Halicalyptra galea, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. ii. fig. 10.
Shell campanulate, rough, about as long as broad, with irregular roundish pores and thick bars. Apical horn stout, three-sided pyramidal, scarcely one-fourth as long as the shell. Beyond its base there arise three prominent, slightly curved lateral ribs, which are prolonged into three pyramidal, slightly divergent stout feet, somewhat shorter than the shell.
Dimensions.—Shell 0.08 to 0.09 diameter, horn 0.02, feet 0.07.
Habitat.—Fossil in Barbados.
3. Tripocalpis tricostata, n. sp.
Shell ovate campanulate, one and a half times as long as broad, with regular circular pores, disposed in alternate longitudinal rows. Apical horn three-sided pyramidal, stout, half as long as the shell. In the middle of the shell there arise three wing-like lateral ribs, which are prolonged into three broad, slightly curved, divergent terminal feet.
Dimensions.—Shell 0.12 long, 0.08 broad, horn and feet 0.06 to 0.08.
Habitat.—Fossil in Barbados.
4. Tripocalpis triserrata, n. sp. (Pl. 51, fig. 6).
Shell ovate, nearly twice as long as broad. The three sides of the shell, between the three large ribs, are provided each with nine delicate parallel, longitudinal, slightly curved ribs, alternating with ten longitudinal rows of regular circular pores about as broad as the bars. Apical horn short and broad, three-sided pyramidal; from the three edges of its base there arise three wing-like serrate main ribs, which are prolonged into three short pyramidal terminal feet.
Dimensions.—Shell 0.12 long, 0.07 broad, horn and feet 0.01.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
5. Tripocalpis cortinaris, n. sp. (Pl. 97, fig. 3).
Shell hemispherical, one and a half times as broad as long, with regular, circular, hexagonally framed pores, Apical horn stout, three-sided pyramidal, with three serrate edges. From the base of the latter arise three strongly dentate and curved lateral ribs, with recurved teeth, and these are prolonged into the serrate convex edge of the three basal feet, which are crescentic and twice as long as the shell.
Dimensions.—Shell 0.07 long, 0.1 broad; horn 0.06 long, feet 0.14 long.
Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs prolonged into three terminal feet. Apex without horn.
The genus Tripodonium differs from the preceding Tripocalpis, its probable ancestral form, only in the loss of the apical horn (already very small in some forms of the latter). It bears therefore to the latter the same relation that Sethopilium does to Dictyophimus.
1. Tripodonium campanulatum, n. sp.
Shell campanulate, somewhat broader than high, with regular circular pores, twice as broad as the bars. Three broad lateral wings, lamellar, triangular, are prolonged over the peristome into three short triangular lamellar feet one-fourth as long as the shell.
Dimensions.—Shell 0.08 long, 0.09 broad; feet 0.02 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
2. Tripodonium ovatum, n. sp.
Shell ovate, one and one-third times as long as broad, with numerous and small circular pores, scarcely as broad as the bars. Three prominent longitudinal ribs, arising in the lower half of the shell-wall, are prolonged into three divergent conical curved feet, about half as long as the shell.
Dimensions.—Shell 0.12 long, 0.09 broad; feet 0.06 long.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral wings and a peristomial corona of numerous terminal feet. Shell ovate, with constricted mouth, without apical horn.
The genus Tripterocalpis is distinguished from the other Archipilida by the remarkable combination of three lateral wings and of numerous (six to nine or more) terminal feet. It may be derived directly from the preceding Tripocalpis by multiplication of the terminal feet. These are sometimes obliquely directed. The central capsule is ellipsoidal or ovate, and fills up the greater part of the shell.
1. Tripterocalpis phylloptera, n. sp. (Pl. 51, fig. 1).
Shell slender, ovate, nearly twice as long as broad. Pores circular, of different sizes and at unequal distances. Along the lower half of the shell there arise three broad triangular lamellar wings. Peristome with twelve conical, nearly parallel and vertical feet, about one-sixth as long as the shell.
