Chapter XI: Literature and History (7)

Pores regular, circular, hexagonally lobed or rosette-shaped, three times as broad as the bars. Ten to twelve pores on the half equator. Shell thick walled; surface smooth. Polar spines three-sided pyramidal, one to two times as long as the axis of the shell, as broad at the base as one pore {124}(very similar to _Xiphostylus phasianus_, Pl. 13, fig. 9, but different in the equal size and similar form of the two large polar spines).

_Dimensions._--Diameter of the sphere 0.12, pores 0.015, bars 0.005; length of the polar spines 0.1 to 0.2, basal breadth 0.02.

_Habitat._--Indian Ocean, Cocos Islands, surface, Rabbe.

5. _Xiphosphæra hebe_, n. sp.

Pores regular, circular, three times as broad as the bars. On the half equator sixteen to twenty pores. Shell thick walled; surface smooth. Polar spines conical or nearly cylindrical, about as long as the axis of the sphere, as broad at the base as two pores.

_Dimensions._--Diameter of the sphere 0.1 to 0.13, pores 0.006, bars 0.002; polar spines 0.1 to 0.15 long, 0.01 thick.

_Habitat._--Pacific, central area, Stations 265 to 268, depths 2700 to 2900 fathoms.

6. _Xiphosphæra maxima_, n. sp.

Pores regular, circular, twice as broad as the bars, funnel-shaped. Twenty to thirty pores on the half equator. Shell very thick walled; surface smooth. Polar spines three-sided pyramidal, about as long as the radius of the sphere, as broad at the base as two pores.

_Dimensions._--Diameter of the sphere 0.22 to 0.35, pores 0.008 to 0.01, bars 0.005; polar spines 0.1 to 0.15 long, 0.02 thick.

_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.

7. _Xiphosphæra euphrosyne_, n. sp.

Pores regular, circular, about as broad as the bars, double contoured. Eight to ten on the half equator. Shell thin walled; surface smooth. Polar spines conical, about as long as the radius of the sphere, as broad at the base as one pore.

_Dimensions._--Diameter of the sphere 0.12 to 0.15, pores and bars 0.02; polar spines 0.06 to 0.09 long, 0.02 thick.

_Habitat._--South Atlantic, Station 323, depth 1900 fathoms.

Subgenus 2. _Xiphosphærella_, Haeckel.

_Definition._--Pores of the spherical shell regular, of nearly equal size and form; surface thorny or spiny, covered with regularly distributed papillæ or thorns (in addition to the two large polar spines).

8. _Xiphosphæra pallas_, n. sp. (Pl. 14, fig. 4).

Pores regular, circular, separated by hexagonal elevated frames, the sharp crest of which is elegantly denticulated; in each corner of the hexagons (between three pores) is a short radial spine, {125}about as long as one pore. On the half equator sixteen to twenty pores, of the same breadth as the bars. Shell thick walled; whole surface spiny. Polar spines cylindrical, at the apex conical, about as long as the axis of the sphere, three to four times as broad as one pore.

_Dimensions._--Diameter of the sphere 0.1, pores and bars 0.005; length of the polar spines 0.07 to 0.11, thickness 0.015 to 0.02.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

9. _Xiphosphæra flora_, n. sp.

Pores regular, circular, with hexagonal frames, twice as broad as the bars. Ten to twelve pores on the half equator. Shell thin walled, with spiny surface; in each corner of the hexagons is one bristle-like radial spine twice as long as one pore. Polar spines three-sided prismatic, at the apex pyramidal, nearly twice as long as the axis of the sphere, as broad at the base as two pores (similar to _Ellipsoxiphus palliatus_, Pl. 14, fig. 7).

_Dimensions._--Diameter of the sphere 0.15, pores 0.01, bars 0.005; length of the polar spines 0.2 to 0.25, breadth 0.02.

_Habitat._--Tropical Atlantic, Station 342, depth 1445 fathoms.

10. _Xiphosphæra juno_, n. sp.

Pores regular, circular, as broad as the bars, funnel-shaped. Fifteen to twenty pores on the half equator. Shell thick walled, covered with bristle-like spines, about twice as long as one pore. Polar spines conical, thick, about as long as the axis of the sphere, twice as broad at the base as one pore.

