Chapter XI: Literature and History (16)

Proportion of the main axes of the four concentric shells about = 1 : 3 : 10 : 11. Network of the two spherical medullary shells (fig. 1_a_) regular, with small circular pores, twice as broad as {336}the bars. Network of the inner cortical shell regular with circular, hexagonally-framed pores, twice as broad as the bars. From every corner of the hexagons (between three pores) arises a very thin, hair-like, short radial spinule. These spinules communicate with one another by tangential branches (at equal distances from the inner cortical shell), and form thereby an outer, delicate cortical network, with large polygonal meshes and very thin bars. Polar spines very strong, pyramidal, with prominent edges, as long as the main radius of the cortical shell, and half as broad at the base.

_Dimensions._--Main axes of the four shells--(A) 0.02, (B) 0.06, (C) 0.2, (D) 0.22; equatorial axes of them--(A) 0.02, (B) 0.06, (C) 0.13, (D) 0.15; pores of the four shells--(A) 0.002, (B) 0.004, (C) 0.008, (D) 0.02; bars 0.001 to 0.003; length of the polar spines 0.1, basal breadth 0.05.

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

Subgenus 2. _Caryatractus_, Haeckel.

_Definition._--Shell composed of two medullary shells and three or more cortical shells.

4. _Cromyatractus cepicius_, n. sp. (Pl. 15, fig. 3).

_Caryostylus cepicius_, Haeckel, 1879, Atlas (pl. xv. fig. 3).

_Caryodoras cepicius_, Haeckel, 1881, Prodromus, p. 454.

Proportion of the main axes of the five concentric shells about = 1 : 2 : 5 : 7 : 8. Network of both spherical medullary shells regular, with small circular pores, about as broad as the bars. Network of the three ellipsoidal cortical shells irregular, with large polygonal meshes, five to ten times as broad as the thin bars. Surface of the outermost shell smooth. Polar spines cylindrical, thorny, about as thick as the innermost shell and as long as the outermost shell, against the apex with a spindle-like intumescence, formed by delicate spongy framework (fig. 3).

_Dimensions._--Main axes of the five concentric shells--(A) 0.03, (B) 0.05, (C) 0.16, (D) 0.2, (E) 0.25; equatorial axes of them--(A) 0.03, (B) 0.05, (C) 0.12, (D) 0.16, (E) 0.2; pores of the two medullary shells 0.002 to 0.004, of the three cortical shells 0.02 to 0.04, bars 0.002; length of the polar spines 0.3, breadth 0.03.

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

5. _Cromyatractus ceparius_, n. sp. (Pl. 15, fig. 4).

_Caryostylus ceparius_, Haeckel, 1881, Prodromus et Atlas (pl. xv. fig.
4).

Proportion of the main axes of the six concentric shells about = 1 : 2 : 7 : 10 : 13 : 18. Network of the three inner shells regular, with small, circular pores, which are about as broad as the bars and in the third shell hexagonally framed. Network of the three outer shells irregular, with large polygonal meshes, six to twelve times as broad as the bars. Surface smooth. Polar spines strong, spindle-shaped, thorny, outside of the sixth shell about as long as inside of it; broader than {337}the innermost shell; the thorns of their outer free part (arising at equal distances) represent perhaps the beginnings of three to four further shells.

_Dimensions._--Main axes of the six concentric shells--(A) 0.02, (B) 0.05, (C) 0.14, (D) 0.2, (E) 0.26, (F) 0.37; equatorial axes--(A) 0.02, (B) 0.05, (C) 0.09, (D) 0.15, (E) 0.21, (F) 0.3; pores of the three inner shells 0.003 to 0.006, of the three outer shells 0.02 to 0.04, bars 0.003 to 0.005; length of the polar spines, from the base of the innermost shell to the apex, 0.35, greatest breadth 0.03.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.

