Legion I. SPUMELLARIA, (continued 4)

Dimensions.—Diameter of the sphere 0.07, pores 0.01 to 0.02, bars 0.003; length of the major spine 0.08, of the minor 0.06, basal thickness 0.02.

Habitat.—Indian Ocean, Sunda Strait, Rabbe, surface.

13. Xiphostylus edolius, n. sp. (Pl. 13, fig. 5).

Pores irregular, roundish, composed of two to six smaller confluent pores. On the half equator six to eight large pores, and twenty to thirty small pores; bars between the smaller very thin. Surface a little rough. Major polar spine conical, S-shaped, about twice as long as the axis of the shell; minor spine pommel-shaped, edged, scarcely as long as its radius.

Dimensions.—Diameter of the sphere 0.12, large pores 0.01 to 0.03, small pores 0.004 to 0.008, bars 0.001 to 0.004; length of the major spine 0.2, of the minor 0.05, basal breadth 0.02.

Habitat.—Central Pacific, Station 273, surface.

Subgenus 4. Xiphostylomma, Haeckel.

Definition.—Pores of the spherical shell irregular, of different size or form; surface thorny or spiny.

14. Xiphostylus emberiza, n. sp. (Pl. 13, fig. 11).

Pores irregular, roundish, one to four times as broad as the bars; six to eight on the half equator. Polar spines very unequal; major cylindrical, twice as long as the axis of the sphere; minor scarcely half as long, obliquely inserted, like a bird's head, surrounded by a group of ten to twenty smaller conical spines. Opposite hemisphere smooth.

Dimensions.—Diameter of the sphere 0.005, pores 0.002 to 0.008, bars 0.002; length of the major spine 0.09, of the minor 0.05, basal breadth 0.01.

Habitat.—South Atlantic, Station 332, surface.

15. Xiphostylus ardea, n. sp.

Pores irregular, roundish, one to three times as broad as the bars; twelve to sixteen on the half equator. Whole surface spiny. Major polar spine three-sided pyramidal, somewhat longer than the diameter of the sphere; minor scarcely so long as its half radius, pommel-like, edged.

Dimensions.—Diameter of the sphere 0.12, pores 0.003 to 0.01, bars 0.003; length of the major polar spine 0.15, of the minor 0.03, basal breadth 0.02.

Habitat.—North Atlantic, Station 64, surface.

Genus 47. Saturnalis,^[70] Haeckel, 1881, Prodromus, p. 450.

Definition.—Stylosphærida with one single lattice-sphere and two equal opposite spines, connected at the distal end by a circular or elliptical ring.

The genus Saturnalis (with simple lattice-sphere) and the two similar genera Saturnulus (with two concentric spheres) and Saturninus (with three spheres) form together the small peculiar group of Saturnalida, distinguished by a remarkable circular or elliptical ring, connecting the distal ends of the two equal opposite polar spines. This ring indicates a certain equatorial plane, and therefore brings these Sphæroidea into relation with the Discoidea.

Subgenus 1. Saturnalina, Haeckel.

Definition.—Ring smooth, without spines or thorns.

1. Saturnalis circularis, n. sp.

Pores of the spherical shell regular, circular, hexagonally framed, twice as broad as the bars. Ten to twelve pores on the half equator. Ring circular, smooth, its diameter three times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.07, pores 0.005, bars 0.0025; diameter of the circular ring 0.2, thickness of the axial beams and the ring 0.01.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Saturnalis annularis, n. sp. (Pl. 13, fig. 16).

Pores of the spherical shell regular, circular, with elevated hexagonal frames, of the same breadth as the bars. Sixteen to twenty pores on the half equator. Ring elliptical, smooth, somewhat constricted at the poles of the axis, its diameter three times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.09, pores and bars 0.005, major axis of the elliptical ring 0.27 to 0.3, minor axis 0.19 to 0.2; thickness of the ring and of the axial beams 0.01.

Habitat.—Pacific, central area, Stations 270 to 274, surface.

3. Saturnalis cyclus, n. sp.

Lithocircus mesocena, Bury, 1862, Polycystins of Barbados, pl. iii. fig. 1.

Pores of the spherical shell regular, circular, without hexagonal frames, twice as broad as the bars. Eight to ten pores on the half equator. Ring circular, smooth, its diameter four times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.07, pores 0.006, bars 0.003; diameter of the circular ring 0.28, thickness of the ring and both axial beams 0.01.

Habitat.—Fossil in the Barbados rocks.

4. Saturnalis circoides, n. sp. (Pl. 13, fig. 12).

Pores of the spherical shell irregular, roundish, often somewhat lobed, one to three times as broad as the bars; fifteen to twenty on the half equator. Ring circular, smooth, with four prominent edges, its diameter twice as great as that of the sphere. (The figured specimen is a young or not fully developed one; afterwards I found in the same locality other specimens with quite perfect rings, similar to the edged ring of Saturnulus annulus, Pl. 16, fig. 17.)

Dimensions.—Diameter of the sphere 0.09 to 0.1, pores 0.003 to 0.01, bars 0.004; diameter of the circular ring 0.2 to 0.24, thickness of the ring and the polar beams 0.01.

Habitat.—Indian Ocean; fossil in the Nicobar rocks; living at great depths near Zanzibar, 2200 fathoms, Pullen.

Subgenus 2. Saturnalium, Haeckel.

Definition.—Ring armed on the periphery with numerous spines or thorns.

5. Saturnalis trochoides, n. sp.

Haliomma species, Bury, 1862, Polycystins of Barbados, pl. xx. fig. 2.

Pores of the spherical shell subregular, circular, twice as broad as the bars. Twelve to sixteen pores on the half equator. Ring circular, armed with ten to twelve strong conical, irregular spines, its diameter twice as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.08, pores 0.006, bars 0.003; diameter of the circular ring 0.16; length of the radial spines 0.02 to 0.04; thickness of the ring and the axial beams 0.01.

Habitat.—Fossil in the Barbados rocks.

6. Saturnalis rotula, n. sp. (Pl. 13, fig. 15).

Pores of the spherical shell regular, circular, twice as broad as the bars; sixteen to twenty on the half equator. Ring circular, armed with fifteen to twenty strong, conical, irregular spines, partly simple, partly divided into two or three irregular branches; diameter of the ring two and a half times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.08, pores 0.004, bars 0.002; diameter of the circular ring 0.2, length of its spines 0.02 to 0.03; thickness of the ring and the radial beams 0.01.

Habitat.—North Pacific, Station 244, surface.

Subfamily Sphærostylida, Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.—Stylosphærida with two concentric, spherical lattice-shells.

Genus 48. Stylosphæra,^[71] Ehrenberg, 1847, Monatsber. d. Berlin Akad., p. 54.

Definition.—Stylosphærida with two concentric lattice-spheres and two free spines of equal size and similar form.

The genus Stylosphæra, the most simple form of the Sphærostylida, can be derived either from Xiphosphæra by duplication of the spherical shell, or from Carposphæra by development of two opposite polar spines. The inner or medullary shell is enclosed in the central capsule, whilst the outer or cortical shell lies outside it; the two are connected by two or more radial beams, piercing the wall of the capsule.

Subgenus 1. Stylosphærantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without spines or thorns.

1. Stylosphæra musa, n. sp.

Radial proportion of the two concentric spheres = 3 : 1. Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the thin bars; twelve on the half equator. Polar spines three-sided pyramidal, as long as the axis of the cortical shell, one-tenth as broad at the base.

Dimensions.—Diameter of the outer shell 0.2, pores 0.01, bars 0.003; diameter of the inner shell 0.06; length of the polar spines 0.2, basal breadth 0.02.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Stylosphæra urania, n. sp.

Radial proportion of the two shells = 4 : 1. Cortical shell thin walled, smooth; pores regular, circular, hexagonally framed, twice as broad as the bars; ten on the half equator. Polar spines conical, as long as the radius of the outer shell.

Dimensions.—Diameter of the cortical shell 0.24, pores 0.012, bars 0.006; medullary shell 0.06; length of the polar spines 0.12, basal breadth 0.024.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

3. Stylosphæra calliope, n. sp. (Pl. 16, fig. 6).

Radial proportion of the two shells = 3 : 1. Cortical shell thick walled, smooth; pores regular, circular, three times as broad as the bars. Each pore on its outer opening with eight regular lobules, flower-like. Nine to ten pores on the half equator. Polar spines three-sided pyramidal, with three strong prominent edges, about as long as the axis, as broad as one pore. (Sometimes, as in the figured specimen, one spine is smaller than the other; this variety, otherwise identical, may be called Sphærostylus calliope.)

Dimensions.—Diameter of the outer shell 0.12, pores 0.015, bars 0.005; inner shell 0.04; length of the polar spine 0.08 to 0.12, breadth 0.02.

Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.

4. Stylosphæra clio, n. sp. (Pl. 16, fig. 7).

Radial proportion of the two shells = 2 : 1. Cortical shell thick walled, smooth; pores regular, circular, three times as broad as the bars; fourteen to sixteen on the half equator. Polar spines three-sided pyramidal, very robust, with thick prismatic edges, about as long as the axis of the cortical shell, one-third as broad at the base. (Sometimes, as in the figured specimen, one spine is greater than the other; this form may be called Sphærostylus clio.)

Dimensions.—Diameter of the outer shell 0.12, pores 0.01, bars 0.003; inner shell 0.06; length of the polar spines 0.08 to 0.12, basal breadth 0.03 to 0.04.

Habitat.—Pacific, central area; Station 272, depth 2600 fathoms.

5. Stylosphæra polyhymnia, n. sp.

Radial proportion of the two spheres = 3 : 1. Cortical shell very thin walled, smooth, with regular, circular pores, three times as broad as the bars; sixteen to twenty on the half equator. Polar spines cylindrical, pointed, once and a half to twice as long as the axis of the outer sphere, scarcely broader than one pore. The two spheres are connected only by the two opposite beams.

Dimensions.—Diameter of the outer shell 0.12 to 0.16, pores 0.006 to 0.009, bars 0.002 to 0.003; inner shell 0.04 to 0.05; length of the polar spines 0.18 to 0.22, breadth 0.01.

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

6. Stylosphæra dixyphos, Haeckel.

Haliomma dixyphos, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83; Mikrogeol., Taf. xxii. fig. 31.

Haliomma dixyphos, Haeckel, 1862, Monogr. d. Radiol. p. 433.

Radial proportion of the two spheres = 2 : 1. Cortical shell thin walled, smooth, with regular, circular pores, twice as broad as the bars; ten to twelve on the half equator. Polar spines about as long as the axis of the outer shell, three-sided pyramidal, at the base twice as broad as one pore. (The two spheres connected by four beams, two opposite in the main axis, two opposite in the equatorial axis.)

Dimensions.—Diameter of the outer shell 0.1, pores 0.01, bars 0.05; inner shell 0.05; length of the polar spines 0.08 to 0.1, basal breadth 0.02.

Habitat.—South Atlantic, Station 332, surface; fossil in Tertiary rocks of Sicily.

Subgenus 2. Stylosphærella, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface thorny or spiny.

7. Stylosphæra setosa, Ehrenberg, 1872.

Stylosphæra setosa, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 320; Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. viii. fig. 15.