_Dimensions._--Diameter of the sphere 0.12, pores and bars 0.01; length of the polar spines 0.14, basal breadth 0.02.

_Habitat._--Fossil in the Barbados rocks; living in the greatest depth of the Tropical Pacific, Station 225, depth 4475.

11. _Xiphosphæra gigantea_, n. sp.

Pores regular, circular, two to three times as broad as the bars; twenty-eight to thirty-two on the half equator. Shell thick walled, covered with short conical thorns. Polar spines three-sided pyramidal, about as long as the radius of the sphere, as broad at the base as three pores.

_Dimensions._--Diameter of the sphere 0.25 to 0.3, pores 0.01, bars 0.004; polar spines 0.1 to 0.15 long, 0.03 broad.

_Habitat._--Fossil in the Tertiary rocks of Barbados and Sicily (Cattanisetta).

Subgenus 3. _Xiphosphærissa_, Haeckel.

_Definition._--Pores of the spherical shell irregular, of different size or form; surface smooth or a little rough, without spines or thorns (other than the polar spines).

{126}12. _Xiphosphæra ceres_, n. sp.

Pores irregular, roundish, of different sizes, two to four times as broad as the bars. Sixteen to twenty pores on the half equator. Shell thin walled, with smooth surface. Polar spines conical, about as long as the axis of the sphere, very thick at the base.

_Dimensions._--Diameter of the sphere 0.15 to 0.2, pores 0.004 to 0.008, bars 0.002; polar spines 0.18 to 0.24 long, at the base 0.02 thick.

_Habitat._--North Atlantic, Station 353, surface.

13. _Xiphosphæra clavigera_, n. sp.

Pores irregular, roundish, double contoured, of very unequal size, two to seven times as broad as the bars; ten to twelve on the half equator. Shell thick walled; surface a little rough. Polar spines club-shaped, with prominent edges, about half as long as the axis of the sphere; thinner at both ends than in the middle. (Differs from _Ellipsoxiphus claviger_, Pl. 14, fig. 3, in the spherical shell and shorter spines.)

_Dimensions._--Diameter of the sphere 0.2, pores 0.005 to 0.02, bars 0.003; polar spines 0.06 long, 0.02 broad.

_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.

Subgenus 4. _Xiphosphæromma_, Haeckel.

_Definition._--Pores of the spherical shell irregular, of different size or form; surface thorny or spiny (besides the two large polar spines).

14. _Xiphosphæra vesta_ n. sp. (Pl. 14, fig. 6).

Pores irregular, roundish, three to five times as broad as the bars; fourteen to sixteen on the half equator. Scattered on the surface of the thick-walled shell are from twenty to thirty strong three-sided pyramidal spines of unequal size, the largest twice as long as the largest pores. Polar spines very strong, nearly three-sided prismatic, with curved edges, nearly as long as the axis of the sphere and twice as broad as the largest pores.

_Dimensions._--Diameter of the sphere 0.17, pores 0.01 to 0.02, bars 0.004; length of the polar spines 0.13, thickness 0.02 to 0.03.

_Habitat._--Pacific, central area. Station 266, depth 2750 fathoms,

15. _Xiphosphæra astræa_, n. sp.

Pores irregular, roundish, one to two times as broad as the bars; ten to twelve on the half equator. Surface of the thick-walled shell covered with numerous short conical thorns. Polar spines cylindro-conical, one and a half to two times as long as the axis of the sphere.

{127}_Dimensions._--Diameter of the sphere 0.18, pores 0.01 to 0.015, bars 0.008; length of the polar spines 0.25 to 0.3, thickness 0.02.

_Habitat._--Indian Ocean, surface; Ceylon, Haeckel.

Genus 46. _Xiphostylus_,[69] Haeckel, 1881, Prodromus, p. 450.

_Definition._--#Stylosphærida# with one single lattice-sphere and two free spines of different size or form.

The genus _Xiphostylus_ differs from the foregoing _Xiphosphæra_ in the unequal size or form of both polar spines, which become more or less differentiated.