Genus 142. _Pipetta_,[181] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and simple medullary shell, with two hollow fenestrated tubes opposite on both poles of the main axis.

The genus _Pipetta_ differs from _Pipettella_ (p. 304) in the possession of an inner (medullary) shell; it exhibits the same tubular prolongations of the cortical shell at both poles of the main axis.

1. _Pipetta fusus_, n. sp. (Pl. 39, figs. 8, 8_a_).

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing over on both poles into the conical tubes, which attain about the same length. Network regular, with circular, hexagonally-framed pores, twice as broad as the bars, sixteen to eighteen on the half equator. In the middle part of the shell the pores arise from their hexagonal bases in the form of short conical funnels; on both tubes they are much smaller and simple, without frame. Medullary shell (fig. 8_a_) spherical, scarcely one-third as broad as the cortical, with regular, circular pores, twice as broad as the bars, eight to nine on the half equator. The two shells are connected only by two opposite beams, lying in the equatorial axis and ramified at the distal insertion (fig. 8_a_).

_Dimensions._--Middle ellipsoidal part of the cortical shell 0.13 to 0.15; polar tubes 0.15 long, 0.06 broad at the base; pores of the former 0.01, bars 0.005; pores of the tubes 0.06, bars 0.003. Medullary shell 0.04, pores 0.004, bars 0.002.

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

2. _Pipetta tuba_, n. sp. (Pl. 39, fig. 7).

Cortical shell nearly spherical in the middle part, which is sharply separated at both poles from the long, nearly cylindrical tubes; these are longer than the main axis, at the distal end open (always broken off). Network regular, with circular, hexagonally-framed pores, of the same breadth as the bars, eighteen to twenty on the half equator. The pores of the polar tubes are of the same shape, only much smaller, and arranged in sixteen to eighteen longitudinal rows. Medullary shell {338}spherical, about one-third as broad as the cortical, with simple circular pores. The connection between the two shells is only made by two simple opposite beams, lying in the equatorial axis.

_Dimensions._--Middle spheroidal part of the cortical shell 0.14 to 0.16; polar tubes 0.15 to 0.2 or longer, 0.03 broad; pores and bars of the former 0.007, of the latter 0.003. Medullary shell 0.04, pores 0.006, bars 0.003.

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

3. _Pipetta salpinx_, n. sp.

Cortical shell ellipsoidal, sharply separated from the cylindrical polar tubes, which reach about the same length (or more). Network regular, with circular pores, three times as broad as the bars, without hexagonal frames, fourteen to fifteen on the half equator. Pores of the polar tubes smaller, arranged in eight to ten longitudinal rows. Medullary shell spherical, one-fourth as broad as the cortical, connected with it by a circle of four to six radial beams, lying in the equatorial plane. Differs from _Pipettella prismatica_ (Pl. 39, fig. 6) in the possession of a medullary shell and the absence of the tube edges.

_Dimensions._--Main axis of the ellipsoid 0.14, equatorial axis 0.12, pores 0.01, bars 0.003; length of the tubes 0.15 or more, breadth 0.03. Medullary shell 0.03, pores 0.002, bars 0.001.

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

4. _Pipetta conus_, n. sp.

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing over at both poles into the conical tubes, which attain only half its length. Network irregular, with roundish or subcircular pores, twice to three times as broad as the bars, twelve to sixteen on the half equator. Medullary shell spherical, one-fourth as broad as the cortical. (Differs from the foregoing species in the short conical tubes and the irregular reticulation.)

_Dimensions._--Middle part of the cortical shell 0.16 long, 0.13 broad; tubes 0.09 long, 0.05 on the base broad; pores 0.005 to 0.01, bars 0.003. Medullary shell 0.04.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.

Genus 143. _Pipettaria_,[182] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and double medullary shell, with two hollow fenestrated tubes opposite on both poles of the main axis.

