Subfamily 2. Larnacalpida, Haeckel

Definition.—Larnacida with a double, trizonal, Larnacilla-shaped medullary shell, enclosed in the central capsule, and enveloped by a simple or double, latticed or spongy, lentelliptical, cortical shell.

Genus 274. Larnacalpis, n. gen.

Definition.—Larnacida with a simple lentelliptical cortical shell, without radial spines. Medullary shell double, Larnacilla-shaped.

The genus Larnacalpis represents the most simple form of the sub-family Larnacalpida, and is very important as the common original form of all those Larcoidea in which a double Larnacilla-shaped medullary shell is surrounded by a simple, perfectly closed, latticed, lentelliptical cortical shell. Therefore the same typical, trizonal, lentelliptical shell, which in Larnacilla represents the external envelop (or cortical shell) of the central capsule, here in Larnacalpis becomes enclosed as an internal nucleus (or medullary shell) in the interior of the central capsule, and this latter becomes overgrown by a new lentelliptical cortical shell. The connection between the two shells of Larnacalpis is either effected by a number of radial beams (e.g., in Larnacalpis triaxonia by six beams situated in the three dimensive axes), or by two lateral, latticed, tube-like wings, which are repetitions of the smaller lateral wings connecting its external shell with the internal medullary shell (as in Larnacalpis lentellipsis). The latter species may be regarded as a Pylonium with a completely latticed shell.

1. Larnacalpis lentellipsis, n. sp. (Pl. , figs. 2, 2a, 2b).

Cortical shell with thorny surface and irregular network; pores roundish, twice to four times as broad as the bars; about sixteen on the half meridian, twelve on the half equator. Proportion of the three dimensive axes = 2 : 3 : 4. Medullary shell one-third as large as the cortical, with four elliptical internal gates, connected with it by two opposite beams in the principal axis and by two latticed wings in the transverse axis; therefore between the two shells are four large kidney-shaped gates, halved by the polar beams (as in Octopyle).

Dimensions.—Length of the cortical shell (or principal axis) 0.14, breadth (or transverse axis) 0.11, height (or sagittal axis) 0.07; pores 0.01 to 0.02, bars 0.005; length of the medullary shell 0.05, breadth 0.04, height 0.03.

Habitat.—Pacific, central area, Station 273, depth 2600 fathoms.

2. Larnacalpis phacodiscus, n. sp.

Cortical shell with thorny surface and regular network; pores circular, twice as broad as the bars; about ten on the half meridian, eight on the half equator. Proportion of the three axes = 2 : 2.5 : 3. Medullary shell half as large as the cortical, with four kidney-shaped internal gates.

Dimensions.—Length of the cortical shell 0.13, breadth 0.11, height 0.09; pores 0.012, bars 0.006; length of the medullary shell 0.06, breadth 0.045, height 0.03.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

3. Larnacalpis macrococcus, n. sp.

Cortical shell with spiny surface and regular network; pores circular, small, of the same breadth as the bars; about twenty-two on the half meridian, nineteen on the half equator. Proportion of the three axes = 2 : 3 : 4. Medullary shell two-thirds as large as the cortical, with four wide internal semicircular gates.

Dimensions.—Length of the cortical shell 0.1, breadth 0.075, height 0.05; pores and bars 0.003; length of the medullary shell 0.066, breadth 0.05, height 0.032.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

4. Larnacalpis subsphærica, n. sp.

Cortical shell with rough surface and irregular network; roundish pores twice to five times as broad as the bars; about twenty-four on the half meridian, twenty-one on the half equator. Proportion of the three axes = 1.2 : 1.3 : 1.4. Medullary shell half as large as the cortical, with four elliptical internal gates.

Dimensions.—Length of the cortical shell 0.14, breadth 0.13, height 0.12; pores 0.004 to 0.01, bars 0.002; length of the medullary shell 0.08, breadth 0.07, height 0.06.