Radial proportion of the two shells = 2 : 1. Cortical shell thin walled, spiny; pores regular, hexagonal, four times as broad as the bars. Six to eight pores on the half equator. Polar spines conical, thin, scarcely as long as the radius of the cortical shell.

Dimensions.—Diameter of the cortical shell 0.1, pores 0.002, bars 0.005; medullary shell 0.05; length of the polar spines 0.04, basal breadth 0.01.

Habitat.—Philippine Sea, depth 3300 fathoms, Ehrenberg; Station 206, depth 2100 fathoms.

8. Stylosphæra euterpe, n. sp.

Radial proportion of the two shells = 3 : 1. Cortical shell thin walled, spiny; pores regular, circular, with hexagonal frames, twice as broad as the bars; eight to ten on the half equator. Polar spines conical, as thick as one pore at the base, about as long as the axis of the cortical shell.

Dimensions.—Diameter of the cortical shell 0.12, pores 0.012, bars 0.006; medullary shell 0.04; length of the polar spines 0.1, basal breadth 0.012.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

9. Stylosphæra melpomene, n. sp. (Pl. 16, fig. 1).

Radial proportion of the two shells = 3 : 1. Cortical shell thin walled, spiny, with regular, circular pores, four times as broad as the bars; eight to ten on the half equator. Polar spines three-sided prismatic, pointed, as broad as one pore, only one-third as long as the axis of the sphere (the two shells connected by four thin beams, two opposite in the main axis, two in the equatorial axis).

Dimensions.—Diameter of the outer shell 0.12, pores 0.012, bars 0.003; inner shell 0.04; length of the polar spines 0.04, thickness 0.013.

Habitat.—Indian Ocean, Cocos Islands, Rabbe.

10. Stylosphæra hispida, Ehrenberg, 1854.

Stylosphæra hispida, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 246; Mikrogeol, Taf. xxxvi. fig. 26.

Haliomma hispidum, Haeckel, 1862, Monogr. d. Radiol., p. 433.

Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, spiny, with regular, circular pores of the same breadth as the bars; ten to fifteen on the half equator. Polar spines three-sided prismatic, pointed, about as long as the axis of the outer sphere, nearly as broad at the base as the inner sphere. (Compare Sphærostylus hispidus; also Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1874, p. 259.)

Dimensions.—Diameter of the outer shell 0.1 to 0.12, pores and bars 0.004; inner shell 0.04; length of the polar spines 0.1 to 0.15, basal breadth 0.03.

Habitat.—Fossil in the Tertiary rocks of Sicily, Barbados, Nicobars, &c.

11. Stylosphæra liostylus, Ehrenberg, 1875.

Stylosphæra liostylus, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 3.

Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, thorny, with regular, circular pores, three times as broad as the bars; eight to ten on the half equator. Polar spines conical, once and a half to twice as long as the axis of the outer sphere, half as broad at the base as its radius. (This species, common in the Barbados rocks, is different from Sphærostylus liostylus, loc. cit., fig. 2, which Ehrenberg believed identical.)

Dimensions.—Diameter of the outer shell 0.1, pores 0.01, bars 0.0035; inner shell 0.03; length of the polar spines 0.14 to 0.18, basal breadth 0.02.

Habitat.—Fossil in the Barbados rocks; living in the depths of the North Atlantic, Gulf Stream, Florida.

Subgenus 3. Stylosphærissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without thorns or spines.

12. Stylosphæra nana, n. sp. (Pl. 16, figs. 12, 13).

Radial proportion of the two spheres = 2 : 1. Cortical shell thick walled, somewhat irregular, smooth, with irregular, roundish pores, one to three times as broad as the bars; eight to ten on the half equator. Polar spines three-sided pyramidal, scarcely as long as the axis of the outer sphere, and nearly as broad at the base as its radius. (A very variable and irregular form.)

Dimensions.—Diameter of the outer shell 0.07 to 0.09, pores 0.003 to 0.009, bars 0.003; inner shell 0.03 to 0.04; length of the polar spines 0.04 to 0.07, basal breadth 0.03.

Habitat.—North Pacific, Stations 241 to 253, surface.

13. Stylosphæra jugata, n. sp.

Radial proportion of the two shells = 2 : 1. Cortical shell thick walled, smooth, with irregular, roundish, double-contoured pores, confluent in groups of two to six. On the half equator six to nine groups and fifteen to twenty pores; bars between them of very variable breadth. Polar spines very strong, three-sided pyramidal, twice as long as the axis of the outer sphere, half as broad at the base as its radius. (Nearly allied to Lithatractus jugatus, Pl. 16, fig. 2, but differs in the truly spherical form of both shells and the double length of the polar spines.)

Dimensions.—Diameter of the outer shell 0.15, pores 0.005 to 0.02; inner shell 0.07; length of the polar spines 0.25 to 0.3, basal breadth 0.03.

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

14. Stylosphæra terpsichore, n. sp.

Radial proportion of the two shells = 3 : 1 or 4 : 1. Cortical shell thick walled, smooth, with irregular, roundish pores, one to three times as broad as the bars; fifteen to twenty-five on the half equator. Polar spines conical, about as long as the axis of the outer sphere, as broad at the base as the inner shell.

Dimensions.—Diameter of the outer shell 0.15 to 0.2, pores 0.005 to 0.02, bars 0.004 to 0.008; inner shell 0.05; length of the polar spines 0.15 to 0.25, basal breadth 0.05.

Habitat.—Western Indian Ocean, Zanzibar, depth 2200 fathoms, Pullen.

Subgenus 4. Stylosphæromma, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

15. Stylosphæra thalia, n. sp.

Radial proportion of the two shells = 2 : 1. Cortical shell thin walled, thorny, with irregular, roundish pores, two to four times as broad as the bars; eight to twelve on the half equator. Polar spines conical, one to one and a half times as long as the axis of the outer sphere, one-fourth to one-sixth as thick at the base. (Resembles Sphærostylus ophidium, Pl. 16, fig. 14, but differs in the straight regular conical polar spines, both of equal length and similar form.)

Dimensions.—Diameter of the outer shell 0.12, pores 0.01 to 0.02, bars 0.005; inner shell 0.06; polar spines 0.1 to 0.16 long, 0.03 broad.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

16. Stylosphæra erato, n. sp.

Radial proportion of the two shells = 3 : 1. Cortical shell thick walled, thorny, with irregular, roundish pores, two to five times as broad as the bars; fourteen to eighteen on the half equator. Polar spines three-sided pyramidal, about as long as the axis of the outer sphere, one-fourth as broad as its radius. (Similar to Xiphosphæra vesta, Pl. 14, fig. 6.)

Dimensions.—Diameter of the outer shell 0.15, pores 0.008 to 0.015, bars 0.003; inner shell 0.05; polar spines 0.12 long, 0.02 broad.

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

Genus 49. Sphærostylus,^[72] Haeckel, 1881, Prodromus, p. 451.

Definition.—Stylosphærida with two concentric lattice-spheres and two free spines, of different size or form.

The genus Sphærostylus differs from Stylosphæra in the different size or form of the two polar spines, and therefore has the same relation to it that Xiphostylus bears to Xiphosphæra.

Subgenus 1. Sphærostylantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without thorns.

1. Sphærostylus liostylus, Haeckel.

Stylosphæra liostylus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 2.

Cortical shell thin walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular, circular, twice as broad as the bars; ten to twelve on the half equator. Polar spines cylindrical, as broad as one pore, with conical apex; the minor spine about as long as the axis of the outer shell, the major three to four times as long.

Dimensions.—Diameter of the outer sphere 0.12, pores 0.12, bars 0.006; diameter of the inner sphere 0.04; length of the major polar spine 0.3 to 0.4, of the minor 0.1 to 0.15, breadth 0.012.

Habitat.—Fossil in the Barbados rocks.

2. Sphærostylus flexuosus, Haeckel.

Stylosphæra flexuosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 5.

Cortical shell thick walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular circular, of the same breadth as the bars; eight to ten on the half equator. Polar spines cylindrical, S-like curved, irregular; the minor scarcely as long as the axis of the outer sphere, the major two to three times as long. (In the figure of Ehrenberg the spines are broken off; I have found them myself constantly irregular and of unequal length, sometimes with conical apex.)

Dimensions.—Diameter of the outer sphere 0.08, pores and bars 0.006; inner sphere 0.03; length of the major polar spine 0.15 to 0.25, of the minor 0.07 to 0.09, breadth 0.02.

Habitat.—Fossil in the Barbados rocks.

3. Sphærostylus clio, n. sp.

Cortical shell thick walled, with smooth surface, twice as broad as the medullary shell; its network has regular, circular pores, three times as broad as the bars; sixteen to twenty on the half equator. Polar spines very strong, three-sided pyramidal; the major nearly twice as long as the axis of the outer sphere, the minor scarcely as long as its radius. (Nearly related to Stylosphæra clio, Pl. 16, fig. 7, but differs in the slender form and unequal length of the polar spines.)

Dimensions.—Diameter of the outer sphere 0.14, pores 0.01, bars 0.03; inner sphere 0.07; length of the major spine 0.25, of the minor 0.06, basal breadth 0.02.

Habitat.—Pacific, central area, Station 274, depth 2750 fathoms.

4. Sphærostylus hippocampus, n. sp. (Pl. 16, figs. 10, 11).

Cortical shell thick walled, with smooth surface and regular network; the pores circular, hexagonally-lobed, three times as broad as the bars; ten to twelve on the half equator. Medullary shell half as large, with very small circular pores, eight to ten on the half equator. Major polar spine scarcely as long as the axis of the outer shell, curved like a horn; minor spine scarcely half as long, pommel-like, edged. (Sometimes, by prolongation of the main axis, the spherical shells become ellipsoidal and thus the species is transformed into Druppatractus hippocampus.)

Dimensions.—Diameter of the outer sphere 0.08, pores 0.009, bars 0.003; inner sphere 0.04; length of the major spine 0.07, of the minor 0.03, breadth 0.02.

Habitat.—Pacific, central area, Station 270, depth 2925 fathoms.

Subgenus 2. Sphærostyletta, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and form; surface spiny or thorny.

5. Sphærostylus diadema, n. sp.

Cortical shell thick walled, spiny, twice as broad as the medullary shell, with regular, circular pores, twice as broad as the bars; eight to ten on the half equator. Major polar spine about as long as the axis of the outer sphere, three-sided pyramidal; minor spine scarcely half as long, pommel-shaped, edged. (Similar in general form to Xiphatractus glyptodon, Pl. 17, figs. 9, 10; but differs in the simple medullary shell, the spherical form of both shells, and the simple circular regular pores.)

Dimensions.—Diameter of the outer sphere 0.12, pores 0.014, bars 0.007; inner sphere 0.06; length of the major spine 0.13, of the minor 0.05, greatest breadth 0.04.

Habitat.—Southern Pacific, surface, Station 289.

Subgenus 3. Sphærostylissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough.

6. Sphærostylus cottus, n. sp.

Cortical shell thick walled, smooth, about twice as broad as the medullary shell, with irregular, roundish pores, scarcely larger than the bars; fifteen to twenty on the half equator. Polar spines conical, the major once and a half to twice as long as the axis of the outer sphere, the minor scarcely as long as its radius.