Dimensions.—Shell 0.2 long, 0.12 broad; wings 0.1 long, feet 0.03 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
2. Tripterocalpis conoptera, n. sp. (Pl. 51, fig. 2).
Shell ovate, nearly as broad as long. Pores regular, circular, quincuncial, twice as broad as the bars. In the middle of the shell there arise three conical, smooth, divergent wings, about half as long as the shell. Peristome with six short triangular, oblique, convergent feet.
Dimensions.—Shell 0.16 long, 0.14 broad; wings 0.09 long; feet 0.02 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
3. Tripterocalpis ogmoptera, n. sp. (Pl. 51, figs. 3-5).
Shell ovate, nearly as broad as long. Pores small and numerous, circular or roundish, partly confluent, double-contoured (fig. 4). In the middle of the shell there arise three very large conical divergent wings, which are longitudinally striped and longer than half the shell. Peristome with nine short triangular, oblique, convergent feet.
Dimensions.—Shell 0.18 long, 0.16 broad; wings 0.12 long, feet 0.02 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs or wings. Mouth smooth, without terminal feet. Apex with a horn.
The genus Trissopilium and the following nearly allied Archipilium differ from the other Archipilida in the absence of terminal feet, the peristome being quite simple, and truncate. But there are three lateral wings, arising either from the apex or from the lateral sides of the monothalamous shell. Trissopilium may perhaps be derived from Lithomelissa by reduction of the cephalis.
1. Trissopilium tetraplecta, n. sp.
Shell in the upper half three-sided pyramidal, in the lower half inversely hemispherical, of equal length and breadth. Pores irregular, roundish, in the upper half larger. From the apex there diverge four equal, straight and stout, three-sided pyramidal spines, one of which is vertically ascending (the horn), the three others obliquely descending (the wings). The distal half of the latter is free, whilst the proximal half forms three ribs, enclosed in the shell-wall. Mouth constricted, half as broad as the shell.
Dimensions.—Shell 0.08 long and broad, horn and wings 0.1 long.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
2. Trissopilium lithomelissa, n. sp.
Shell ovate, one and one-third times as long as broad. Pores circular, of different sizes, small and numerous. Apical horn very large, straight, cylindrical, vertical, longer than the shell. Three lateral wings shorter, arising from the middle of the shell, conical, curved, divergent. Mouth truncate, two-thirds as broad as the shell.
Dimensions.—Shell 0.11 long, 0.08 broad; horn 0.13 long, wings 0.09 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs or wings. Mouth truncate, without terminal feet. Apex without horn.
The genus Archipilium differs from the nearly allied Trissopilium, its probable ancestral form, in the absence of the apical horn. The three lateral wings of the ovate shell are stout spines. It may also be derived from the similar Sethopilium by reduction and loss of the cephalis.
1. Archipilium orthopterum, n. sp. (Pl. 98, fig. 7).
Shell ovate, smooth, nearly cylindrical, scarcely broader than the truncate, widely open mouth. Pores numerous, irregular, roundish, of very different sizes. Three lateral wings arising from the middle zone, twice as long as the shell, straight, divergent, stout, cylindrical, longitudinally striped.
Dimensions.—Shell 0.08 long, 0.06 broad; wings 0.15 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
2. Archipilium sigmopterum, n. sp.
Shell ovate, smooth, nearly campanulate, of equal length and breadth, one and one-third times as broad as the truncate, slightly constricted mouth. Pores scarce, irregularly formed and scattered, of very different sizes. Three lateral wings, stout, prismatic, about as long as the shell widely divergent and S-shaped, curved.
Dimensions.—Shell 0.08 diameter, wings 0.08 long.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
3. Archipilium cyrtopterum, n. sp.
Shell ovate, rough, twice as broad as the constricted mouth. Pores small and numerous, subregular, circular, smaller than the bars. Three lateral wings cylindrical, crescentic, in the upper half divergent, in the lower convergent, one and one-half times as long as the shell.
