Subfamily 3. Stauracanthida, Haeckel

Definition.—Astrolonchida with a cross of four free apophyses (or four crossed longitudinal rows of apophyses) on each radial spine.

Genus 330. Xiphacantha, Haeckel, 1862, Monogr. d. Radiol., p. 384.

Definition.—Astrolonchida with four simple apophyses on each radial spine, opposite in pairs in the form of a cross.

The genus Xiphacantha was founded by me in 1862 for all those Acanthometrida which bear simple or branched apophyses on their twenty equal spines. I restrict here the genus to those Astrolonchida which bear on each spine a cross of four simple, not branched, apophyses. These are either conical teeth or broad wings, sometimes extremely thin leaves. Xiphacantha may be regarded as the ancestral form not only of the subfamily Stauracanthida, but also of the Tessaraspida, derived from the latter.

Subgenus 1. Xiphacanthonia, Haeckel.

Definition.—Apophyses of the radial spines small, formed like a tooth or a hook, not wing-shaped. Edges of the spines commonly narrow, little prominent.

1. Xiphacantha quadridentata, Haeckel.

Xiphacantha quadridentata, Haeckel, 1862, Monogr. d. Radiol., p. 387, Taf. xviii. figs. 15a, 15b.

Acanthometra quadridentata, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 48, Taf. x. fig. 3.

Spines slender, four-sided prismatic, gradually thinner towards the simple pyramidal apex. Base with large wing-cross. Four apophyses about in the middle of each spine, conical, straight, smooth, about as long as the basal breadth of the spine. Central capsule opaque, reddish-brown.

Dimensions.—Length of the spines 0.2 to 0.3, breadth in the middle part 0.012, on the base 0.02; length of the apophyses 0.02 to 0.03.

Habitat.—Mediterranean, Atlantic, Stations 348, 354, surface.

2. Xiphacantha crucifera, n. sp.

Spines slender, four-sided prismatic, thin, of nearly equal breadth throughout the whole length. Base with small wing-cross. Four apophyses much nearer the proximal than the distal end, thin, straight smooth, three to six times as long as the basal breadth of the spine. Central capsule pellucid, with yellow bodies.

Dimensions.—Length of the spines 0.4 to 0.5, breadth 0.002 to 0.004; length of the apophyses 0.01 to 0.02.

Habitat.—Central Pacific, Station 266, surface.

3. Xiphacantha spinulosa, Haeckel.

Xiphacantha spinulosa, Haeckel, 1862, Monogr. d. Radiol., p. 388, Taf. xvii. fig. 4.

Acanthometra spinulosa, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 807.

Spines stout, four-sided prismatic, of nearly equal breadth throughout the whole length, on the distal apex truncated, two-edged. Base with large wing-cross. Four apophyses about in the middle of each spine, conical, straight, spinulated, twice to four times as long as the basal breadth of the spine. Central capsule opaque, yellow.

Dimensions.—Length of the spines 0.27, breadth 0.014; length of the apophyses 0.05.

Habitat.—Mediterranean (Messina), surface.

4. Xiphacantha emarginata, n. sp.

Spines stout, four-sided, in the proximal half prismatic, in the distal half pyramidal, with emarginated apex. Base with very large wing-cross. Four apophyses about in the middle of each spine, compressed, straight, two-edged, with emarginated ends, about twice as long as the basal breadth of the spine. Central capsule small, pellucid.

Dimensions.—Length of the spines 0.2 to 0.3, breadth 0.02 to 0.03; length of the apophyses 0.04 to 0.06.

Habitat.—South Pacific, Station 291, surface.

5. Xiphacantha falcata, n. sp.

Spines slender, four-sided prismatic, gradually thickened from both ends towards the middle part, with simple apex. Base with very small wing-cross. Four apophyses about in the middle part of each spine, falcated, compressed, recurved, twice to three times as long as the greatest breadth of the spine.

Dimensions.—Length of the spines 0.3 to 0.4, greatest breadth 0.015; length of the apophyses 0.03 to 0.05.

Habitat.—Central Pacific, Station 270, surface.

6. Xiphacantha ancorata, n. sp.

Spines slender, four-sided prismatic, gradually thickened from the narrow base towards the short, simple, pyramidal apex. Base with large wing-cross. Four apophyses on the distal end, immediately below the pyramidal apex, falcated, strongly recurved, like an anchor with four strong teeth.

Dimensions.—Length of the spines 0.4 to 0.5, basal breadth 0.005, distal breadth 0.015; length of the apophyses 0.04.