Dimensions.—Diameter of the outer sphere 0.14, pores and bars 0.008 to 0.012; inner sphere 0.065; length of the major spine 0.2 to 0.3, of the minor 0.05 to 0.07, basal breadth 0.03.

Habitat.—Northern Atlantic, Færöe Channel, surface, John Murray.

7. Sphærostylus trigla, n. sp.

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with irregular, roundish pores, two to three times as broad as the bars; ten to twelve on the half equator. Polar spines very unequal; the major three-sided pyramidal, one and a half times as long as the axis of the outer sphere; the minor scarcely as long as its radius, edged, pommel-like.

Dimensions.—Diameter of the outer sphere 0.12, pores 0.01 to 0.015, bars 0.005; inner sphere 0.04; length of the major spine 0.2, of the minor 0.05, breadth 0.03.

Habitat.—Northern Pacific, Station 241, depth 2300 fathoms.

Subgenus 4. Sphærostylomma, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

8. Sphærostylus ophidium, n. sp. (Pl. 16, figs. 14, 15).

Stylosphæra ophidium, Haeckel, 1878, Atlas, loc. cit.

Cortical shell thin walled, thorny, twice as broad as the medullary shell, with irregular, roundish pores; eight to ten on the half equator. Polar spines conical, more or less curved or S-shaped; the minor scarcely as long as the axis of the outer sphere, the major two to three times as long.

Dimensions.—Diameter of the outer sphere 0.11, pores 0.01 to 0.017, bars 0.003 to 0.007; diameter of the inner sphere 0.06, pores 0.005 to 0.008, bars 0.002 to 0.004; length of the major polar spine 0.25, of the minor 0.1, basal breadth 0.03.

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

Genus 50. Saturnulus,^[73] Haeckel, 1881, Prodromus, p. 451.

Definition.—Stylosphærida with two concentric lattice-spheres and two equal opposite spines, the distal ends of which are connected by a circular or elliptical ring.

The genus Saturnulus differs from the similar Saturnalis by the duplication of the spherical lattice-shell; the inner lies within, the outer without the central capsule.

1. Saturnulus circulus, n. sp.

Cortical shell smooth, twice as broad as the medullary shell, with regular, circular, hexagonally framed pores, of the same breadth as the bars; fourteen to sixteen on the half equator. Ring circular, smooth, without edges, its diameter three times as great as that of the sphere.

Dimensions.—Diameter of the outer sphere 0.08, pores and bars 0.004; of the inner sphere 0.04, of the ring 0.24.

Habitat.—Central Pacific, Station 272, surface.

2. Saturnulus annulus, n. sp.

Cortical shell smooth, three times as broad as the medullary shell, with regular, circular, hexagonally framed pores, of the same breadth as the bars; eighteen to twenty on the half equator. Ring elliptical, smooth, without edges, somewhat constricted at the poles of the minor axis, its major diameter four times as great as that of the sphere. Differs from Saturnalis annularis, Pl. 13, fig. 16, mainly in the possession of a medullary shell.

Dimensions.—Diameter of the outer sphere 0.1, pores and bars 0.005; inner sphere 0.033; major axis of the ring 0.4, minor 0.3.

Habitat.—North Pacific, Station 244, surface.

3. Saturnulus ellipticus, n. sp. (Pl. 16, fig. 16).

Cortical shell smooth, three times as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; sixteen to eighteen on the half equator. Ring elliptical, smooth, without edges, its major diameter three times as great as that of the sphere.

Dimensions.—Diameter of the outer sphere 0.09, pores 0.006, bars 0.002; inner sphere 0.03; major axis of the elliptical ring 0.28, minor 0.24; thickness of the ring and the axial beams 0.008.

Habitat.—South Pacific, Station 300, surface.

4. Saturnulus planetes, n. sp. (Pl. 16, fig. 17).

Cortical shell smooth, twice as broad as the medullary shell, with regular, circular pores, of the same breadth as the bars; sixteen to eighteen on the half equator. Ring elliptical, smooth, with strong prominent edges, constricted at the poles of the minor axis, its major diameter three times as great as that of the outer sphere.

Dimensions.—Diameter of the outer sphere 0.08, pores and bars 0.005; inner sphere 0.035; major axis of the ring 0.25, minor axis 0.2; thickness of the ring and the axial beams 0.012.

Habitat.—Indian Ocean, Sunda Strait, Rabbe; Station 200, surface.

Subfamily Amphistylida, Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.—Stylosphærida with three concentric spherical lattice-shells.

Genus 51. Amphisphæra, Haeckel,^[74] 1881, Prodromus, p. 452.

Definition.—Stylosphærida with three concentric lattice-spheres and two free spines of equal size and similar form.

The genus Amphisphæra differs from its probable ancestral form, Stylosphæra, in the triple spherical lattice-shell. Commonly two of these lie within the central capsule (medullary shell), whilst the third lies outside it (cortical shell). But sometimes this order is inverted, the cortical shell being double, the medullary shell simple; and perhaps these forms may better represent a peculiar genus, Amphisphæridium.

Subgenus 1. Amphisphærantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without spines or thorns.

1. Amphisphæra neptunus, n. sp.

Radial proportion of the three concentric spheres = 4 : 2 : 1. Cortical shell thick walled, smooth, with regular, circular, hexagonally framed pores, of the same breadth as the bars; twelve to fifteen on the half equator. Polar spines three-sided pyramidal, with strong prominent edges, about as long as the radius of the outer shell, half as broad at the base. (Similar to Stylatractus neptunus, Pl. 17, fig. 6, but differs in the purely spherical form of the three concentric shells and the regular form of the network and of the polar spines.)

Dimensions.—Diameter of the outer shell 0.16, middle shell 0.08, inner shell 0.04; pores and bars of the cortical shell 0.008; length of the polar spines 0.08, basal breadth 0.04.

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

2. Amphisphæra uranus, n. sp.

Radial proportion of the three spheres = 4 : 2 : 1. Cortical shell thick walled, smooth, with regular, circular pores, three times as broad as the bars; ten to twelve on the half equator. Polar spines three-sided pyramidal, about as long as the diameter of the outer shell, twice as broad at the base as one pore.

Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.03; pores of the cortical shell 0.012, bars 0.004; length of the polar spines 0.1, basal breadth 0.024.

Habitat.—Western Indian Ocean, Zanzibar, 2200 fathoms, Pullen.

3. Amphisphæra jupiter, n. sp.

Radial proportion of the three spheres = 10 : 3 : 2. Cortical shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; twenty to twenty-five on the half equator. Polar spines cylindro-conical, nearly as long as the axis of the outer shell, twice as broad at the base as one pore.

Dimensions.—Diameter of the outer shell 0.2, middle 0.06, inner 0.04; pores of the cortical shell 0.01, bars 0.005; length of the polar spines 0.15 to 0.18, breadth 0.02.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Subgenus 2. Amphisphærella, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface thorny or spiny.

4. Amphisphæra apollo, n. sp.

Radial proportion of the three spheres = 3 : 1.5 : 1. Cortical shell thick walled, spiny, with regular, circular, hexagonally framed pores, of the same breadth as the bars; twenty to twenty-two on the half equator. In each hexagon-corner (between three pores) a bristle-like radial spine. Polar spines cylindrical, with conical apex; one to one and a half times as long as the axis of the outer shell, as broad as three pores at the base. (Resembles closely Xiphosphæra pallas, Pl. 14, fig. 4, but differs in the presence of two medullary shells and the absence of the fine denticulations on the hexagonal crests.)

Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.04; pores and bars of the cortical shell 0.006; length of the polar spines 0.15, breadth 0.02.

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

5. Amphisphæra mercurius, n. sp.

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thin walled, spiny, with regular, circular pores, twice as broad as the bars; fifteen to eighteen on the half equator; between them short bristle-like radial spines. Polar spines three-sided pyramidal, about as long as the radius of the outer shell, one-third as broad at the base.

Dimensions.—Diameter of the outer shell 0.15, middle 0.09, inner 0.05; pores of the cortical shell 0.01, bars 0.005; length of the polar spines 0.09, basal breadth 0.03.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

Subgenus 3. Amphisphærissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without spines or thorns.

6. Amphisphæra cronos, n. sp. (Pl. 17, fig. 5).

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thin walled, smooth, with irregular, roundish pores, two to four times as broad as the bars; eight to ten on the half equator. Outer medullary shell similar, but with pores of half the size, connected with the cortical shell by numerous radial beams; inner medullary shell with very small pores. Polar spines three-sided pyramidal, as long as the axis of the inner medullary shell, half as broad at the base.

Dimensions.—Diameter of the outer shell 0.12, middle 0.08, inner 0.04; pores of the cortical shell 0.01 to 0.02, bars 0.05; length of the polar spines 0.04, basal breadth 0.02.

Habitat.—South Atlantic, Station 330, surface.

7. Amphisphæra pluto, n. sp. (Pl. 17, figs. 7, 8).

Radial proportion of the three spheres about = 4 : 2 : 1 (or 11 : 7 : 3). Cortical shell thick walled, smooth, with very irregular, roundish pores, two to four times as broad as the bars; eight to ten on the half equator; often two to four pores confluent. Margin of their outer aperture double. Polar spines conical, double contoured, as long as the radius of the outer shell, one-third as broad at the base.

Dimensions.—Diameter of the outer shell 0.11, middle shell 0.07, inner shell 0.03; pores of the cortical shell 0.01 to 0.02, bars 0.06, length of the polar spines 0.06, basal breadth 0.02.

Habitat.—Central Pacific, Station 268, surface.

Subgenus 4. Amphisphæromma, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

8. Amphisphæra mars, n. sp.

Radial proportion of the three spheres = 10 : 3 : 2. Cortical shell thin walled, thorny, with irregular, roundish pores, one to three times as broad as the bars; sixteen to twenty on the half equator. Irregularly scattered between them short conical thorns. Polar spines conical, about as long as the axis of the outer shell, as broad at the base as the inner shell.

Dimensions.—Diameter of the outer shell 0.2, middle shell 0.06, inner shell 0.04; pores of the cortical shell 0.005 to 0.02, bars 0.006; length of the polar spines 0.17, basal breadth 0.04.

Habitat.—North Atlantic, Gulf Stream, near Florida, depth 1500 fathoms, Schaffner.

Genus 52. Amphistylus,^[75] Haeckel, 1881, Prodromus, p. 452.

Definition.—Stylosphærida with three concentric lattice-spheres and two free spines of different size or form.

The genus Amphistylus differs from its ancestral form, Amphisphæra, by the differentiation of both polar spines, and exhibits therefore the same relation to it that Sphærostylus bears to Stylosphæra.

1. Amphistylus clio, n. sp.

Radial proportion of the three spheres = 4 : 2 : 1. Cortical shell thick walled, smooth; its pores regular, circular, three times as broad as the bars; eighteen to twenty on the half equator. Polar spines three-sided pyramidal, very stout, as broad at the base as the inner medullary shell; major spine somewhat longer than the diameter of the cortical shell; minor spine scarcely half as long. (Similar to Stylosphæra clio, Pl. 16, fig. 7, but different in the double medullary shell and the different length of the polar spines.)