Dimensions.—Shell 0.09 long, 0.07 broad; wings 0.14 long.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) without lateral ribs, with three simple or branched terminal feet and an apical horn.
The genus Tripilidium differs from Tripodonium in the absence of the three lateral ribs, and may be derived either from this ancestral form, or directly from Tripospyris (by loss of the sagittal ring and constriction); perhaps also from Lychnocanium (by reduction of the cephalis). We distinguish as two subgenera, Tristylocorys (with simple feet) and Tripodocorys (with branched feet).
Definition.—Feet simple, not branched.
1. Tripilidium cortina, n. sp.
Shell campanulate, rough, about as long as broad. Pores subregular, circular, larger in the middle zone, twice to three times as broad as the bars. Mouth constricted, half as broad as the shell. Apical horn straight and stout, three-sided pyramidal, about as long as the shell. Three feet divergent, slightly S-shaped, curved, somewhat longer the the shell.
Dimensions.—Shell 0.1 diameter, horn 0.09 long, feet 0.13 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
2. Tripilidium hemisphæricum, n. sp.
Shell hemispherical, smooth, nearly twice as broad as long. Pores large, with thin bars, irregular, roundish, of very different sizes. Mouth wide open. Apical horn conical, half as long as the shell. Three feet slender cylindrical, widely divergent, curved, nearly twice as long as the shell.
Dimensions.—Shell 0.08 long, 0.14 broad; horn 0.05 long, feet 0.15 long.
Habitat.—South Pacific, Station 298, depth 2225 fathoms.
3. Tripilidium lychnocanium, n. sp.
Shell hemispherical, thorny, one and a half times as broad as long. Pores regular, circular, hexagonally framed, as broad as the bars. Mouth slightly constricted. Apical horn stout and short, three-sided pyramidal. Three feet cylindrical, straight, divergent, twice to three times as long as the shell. (Similar to Lychnocanium favosum, Pl. 61, fig. 6, perhaps derived from it by reduction of the cephalis.)
Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.02 long, feet 0.2 long.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
4. Tripilidium ovatum, n. sp.
Shell ovate, smooth, one and one half times as long as broad. Pores regular, circular, as broad as the bars. Mouth constricted, half as broad as the shell. Horn short, conical. Three feet conical, curved, convergent, scarcely one-third as long as the shell.
Dimensions.—Shell 0.15 long, 0.11 broad; horn 0.02 long, feet 0.04 long.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
5. Tripilidium clavatum, n. sp.
Shell nearly spherical, tuberculate, a little broader than long. Pores regular, circular, as broad as the bars. Mouth constricted, half as broad as the shell. Apical feet and the three divergent feet of equal size and similar form, about as long as the shell, straight, in the basal half smooth, cylindrical, in the distal half club-shaped, dimpled. (Very similar to Tripospyris conifera and Tripospyris eucolpos, Pl. 84, figs. 7 and 4; but the spherical shell exhibits no trace of sagittal ring or constriction, and the simple shell-cavity has a wide open mouth, and is not closed by a basal plate.)
Dimensions.—Shell 0.1 diameter, horn and feet 0.08 to 0.09 long.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
6. Tripilidium costatum, n. sp. (Pl. 98, figs. 8, 8a, 8b).
Shell ovate, spinulate and costate, nearly twice as broad as long. Surface with fifteen to twenty prominent longitudinal ribs, which are convergent towards each pole and elegantly denticulate. The deep furrows between them are divided by delicate, parallel, transverse ribs into numerous short and broad dimples (thirty to forty in each furrow); each dimple contains a small pore, like a transverse fissure. The apex bears a short and stout, three-sided pyramidal horn, the hollow base of which is closed by a small cortinar septum with three collar pores (fig. 8b). This seems to indicate a rudimentary cephalis and the derivation of this species from Lychnocanium (Pl. 61). Peristome constricted, only one-fourth as broad as the shell, with three short, conical, nearly vertical feet. The central capsule (fig. 8a) in the specimen examined was well preserved, hemispherical, not lobate, and filled up the upper half of the shell-cavity (beyond the rudiment of the cortinar septum).