Habitat.—Indian Ocean, Madagascar, Rabbe.

Subgenus 2. Xiphacanthidium, Haeckel.

Definition.—Apophyses of the radial spines broad, compressed, wing-shaped, formed like a large thin plate. Edges of the spines commonly broad, strongly prominent.

7. Xiphacantha stauroptera, n. sp.

Spines four-winged, from the middle part little thinner towards both ends. Apex simple pyramidal. Base with small wing-cross. Four apophyses wing-shaped, isosceles triangular or truncated quadrangular; their base is about half as broad as their length, and occupies in the basal half of each spine about one-sixth to one-eighth of its length.

Dimensions.—Length of the spines 0.1 to 0.15; greatest breadth (diagonal of the cross of the apophyses) 0.006 to 0.009.

Habitat.—South Atlantic, Station 332, surface.

8. Xiphacantha trigonoptera, n. sp.

Spines four-winged, tapering rapidly from the broad middle part towards both ends. Apex simple pyramidal. Base with a small wing-cross. Four apophyses equilateral triangular; their base occupies the middle of each spine, extending to about one-fifth of its length.

Dimensions.—Length of the spines 0.15 to 0.2, greatest breadth (diagonal of the cross of the apophyses) 0.06 to 0.08.

Habitat.—Central Pacific, Station 272, surface.

9. Xiphacantha macroptera, n. sp.

Spines four-winged, from the broad middle part gradually thinner towards both ends. Apex simple pyramidal. Base with small wing-cross. Four apophyses wing-shaped, very long and broad, triangular; their base occupies about the middle third of each spine; the proximal side of each wing is the shortest, truncated or concave.

Dimensions.—Length of the spines 0.4 to 0.5, greatest breadth (diagonal of the middle leaf-cross) 0.08 to 0.12.

Habitat.—North Pacific, Stations 253 to 256, surface.

10. Xiphacantha platyptera, n. sp.

Spines four-winged, nearly prismatic in the basal and distal parts. Apex truncated. Base with small wing-cross. Four apophyses wing-shaped, very broad and thin, extremely delicate, of irregular quadrangular or nearly rhomboidal form; their base occupies the middle half of the length of the spines (second and third quarter). Very variable in form. Often the edges of the wing-apophyses of the neighbouring spines seem to meet.

Dimensions.—Length of the spines 0.2 to 0.3, greatest breadth (diagonal of the leaf-cross) 0.06 to 0.08.

Habitat.—Pacific, widely distributed, Stations 239, 253, 272, 288, &c., surface.

11. Xiphacantha ciliata, n. sp. (Pl. , figs. 4, 5).

Spines four-winged, prismatic in the basal and the distal third. Apex pyramidal, short. Base with large leaf-cross. Four apophyses wing-shaped, nearly semicircular, with dentated edges and rough spinulate or porous faces; their base occupies the middle third of the length of each spine.

Dimensions.—Length of the spines 0.2 to 0.3, greatest breadth (diagonal of the apophysial cross) 0.08 to 0.12.

Habitat.—Tropical Atlantic, Stations 342 to 352, surface.

12. Xiphacantha alata, Haeckel.

Xiphacantha alata, Haeckel, 1862, Monogr. d. Radiol., p. 388.

Acanthometra alata, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 48, Taf. ix. figs. 1-3.

Spines four-winged, prismatic in the basal quarter, more slender in the distal half. Apex simple pyramidal. Base with small wing-cross. Four apophyses wing-shaped, nearly semicircular, with denticulated edges (and often also with spinulate faces); their base occupies the second quarter of the length of each spine.

Dimensions.—Length of the spines 0.3 to 0.4, greatest breadth (diagonal of the apophysial cross) 0.05 to 0.06.

Habitat.—Mediterranean (Nice), Müller, (Portofino), Haeckel.

Genus 331. Stauracantha, Haeckel, 1881, Prodromus, p. 465.

Definition.—Astrolonchida with four branched (but not latticed) apophyses on each radial spine, opposite in pairs in the form of a cross.

The genus Stauracantha differs from its ancestral form, Xiphacantha, in the ramification of the four crossed apophyses on each spine. These bear either lateral branches, which are parallel to the cross axes of the radial spine itself (subgenus Stauracanthonium), or they are forked, with divergent branches not parallel to those cross axes (subgenus Stauracanthidium). Both subgenera may perhaps be better separated as genera. They form the transition to the Stauraspida.

Subgenus 1. Stauracanthonium, Haeckel.