Subgenus 1. _Xiphostylantha_, Haeckel.

_Definition._--Pores of the spherical shell regular, of nearly equal size and form; surface smooth or a little rough, without spines or thorns.

1. _Xiphostylus alcedo_, n. sp. (Pl. 13, fig. 4).

Pores regular, circular, with elevated hexagonal frames, twice as broad as the bars. Eight to ten pores on the half equator. Surface smooth. Polar spines three-sided pyramidal, as broad at the base as one hexagon; the major spine four to five times as long as the minor, which is about equal to the radius of the sphere.

_Dimensions._--Diameter of the sphere 0.12, pores 0.012, bars 0.006; length of the major polar spine 0.16 to 0.2, of the minor 0.04 to 0.06, basal breadth 0.02.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475.

2. _Xiphostylus phasianus_, n. sp. (Pl. 13, fig. 9).

Pores regular, circular, twice as broad as the bars. Eight to ten pores on the half equator. Outer opening of each pore elegantly lobed, with eight indentations. Surface a little rough. Polar spines very unequal; major spine sword-like, sharply edged, about as long as the diameter of the sphere; minor spine scarcely half so long, pommel-shaped, with nine (?) wing-like edges.

_Dimensions._--Diameter of the sphere 0.13, inner circular opening of the pores 0.01, outer eight-lobed opening 0.015, bars 0.005; length of the major polar spine 0.14, of the minor 0.06, breadth 0.03.

_Habitat._--Australian Sea, Station 162, surface.

3. _Xiphostylus motacilla_, n. sp.

Pores regular, circular, three times as broad as the bars; sixteen to twenty on the half equator. Surface smooth. Polar spines compressed, two-edged, at the base three to four times as broad as {128}one pore; the major spine somewhat longer than the diameter of the shell, the minor scarcely one-third or one-half as long.

_Dimensions._--Diameter of the sphere 0.14, pores 0.006, bars 0.002; length of the major spine 0.16 to 0.18, of the minor 0.05 to 0.07, basal breadth 0.02.

_Habitat._--Indian Ocean, Zanzibar, 2200 fathoms, Pullen.

4. _Xiphostylus gallus_, n. sp.

Pores regular, circular, five times as broad as the bars. Twelve to sixteen pores on the half equator. Surface smooth. Polar spines very unequal; the major conical spine one and a half to three times as long as the diameter of the sphere; the minor pommel-shaped, scarcely one-third as long (length of both spines very variable).

_Dimensions._--Diameter of the sphere 0.13, pores 0.01, bars 0.002; length of the major spine 0.2 to 0.4, of the minor 0.05 to 0.08.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

5. _Xiphostylus alauda_, n. sp. (Pl. 14, fig. 15).

_Lithomespilus alauda_, Haeckel, 1881, Prodrom. et Atlas, _loc. cit._

Pores subregular, circular, three to four times as broad as the bars; fifteen to eighteen on the half equator. Surface a little rough. Polar spines irregularly conical or pyramidal, scarcely as long as the radius of the sphere; one spine simple, the other composed of a bunch of four or five spines united at the base.

_Dimensions._--Diameter of the sphere 0.11, pores 0.01, bars 0.003; length of the polar spines 0.03 to 0.05, basal breadth 0.02.

_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.

6. _Xiphostylus anhinga_, Haeckel.

_Rhabdolithis pipa_, Bury, 1862, Polycystins of Barbados, pl. iii. fig.
4.

Pores subregular, circular, about the same breadth as the bars; eight to ten on the half equator. Surface smooth or a little rough. Polar spines cylindrical, very irregularly curved like S or contorted, the major three to six times as long as the diameter of the sphere, the minor scarcely one-fourth as long as the former, at the end truncated.

_Dimensions._--Diameter of the sphere 0.07, pores and bars 0.005; length of the major polar spine 0.2 to 0.4, of the minor 0.06 to 0.09, basal breadth 0.01.

_Habitat._--Fossil in the Barbados rocks.

Subgenus 2. _Xiphostyletta_, Haeckel.

_Definition._--Pores of the spherical shell regular, of nearly equal size and form; surface thorny or spiny (other than the two large polar spines).