Dimensions.—Shell 0.2 long, 0.12 broad; horn 0.01 long, feet 0.02 long.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.
7. Tripilidium elongatum, n. sp.
Shell elongate, smooth, nearly cylindrical, in the upper third conical. Pores small and numerous, regular, circular, half as broad as the bars, disposed in about thirty longitudinal alternating rows. Peristome scarcely constricted. The apical horn and the three parallel feet are of equal size and similar form, straight, conical, one-sixth as long as the shell.
Dimensions.—Shell 0.12 long, 0.06 broad; horn and feet 0.02 long.
Habitat.—Fossil in Barbados.
Definition.—Feet forked or branched.
8. Tripilidium dichopodium, n. sp.
Shell hemispherical, nearly twice as broad as long, smooth. Pores irregular, roundish, twice to four times as broad as the bars. Mouth wide open. Apical horn spindle-shaped, half as long as the shell. Three feet cylindrical, nearly straight and parallel, as long as the shell, forked at the distal end. (Exhibits an external similarity to Tripospyris semantis, Pl. 84, fig. 2, but has no trace of sagittal ring and constriction, and the simple shell-cavity has a wide open mouth.)
Dimensions.—0.06 long, 0.1 broad; horn 0.03 long, feet 0.07 long.
Habitat.—North Pacific, Station 241, depth 2300 fathoms.
9. Tripilidium cladopodium, n. sp.
Shell campanulate, rough, about as long as broad. Pores subregular, circular, as broad as the bars. Mouth slightly constricted. Apical horn and three divergent feet of nearly equal size and form, three-sided prismatic, straight and stout, irregularly dentate and branched, somewhat longer than the shell.
Dimensions.—Shell 0.08 diameter; horn and feet 0.1 to 0.12 long.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) without lateral ribs and apical horn, with three simple or branched terminal feet.
The genus Tripodiscium may be derived either from the preceding Tripilidium by loss of the apical horn, or from the nearly related Tristylospyris by loss of the sagittal ring and constriction. Some forms of the latter genus can scarcely be distinguished from similar species of the former.
Definition.—Feet simple, not branched nor forked.
1. Tripodiscium tristylospyris, n. sp.
Shell subspherical, with regular, circular pores, twice as broad as the bars. Mouth constricted, half as broad as the shell, with three short spindle-shaped feet, which are nearly parallel and vertical, half as long as the shell. (Similar to Tristylospyris scaphipes, Pl. 84, fig. 13, but without sagittal ring and constriction.)
Dimensions.—Shell 0.08 long, 0.07 broad; feet 0.04 long.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
2. Tripodiscium ovatum, n. sp.
Shell ovate, rough, nearly as broad as long. Pores regular circular, double-contoured, twice as broad as the bars. Mouth constricted, one-third as broad as the shell, with three convergent short triangular feet.
Dimensions.—Shell 0.1 long, 0.09 broad; feet 0.02 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
3. Tripodiscium clavatum, n. sp.
Shell ovate, smooth, one and a half times as long as broad. Pores irregular roundish, of different sizes. Mouth constricted, two-thirds as broad as the shell, with three divergent, straight club-shaped feet, nearly as long as the shell.
Dimensions.—Shell 0.12 long, 0.08 broad; feet 0.1 long.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.
4. Tripodiscium campanula, Haeckel.
Carpocanium campanula, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii. fig. 9.
Shell campanulate or subspherical, smooth, about as long as broad. Pores small, regular circular, as broad as the bars. Mouth constricted, about half as broad as the shell, with three short conical descending feet.
Dimensions.—Shell 0.06 long, 0.05 broad; feet 0.02 long.