Dimensions.—Diameter of the outer sphere 0.15, middle 0.08, inner 0.04; pores of the outer shell 0.01, bars 0.003; length of the major spine 0.17, minor 0.07, basal breadth 0.04.

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

2. Amphistylus hippocampus, n. sp.

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thick walled, smooth; its pores regular, circular, hexagonally lobed, three times as broad as the bars; twelve to fifteen on the half equator. Major polar spine three-sided pyramidal, about as long as the axis of cortical shell; minor spine pommel-like, edged, scarcely one-third as long. (Similar to Sphærostylus hippocampus, Pl. 16, figs. 10, 11, but differs in the larger size, the double medullary shell, and the straight, not curved, major spine.)

Dimensions.—Diameter of the outer sphere 0.11, middle 0.07, inner 0.035; pores of the outer shell 0.011, bars 0.004; length of the major spine 0.12, of the minor 0.04, breadth 0.03.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

3. Amphistylus glyptodon, n. sp.

Radial proportion of the three spheres = 6 : 3 : 1. Cortical shell thick walled, spiny, with irregular, roundish pores, two to four times as broad as the bars; ten to twelve on the half equator. Inner aperture of each pore closed by a thin fenestrated lamella with five to seven small pores. Major polar spine three-sided pyramidal, longer than the diameter of the outer sphere; minor polar spine scarcely as long as its radius, pommel-shaped. (Similar to Xiphatractus glyptodon, Pl. 17, figs. 9, 10, but differs in the spherical, not ellipsoidal, form of the three shells and the size of the polar spines.)

Dimensions.—Diameter of the outer sphere 0.12, middle 0.06, inner 0.02; pores and spines of the outer shell 0.01 to 0.02, bars and porules 0.006; length of the major polar spine 0.15, of the minor 0.05, breadth 0.04.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

Genus 53. Saturninus,^[76] n. gen.

Definition.—Stylosphærida with three concentric lattice-spheres and two equal opposite spines, connected at the distal end by a circular or elliptical ring.

The genus Saturninus differs from the similar Saturnulus by the triplication of the spherical lattice-shell; the inner shell is enclosed in the central capsule, whilst both the others lie outside it.

1. Saturninus triplex, n. sp.

Radial proportion of the three spheres = 4 : 3 : 1. Inner cortical shell with regular, circular pores, of the same breadth as the bars, sixteen to eighteen on the half equator; outer cortical shell connected with the inner by numerous bristle-like radial spines, network very delicate, cobweb-shaped, with irregular polygonal meshes. Ring elliptical, two and a half times as broad as the outer shell.

Dimensions.—Diameter of the inner sphere 0.03, middle 0.09, outer 0.12; pores and bars of the middle shell 0.004; major axis of the elliptical ring 0.3, minor 0.25; thickness of the ring and the axial beams 0.008.

Habitat.—Central Pacific, Station 272, surface.

Subfamily Cromyostylida, Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Stylosphærida with four concentric spherical lattice-shells (two medullary and two cortical).

Genus 54. Stylocromyum,^[77] Haeckel, 1881, Prodromus, p. 453.

Definition.—Stylosphærida with four concentric lattice-spheres and two free spines of equal size and similar form.

The genus Stylocromyum differs from its probable ancestral form, Amphisphæra, by the duplication of the cortical shell; two opposite radial beams, piercing the wall of the central capsule, connect it with the double medullary shell, and are prolonged outside into two equal spines.

1. Stylocromyum amphiconus, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 1 : 2 : 8 : 9. Two medullary shells inside the central capsule, two cortical shells outside it. Interval between the second and third shells the greatest. Pores of all the shells regular, circular, two to four times as broad as the bars. Both polar spines equal, conical, about as long as the axis of the outermost sphere, as broad at the base as the innermost.

Dimensions.—Diameter of the four spheres—(A) inner medullary shell 0.03, (B) outer medullary shell 0.06, (C) inner cortical shell 0.25, (D) outer cortical shell 0.28; length of the polar spines 0.3, basal breadth 0.03.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

2. Stylocromyum amphipyramis, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 2 : 3 : 6 : 8. Both medullary shells with regular, circular pores, twice as broad as the bars. Both cortical shells with irregular, roundish, much larger pores, three to six times as broad as the bars. Both polar spines equal or nearly equal, three-sided pyramidal, about as long as the axis of the third shell.

Dimensions.—Diameter of the four spheres—(A) 0.04, (B) 0.06, (C) 0.12, (D) 0.16; length of the polar spines 0.11, basal breadth 0.02.

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

Genus 55. Cromyostylus,^[78] Haeckel, 1881, Prodromus, p. 453.

Definition.—Stylosphærida with four concentric lattice-spheres and two free spines of different size or form.

The genus Cromyostylus differs from its ancestral form, Stylocromyum, in the differentiation of the two unequal polar spines.

1. Cromyostylus gladius, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 1 : 3 : 10 : 12. Both medullary shells with regular, circular, simple pores. Inner cortical shell with regular, circular, hexagonally framed pores, twice as broad as the bars. From each hexagon-corner arises a bristle-shaped radial spine, which at the distal end gives off three thread-like branches; by communication of these threads (at equal distances from the centre) the delicate outer medullary shell is formed. The polar spines very different; major spine six-sided pyramidal, longer than the diameter of the shell; minor pommel-shaped, shorter than the radius (similar to Xiphatractus glyptodon, Pl. 17, figs. 9, 10, but different in the double spherical cortical shell).

Dimensions.—Diameter of the four spheres—(A) 0.02, (B) 0.06, (C) 0.2, (D) 0.24; length of the major spine 0.3, of the minor 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subfamily Caryostylida, Haeckel, 1881, Prodromus, pp. 449, 454.

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

Genus 56. Caryostylus, Haeckel, 1881, Prodromus, p. 454.

Definition.—Stylosphærida with five to six or more concentric lattice-shells and two free opposite spines of equal size and similar form.

The genus Caryostylus differs from its ancestral form, Stylocromyum, by the multiplication of the concentric spheres, the number of which amounts to five or six or more. I have only observed one single species of this genus. Some similar forms which in my Prodromus (1881, p. 454) were annexed to it, and disposed in three nearly allied genera (Caryoxiphus, Caryodoras, Caryolonche), have now been proved to belong to other groups, mainly ellipsoidal Druppulida.

1. Caryostylus hexalepas, n. sp.

Surface of the spherical shell smooth. Radial proportion of the component six concentric shells = 1 : 2 : 7 : 9 : 12 : 15. Both medullary shells connected only by six radial beams, opposite in pairs in the three dimensive axes. Between second and third shell numerous (twenty regularly disposed?) radial beams. Four cortical shells connected by very numerous (sixty to eighty or more?) short radial beams. Pores of all six shells regular, circular, the size increasing towards the surface, two to three times as broad as the bars. Two opposite polar spines very large, of equal size, three times as long as the shell radius, cylindrical, club-shaped at the thicker distal end. (The whole shell structure is similar to Pl. 15, fig. 2, but the shells are spherical, not ellipsoidal.)

Dimensions.—Diameter of the six spheres—(A) 0.02, (B) 0.04, (C) 0.15, (D) 0.18, (E) 0.24, (F) 0.3; length of the spines 0.5.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.

Subfamily Spongostylida, Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.—Stylosphærida with spherical spongy shell (with or without enclosed latticed medullary shells).

Genus 57. Spongolonchis,^[79] Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with a solid sphere of spongy framework, and with two opposite free radial spines.

The genus Spongolonchis differs from its probable ancestral form, Styptosphæra, by the development of two opposite radial spines situated in one axis.

1. Spongolonchis compacta, n. sp.

Spongy framework of the spherical shell very compact, with small meshes, three to four times as broad as the bars. Surface rough, but not spiny. Two polar spines pyramidal, only as long as the radius of the shell, one-third as broad at the base.

Dimensions.—Diameter of the shell 0.2; length of the spines 0.1, basal breadth 0.03.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Spongolonchis laxa, n. sp.

Spongy framework loose, with large meshes, ten to twelve times as broad as the bars. Surface spiny. Two polar spines three-sided prismatic, longer than the diameter of the shell (broken off in the observed specimen).

Dimensions.—Diameter of the shell 0.5; length of the spine 0.6 and more, breadth 0.02.

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

Genus 58. Spongostylus,^[80] Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with spongy spherical cortical shell, enclosing in the centre a simple latticed medullary shell, and with two opposite free radial spines.

The genus Spongostylus may probably be derived from Spongoplegma by development of two opposite radial spines in one axis.

1. Spongostylus hastatus, n. sp.

Spongy cortical shell with compact framework, twice as broad as the enclosed medullary shell, the pores of which are regular, circular, twice as broad as the bars. Two polar spines, three times as long as the radius of the shell, in the basal two-thirds cylindrical, in the distal third compressed, two-edged, spear-shaped.

Dimensions.—Diameter of the cortical shell 0.1, medullary shell 0.05; length of the spines 0.15.

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

2. Spongostylus gladiatus, Haeckel.

Stylosphæra holosphæra, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 14.

Spongy cortical shell with rather compact framework, four times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, three to four times as broad as the bars. Two polar spines sword-shaped, two-edged, as long as the shell diameter.

Dimensions.—Diameter of the cortical shell 0.24, medullary shell 0.06; length of the spines 0.25.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; Philippine Sea, depth 3300 fathoms.

3. Spongostylus serratus, n. sp.

Spongy cortical shell with lax framework, ten to twelve times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, once and a half to twice as broad as the bars. Two polar spines longer than the shell diameter (broken off in the observed specimen), three-sided prismatical, with three straight serrated edges.

Dimensions.—Diameter of the cortical shell 0.5, medullary shell 0.04; length of the spines 0.6 or more.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

Genus 59. Spongostylidium,^[81] Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with spongy spherical cortical shell, enclosing two concentric spherical latticed medullary shells, and with two opposite, free radial spines.

The genus Spongostylidium differs from Spongostylus by duplication of the latticed medullary shell, and therefore bears the same relation to it as Spongodictyon to Spongoplegma.

1. Spongostylidium streptacanthum, n. sp.

Both medullary shells spherical, with small, regular, circular pores, twice as broad as the bars (outer twice as broad as the inner). Spongy cortical shell enclosing it with dense framework, four times as broad as the outer medullary shell. Two polar spines very large, four times as long as the diameter of the outer shell; as broad as the inner medullary shell, with three dentated, spirally contorted edges. (Very similar to the common Spongosphæra streptacantha and to Hexadoridium streptacanthum, but with only two opposite spines in one axis.)

Dimensions.—Diameter of the cortical shell 0.16, of the outer medullary shell 0.04, inner 0.02; length of the spines 0.7 and more, breadth 0.02.

Habitat.—Indian Ocean, Cocos Islands, Rabbe.

Family VIII. Staurosphærida, Haeckel (Pl. 15).

Staurosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea with four radial spines on the surface of the spherical shell, forming a regular cross, being opposite in pairs in two axes perpendicular to one another; living solitary (not associated in colonies).

