six or more concentric spherical lattice-shells; two inner (intracapsular) medullary and three or more outer (extracapsular) cortical shells, composed of ordinary lattice-work; distance between the former and the latter greater than between any other two shells.

The genus Caryomma may be regarded as a Cromyomma, in which the number of the cortical shells is increased to three, four, or more. These lie outside the central capsule, whilst two medullary shells lie within it, and are connected with the former by numerous radial spines piercing the wall of the capsule. The ordinary lattice-work is not arachnoidal, as in the three following genera.

1. Caryomma regulare, n. sp.

Radial proportion of the five shells = 1 : 2 : 6 : 8 : 10. All five shells with regular, circular pores, twice to three times as broad as the bars, and gradually increasing in size from the innermost to the outermost shell. Radial beams connecting them twenty, prolonged on the surface into twenty stout, three-sided pyramidal, radial spines, half as long as the radius, regularly disposed.

Dimensions.—Diameter of the five shells—(A) 0.25, (B) 0.2, (C) 0.15, (D) 0.05, (E) 0.025.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Caryomma irregulare, n. sp.

Radial proportion of the six shells = 1 : 2.5 : 8 : 10.5 : 13 : 15. Both inner (medullary) shells with regular, circular pores, the other four (cortical) shells with irregular, roundish pores, gradually increasing in size from the innermost to the outermost shell. Radial spines sixty to eighty, pyramidal, irregularly disposed.

Dimensions.—Diameter of the six shells—(A) 0.3, (B) 0.26, (C) 0.21, (D) 0.16, (E) 0.05, (F) 0.02.

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

Genus 108. Arachnopila, n. gen.

Definition.—Astrosphærida with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin cobweb-like network; innermost shell with hexagonal (regular) or polygonal (irregular) meshes; other shells with simple triangular meshes, without diagonal threads between them.

The genus Arachnopila, together with the two following genera, forms the peculiar small group of large Arachnosphærida, separated from the true Caryommida by the totally different structure and disposition of the numerous concentric shells; the former exhibits a similar relation to the latter that the Diplosphærida bears to the Elatommida among the dispherical Haliommida. The concentric shells (five to ten or more) lie outside the central capsule, and are composed of very delicate, cobweb-like threads. From the innermost shell arise numerous, three-sided prismatic, very long spines, from which at equal regular distances arise lateral branches (three pairs from each spine, and one pair from each corner). In Arachnopila these threads pass directly from one spine to the other, and form simple, large, triangular meshes between them. The concentric shells are not connected by interwoven diagonal threads.

1. Arachnopila hexagonella, n. sp.

Innermost shell with regular hexagonal pores; its diameter twice as long as the equal distance between every two concentric shells. Radial spines twenty to forty, each with twenty to twenty-four verticils.

Dimensions.—Diameter of the innermost shell 0.1; distance between the concentric shells 0.05.

Habitat.—Central Pacific, Station 271, surface.

2. Arachnopila polygonella, n. sp.

Innermost shell with irregular, polygonal pores; its diameter fully as long as the equal distance between every two concentric shells. Radial spines sixty to eighty, each with twelve to sixteen verticils.

Dimensions.—Diameter of the innermost shell 0.04; distance between the concentric shells 0.04.

Habitat.—Central Pacific, Station 266, surface.

Genus 109. Arachnopegma, Haeckel, 1881, Prodromus, p. 454.

Definition.—Astrosphærida with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin, cobweb-like network; innermost shell with hexagonal or polygonal meshes; other shells with simple triangular meshes, connected to one another by diagonal threads between them.

The genus Arachnopegma differs from its ancestral form Arachnopila, in the possession of peculiar diagonal threads, which connect the verticils or nodal-points of every two neighbouring radial spines in two different neighbouring concentric shells. In this case, therefore, not only do triangular meshes lie in the spherical faces of the concentric spheres, but also between them, in numerous oblique diagonal planes; a very rare and remarkable structure, and forming a transition to spongy shells.

1. Arachnopegma verticillatum, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter is the same as the equal distance between each of the two shells. Threads of the network smooth. Radial spines twenty to forty, each with fifteen to twenty verticils.

Dimensions.—Diameter of the innermost shell 0.04, distance between the concentric shells 0.03 to 0.04.

Habitat.—Central Pacific, Station 266, surface.

2. Arachnopegma longispinum, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter half as large as the equal distance between every two shells. Threads of the network dentated or with small knots. Radial spines fifty to sixty, each with twenty to twenty-five verticils.

Dimensions.—Diameter of the innermost shell 0.02; distance between the concentric shells 0.04 to 0.05.