Habitat.—Pacific, central area, Station 266, depth 2750 fathoms.

5. Larnacalpis triaxonia, n. sp. (Pl. , fig. 3).

Cortical shell with smooth surface and peculiar network, composed of four meridian rows of larger pores (five large elliptical pores on each half meridian, the largest in the equator) and numerous small irregular pores between them. Proportion of the three axes = 2 : 3 : 4. Medullary shell with four semicircular internal gates, about one-fourth as large as the cortical, connected with it by six thin radial beams, opposite in pairs in the three dimensive axes.

Dimensions.—Length of the cortical shell 0.14, breadth 0.1, height 0.07; large pores 0.03, small pores 0.002 to 0.01, bars 0.002 to 0.01; length of the medullary shell 0.04, breadth 0.03, height 0.02.

Habitat.—Pacific, central area, Station 263, depth 2650 fathoms.

Genus 275. Larnacantha, n. gen.

Definition.—Larnacida with a simple lentelliptical cortical shell, armed with symmetrically disposed radial spines. Medullary shell double, Larnacilla-shaped.

The genus Larnacantha has the same characteristic shell-formation as the foregoing Larnacalpis, and differs from it only in the possession of radial spines, which are symmetrically distributed on the surface in a definite order. Commonly these spines are external prolongations of the internal radial beams, which connect the double Larnacilla-shaped medullary shell with the simple lentelliptical cortical shell.

1. Larnacantha dissacantha, n. sp.

Cortical shell smooth, with two large cylindrical spines, opposite on the poles of the principal axis, and somewhat longer than it. Pores regular, circular, three times as broad as the bars; about eleven on the half meridian. Proportion of the three axes = 2 : 3 : 4. Medullary shell one-third as large as the cortical shell.

Dimensions.—Length of the cortical shell (principal axis) 0.13, breadth (transverse axis) 0.1, height (sagittal axis) 0.07; pores 0.009, bars 0.003; length of the Larnacilla-shaped medullary shell 0.045.

Habitat.—North Pacific, Station 256, depth 2950 fathoms.

2. Larnacantha stauracantha, n. sp.

Cortical shell smooth, with four large conical spines in the lateral plane, two larger opposite on the poles of the principal, two smaller on those of the transverse axis. Pores regular, circular, twice as broad as the bars; about seventeen on the half meridian. Proportion of the three axes = 3 : 3.5 : 4. Medullary shell one-third as large as the cortical shell.

Dimensions.—Length of the cortical shell 0.15, breadth 0.13, height 0.11; pores 0.008, bars 0.004; length of the medullary shell 0.05.

Habitat.—Pacific, central area, Station 274, surface.

3. Larnacantha quadricornis, n. sp.

Cortical shell spiny, with four strong, horn-like curved spines in the lateral plane, opposite in pairs on the poles of the crossed diagonal axes. Pores irregular, roundish, twice to four times as broad as the bars; about fourteen on the half meridian. Proportion of the three axes = 2 : 3 : 4. Medullary shell one-third as large as the cortical shell.

Dimensions.—Length of the cortical shell 0.14, breadth 0.11, height 0.07; pores 0.006 to 0.012, bars 0.003; length of the medullary shell 0.05.

Habitat.—Pacific, central area, Station 270, surface.

4. Larnacantha hexacantha, n. sp. (Pl. , fig. 4).

Cortical shell thorny, with six strong conical radial spines in the lateral plane, two opposite on the poles of the principal axis, four others opposite in pairs on the poles of the two crossed diagonal axes. Pores with peculiar distribution; twelve large elliptical pores (nearly of the size of the medullary shell) symmetrically disposed in four crossed meridians (between the sagittal and the lateral meridians), separated by bands of smaller irregular pores. Proportion of the three axes = 3 : 4 : 5. Medullary shell hexagonal, one-third as large as the cortical shell.

Dimensions.—Length of the cortical shell 0.14, breadth 0.11, height 0.08; large pores 0.04, small pores 0.003 to 0.01, bars 0.004; length of the medullary shell 0.05.