The genus _Pipettaria_ differs from the foregoing _Pipetta_ only in the duplication of the medullary shell; as in this, the tubular prolongations of the main axis of the cortical shell may be either conical (with closed apex) or cylindrical (with apical opening?).

{339}1. _Pipettaria fusaria_, n. sp.

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing over on both poles into the conical tubes, which attain about half its length. Pores regular, circular, twice as broad as the bars, sixteen to eighteen on the half equator; pores of the tubes smaller. Both medullary shells spheroidal, compressed. (The appearance of the cortical shell resembles that of _Cannartiscus amphiconus_, Pl. 39, fig. 19, but without the equatorial constriction.)

_Dimensions._--Main axis of the ellipsoid 0.15, equatorial axis 0.13; length of the polar tubes 0.08, basal breadth 0.05; pores of the former 0.008, bars 0.004; diameter of the medullary shells 0.04 and 0.02.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.

2. _Pipettaria tubaria_, n. sp. (Pl. 39, fig. 15).

_Cannartidium tubarium_, Haeckel, 1882, Atlas (pl. xxxix. fig. 15).

Cortical shell ellipsoidal, on both poles distinctly separated from the short conical tubes, the length and breadth of which equal the outer medullary shell. In the equatorial plane arises a circle of four to six short conical protuberances, similar to the polar tubes. Pores subregular, circular, or roundish, scarcely broader than the bars, sixteen to twenty on the half equator. Both medullary shells spheroidal, somewhat compressed in the direction of the two poles (as in fig. 18_a_).

_Dimensions._--Main axis of the ellipsoid 0.12, equatorial axis 0.09; pores 0.005, bars 0.004; size of the equatorial protuberances and of the polar tubes 0.02.

_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.

Family XIII. #SPONGURIDA#, Haeckel (Pl. 48, figs. 6, 7).

_Spongurida_, Haeckel, 1862, Monogr. d. Radiol., p. 447 (_sensu emendato_).

_Definition._--#Prunoidea# with spongy ellipsoidal or cylindrical shell, composed wholly or partially of a spongy framework, without equatorial stricture, with or without an enclosed medullary shell.

The family #Spongurida# comprises, in the sense here restricted, all those #Prunoidea# in which the ellipsoidal or cylindrical shell is composed wholly or partially of an irregular siliceous framework, not of simple lattice-work. It contains two subfamilies, differing in the absence or presence of a latticed medullary shell in the middle of the central capsule; in the Spongellipsida it is absent, in the Spongodruppida present; the former are most nearly related to the Ellipsida, the latter to the Druppulida, the difference consisting only in the spongy structure of the cortical shell.

In my Monograph (1862, p. 447) the family Spongurida had a much wider extent, comprising also a number of #Sphæroidea# and #Discoidea#, agreeing in the spongy {340}structure of the shell. Here we restrict the definition to those spongy #Sphærellaria# in which the central capsule and the enclosing spongy cortical shell are ellipsoidal or cylindrical, therefore each transverse section is a circle, and each meridional section an ellipse, as in all #Prunoidea#.

_The Cortical Shell_ in all Spongurida is composed of a delicate framework of irregularly branched and interwoven siliceous threads; commonly this spongy structure is rather dense or compact, but sometimes also very loose. In the simplest form, _Spongellipsis_, the spongy cortical shell contains a large cavity, in which lies freely the central capsule. In _Spongurus_ this cavity is completely distended by a spongy framework. In this case the solid spongy shell becomes often prolonged, and its original ellipsoidal form passes over into a cylindrical one (as in many Zygartida). Sometimes (particularly in _Spongocore_, Pl. 48, fig. 6) the cylinder becomes three-jointed by two more or less distinct annular constrictions. _Spongocore_ is distinguished by an outer veil, a thin lattice-lamella, which envelops the spongy shell and is connected with it by radial beams.