{129}7. _Xiphostylus cuculus_, n. sp.

Pores regular, circular, hexagonally framed, three times as broad as the bars; ten to twelve on the half equator. Surface thorny, between every three pores a short conical thorn. Polar spines three-sided prismatic, the major somewhat longer than the diameter of the sphere, the minor scarcely one-third as long, pommel-shaped.

_Dimensions._--Diameter of the sphere 0.17, pores 0.012, bars 0.004; length of the major polar spine 0.2, of the minor 0.05, basal breadth 0.015.

_Habitat._--South Atlantic, surface; Station 335, depth 1425 fathoms.

8. _Xiphostylus trochilus_, n. sp. (Pl. 13, fig. 10).

Pores regular, circular, four times as broad as the bars; eight to nine on the half equator. Polar spines cylindrical, the major somewhat longer than the axis of the sphere, the minor shorter, surrounded by a group of from four to eight shorter conical spines. Surface of the opposite hemisphere smooth, without by-spines.

_Dimensions._--Diameter of the sphere 0.07 to 0.08, pores 0.01, bars 0.0025.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

9. _Xiphostylus picus_, n. sp. (Pl. 14, fig. 13).

_Lithomespilus picus_, Haeckel, 1881, Prodrom. et Atlas.

Pores regular, circular, twice as broad as the bars; sixteen to eighteen on the half equator. Polar spines cylindrical, conical at the apex, the major once and a half to twice as long as the diameter of the shell, the minor scarcely half so long; around the latter a group of twelve to twenty shorter conical spines, irregularly scattered. Surface of the other hemisphere smooth.

_Dimensions._--Diameter of the sphere 0.13, pores 0.006, bars 0.003; length of the major polar spine 0.2 to 0.24, of the minor 0.08 to 0.09, basal breadth 0.02.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 3. _Xiphostylissa_, Haeckel.

_Definition._--Pores of the spherical shell irregular, of unequal size or form; surface smooth or a little rough, without thorns.

10. _Xiphostylus trogon_, n. sp. (Pl. 14, fig. 12).

_Lithomespilus trogon_, Haeckel, 1881, Prodrom. et Atlas.

Pores irregular, roundish or subcircular, two to three times as broad as the bars; ten to twelve on the half equator. Surface smooth. Major polar spine three-sided prismatic, once and a half to twice as long as the axis of the sphere; minor spine quite rudimentary, scarcely longer than broad, but surrounded by a group of from three to six similar short spines.

{130}_Dimensions._--Diameter of the sphere 0.1, pores 0.005 to 0.015, bars 0.005 to 0.008; length of the major spine 0.15 to 0.18, of the minor 0.01 to 0.02, basal breadth 0.02.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

11. _Xiphostylus falco_, n. sp. (Pl. 13, fig. 14).

Pores irregular, roundish, two to five times as broad as the bars; sixteen to eighteen on the half equator. Surface smooth. Polar spines cylindrical, very stout, nearly half as thick as the radius of the shell; major spine two to four times as long as the diameter of the shell; minor spine obliquely inserted, scarcely longer than the diameter, divided at the end into two short, hook-shaped, curved branches.

_Dimensions._--Diameter of the sphere 0.08, pores 0.002 to 0.005, bars 0.001; breadth of the spines 0.02, length of the major spine 0.15 to 0.2, of the minor 0.09.

_Habitat._--South Pacific, Station 302, depth 1450 fathoms.

12. _Xiphostylus alca_, n. sp. (Pl. 13, fig. 13).

Pores irregular, roundish, two to six times as broad as the bars; six to eight on the half equator. Each pore with three to six lobes, composed of three to six confluent smaller pores. Surface smooth. Major spine conical, curved, somewhat longer than the axis of the sphere; minor spine somewhat shorter, pommel-like, edged.

_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.

{131}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.

{132}_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.

{133}_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.

{134}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.

{135}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).

{136}_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.

{137}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. {138}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.)

{139}_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.)

{140}_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.

{141}_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.

{142}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.

{143}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 {144}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 {145}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. {146}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.

{147}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.