Habitat.—Pacific, central area, Station 263, depth 2650 fathoms.

5. Larnacantha bicruciata, n. sp. (Pl. , fig. 5).

Cortical shell thorny, in the lateral plane with eight strong conical radial spines, alternating with eight smaller spines; four of the eight stronger spines opposite on the poles of the principal and transverse axes (in the figure 5, by mistake, not represented large enough), four others between those, opposite on the poles of the two crossed diagonal axes. Pores with a peculiar disposition; on both flat sides of the lentellipsis an elliptical ring of eight large elliptical pores (alternating with the eight stronger radial spines), separated by bands of smaller irregular pores. Proportion of the three axes = 2 : 3 : 4. Medullary shell nearly half as long as the cortical shell.

Dimensions.—Length of the cortical shell 0.16, breadth 0.13, height 0.08; large pores 0.03, small pores 0.003 to 0.01, bars 0.006; length of the medullary shell 0.07.

Habitat.—Indian Ocean, surface, Madagascar (Rabbe).

6. Larnacantha octacantha, n. sp.

Cortical shell thorny, with eight long and thin, cylindrical, radial spines, lying opposite in pairs in two crossed diagonal planes. Pores irregular, roundish, twice to five times as broad as the bars; about sixteen on the half meridian. Proportion of the three axes = 1 : 1⅓ : 2. Medullary shell scarcely one-fourth as long as the cortical shell. (This species resembles closely the common Tetrapyle octacantha, from which it seems to be developed by a complete over-growing of the four gates, which become closed by a network connecting the free edges of the transverse and lateral girdles.)

Dimensions.—Length of the cortical shell 0.18, breadth 0.13, height 0.1; pores 0.005 to 0.015, bars 0.003; length of the medullary shell 0.04.

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

7. Larnacantha cladacantha, n. sp.

Cortical shell very spiny, with eight longer ramified spines, lying opposite in pairs in two crossed diagonal planes; each spine with two to six irregular, lateral branches. Pores irregular, roundish, twice to three times as broad as the bars; about twelve on the half meridian. Proportion of the three axes = 5 : 6 : 7. Medullary shell nearly half as long as the cortical shell. (Differs from the foregoing by the branching spines end the larger medullary shell.)

Dimensions.—Length of the cortical shell 0.15, breadth 0.13, height 0.11; pores 0.01 to 0.015, bars 0.005; length of the medullary shell 0.07.

Habitat.—Indian Ocean, surface, Cocos Islands (Rabbe).

8. Larnacantha prismatica, n. sp. (Pl. , fig. 6).

Cortical shell smooth, four-sided prismatic, with eight short, parallel, three-sided pyramidal spines; these lie opposite in pairs in four parallel longitudinal lines, as prolongations of the four lateral edges of the prism, and arise from its eight corners. Pores regular, circular, three times as broad as the bars; about fourteen on the half meridian. Proportion of the three axes = 2 : 3 : 4. Medullary shell half as long as the cortical shell.

Dimensions.—Length of the cortical shell 0.11, breadth 0.07, height 0.05; pores 0.006, bars 0.002; length of the medullary shell 0.06.

Habitat.—Pacific, central area, Station 263, depth 2650 fathoms.

9. Larnacantha decacantha, n. sp.

Cortical shell thorny, with ten short and stout, conical, radial spines, two opposite on the poles of the principal axis (as prolongations of inner axial beams), eight others opposite in pairs in two crossed diagonal planes. Pores irregular, roundish, twice to four times as broad as the bars; about sixteen on the half meridian. Proportion of the three axes = 3 : 3.75 : 4. Medullary shell about one-third as long as the cortical shell.

Dimensions.—Length of the cortical shell 0.16, breadth 0.15, height 0.12; pores 0.008 to 0.016, bars 0.004; length of the medullary shell 0.06.