The family Staurosphærida is distinguished from the other Sphæroidea by the possession of four radial spines, which are opposite in pairs in two perpendicularly crossed axes. By these "two main axes" an equatorial plane is determined, which approximates them to the Discoidea. But in the latter the shells as well as the central capsule become more or less flattened, lenticular, or discoidal, whilst in the former they remain spherical. However, some forms of both groups are very similar, and inspection from different sides (and mainly from the margin of the equatorial plane) is required to determine the spherical (not compressed) shell-form of the Staurosphærida. As a rule the species of this family are much rarer, and much less numerous, than those of all the other Sphæroidea.

The most simple Staurosphærida are the Staurostylida, with one single spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Staurosphærida concentrica," since their carapace is composed of two or more concentric lattice-shells; two in the Staurolonchida, three in the Stauracontida, four in the Staurocromyida, five or more in the Staurocaryida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated spheres. In a sixth subfamily, in the Staurodorida, the shell is wholly or partially composed of irregular spongy wickerwork, with or without a medullary shell in the centre.

The Four Radial Spines in all Staurosphærida are normally opposed in pairs in two axes perpendicular one to another, and therefore together form a rectangular cross. But in many species besides this normal form individual abnormalities occur, in which the four spines in the equatorial plane are not quite accurately opposed, so that the four angles between them are not right angles, but more or less unequal. More rarely also their position in the equatorial plane is not accurately retained, so that they are placed in two, three, or four different meridian planes, intersecting at very small variable angles.

In the greater part of Staurosphærida all four radial spines are quite equal, and of the same size and form. But in some genera there takes place a more or less considerable differentiation of the four spines, commonly in pairs, so that the two opposite spines of each pair are equal, but the pairs different (Staurostylus, Staurolonchidium). More rarely also both spines of one pair become unequal, whilst those of the other pair remain equal (Stauroxiphos). Very rarely all four spines assume a different size or form.

Synopsis of the Genera of Staurosphærida.

I. Subfamily Staurostylida. (Shell one single lattice-sphere.) All four spines equal, 60. Staurosphæra.

Four spines different in pairs, 61. Staurostylus.

One spine larger than the three others, 62. Stylostaurus.

II. Subfamily Staurolonchida. (Shell with two concentric lattice-spheres.) All four spines equal, Simple, 63. Staurolonche.

Branched, 64. Staurancistra.

Four spines different in pairs, 65. Staurolonchidium.

One spine larger than the three others, 66. Stauroxiphos.

III. Subfamily Stauracontida. (Shell with three concentric spheres.) All four spines equal, simple, 67. Stauracontium.

IV. Subfamily Staurocromyida. (Shell with four concentric spheres.) All four spines equal, Simple, 68. Staurocromyum.

Branched, 69. Cromyostaurus.

V. Subfamily Staurocaryida. (Shell with five or more concentric spheres.) All four spines equal, 70. Staurocaryum.

VI. Subfamily Staurodorida. (Shell a spongy sphere.) Solid spongy sphere without medullary shell, 71. Staurodoras.

I. Subfamily Staurostylida. (Shell one single lattice-sphere.)

All four spines equal,

60. Staurosphæra.

Four spines different in pairs,

61. Staurostylus.

One spine larger than the three others,

62. Stylostaurus.

II. Subfamily Staurolonchida. (Shell with two concentric lattice-spheres.)

All four spines equal,

Simple,

63. Staurolonche.

Branched,

64. Staurancistra.

Four spines different in pairs,

65. Staurolonchidium.

One spine larger than the three others,

66. Stauroxiphos.

III. Subfamily Stauracontida. (Shell with three concentric spheres.)

All four spines equal, simple,

67. Stauracontium.

IV. Subfamily Staurocromyida. (Shell with four concentric spheres.)

All four spines equal,

Simple,

68. Staurocromyum.

Branched,

69. Cromyostaurus.

V. Subfamily Staurocaryida. (Shell with five or more concentric spheres.)

All four spines equal,

70. Staurocaryum.

VI. Subfamily Staurodorida. (Shell a spongy sphere.)

Solid spongy sphere without medullary shell,

71. Staurodoras.

Subfamily Staurostylida,^[82] Haeckel, Prodromus, 1881, pp. 449, 450.

Definition.—Staurosphærida with one single spherical lattice-shell.

Genus 60. Staurosphæra,^[83] Haeckel, 1881, Prodromus, p. 450.

Definition.—Staurosphærida with a single lattice-sphere and four crossed equal spines.

The genus Staurosphæra may be regarded as the common ancestral form of this subfamily, since it represents their most simple and primitive form. From the surface of the simple lattice-sphere, enclosing the central capsule, arise four equal, simple, radial spines, opposite in pairs in two diameters, perpendicular one to another. Staurosphæra may be derived phylogenetically either from Cenosphæra by production of the four spines, or from Hexastylus by reduction of two opposite spines.

Subgenus 1. Staurosphærantha, Haeckel.

Definition.—Pores regular, all of nearly equal size and similar form; surface smooth.

1. Staurosphæra cruciata, n. sp.

Shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars; ten to twelve on the quadrant. Four crossed radial spines three-sided pyramidal, as long as the diameter of the shell, as broad at the base as one pore (very similar to Hexastylus phænaxonius, Pl. 21, fig. 3, but with only four spines).

Dimensions.—Diameter of the shell 0.12, of the pores 0.008, bars 0.002.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Staurosphæra christiana, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, three times as broad as the bars; six to eight on the quadrant. Four crossed spines six-sided pyramidal, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.13, pores 0.012, bars 0.004.

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

3. Staurosphæra johannis, n. sp.

Shell thick walled, smooth, with regular, circular pores, four times as broad as the bars; five to six on the quadrant. Four spines six-sided pyramidal, half as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.15, pores 0.02, bars 0.005.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Staurosphæra pauli, n. sp.

Shell very thick walled, smooth, with regular, circular, double-edged pores, four times as broad as the bars; eight to ten on the quadrant. Four spines conical, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.15, pores 0.016, bars 0.004.

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

5. Staurosphæra petri, n. sp.

Shell thin walled, smooth, with regular, circular pores, three times as broad as the bars; twenty to twenty-two on the quadrant. Four spines conical, half as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.22, pores 0.006, bars 0.002.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms; also fossil in Barbados.

6. Staurosphæra jacobi, n. sp.

Shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; eleven to twelve on the quadrant. Four spines cylindrical, three times as long as the radius, three times as broad as one mesh.

Dimensions.—Diameter of the shell 0.1, pores 0.006, bars 0.003.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

7. Staurosphæra simonis, n. sp.

Haliomma with four spines, Bury, 1862, Polycystins of Barbados, pl. iv. fig. 4.

Shell thick walled, smooth, with regular, circular pores, of the same breadth as the bars; eight to ten on the quadrant. Four spines cylindrical, twice as long as the radius, five times as broad as one mesh.

Dimensions.—Diameter of the sphere 0.1, pores and bars 0.003.

Habitat.—Fossil in Barbados.

Subgenus 2. Staurosphærella, Haeckel.

Definition.—Pores regular, all of nearly equal size and similar form; surface covered with by-spines or accessory thorns.

8. Staurosphæra philippi, n. sp. (Pl. 15, fig. 6).

Shell thin walled, covered with bristle-shaped by-spines, as long as the radius. Pores regular, circular, twice as broad as the bars; six to eight on the quadrant. Four main spines cylindrical, five to ten times as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.08, pores 0.006, bars 0.003.

Habitat.—Central Pacific, Station 272, surface.

9. Staurosphæra andreæ, n. sp.

Shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars; nine to ten on the quadrant. From each hexagon-corner arises a bristle-shaped by-spine, half as long as the radius. Four main spines three-sided pyramidal, with spirally contorted edges, as long as the radius (very similar to Hexastylus solonis, Pl. 21, fig. 11, but with only four spines).

Dimensions.—Diameter of the shell 0.16, pores 0.01, bars 0.003.

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

10. Staurosphæra thomæ.

Shell thick walled, with regular, circular pores, twice as broad as the bars; twelve to fourteen on the quadrant; surface covered with short conical by-spines. Four main spines conical, twice as long as the radius, twice as broad as one mesh.

Dimensions.—Diameter of the sphere 0.2, pores 0.012, bars 0.006.

Habitat.—South Atlantic, Station 332, depth, 2200 fathoms.

Subgenus 3. Staurosphærissa, Haeckel.

Definition.—Pores irregular, of different size or form; surface smooth.

11. Staurosphæra judæ, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores, twice to four times as broad as the bars; six to ten on the quadrant. Four main spines three-sided pyramidal, as long as the radius.

Dimensions.—Diameter of the sphere 0.15, pores 0.006 to 0.012, bars 0.003.

Habitat.—Central Pacific, Station 273, depth, 2350 fathoms.

12. Staurosphæra crassa, Dunikowski.

Staurosphæra crassa, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 27, Taf. v. figs. 52-55.

Shell thick walled, smooth, with irregular, roundish pores, scarcely broader than the bars; eight to ten on the quadrant. Four spines three-sided pyramidal, nearly as long as the shell diameter.

Dimensions.—Diameter of the sphere 0.19, pores and bars 0.015.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg, Dunikowski).

13. Staurosphæra apostolorum, Haeckel.

? Cenosphæra megapora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iii. fig. 1.

? Cenosphæra micropora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iii. fig. 2.

Shell thin walled, smooth, with large, irregular, roundish pores, twice to six times as broad as the bars; four to six on the quadrant. Four spines conical, very stout, about as long as the shell diameter, often more or less irregularly disposed.

Dimensions.—Diameter of the sphere 0.12 to 0.2, pores 0.01 to 0.03, bars 0.005.

Habitat.—Fossil in Barbados.

Subgenus 4. Staurosphæromma, Haeckel.

Definition.—Pores irregular, of different size or form; surface covered with by-spines or accessory thorns.

14. Staurosphæra bartholomæi, n. sp.

Shell thin walled, with irregular, polygonal pores, three times as broad as the bars; six to eight on the quadrant; surface covered with short bristle-shaped by-spines. Four main spines three-sided pyramidal, twice as long as the radius.

Dimensions.—Diameter of the shell 0.14, pores 0.008 to 0.016, bars 0.003 to 0.005.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

15. Staurosphæra thaddæi, n. sp.

Shell thick walled, with irregular, roundish, polygonally framed pores, twice to three times as broad as the bars; five to seven on the quadrant; surface covered with bristle-shaped spines, half as long as the radius. Four main spines pyramidal, as long as the radius.

Dimensions.—Diameter of the shell 0.12, pores 006 to 0.012, bars 0.004.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; also fossil in Barbados.

16. Staurosphæra matthæi, n. sp.

Shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; ten to twelve on the quadrant; surface covered with short conical thorns or by-spines. Four main spines conical, as long as the radius.

Dimensions.—Diameter of the shell 0.15, pores 0.004 to 0.01, bars 0.002.

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

Genus 61. Staurostylus,^[84] Haeckel, 1881, Prodromus, p. 450.

Definition.—Staurosphærida with one single lattice-sphere and four crossed spines which are arranged in opposite pairs, one pair opposite being larger than the other.

The genus Staurostylus has been developed from Staurosphæra by differentiation of the four crossed spines in pairs; two opposite spines growing much more strongly than the other two.

1. Staurostylus græcus, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, twice as broad as the bars; six to eight on the quadrant. Spines three-sided prismatic, pointed, as broad as one mesh; two opposite larger spines as long as the diameter of the shell, two smaller only as long as the radius.