_The Medullary Shell_, absent in the Spongellipsida, is constant in the second subfamily Spongodruppida. It is either a simple latticed shell (_Spongodruppa_) or double, composed of two concentric latticed shells (_Spongoliva_); its form is either spherical or ellipsoidal. It lies in the middle of the central capsule, and is connected by radial beams (perforating the membrane of the latter) with the enveloping spongy cortical shell.

In many Spongurida the surface of the shell is armed with radial spines, and in some genera (_Spongoprunum_, _Spongatractus_, &c., Pl. 17, fig. 12), on both poles of the main axis, are developed two strong opposite polar spines, as in many other #Prunoidea#.

_The Central Capsule_ of the Spongurida is either ellipsoidal or cylindrical. Only in _Spongellipsis_ it lies freely in the internal cavity of the spongy shell. In all other genera it is perforated by a part of the skeleton; in the Spongodruppida it contains the simple or double medullary shell, and the radial beams which perforate its membrane and connect the latter with the external spongy cortical shell. In _Spongurus_ and the allied genera (_Spongocore_, _Spongoprunum_) the whole central capsule is filled with a spongy framework which also envelops its surface.

{341}_Synopsis of the Genera of Spongurida._

-------------------------------------------------------------------------
I. Subfamily Spongellipsida.
(Ellipsoidal shell composed only of a spongy framework without a
latticed medullary shell in the centre.)
-------------------------------------------------------------------------
Spongy shell }No polar spines, 144. _Spongellipsis_.
with internal }
cavity. }

{Without lattice
Spongy shell { mantle. No polar
solid, without { spines, 145. _Spongurus_.
internal {
cavity. {With lattice
{ mantle.
{ No polar spines, 146. _Spongocore_.
{
{Without lattice
{ mantle. Two
{ opposite spines
{ on the poles of
{ the axis, 147. _Spongoprunum_
-------------------------------------------------------------------------
II. Subfamily Spongodruppida.
(Ellipsoidal shell composed of an outer spongy cortical shell and an
inner latticed medullary shell.)
-------------------------------------------------------------------------
Medullary shell {No polar spines, 148. _Spongodruppa_.
simple. {
{Two opposite spines
{ on the poles of
{ the axis, 149. _Spongatractus_.

Medullary shell {No polar spines, 150. _Spongoliva_.
double. {
{
{Two opposite spines
{ on the poles of
{ the axis, 151. _Spongoxiphus_.

Subfamily 1. SPONGELLIPSIDA, Haeckel.

_Definition._--#Spongurida# with a spongy ellipsoidal or cylindrical shell, without an internal latticed medullary shell.

Genus 144. _Spongellipsis_,[183] n. gen.

_Definition._--#Spongurida# with an ellipsoidal or cylindrical spongy shell, containing an internal cavity, without a latticed medullary shell. Polar spines absent.

The genus _Spongellipsis_ embraces those very simple Spongurida in which the ellipsoidal central capsule is enclosed in a spongy cortical shell of the same form. It corresponds, therefore, to _Plegmosphæra_ among the #Sphæroidea#, to _Plegmodiscus_ among the #Discoidea#, and to _Spongolarcus_ among the #Larcoidea#. In some species the ellipsoidal form is prolonged and passes into a cylindrical one.

Subgenus 1. _Spongellipsarium_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial spines.

{342}1. _Spongellipsis lævis_, n. sp.

Shell ellipsoidal, with smooth surface, its spongy wall scarcely one-tenth as thick as the minor axis of the inner cavity. Spongy framework very compact, with small meshes, three to six times as broad as the bars. Proportion of the major axis to the minor = 3 : 2.

_Dimensions._--Major axis (or length) of the shell 0.36, minor axis (or breadth) 0.24.

_Habitat._--Pacific, central area, Station 265, surface.

2. _Spongellipsis aspera_, n. sp.

Shell ellipsoidal, with rough surface, its spongy wall nearly half as thick as the minor axis of the inner cavity. Spongy framework very loose, with large meshes, ten to twenty times as broad as the bars. Proportion of the major axis to the minor = 4 : 3.