Definition.—Apophyses of the radial spines not forked, but crossed by perpendicular branches, which are placed in tangential planes and parallel to the cross axes of the quadrangular spine itself.

1. Stauracantha orthostaura, n. sp. (Pl. , fig. 5).

Spines four-sided prismatic, with simple apex and small leaf-cross at the base; with four thin slender conical apophyses in the proximal third. Each apophysis represents a regular rectangular cross, being intersected in its middle by one perpendicular rod of its own length.

Dimensions.—Length of the spines 0.3, breadth 0.02; distance of the apophyses from the apex 0.15 to 0.2.

Habitat.—South Pacific, Station 169, surface.

2. Stauracantha tetrastaura, n. sp.

Spine four-winged prismatic, with four broad prominent edges, pyramidal apex, and large basal leaf-cross, with four broad compressed apophyses about in the middle. Each apophysis represents a vertical lamella (placed in a meridian) with convex distal and concave proximal edge, and is crossed in its apical part by one perpendicular short rod.

Dimensions.—Length of the spines 0.5, breadth 0.03; distance of the apophyses from the centre 0.2.

Habitat.—Central Pacific, Station 272, surface.

3. Stauracantha diplostaura, n. sp.

Spines four-sided prismatic, with truncated apex and broad basal leaf-cross; in the proximal half with four slender conical apophyses. Each apophysis is crossed in its apical half at right angles by two short parallel transverse rods.

Dimensions.—Length of the spines 0.32, breadth 0.012; distance of the apophyses from the centre 0.11.

Habitat.—South Pacific, Station 291, surface.

4. Stauracantha scalaris, n. sp.

Spines four-winged prismatic, with four broad prominent edges, truncated apex, and small basal leaf-cross; in the proximal third with four compressed lamellar apophyses. Each apophysis is pinnate with opposite pinnulæ, or crossed at right angles by three to six parallel transverse rods.

Dimensions.—Length of the spines 0.24, breadth 0.016; central distance of the apophyses 0.12.

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

5. Stauracantha johannis, n. sp. (Pl. , fig. 11).

Spines four-sided pyramidal, with simple apex and broad basal leaf-cross, with four large conical apophyses about in their middle. Each apophysis bears two irregular rows of alternating perpendicular lateral branches, the length of which decreases from the base towards the apex of the apophysis.

Dimensions.—Length of the spines 0.2, middle breadth 0.02; central distance of the apophyses 0.1.

Habitat.—South-east Pacific (off Juan Fernandez), Station 300, surface.

6. Stauracantha murrayana, Haeckel.

Xiphacantha species, Wyville Thomson, 1877, The Atlantic, vol. i. p. 235, fig. 53.

Xiphacantha murrayana, Haeckel, 1878, Protistenreich, p. 45, fig. 33.

Spines quadrangular prismatic, with pyramidal apex and small basal leaf-cross, with four regular conical apophyses in the proximal part. Each apophysis is crossed at right angles by two parallel transverse rods; the smaller apical rod is simple; the larger basal rod is crossed again on each side by a secondary perpendicular branch, which therefore is parallel to the apophysis itself.

Dimensions.—Length of the spines 0.3, breadth 0.01, distance of the apophyses 0.08.

Habitat.—South Atlantic, Station 332, surface.

7. Stauracantha pinnulata, n. sp.

Spines four-winged pyramidal, with prominent edges, simple apex and large basal leaf-cross, in the middle with doubly pinnate triangular apophyses. Each apophysis is crossed at right angles by three to four transverse parallel rods, which bear again perpendicular secondary branches; the outline of the doubly pinnate apophysis is an isosceles triangle.

Dimensions.—Length of the spines 0.3, middle breadth 0.02; distance of the apophyses 0.12.

Habitat.—North Pacific, Station 244, surface.

Subgenus 2. Stauracanthidium, Haeckel.

Definition.—Apophyses of the radial spines forked, each with two divergent terminal branches, which are not parallel to the cross axes of the quadrangular spine.

8. Stauracantha stauraspis, Haeckel.

Dorataspis polyancistra, juvenis, Haeckel, 1862, Monogr. d. Radiol., p. 418, Taf. xxi. fig. 7.

Spines slender, quadrangular prismatic, with simple apex and pyramidal base (without basal leaf-cross); with four slender apophyses, which are simply forked in the outer third. Each apophysis with two recurved fork branches.

Dimensions.—Length of the spines 0.12, breadth 0.004; distance of the apophyses 0.06.

Habitat.—Mediterranean (Messina), surface.