Dimensions.—Diameter of the shell 0.15, pores 0.01, bars 0.005; length of the major spines 0.16, minor 0.08.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Staurostylus latinus, n. sp.

Shell thin walled, smooth, with regular, circular, double-edged pores, three times as broad as the bars; twelve to fourteen on the quadrant. Spines conical, twice as broad at the base as one mesh; two opposite larger spines as long as the radius of the shell, two smaller only one-third as long.

Dimensions.—Diameter of the shell 0.24, pores 0.012, bars 0.004; length of the major spines 0.12, minor 0.04.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

3. Staurostylus germanicus, n. sp.

Shell thick walled, covered with bristle-shaped by-spines, half as long as the radius. Pores regular, circular, hexagonally framed, twice as broad as the bars; eight to ten on the quadrant. From each hexagon-corner arises one short by-spine. Four main spines three-sided pyramidal, as broad at the base as one mesh; two opposite larger spines one and a half times as long as the radius, two smaller two-thirds as long.

Dimensions.—Diameter of the shell 0.16, pores 0.008, bars 0.004; length of the major spines 0.12, minor 0.08.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

Genus 62. Stylostaurus,^[85] 1881, Prodromus, p. 450.

Definition.—Staurosphærida with one single lattice-sphere and four crossed spines, one of which is much larger than the other three.

The genus Stylostaurus differs from the preceding in the extraordinary development of one of the four spines, which is much longer than the other three; these may be equal or different.

1. Stylostaurus caudatus, n. sp. (Pl. 13, fig. 7).

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, twice as broad as the bars; five to six on the quadrant. Spines three-sided pyramidal, as broad at the base as one mesh; one of the spines longer than the shell diameter, the opposite spine nearly as long as the shell radius; both lateral spines scarcely one-third as long.

Dimensions.—Diameter of the shell 0.1, pores 0.01, bars 0.005; length of the major spine 0.14, of the opposite 0.04, of both lateral spines 0.012.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Stylostaurus gladiatus, n. sp.

Shell thick walled, smooth, with regular, circular pores, three times as broad as the bars; nine to ten on the quadrant. Spines three-sided prismatic, as broad at the base as one mesh; one of the spines longer than the shell diameter, and much larger than the other three, which are nearly equal (half as long as the radius).

Dimensions.—Diameter of the shell 0.2, pores 0.015, bars 0.005; length of the major spine 0.25, of the three others 0.005.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subfamily Staurolonchida,^[86] Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.—Staurosphærida with two concentric spherical lattice-shells.

Genus 63. Staurolonche,^[87] Haeckel, 1881, Prodromus, p. 451.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed, equal, simple spines.

The genus Staurolonche may be derived either from Staurosphæra by the duplication of the lattice-sphere, or from Carposphæra by the production of four crossed radial spines, lying in one meridional plane, or from Hexalonche by the reduction of two opposite spines.

Subgenus 1. Staurolonchantha, Haeckel.

Definition.—Pores of the cortical shell regular, and of nearly equal size and similar form; surface smooth.

1. Staurolonche hexagona, n. sp.

Haliomma hexagonum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvb., Bd. iv. fig. 17.

Haliomma hexagonum, Haeckel, 1862, Monogr. d. Radiol., p. 434.

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with regular, hexagonal pores, four times as broad as the bars; seven to eight on the quadrant. Four spines three-sided pyramidal, somewhat longer than the radius, as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.012, bars 0.003; length of the spines 0.08.

Habitat.—North Atlantic, Station 64, depth 2700 fathoms.

2. Staurolonche spinozæ, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell, with regular, circular, hexagonally framed pores, three times as broad as the bars; five to six on the quadrant. Four spines three-sided pyramidal, half as long as the radius, as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.16, inner 0.08; cortical pores 0.012, bars 0.004; length of the spines 0.04.

Habitat.—Central Pacific, Station 271, surface.

3. Staurolonche aperta, Haeckel.

Haliomma apertum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxviii. fig. 5.

Cortical shell thin walled, smooth, three times as broad as the medullary shell; pores regular, circular, five times as broad as the bars; four to five on the quadrant. Four spines conical, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.1, inner 0.03; cortical pores 0.015, bars 0.003; length of the spines 0.05.

Habitat.—Fossil in Barbados.

4. Staurolonche brunonis, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; eight to ten on the quadrant. Four spines cylindro-conical, longer than the diameter, twice as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.08, inner 0.04; cortical pores 0.006, bars 0.002; length of the spines 0.12.

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

5. Staurolonche pertusa, n. sp. (Pl. 15, figs. 5, 5a).

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; eight to ten on the quadrant. Pores of the medullary shell only one-third as large, also circular. Four spines three-sided prismatic, three times as long as the radius; each of their three thin wings perforated by a single row of small pores.

Dimensions.—Diameter of the outer shell 0.1, inner 0.033; cortical pores 0.01, bars 0.003; length of the spines 0.15.

Habitat.—North Atlantic, Station 353, surface.

Subgenus 2. Staurolonchella, Haeckel.

Definition.—Pores of the cortical shell regular, and of nearly equal size and similar form; surface covered with by-spines or thorns.

6. Staurolonche straussii, n. sp.

Cortical shell thin walled, four times as broad as the medullary shell, and covered with numerous bristle-shaped by-spines, half as long as the radius. Pores regular, circular, hexagonally framed, twice as broad as the bars; six to eight on the radius. On each hexagonal frame twelve by-spines (six at the corners, six in the middle between them). Four main spines six-sided pyramidal, about as long as the radius, twice as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.16, inner 0.04; cortical pores 0.016, bars 0.008; length of the spines 0.1.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.

7. Staurolonche feuerbachii, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with short conical by-spines. Pores regular, circular, twice as broad as the bars; twenty to twenty-two on the quadrant. Four main spines three-sided prismatic, with pyramidal apex, two to three times as long as the radius, twice as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.27, of the inner 0.055; cortical pores 0.008, bars 0.004; length of the spines 0.3 to 0.4.

Habitat.—Fossil in Barbados.

8. Staurolonche moleschottii, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, and covered with short conical by-spines. Pores regular, circular, of the same breadth as the bars; fourteen to sixteen on the quadrant. Four main spines conical, as long as the radius, three times as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; cortical pores and bars 0.004; length of the spines 0.08.

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

Subgenus 3. Staurolonchissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth.

9. Staurolonche holbachii, n. sp.

Cortical shell thin walled, with smooth surface, three times as broad as the medullary shell. Pores irregular, polygonal, twice to four times as broad as the bars. Four main spines three-sided prismatic, longer than the shell diameter.

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.15.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

10. Staurolonche gassendii, n. sp.

Cortical shell thick walled, with smooth surface, four times as broad as the medullary shell. Pores irregular, roundish, three to five times as broad as the bars. Four main spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.2, inner 0.05; cortical pores 0.01 to 0.02, bars 0.004; length of the spines 0.1.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

Subgenus 4. Staurolonchura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface covered with by-spines or thorns.

11. Staurolonche epicurii, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with numerous bristle-shaped by-spines (half as long as the radius). Pores irregular, roundish, polygonally framed, twice to three times as broad as the bars. Four main spines pyramidal, as long as the radius.

Dimensions.—Diameter of the outer shell 0.22, inner 0.044; cortical pores 0.02 to 0.04, bars 0.012; length of the spines 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

12. Staurolonche lucretii, n. sp.

Cortical shell thick-walled, three times as broad as the medullary shell, and covered with numerous short, conical thorns. Pores irregular, roundish, twice to four times as broad as the bars. Four main spines conical, half as long as the radius.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; cortical pores 0.015 to 0.03, bars 0.008; length of the spines 0.04.

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

Genus 64. Staurancistra,^[88] Haeckel, 1881, Prodromus, p. 451.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed, equal, branched spines.

The genus Staurancistra differs from its ancestral form, Staurolonche, in the ramification of the four crossed spines.

1. Staurancistra quadricuspis, n. sp.

Cortical shell thin walled, with rough, thorny surface, and irregular, roundish pores, twice to four times as broad as the bars; six to eight on the quadrant. Medullary shell one-third as large, with regular, circular pores; connected with the cortical shell by four crossed radial beams. These are prolonged outside into four strong three-sided prismatic spines, nearly as long as the shell diameter, each having three curved branches below the distal end. (Similar to Hexancistra quadricuspis, Pl. 22, fig. 11, but with only four spines.)

Dimensions.—Diameter of the cortical shell 0.16, of the medullary shell 0.05; pores of the former 0.06 to 0.012, bars 0.003; length of the spines 0.14, breadth 0.012.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 65. Staurolonchidium,^[89] n. gen.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed simple spines which are disposed in two different pairs, two opposite being larger than the other two.

The genus Staurolonchidium has arisen from Staurolonche by the stronger growth of the two opposite spines, the other two remaining stationary; both spines of each pair equal.

1. Staurolonchidium artioscelides, n. sp.

Cortical shell thin walled, with smooth surface, three times as broad as the medullary shell. Pores regular, circular, hexagonally framed, twice as broad as the bars; eight to ten on the quadrant. Four radial spines three-sided pyramidal, as broad as one mesh; two opposite larger spines three times as long as the two smaller, which are about equal to the radius.

Dimensions.—Diameter of the cortical shell 0.16, medullary shell 0.05; pores of the former 0.012, bars 0.006; length of the major spines 0.24, minor 0.08.

Habitat.—Central Pacific, Station 265, surface.

2. Staurolonchidium perspicuum, Haeckel.

Haliomma perspicuum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxix. fig. 1.

Cortical shell thin walled, covered with small conical by-spines, five times as broad as the medullary shell. Pores regular, circular, eight times as broad as the bars; three to four on the quadrant. Four radial spines three-sided pyramidal, scarcely one-third as broad as one mesh; two opposite larger spines four times as long as the two smaller, which are about equal to half the radius.

Dimensions.—Diameter of the cortical shell 0.12, medullary shell 0.025; pores of the former 0.03, bars 0.004; length of the major spines 0.12, minor 0.03.

Habitat.—Fossil in Barbados.

Genus 66. Stauroxiphos,^[90] n. gen.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed simple spines, one of which is much larger than the other three.

The genus Stauroxiphos differs from its ancestral form, Staurolonche, in the greater development of one single spine, and exhibits therefore the same relation to it that Stylostaurus bears to Staurosphæra.

1. Stauroxiphos gladius, n. sp. (Pl. 15, fig. 7).

Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores of the outer shell regular, circular, regularly six-lobed on the outer opening, four times as broad as the bars; about six on the quadrant. Pores of the inner shell only one-third as large, simple, circular. Three of the four radial spines of nearly equal size, pommel-shaped, with three prominent, dentated wings, somewhat shorter than the shell radius and about half as broad as long; the fourth spine much larger, sword-like, about three times as long as the shell radius.

Dimensions.—Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.01, bars 0.0025; pores of the latter 0.003, bars 0.001; length of the major spine 0.18, of the three minor 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subfamily Stauracontida,^[91] Haeckel, 1881, Prodromus, p. 52.

Definition.—Staurosphærida with three concentric spherical lattice-shells.

Genus 67. Stauracontium,^[92] Haeckel, 1881, Prodromus, p. 452.