Habitat.—North Pacific, Station 244, depth 2900 fathoms; fossil in Sicily.
Definition.—Feet branched or forked.
5. Tripodiscium furcatum, n. sp.
Shell ovate, rough, nearly as broad as long. Pores subregular, circular, twice as broad as the bars. Mouth constricted, two-thirds as broad as the shell, with three divergent parallel and vertical feet, which are as long as the shell, and forked at the distal end.
Dimensions.—Shell 0.09 long, 0.08 broad; feet 0.07 long.
Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.
6. Tripodiscium ramosum, n. sp.
Shell ovate, tuberculate, nearly as broad as long. Pores irregular, roundish, of very different sizes. Mouth constricted, half as broad as the shell, with three large, divergent, irregularly branched feet, nearly twice as long as the shell. (Similar to Tristylospyris ramosa, Pl. 52, fig. 23, but without sagittal ring and constriction.)
Dimensions.—Shell 0.07 long, 0.06 broad; feet 0.15 long.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
7. Tripodiscium sphærocephalum, n. sp. (Pl. 52, fig. 21).
Shell subspherical, rough, with circular pores of different sizes. Mouth constricted, circular, simple, two-thirds as broad as the shell, with three large divergent feet, which are three-sided prismatic, irregularly branched, and twice as long as the shell.
Dimensions.—Shell 0.07 long, 0.08 broad; feet 0.12 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three latticed terminal feet. Shell ovate or subconical, with an apical horn.
The genus Tridictyopus differs from the nearly allied Tripilidium in the possession of three large fenestrated shovel-shaped feet, forming direct prolongations of the large conical shell. The lattice work exhibits a peculiar elegant structure recurring in the similar, perhaps nearly related, Cephalospyris (Pl. 83, fig. 10; Pl. 96, fig. 28). The central capsule is large, ellipsoidal or ovate, and fills up the greater part of the shell cavity (compare R. Hertwig, 1879, loc. cit., p. 75).
1. Tridictyopus vatillum, n. sp. (Pl. 51, fig. 8).
Shell campanulate, about as long as broad (excluding horn and feet). Pores irregular, polygonal, in the middle part more regular, triangular. Horn short and stout, three-sided pyramidal. Three feet large, triangular, shovel-shaped, about half as long as the shell.
Dimensions.—Shell 0.14 long, 0.15 broad.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
2. Tridictyopus conulus, n. sp. (Pl. 51, fig. 7).
Shell campanulate conical, about one and a half times as long as broad (excluding horn and feet). Pores mostly triangular, disposed in subregular hexagonal figures, which are separated by bands of smaller irregular polygonal pores. Horn short and stout, three-sided pyramidal. Three feet triangular shovel-shaped, convergent, about one-sixth as long as the shell.
Dimensions.—Shell 0.3 long, 0.2 broad; horn 0.04 long, feet 0.05 long.
Habitat.—Equatorial Atlantic, Station 347, depth 2250 fathoms.
3. Tridictyopus elegans, R. Hertwig.
Tridictyopus elegans, R. Hertwig, 1879, Organismus d. Radiol., p. 75, Taf. vii. fig. 3, 3a, 3b.
Shell slender, conical, campanulate, about twice as long as broad (excluding horn and feet). Most pores subregular triangular, with some irregular polygonal ones intermingled. The horn in the two observed specimens was broken off, together with the conical apex of the shell. Three feet triangular shovel-shaped, about one-sixth as long as the shell.
Dimensions.—Shell 0.3 long, 0.15 broad; feet 0.05 long.
Habitat.—Mediterranean (Messina), R. Hertwig, surface.
Definition.—Tripocalpida with the basal mouth of the shell fenestrated (vel Monocyrtida triradiata clausa).
Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free simple internal columella, prolonged into an apical horn. Three basal feet free, without lateral wings.