Habitat.—North Atlantic, Station 354, surface.

10. Larnacantha dodecantha, n. sp.

Cortical shell nearly smooth, but with twelve strong conical radial spines; four in the lateral plane opposite in pairs (two on the poles of the principal, and two on the poles of the transverse axis); eight others opposite in pairs in two crossed diagonal planes. Pores with a peculiar disposition: twelve large elliptical pores in two crossed meridian planes (alternating with the twelve spines), separated by bands of irregular small pores. Proportion of the three axes = 1 : 1.5 : 2. Medullary shell hexagonal, one-third as long as the cortical shell.

Dimensions.—Length of the cortical shell 0.15, breadth 0.11, height 0.08; large pores 0.03, small pores 0.005 to 0.01, bars 0.003; length of the medullary shell 0.05.

Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.

11. Larnacantha drymacantha, n. sp.

Cortical shell very spiny, on the whole surface covered with a forest of numerous (thirty to fifty or more) large branched spines, about the length of the shell; each spine with three to nine lateral branches, simple or forked (very similar to Cromyodrymus abietinus, Pl. , fig. 6). Pores very irregular, roundish. Proportion of the three axes = 2 : 2.5 : 3. Medullary shell half as long as the cortical shell.

Dimensions.—Length of the cortical shell 0.16, breadth 0.13, height 0.1; pores 0.005 to 0.015, bars 0.03; length of the medullary shell 0.08.

Habitat.—Pacific, central area, Station 271, depth 2425 fathoms.

Genus 276. Larnacoma, n. gen.

Definition.—Larnacida with double lentelliptical cortical shell, without radial spines. Medullary shell double, Larnacilla-shaped.

The genus Larnacoma has originated from the nearly allied Larnacalpis by duplication of the cortical shell. Whilst in both genera the connection between the Larnacilla-shaped medullary shell and the primary cortical shell is the same, many short radial beams arise from the surface of the latter in Larnacoma, which at constant equal distances from it unite by a network forming the secondary or outer cortical shell. It differs from the similar Druppulida (Cromyodruppa) by the sagittal flattening of the lentelliptical shell and the Larnacilla-form of the double medullary shell.

1. Larnacoma lentellipticum, n. sp.

Shell with smooth surface and elliptical perimeter, one and a third times as long as broad. All four shells lentelliptical. Distance between the two cortical shells about twice as great as the distance of the inner cortical and outer medullary shell. Network of both outer shells irregular, with large roundish pores, twice to six times as broad as the bars.

Dimensions.—Length (or principal axis) of the first (innermost) shell 0.03, second 0.08, third 0.16, fourth (outermost) 0.27, breadth (or transverse axis) corresponding—(A) 0.02, (B) 0.05, (C) 0.11, (D) 0.2.

Habitat.—South Atlantic, Station 323, depth 1900 fathoms.

2. Larnacoma quadruplex, n. sp.

Shell with thorny surface and elliptical perimeter, one and a fifth times as long as broad. All four shells lentelliptical. Distance between the two cortical shells somewhat smaller than the distance between the inner cortical and outer medullary shell. Network of both outer shells irregular, with large roundish pores, twice to ten times as broad as the bars.

Dimensions.—Length of the first shell 0.02, second 0.06, third 0.15, fourth 0.24; breadth corresponding—(A) 0.016, (B) 0.04, (C) 0.11, (D) 0.2.

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

3. Larnacoma hexagonium, n. sp.

Shell with thorny surface and hexagonal perimeter, as long as broad. All four shells hexagonal, connected by six piercing radial beams (two in the principal axis, four others in two crossed diagonals). Distance between the two cortical shells somewhat greater than the distance between the inner cortical and outer medullary shell. Network of both outer shells subregular, with small circular pores, twice as broad as the bars.

Dimensions.—Length of the first shell 0.02, second 0.05, third 0.09, fourth 0.16; breadth corresponding—(A) 0.015, (B) 0.035, (C) 0.065, (D) 0.12.