Definition.—Staurosphærida with three concentric lattice-spheres and four crossed, equal, simple spines.

The genus Stauracontium differs from its probable ancestral form, Staurolonche, in the duplication of the cortical shell.

Subgenus 1. Stauracontarium, Haeckel.

Definition.—Pores of the cortical shell regular, all of nearly equal size and similar form; surface smooth.

1. Stauracontium cruciferum, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars; eight to ten on the quadrant. Radial proportion of the three spheres = 1 : 3 : 9. Connecting radial beams between them six (opposite in pairs in the three dimensive axes), but only four of them are prolonged outside into four stout three-sided prismatic spines, lying in one equatorial plane, as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.22, middle 0.07, inner 0.025; cortical pores 0.012, bars 0.003; length of the spines 0.2.

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

2. Stauracontium tetracanthum, Haeckel.

Haliomma tetracanthum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. x. figs. 7, 8.

Cortical shell thin walled, smooth, with regular, circular pores, three times as broad as the bars; five to six on the quadrant. Radial proportion of the three spheres = 1 : 3 : 12. Radial spines three-sided pyramidal, about as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.12, middle 0.03, inner 0.01; cortical pores 0.01, bars 0.003; length of the spines 0.1.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms, Pullen.

3. Stauracontium tetracontium, Haeckel.

Actinomma tetracanthum, Stöhr, 1880, Palæontogr. 26, p. 91, Taf. ii. fig. 6.

Cortical shell thin walled, rough, with regular, circular pores, of the same breadth as the bars; six to seven on the quadrant. Radial proportion of the three spheres = 1 : 2.5 : 8. Radial spines three-sided pyramidal, nearly as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.1, middle 0.03, inner 0.013; cortical pores and bars 0.006; length of the spines 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.

Subgenus 2. Stauracontellium, Haeckel.

Definition.—Pores of the cortical shell regular, and of nearly equal size and similar form; surface covered with numerous small thorns or by-spines.

4. Stauracontium daturæforme, Haeckel.

Actinomma daturæforme, Stöhr, 1880, Palæontogr. 26, p. 93, Taf. ii. fig. 13.

Cortical shell thick walled, covered with short thorns, and with regular, hexagonal pores, five times as broad as the bars; six to seven on the quadrant. Radial proportion of the three spheres = 1 : 3 : 3.5. Radial spines six-sided pyramidal, about half as long as the radius and one-fourth as broad.

Dimensions.—Diameter of the outer shell 0.15, middle 0.13, inner 0.04; cortical pores 0.017, bars 0.003; length of the spines 0.03.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Stöhr.

5. Stauracontium sparganium, n. sp.

Cortical shell thick walled, covered with very numerous, short, conical spines, and with regular, circular pores, five times as broad as the bars; sixteen to eighteen on the quadrant. Radial proportion of the three spheres = 2 : 3 : 9. Radial main spines three-sided prismatic, as long as the radius or longer.

Dimensions.—Diameter of the outer shell 0.275, middle 0.09, inner 0.06; cortical pores 0.01, bars 0.002; length of the spines 0.15.

Habitat.—Fossil in Barbados.

Subgenus 3. Stauracontidium, Haeckel.

Definition.—Pores irregular, of different size or form; surface smooth.

6. Stauracontium antarcticum, n. sp.

Cortical shell thin walled, smooth. Pores irregular, roundish, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 8. Radial spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.2, middle 0.05, inner 0.025; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.1.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Stauracontonium, Haeckel.

Definition.—Pores irregular, of different size or form; surface covered with thorns or by-spines.

7. Stauracontium setosum, n. sp.

Cortical shell thin walled, covered with thin bristle-shaped by-spines, half as long as the radius. Pores irregular, polygonal, three to five times as broad as the bars. Proportion of the three spheres = 1 : 2 : 6. Radial main spines pyramidal, nearly as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.15, middle 0.05, inner 0.025; cortical pores 0.01 to 0.015, bars 0.003; length of the spines 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

8. Stauracontium papillosum, n. sp.

Cortical shell thick walled, covered with short conical papillæ or by-spines. Pores irregular, roundish, two to four times as broad as the bars. Proportion of the three spheres = 1 : 3 : 12. Radial main spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.24, middle 0.06, inner 0.02; cortical pores 0.007 to 0.015, bars 0.004; length of the spines 0.12.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subfamily Staurocromyida,^[93] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Staurosphærida with four concentric spherical lattice-shells.

Genus 68. Staurocromyum,^[94] Haeckel, 1881, Prodromus, p. 453.

Definition.—Staurosphærida with four concentric lattice-spheres and four crossed, equal, simple spines.

The genus Staurocromyum has arisen probably from Stauracontium by duplication of the cortical shell, two concentric shells lying within, two others outside the central capsule.

1. Staurocromyum quadruplex, n. sp.

Radial proportion of the four spheres = 1 : 2 : 8 : 10. Both medullary shells with very small, regular, circular pores. Inner cortical shell with regular, circular, hexagonally-framed pores, twice as broad as the bars; from each hexagon-corner arises a small by-spine, and these, connected by tangential branches at equal distances from the centre, form the delicate outer cortical shell, with spiny surface. Four main spines three-sided pyramidal, as long as the shell radius.

Dimensions.—Diameter of the four shells—(A) 0.25, (B) 0.2, (C) 0.05, (D) 0.025; length of the spines 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Staurocromyum quadrispinum, n. sp.

Radial proportion of the four spheres = 1 : 3 : 9 : 12. Both medullary shells with small, regular, circular pores. Both cortical shells with irregular, roundish pores. Surface covered with short, conical by-spines. Four main spines cylindro-conical, somewhat longer than the shell diameter.

Dimensions.—Diameter of the four shells—(A) 0.24, (B) 0.18, (C) 0.06, (D) 0.02.

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

Genus 69. Cromyostaurus,^[95] Haeckel, 1881, Prodromus, p. 453.

Definition.—Staurosphærida with four concentric lattice-spheres and four crossed, equal, branched spines.

The genus Cromyostaurus differs from the preceding Staurocromyum, its ancestral form, in the ramification of the four crossed spines.

1. Cromyostaurus verticillatus, n. sp.

Radial proportion of the four spheres = 1 : 3 : 11 : 13. Both medullary shells with small, regular, circular pores; inner cortical shell with regular, hexagonal pores; from the hexagon-corners arise small, radial by-spines, which at equal distances from the centre send out forked tangential branches, three from each spine, and by communication of these form the outer, delicate, cortical shell. Four main spines nearly as long as the shell diameter, three-sided prismatic, with four to six verticils of ramified lateral branches, each verticil composed of three forked branches, which ramify again.

Dimensions.—Diameter of the four shells—(A) 0.26, (B) 0.22, (C) 0.06, (D) 0.02; length of the spines 0.24.

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

Subfamily Staurocaryida,^[96] Haeckel, 1881, Prodromus, pp. 449, 454.

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

Genus 70. Staurocaryum,^[97] Haeckel, 1881, Prodromus, p. 454.

Definition.—Staurosphærida with five or more concentric lattice-spheres and four crossed, equal spines.

The genus Staurocaryum has arisen from the preceding Staurocromyum by the further multiplication of the concentric spheres; in the only observed form there are six, at nearly equal distances apart.

1. Staurocaryum arborescens, n. sp. (Pl. 15, fig. 8).

Shell composed of six concentric latticed spheres, at nearly equal distances apart, and with somewhat regular, circular pores, the size of which gradually increases from the first to the sixth shell. The surface of the outermost shell is densely covered with numerous arborescent by-spines, which bifurcate from three to four times, and are three-sided pyramidal at the base, and twice as long as the distance between each two shells. The six shells are connected only by four crossed, conical, radial beams, which increase in diameter from the centre, and are prolonged outside into very stout cylindrical, radial spines, irregularly covered with small thorns and forked ramules, and nearly as long as the shell diameter. Only a single specimen was observed.

Dimensions.—Diameter of the whole shell 0.22; distance between each two shells 0.02; length of the by-spines 0.05, of the main spines 0.2.

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

Subfamily Staurodorida,^[98] Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.—Staurosphærida with spongy, spherical shell (with or without enclosed concentric lattice-shells).

Genus 71. Staurodoras,^[99] Haeckel, 1881, Prodromus, p. 455.

Definition.—Staurosphærida with solid, spongy, spherical shell and four crossed simple spines.

The genus Staurodoras may be developed from Styptosphæra by the production of four crossed spines on the simple, spongy, spherical shell, which is composed of looser or denser irregular wicker-work, without enclosed medullary shell.

1. Staurodoras spongosphæra, n. sp.

Four crossed spines, two to three times as long as the diameter of the spongy sphere, three-sided prismatic, with three dentated and spirally contorted edges. (Form of Spongosphæra streptacantha, but without medullary shell and with four equal spines, crossed regularly at right angles.)

Dimensions.—Diameter of the sphere 0.25; length of the spines 0.4 to 0.7.

Habitat.—Central Pacific, Station 271, surface.

2. Staurodoras mojsisovicsi, Dunikowski.

Staurodoras mojsisovicsi, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 56.

Four crossed spines, one and a half times as long as the diameter of the spongy sphere, three-sided pyramidal, with three smooth edges. (What Dunikowski describes as "inner canals" of the spines are their edges.)

Dimensions.—Diameter of the sphere 0.14; length of the spines 0.18 to 0.2. basal breadth 0.04.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg).

3. Staurodoras liassica, Dunikowski.

Staurodoras liassica, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 57.

Four crossed spines, shorter than the diameter of the spongy sphere, conical or pyramidal (?).

Dimensions.—Diameter of the sphere 0.19; length of the spine 0.13, basal breadth 0.045.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg).

4. Staurodoras wandae, Dunikowski.

Staurodoras wandae, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 58.

Four crossed spines shorter than the radius of the spongy sphere, conical. (May be the young form of the preceding species.)

Dimensions.—Diameter of the sphere 0.14; length of the spines 0.06, basal breadth 0.05.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg).

Family IX. Cubosphærida, Haeckel (Pls. 21-25).

Cubosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea with six radial spines on the surface of the spherical shell, opposite in pairs in the three dimensive axes, perpendicular one to another; living solitary (not associated in colonies).

The family Cubosphærida is distinguished from the other Sphæroidea by the possession of six radial spines, which are opposite in pairs in three different axes, one perpendicular to the other two. These three axes are the typical "dimensive axes," which are more or less differentiated in the Larcoidea. But in these latter the shell itself and the enclosed central capsule become affected by the unequal growth in the three axes, whilst in the former the capsule constantly, and commonly also the shell, remains spherical. Sometimes the shell assumes the form of a regular octahedron, from the six corners of which arise the six radial spines, indicating its three axes.

The most simple Cubosphærida are the Hexastylida, with one single, spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Cubosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells—two in the Hexalonchida, three in the Hexacontida, four in the Hexacromyida, five or more in the Hexacaryida. In all these four subfamilies the concentric shells are simple (not spongy), fenestrated spheres. In a sixth subfamily, in the Hexadorida, the shell is wholly or partially composed of irregular, spongy wicker-work or loose reticulations, with or without a medullary shell in the centre.