The genus Euscenium and the three following nearly allied genera form together the remarkable small group of Euscenida, probably one of the oldest and most primitive of all Cyrtoidea, and perhaps the common root of this suborder, arising directly from the Plectoidea. The simple skeleton is composed of four radial beams united in one point (the cortinar centrum). Three beams are directed downwards, and form three divergent basal feet; the fourth beam is directed upwards and represents an apical horn; its basal part is enclosed as "columella" in the cavity of the simple shell, the lattice-work of which connects the four spines (compare above, Plectaniscus, p. 924). In the genus Euscenium, the simplest of all, the columella is simple, and the three feet also simple, without wings.
Definition.—Three feet simple, not branched.
1. Euscenium plectaniscus (Pl. 98, fig. 1).
Shell three-sided pyramidal, thorny, about as long as broad, with three dentate edges. Framework very loose, with irregular polygonal meshes; in the middle of each of the three triangular sides a horizontal band of denser network. Basal plate with three very large simple collar-holes. The apical horn and the three feet are three-sided pyramidal, about half as long as the columella, with three prominent irregularly dentate edges. The horn is straight, whilst the three feet are hook-shaped, its distal end being curved downwards and inwards.
Dimensions.—Shell 0.11 long, 0.13 broad.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
2. Euscenium archicyrtis, n. sp.
Shell three-sided pyramidal, smooth, nearly as long as broad, with three straight edges connected by irregular loose framework with polygonal meshes. Basal plate with three very large simple collar-holes. The apical horn and the three feet are three-sided prismatic, smooth, about twice as long as the columella, straight and widely divergent.
Dimensions.—Shell 0.08 long, 0.1 broad.
Habitat.—Tropical Pacific, Station 225, depth 4475 fathoms.
3. Euscenium hemisphæricum, n. sp.
Shell hemispherical smooth, half as long as broad, with small and numerous subregular circular pores. Basal plate with three large triangular simple collar-holes. Horn slender, three-sided prismatic, twice as long as the columella. Feet very slender, with three denticulate edges, widely divergent and curved like the quadrant of a circle.
Dimensions.—Shell 0.04 long, 0.06 broad.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
4. Euscenium tricolpium, n. sp. (Pl. 53, fig. 12).
Archiscenium tricolpium, Haeckel, 1881, Prodromus et Atlas, loc. cit.
Shell cap-shaped, nearly hemispherical, with three vaulted hemispherical bosoms between the three arches ascending from the feet to the horn. Network very irregular, with polygonal meshes, of different form and size. Basal plate with three large primary and some smaller irregular accessory collar-holes. Horn slender, straight, twice as long as the columella. Feet of the same length, slender, widely divergent, slightly curved. The three edges of the horn and the feet are elegantly denticulated.
Dimensions.—Shell 0.04 long, 0.08 broad.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
5. Euscenium tripospyris, n. sp. (Pl. 84, fig. 8).
Tripospyris euscenium, Haeckel, 1881, Prodromus et Atlas.
Shell nearly spherical, smooth, with numerous small circular pores. Basal plate also with numerous small pores. Horn and feet stout, three-sided prismatic, straight or slightly curved, about as long as the thin, somewhat curved columella. This species is closely allied to Tripospyris.
Dimensions.—Shell 0.11 to 0.12 diameter, horn and feet 0.08 to 0.1 long.
Habitat.—South Pacific, Station 298, depth 2225 fathoms.
Definition.—Feet forked or branched.
6. Euscenium furcatum, n. sp.
Shell campanulate, smooth, with numerous irregular roundish pores. Basal plate with nine pores (three larger central and six smaller distal). Horn club-shaped, half as long as the columella. Feet twice as long, cylindrical, parallel, vertical, forked at the distal end. (Similar to Tripospyris semantis, Pl. 84, fig. 2, but without sagittal feet.)
Dimensions.—Shell 0.07 long, 0.06 broad; horn 0.04 long, feet 0.1 long.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.