Habitat.—South Atlantic, west of Tristan da Cunha, Station 332, depth 2200 fathoms.

Genus 277. Larnacospongus, n. gen.

Definition.—Larnacida with spongy lentelliptical cortical shell, without radial spines. Medullary shell double, Larnacilla-shaped.

The genus Larnacospongus differs from the nearly allied genera Larnacalpis and Larnacoma by the spongy texture of the lentelliptical cortical shell whilst the enclosed medullary shell in both genera is the same trizonal Larnacilla-shell. Therefore Larnacospongus (and the following nearly related Larnacostupa) can be derived directly by development of a spongy envelop either from Larnacilla and Larnacalpis, or from Trizonium and Amphipyle. But some species of these spongy genera appear to be derived rather from Tetrapyle or Pylonium, perhaps also from Cubotholus. Their phylogenetic origin may be explained in different ways.

1. Larnacospongus larnacillifer, n. sp.

Cortical shell lentelliptical, one and a half times as long as broad, with rough surface and rather loose spongy framework, directly enclosing a trizonal Larnacilla-shell of the same form, but of only one-third its size.

Dimensions.—Length of the whole shell 0.17, breadth 0.12; length of the medullary shell 0.06, breadth 0.04.

Habitat.—South Atlantic, east coast of Patagonia, Station 319, surface.

2. Larnacospongus tetrapylifer, n. sp.

Cortical shell lentelliptical, one and a third times as long as broad, with thorny surface; composed of an outer envelop of loose spongy framework and an inner lattice-shell with four kidney-shaped gates, like Tetrapyle; the latter encloses a trizonal medullary shell of one-fourth its size.

Dimensions.—Length of the whole shell 0.22, breadth 0.16; length of the medullary shell 0.045, breadth 0.035.

Habitat.—South Atlantic, west of Tristan da Cunha, Station 332, surface.

Genus 278. Larnacostupa, n. gen.

Definition.—Larnacida with spongy lentelliptical cortical shell, with radial spines on the surface. Medullary shell double, Larnacilla-shaped.

The genus Larnacostupa differs from the preceding Larnacospongus only in the possession of radial spines, covering either the whole surface irregularly or disposed in a certain symmetrical order.

1. Larnacostupa octacantha, n. sp.

Cortical shell lentelliptical, with thorny surface, and rather dense, irregular, spongy framework, which arises from an inner latticed cortical shell, like that of Tetrapyle or Pylonium. This latter is twice as large as the enclosed Larnacilla-shell. Eight long and thin, cylindrical, radial spines, opposite in pairs in two diagonal planes. (Seems to be the common Tetrapyle octacantha, enveloped by an outer spongy framework mantle.)

Dimensions.—Length of the whole shell (without spines) 0.22, breadth 0.16; length of the medullary shell 0.06, breadth 0.04.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

2. Larnacostupa spinosa, n. sp.

Cortical shell lentelliptical, about one and a half times as long as broad, with very lax and irregular spongy framework, arising from a nearly quadrangular lattice-shell like that of Tetrapyle; this latter encloses a Larnacilla-shell of half its size. Whole surface covered with thin bristle-like radial spines, of about the length of the shell.

Dimensions.—Length of the whole shell (without spines) 0.18, breadth 0.12; length of the medullary shell 0.05, breadth 0.035.

Habitat.—Antarctic Ocean, off Kerguelen, Station 150, surface.

3. Larnacostupa dendrophora, n. sp.

Cortical shell nearly spherical, scarcely longer than broad, with lax, irregular spongy framework, arising from a lentelliptical trizonal medullary shell (like Larnacilla). Whole surface covered with thin arborescent radial spines, about half as long as the shell, each spine with three to six irregular branches.

Dimensions.—Length of the whole shell (without spines) 0.15, breadth 0.13; length of the medullary shell 0.07, breadth 0.04.

Habitat.—Antarctic Ocean, Station 154, surface.