The Six Radial Spines of the Cubosphærida are normally opposite in pairs in the three dimensive axes, each of which is perpendicular to the other two. But in many species besides this normal form occur individual abnormalities, in which the six spines are not quite accurately opposed, but more or less divergent; and often also the three dimensive planes (determined each by two axes) are not quite regular, but more or less uneven. More rarely the six spines appear disposed in quite an irregular manner.

In the greater part of the Cubosphærida all six spines are quite equal, of the same size and form. But in some genera a more or less considerable differentiation takes place, so that two pairs or all three pairs of spines become different; very rarely, also both spines of one pair become unequal (probably only an individual abnormality). Those variations correspond to the differences between the crystalline systems. The common Cubosphærida, with three equal spine-pairs, correspond to the regular or cubic system, with three equal axes. The rarer forms (Hexastylarium, Hexaloncharium, Hexacontarium) exhibit two equal pairs and one different pair; they correspond to the quadratic system, with three perpendicular axes, two of which are equal, the third unequal. Still more rare are those forms (Hexastylidium, Hexalonchidium), in which all three pairs of spines are different, corresponding to the three unequal axes of the rhombic crystalline system.

Synopsis of the Genera of Cubosphærida.

I. Subfamily Hexastylida. (Shell one simple latticed sphere.) All six radial spines simple, of equal size, 72. Hexastylus.

Six spines of different sizes, all six simple. Two pairs equal, one pair different, 73. Hexastylarium.

All three pairs different, 74. Hexastylidium.

II. Subfamily Hexalonchida. (Shell composed of two concentric latticed spheres.) All six radial spines of equal size. Spines simple, 75. Hexalonche.

Spines branched, 76. Hexancistra.

Six spines simple, in pairs of different sizes. Two pairs equal, one pair different, 77. Hexaloncharium.

All three pairs different, 78. Hexalonchidium.

III. Subfamily Hexacontida. (Shell composed of three spheres.) All six radial spines of equal size. Spines simple, 79. Hexacontium.

Spines branched, 80. Hexadendron.

Six spines simple, of different sizes. Two pairs equal, one pair different, 81. Hexacontarium.

IV. Subfamily Hexacromyida. (Four concentric spheres.) All six radial spines of equal size. Spines simple, no branched, 82. Hexacromyum.

V. Subfamily Hexacaryida. (Five or more spheres.) All six radial spines of equal size. Spines simple, 83. Cubosphæra.

Spines branched, 84. Hexacaryum.

VI. Subfamily Hexadorida. (Shell a spongy sphere, with or without an enclosed central medullary shell.) All six radial spines of equal size, simple (not branched). Without latticed medullary shell, 85. Cubaxonium.

With one single medullary shell, 86. Hexadoras.

With two medullary shells, 87. Hexadoridium.

I. Subfamily Hexastylida. (Shell one simple latticed sphere.)

All six radial spines simple, of equal size,

72. Hexastylus.

Six spines of different sizes, all six simple.

Two pairs equal, one pair different,

73. Hexastylarium.

All three pairs different,

74. Hexastylidium.

II. Subfamily Hexalonchida. (Shell composed of two concentric latticed spheres.)

All six radial spines of equal size.

Spines simple,

75. Hexalonche.

Spines branched,

76. Hexancistra.

Six spines simple, in pairs of different sizes.

Two pairs equal, one pair different,

77. Hexaloncharium.

All three pairs different,

78. Hexalonchidium.

III. Subfamily Hexacontida. (Shell composed of three spheres.)

All six radial spines of equal size.

Spines simple,

79. Hexacontium.

Spines branched,

80. Hexadendron.

Six spines simple, of different sizes.

Two pairs equal, one pair different,

81. Hexacontarium.

IV. Subfamily Hexacromyida. (Four concentric spheres.)

All six radial spines of equal size.

Spines simple, no branched,

82. Hexacromyum.

V. Subfamily Hexacaryida. (Five or more spheres.)

All six radial spines of equal size.

Spines simple,

83. Cubosphæra.

Spines branched,

84. Hexacaryum.

VI. Subfamily Hexadorida. (Shell a spongy sphere, with or without an enclosed central medullary shell.)

All six radial spines of equal size, simple (not branched).

Without latticed medullary shell,

85. Cubaxonium.

With one single medullary shell,

86. Hexadoras.

With two medullary shells,

87. Hexadoridium.

Subfamily Hexastylida,^[100] Haeckel, 1881, Prodromus, pp. 449, 450.

Definition.—Cubosphærida with one single spherical lattice-shell.

Genus 72. Hexastylus,^[101] Haeckel, 1881, Prodromus, p. 450.

Definition.—Cubosphærida with one simple lattice-sphere and six simple spines of equal size.

The genus Hexalonche is the most simple form of all Cubosphærida, and may be regarded as the common ancestral form of this family. It can be derived phylogenetically from Cenosphæra, by development of six radial spines on the surface of the simple spherical lattice-shell. These six simple spines are of equal size and opposite in pairs in the three dimensive axes, corresponding to the three equal axes of a cubic crystal.

Subgenus 1. Hexastylanthus, Haeckel.

Definition.—Pores regular or subregular, of nearly equal size and form; surface of the cortical shell smooth, without radial by-spines (other than the six main spines).

1. Hexastylus phænaxonius, n. sp. (Pl. 21, fig. 3).

Shell thin walled, with smooth surface. Pores subregular, hexagonal, five to six times as broad as the bars; nine to ten on the radius. Six spines triangular pyramidal, as long as the radius of the shell, as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.13, pores 0.008 to 0.01, bars 0.0015; length of the spines 0.07, basal breadth 0.008 to 0.012.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Hexastylus sapientum, n. sp.

Shell thin walled, with smooth surface. Pores regular, hexagonal, eight to ten times as broad as the bars; six to seven on the radius. Six spines bristle-shaped, longer than the diameter of the shell. (Lattice-work and spines similar to those of Heliosphæra actinota, Monogr. d. Radiol., Taf. ix. fig. 3.)

Dimensions.—Diameter of the shell 0.15, pores 0.016, bars 0.002; length of the spines 0.2, breadth 0.002.

Habitat.—North Atlantic, Station 354, surface.

3. Hexastylus thaletis, n. sp. (Pl. 21, fig. 4).

Shell thin walled, with smooth surface. Pores subregular, circular, hexagonally framed, somewhat funnel-shaped, of the same breadth as the bars; eight to nine on the radius. Six spines triangular pyramidal, with prominent edges, as long as the radius, three to four times as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.1, pores and bars 0.005; length of the spines 0.05, basal breadth 0.02.

Habitat.—Tropical Pacific, Station 225, depth 4575 fathoms.

4. Hexastylus favosus, n. sp.

Shell thick walled, with smooth surface. Pores regular, circular, hexagonally framed, deep funnel-shaped, of the same breadth as the bars; six to seven on the radius. Six spines triangular pyramidal, as long as the diameter, twice as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.12, pores and bars 0.01; length of the spines 0.12, basal breadth 0.02.

Habitat.—South Atlantic, Station 320, surface.

5. Hexastylus longissimus, n. sp.

Shell thick walled, with smooth surface. Pores regular, circular, hexagonally framed, of the same breadth as the bars; five to six on the radius. Six spines triangular prismatic, extremely elongated, ten to twenty times as long as the diameter of the shell, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.08, pores and bars 0.008; length of the spines 1.0 to 1.5, breadth 0.015.

Habitat.—Tropical Atlantic, Station 347, surface.

6. Hexastylus minimus, n. sp. (Pl. 21, fig. 5).

Shell thin walled, with smooth surface. Pores subregular, circular, twice as broad as the bars; five to six on the radius. Six spines triangular pyramidal, scarcely as long as the radius, at the base half as broad as long.

Dimensions.—Diameter of the shell 0.05, pores 0.004, bars 0.002; length of the spines 0.02, basal breadth 0.01.

Habitat.—Tropical Pacific, Station 225, depth 4575 fathoms.

7. Hexastylus biantis, n. sp.

? Haliphormis hexacantha, Ehrenberg, 1872, L. N. 24, Taf. x. fig. 6.

Shell thin walled, smooth. Pores regular, circular, four times as broad as the bars; eight to nine on the radius. Six spines conical, as long as the radius, at the base as broad as one pore.

Dimensions.—Diameter of the shell 0.12, pores 0.012, bars 0.003; length of the spines 0.06, basal breadth 0.012.

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

8. Hexastylus pittaci, n. sp.

Shell thin walled, smooth. Pores regular, circular, ten to twelve times as broad as the bars; six to seven on the radius. Six spines triangular pyramidal, as long as the radius, as broad as one pore.

Dimensions.—Diameter of the shell 0.12, pores 0.02, bars 0.002; length of the spines 0.06, basal breadth 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

9. Hexastylus maximus, n. sp.

Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars; twelve to sixteen on the radius. Six spines six-sided pyramidal, half as long as the radius, three times as broad as one pore.

Dimensions.—Diameter of the shell 0.3, pores 0.01, bars 0.005; length of the spines 0.08, basal breadth 0.03.

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

10. Hexastylus periandri, n. sp.

Shell thick walled, smooth. Pores regular, circular, double-edged, four times as broad as the bars; six to seven on the radius. Six spines conical, as long as the radius, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.2, pores 0.012, bars 0.003; length of the spines 0.1, basal breadth 0.025.

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

Subgenus 2. Hexastylettus, Haeckel.

Definition.—Pores regular or subregular, of nearly equal size and form; surface of the spherical shell spiny, covered with numerous conical or bristle-shaped radial by-spines.

11. Hexastylus solonis, n. sp. (Pl. 21, fig. 11).

Shell thick walled, covered with numerous bristle-shaped radial spines (one-third to one-half as long as the six main spines, arising from the lattice-knots). Pores regular, circular, enclosed by prominent, hexagonal frames, four to six times as broad as the bars; seven to eight on the radius. Six main spines triangular pyramidal, with spirally contorted prominent edges, as long as the radius, as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.13, pores 0.01, bars 0.002; length of the spines 0.06 to 0.8, basal breadth 0.01.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

12. Hexastylus cochleatus, n. sp. (Pl. 21, fig. 1).

Shell thick walled, covered with numerous short, conical spines (about as large as one pore). Pores regular, circular, three times as broad as the bars; eight to nine on the radius. Six main spines triangular pyramidal, with prominent, spirally-twisted edges, as long as the diameter of the shell, and twice as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.17, pores 0.015, bars 0.005; length of the spines 0.16, breadth 0.03.

Habitat.—Mediterranean, Corfu, Haeckel, surface.

13. Hexastylus setosus, Haeckel.

Acanthosphæra setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ix. fig. 11.

Shell thin walled, covered with numerous short, bristle-shaped spines (not larger than one pore). Pores regular, circular, four times as broad as the bars; thirteen to sixteen on the radius. Six main spines three-sided pyramidal, scarcely one-third as long as the radius. (In the figure of Ehrenberg, loc. cit., only four spines are in regular, crossed disposition, two others opposite in oblique direction; this is either an individual abnormality, or an error of drawing; the same species occurs with six spines exactly regularly disposed in the three dimensive axes.)

Dimensions.—Diameter of the shell 0.15; pores 0.008, bars 0.002; length of the spines 0.02 to 0.03, basal breadth 0.005.