7. Euscenium quadratum, n. sp.
Shell campanulate, smooth with subregular square pores. Basal plate with three large pores. Horn and feet of the same size and shape, twice as long as the columella, three-sided prismatic, each with four or five verticils of lateral branches. (Similar to the cephalis of Clathrocorys murrayi, Pl. 64, fig. 8, but with four free spines without connecting lattice-wings.)
Dimensions.—Shell 0.06 long, 0.05 broad; horn and feet 0.12 long.
Habitat.—Central Pacific, Station 272, surface.
8. Euscenium ramosum, n. sp.
Shell subspherical, rough, with small subregular circular pores. Basal plate with nine pores (three larger central and six smaller distal pores). Horn and feet of the same size and form, three to four times as long as the columella, three-sided prismatic, irregularly branched.
Dimensions.—Shell 0.06 diameter, horn and feet 0.15 to 0.2 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free branched internal columella, prolonged into an apical horn. Three basal feet free, without lateral wings.
The genus Cladoscenium differs from the preceding Euscenium only in the ramification of the internal columella, which bears one or more verticils of three ascending lateral branches. The three branches of each verticil lie in the same equidistant meridian planes as the three basal feet, and are inserted with their distal ends on the inner surface of the simple lattice-shell. The three feet are also branched, but without vertical lattice-wings. Cladoscenium is perhaps closely allied to Clathrocorys.
1. Cladoscenium fulcratum, n. sp.
Shell subspherical, smooth, with large irregular roundish pores. Basal plate with three large pores. Columella with a single verticil of three ascending lateral branches. Apical horn as long as the columella, simple, three-sided prismatic. Feet twice as long, widely divergent, straight, prismatic, with some irregular basal branches.
Dimensions.—Shell 0.06 diameter, horn 0.05 long, feet 0.1 long.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
2. Cladoscenium ancoratum, n. sp. (Pl. 53, fig. 13).
Shell campanulate, smooth, with irregular polygonal pores. Basal plate with six pores (two large cardinal, two smaller jugular and two still smaller cervical pores). Columella with a single verticil of three ascending lateral branches (by mistake not distinct in the figure). Apical horn and the three feet of the same form and size, slender, prismatic, twice to three times as long as the shell, straight, in the distal half with three slender recurved branches, anchor-shaped.
Dimensions.—Shell 0.05 long, 0.04 broad; horn and feet 0.1 to 0.15 long.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
3. Cladoscenium gladiatum, n. sp.
Shell subspherical, with irregular polygonal pores. Basal plate with three large pores. Columella with two verticils of three ascending lateral branches. Apical horn as long as the columella, three-sided prismatic. Feet of the same form, twice as long, in the distal half with two opposite transverse branches, sword-shaped.
Dimensions.—Shell 0.05 long, 0.06 broad; horn 0.04 long, feet 0.1 long.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
4. Cladoscenium pinnatum, n. sp.
Shell campanulate, with irregular polygonal pores. Basal plate with four pores (two major cardinal and two minor jugular). Columella with two verticils of three ascending lateral branches, and prolonged into a slender prismatic apical horn of twice the length, which bears four such verticils. Feet twice as long as the horn, pinnate, each with four or five pairs of opposite lateral branches, decreasing towards the thin distal end.
Dimensions.—Shell 0.06 long, 0.05 broad; horn 0.1 long, feet 0.2 long.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
5. Cladoscenium verticillatum, n. sp.
Shell campanulate, with subregular square pores. Basal plate with nine pores (three larger central and six smaller distal). Columella with three verticils of three ascending lateral branches. Apical horn and the three basal feet of equal size and similar form, four to six times as long as the columella, three-sided prismatic, each with four to five verticils of three lateral branches, which are irregularly ramified and tapering towards the distal end. (Similar to Clathrocorys teuscheri, Pl. 64, fig. 10, but with four free spines, without connecting lattice-wings.)