9. Stauracantha bifurca, n. sp.

Spines stout, four-winged prismatic, with pyramidal apex and pyramidal base (without leaf-cross); in their middle with four compressed, little curved apophyses (convex on the outer, concave on the inner edge), which are simply forked at the end. Each apophysis with two short straight fork branches.

Dimensions.—Length of the spines 0.2, breadth 0.006; distance of the apophyses 0.08.

Habitat.—Central Pacific, Station 266, surface.

10. Stauracantha quadrifurca, n. sp. (Pl. , fig. 4).

Spines slender, four-sided prismatic, with simple apex and pyramidal base (without leaf-cross); with four slender apophyses, which are doubly forked about in their middle. Each apophysis with four short and thin terminal branches.

Dimensions.—Length of the spines 0.2, breadth 0.002; distance of the apophyses from the centre 0.08.

Habitat.—South Atlantic, Stations 325 to 330, surface.

Genus 332. Phatnacantha, Haeckel, 1881, Prodromus, p. 465.

Definition.—Astrolonchida with four apophyses on each radial spine, opposite in pairs in cross form, and forming a lattice-plate by communicating branches.

The genus Phatnacantha has been derived from the preceding Stauracantha by concrescence of the branches of the apophyses. Therefore each spine bears a lattice-plate or a fenestrated shield. If the growing plates of the neighbouring spines meet together, then the characteristic lattice-shell of the Tessaraspida is perfect. Either each plate bears four crossed pores (like Tessaraspis), or a larger number of pores (four aspinal and four to eight or more coronal) like Icosaspis.

1. Phatnacantha tessaraspis, n. sp.

Spines quadrangular prismatic, with simple pyramidal apex and small basal leaf-cross. Each spine bears in the basal half a square plate, which is perforated by four square pores; margin of the plate with twelve short straight teeth.

Dimensions.—Length of the spines 0.12, breadth 0.005.

Habitat.—Central Pacific, Station 265, surface.

2. Phatnacantha icosaspis, n. sp. (Pl. , fig. 6).

Spines quadrangular with prominent edges; prismatic in the basal half, with a broad basal leaf-cross, pyramidal in the distal half, with a simple or truncate apex. Each spine bears in the middle part a square plate, which is perforated by eight to sixteen or more square pores (four aspinal and four to eight or more coronal); margin of the plate with twenty-four to forty-eight or more short straight irregular compressed teeth.

Dimensions.—Length of the spines 0.18, breadth 0.008.

Habitat.—Central Pacific, Station 273, surface.

Genus 333. Pristacantha, n. gen.

Definition.—Astrolonchida with numerous simple apophyses (eight to sixteen or more on each radial spine) which are arranged in four longitudinal rows opposite in pairs in the form of a cross.

The genus Pristacantha differs from all other Stauracanthida in the multiplication of the crossed apophyses (at least eight on each spine), and exhibits therefore to them the same relation as Astrolonche exhibits to the other Phractacanthida. The remarkable Astrolonchidium serratum appears intermediate between both groups.

1. Pristacantha octodon, n. sp. (Pl. , fig. 9).

Spines four-sided prismatic, a little broader in the middle part than at either end, with thin prominent edges. Apex truncate or pyramidal. Base pyramidal, with a small leaf-cross. From the four edges arise in the basal half (between first and second third of the length) eight slender, conical, or triangular apophyses (two on each edge).

Dimensions.—Length of the spines 0.4 to 0.6, breadth 0.02 to 0.04.

Habitat.—Central Pacific, Station 271, surface.

2. Pristacantha dodecodon, n. sp. (Pl. , fig. 8).

Spines four-winged, of lanceolate outline, tapering from the broader middle towards the two ends. Apex pyramidal. Base with a large leaf-cross. From the four wings arise in the basal part (between first and second third of the length) twelve triangular apophyses (three from each wing).

Dimensions.—Length of the spines 0.3, breadth in the middle 0.03.

Habitat.—North Pacific, Station 244, surface.

3. Pristacantha polyodon, n. sp. (Pl. , fig. 7).

Spines in the distal half four-sided prismatic, thin, with pyramidal apex; in the basal half much broader, four-winged, with a large leaf-cross on the base. From the four wings of the basal half arises a variable number of slender teeth or triangular apophyses, commonly sixteen to twenty-four, often irregular (four to six from each wing).

Dimensions.—Length of the spines 0.3 to 0.4, breadth in the distal part 0.007 to 0.01, in the basal part 0.02 to 0.03.

Habitat.—South Pacific (off New Zealand), Station 169, surface.