Habitat.—Central Pacific, Station 272, surface.

3. Arachnopegma increscens, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter quite as large as the distance between it and the second shell; only half as large as the distance between the fourth and fifth shells. Forty to fifty radial spines, each with fifteen to twenty verticils.

Dimensions.—Diameter of the innermost shell (A) 0.025; distance between the following shells—A, B = 0.025, B, C = 0.03, C, D = 0.04, D, E = 0.048, E, F = 0.056, F, G = 0.064, &c.

Habitat.—Central Pacific, Station 274, surface.

Genus 110. Arachnosphæra, Haeckel, 1862, Monogr. d. Radiol., p. 355.

Definition.—Astrosphærida with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin cobweb-like network; innermost shell with hexagonal (regular) or polygonal (irregular) meshes; other shells with larger, irregular, polygonal meshes.

The genus Arachnosphæra (accurately described by me in 1862, loc. cit.) differs from the two preceding genera in the irregular form of the large meshes in all shells (except often the innermost). This is caused by the ramification of the thin threads, which on each shell connect the neighbouring spines. In Arachnopila and Arachnopegma the threads pass directly and undivided from each spine to the neighbouring spine (three pairs from the three edges), and therefore all meshes are triangular. In Arachnosphæra they become polygonal by irregular ramification of the threads. There are here no diagonal threads.

Subgenus 1. Arachnosphærella, Haeckel.

Definition.—Pores of the innermost shell regular, hexagonal.

1. Arachnosphæra oligacantha, Haeckel.

Arachnosphæra oligacantha, Haeckel, 1862, Monogr. d. Radiol., p. 356, Taf. x. fig. 2, Taf. xi. fig. 3.

Innermost shell with regular, hexagonal meshes; its diameter three times as long as the equal distances between every two concentric shells. Fifteen to twenty radial spines scattered at wide intervals, each with six to eight verticils.

Dimensions.—Diameter of the innermost shell 0.12; distance between the concentric shells 0.04 to 0.05.

Habitat.—Mediterranean (Messina), surface, Haeckel.

2. Arachnosphæra myriacantha, Haeckel.

Arachnosphæra myriacantha, Haeckel, 1862, Monogr. d. Radiol., p. 357, Taf. x. fig. 3, Taf. xi. fig. 4.

Innermost shell with regular, hexagonal meshes; its diameter twice as long as the equal distances between every two concentric shells. At each nodal-point occurs one radial spine with six to eight verticils (spines in all one hundred to one hundred and twenty or more).

Dimensions.—Diameter of the innermost shell 0.1; distance between the concentric shells 0.04 to 0.05.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

3. Arachnosphæra dolichacantha, n. sp.

Innermost shell with regular, hexagonal meshes, very small; its diameter only as long as the equal distances between every two concentric shells. At each nodal-point occurs one radial spine with twelve to sixteen verticils (altogether thirty to forty spines).

Dimensions.—Diameter of the innermost shell 0.05; distance between the concentric shells 0.04 to 0.05.

Habitat.—Central Pacific, Station 265 to 274, surface.

4. Arachnosphæra increscens, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter three times as long as the distance between it and the second shell, quite as long as the distance between the fifth and sixth shells; the distances between the concentric shells gradually increasing from the centre. Radial spines about fifty to sixty, each with six to eight verticils.

Dimensions.—Diameter of the innermost shell (A) 0.75; distances between the following shells—A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E = 0.062, E, F = 0.075, &c.

Habitat.—Central Pacific, Station 271, surface.

Subgenus 2. Arachnosphæromma, Haeckel.

Definition.—Pores of the innermost shell irregular, polygonal.

5. Arachnosphæra tenuissima, n. sp.

Innermost shell with irregular, polygonal meshes; its diameter twice as long as the equal distance between every two concentric shells. Forty to fifty radial spines, each with twelve to sixteen verticils.

Dimensions.—Diameter of the innermost shell 0.1, distance between the concentric shells 0.04 to 0.05.

Habitat.—South Atlantic, Station 332, surface.

6. Arachnosphæra velaris, n. sp.

Innermost shell with irregular, polygonal meshes; its diameter twice as long as the distance between it and the second shell, quite as long as the distance between the third and fourth shells; the distance between the concentric shells gradually increasing from the centre. Radial spines twenty to thirty, each with ten to twelve verticils.

Dimensions.—Diameter of the innermost shell (A) 0.5; distances of the following shells—A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E = 0.062, E, F = 0.075.

Habitat.—Tropical Atlantic, Station 347, surface.