Dimensions.—Shell 0.07 long, 0.06 broad; horn and feet 0.2 to 0.25 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
6. Cladoscenium pectinatum, n. sp. (Pl. 98, fig. 2).
Shell subspherical, with irregular roundish pores. Basal plate with three large holes. Columella with two verticils of three ascending lateral branches. Apical horn and the three feet of nearly the same size and form, three to four times as long as the columella, straight, three-sided prismatic, each with five to eight verticils of three simple lateral branches, tapering towards the distal end.
Dimensions.—Shell 0.07 long, 0.08 broad; horn and feet 0.16 to 0.22 long.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free simple internal columella, prolonged into an apical horn. Three basal feet connected with the horn by three vertical lateral wings.
The genus Archiscenium and the following nearly allied Pteroscenium are derived from the two preceding genera, from which they differ in the development of three free vertical lateral lattice-wings; these arise from the upper edge of the three basal feet and connect them with the three edges of the apical horn. The basal part of the latter, enclosed in the shell, forms an internal free columella, which in Archiscenium is simple, not branched.
1. Archiscenium quadrispinum, n. sp. (Pl. 53, fig. 11).
Shell hemispherical, smooth, with a small number of large irregular polygonal meshes and thin bars. Basal lattice with three very large central meshes and six smaller peripheral meshes (two on the base of each foot). Apical horn and the three feet of equal size and similar form, slender, pyramidal, widely divergent, straight, as long as the shell-diameter. Three lateral wings small, little prominent, each with two or three irregular meshes. Central capsule subspherical.
Dimensions.—Shell 0.05 long, 0.1 broad.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
2. Archiscenium clathrocorys, n. sp.
Shell campanulate, smooth, with numerous irregular square meshes. Basal lattice with three very large meshes. Apical horn and the three feet of equal size and similar form, three-sided prismatic, widely divergent, straight, twice as long as the shell-diameter. Three lateral wings broad, each with a basal row of few very large irregular roundish meshes, and several distal rows of small square meshes. This species is very similar to Clathrocorys murrayi (Pl. 64, fig. 8), but has no trace of thorax-wall. The latter species may be derived from the former by development of the thoracic lattice, which connects the three free feet.
Dimensions.—Shell 0.05 long, 0.06 broad.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
3. Archiscenium tripterygium, n. sp.
Shell hemispherical, smooth, with numerous irregular roundish meshes of very different sizes. Basal lattice with four large meshes, two major cardinal and two minor cardinal pores. Apical horn and the three feet of similar form and size, slender prismatic, three to four times as long as the shell; the horn straight, the feet curved. Three lateral wings very delicate, with a basal row of few large irregular polygonal meshes, and several distal rows of similar small pores.
Dimensions.—Shell 0.04 long, 0.05 broad.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
4. Archiscenium cyclopterum, n. sp. (Pl. 98, fig. 3).
Shell hemispherical, with small irregular roundish pores. Basal lattice with four large meshes, two major cardinal and two minor jugular pores. Apical horn and the three feet of similar form and size, slender prismatic, straight, twice to four times as long as the shell. Three lateral wings nearly semicircular, densely latticed, with the same pores as the shell, and smooth convex margin.
Dimensions.—Shell 0.05 long, 0.06 broad.
Habitat.—South Pacific, Station 295, depth 1500 fathoms.
5. Archiscenium callimitra, n. sp.
Shell campanulate, with irregular polygonal pores. Basal lattice with nine meshes (three larger central and six smaller distal pores, as in Callimitra carolotæ, Pl. 63, fig. 8). Apical horn straight, prismatic, slender, conical, twice as long as the shell. Feet longer and more slender, slightly curved. Three lateral wings very broad, densely fenestrated, with irregular polygonal pores of the same shape as in the similar Callimitra carolotæ (Pl. 63, fig. 1).
Dimensions.—Shell 0.05 long, 0.04 broad.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free branched internal columella, prolonged into an apical horn. Three basal feet connected with the horn by three vertical lateral wings.