_Dimensions._--Length of the shell 0.24, breadth 0.18.

_Habitat._--North Pacific, Station 253, surface.

3. _Spongellipsis aplysina_, n. sp.

Shell nearly cylindrical, with rough surface, its spongy wall about one-fourth as thick as the minor axis of the internal cavity. Spongy framework loose, with large meshes, four to eight times as broad as the bars. Proportion of both axes = 6 : 1. (Similar to a spongy cylinder of Aplysina.)

_Dimensions._--Length of the shell 0.3, breadth 0.05.

_Habitat._--North Atlantic, Station 64, surface.

Subgenus 2. _Spongellipsidium_, Haeckel.

_Definition._--Surface of the shell covered with radial spines.

4. _Spongellipsis setosa_, n. sp.

Shell ellipsoidal, covered with numerous (sixty to eighty) thin, bristle-shaped, radial spines, about half as long as the major axis. Spongy framework loose, with large meshes, ten to twenty times as broad as the bars. Minor axis of the inner cavity twice as long as the thickness of the spongy wall. Proportion of both axes = 5 : 3.

_Dimensions._--Length of the shell 0.2, breadth 0.12.

_Habitat._--South Atlantic, Station 325, surface.

5. _Spongellipsis spinosa_, n. sp.

Shell nearly cylindrical, covered with numerous thorns and thirty to forty larger conical radial spines, somewhat longer than the major axis. Spongy framework compact, with small meshes, four {343}to eight times as broad as the bars. Minor axis of the inner cavity about six times as large as the thickness of the spongy wall. Proportion of both axes = 4 : 1.

_Dimensions._--Length of the shell 0.24, breadth 0.06.

_Habitat._--South Pacific, Station 300, surface.

Genus 145. _Spongurus_,[184] Haeckel, 1862, Monogr. d. Radiol., p. 465.

_Definition._--#Spongurida# with ellipsoidal or cylindrical (sometimes three-jointed) shell, of solid spongy framework, without internal cavity and without latticed medullary shell. Polar spines and outer lattice-mantle absent.

The genus _Spongurus_ was founded by me in 1862 for the common cosmopolitan _Spongurus cylindricus_, a massive spongy cylinder with radial spines. I enlarge here the conception of the genus, in receiving also ellipsoidal, massive spongy #Prunoidea#, with or without radial spines. Sometimes the cylindrical shell is more or less distinctly three-jointed, with two annular strictures, as also in the following and nearly allied genus.

Subgenus 1. _Spongurantha_, Haeckel.

_Definition._--Spongy framework everywhere of the same structure; surface smooth or rough, but without radial spines.

1. _Spongurus stuparius_, n. sp.

Shell ellipsoidal, one and a half times as long as broad, with nearly smooth surface. Spongy framework everywhere of equal structure, with small meshes, four to six times as broad as the bars.

_Dimensions._--Length of the shell (or major axis) 0.2, breadth of it (or minor axis) 0.14.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.

2. _Spongurus stypticus_, n. sp.

Shell ellipsoidal, twice as long as broad, with thorny surface. Spongy framework everywhere of equal structure, with large meshes, ten to twenty times as broad as the bars.

_Dimensions._--Length of the shell 0.3, breadth 0.15.

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

3. _Spongurus phalanga_, Haeckel.

_Spongurus cylindricus_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 119,
Taf. vii. fig. 3.

Shell nearly cylindrical, five times as long as broad, with thorny surface. Spongy framework compact, everywhere of equal structure, with small meshes, scarcely broader than the bars.

{344}_Dimensions._--Length of the shell 0.24, breadth 0.05.

_Habitat._--Pacific, central area, Station 268, depth 2600 fathoms; fossil in the Tertiary rocks of Sicily, Stöhr.

Subgenus 2. _Spongurella_, Haeckel.

_Definition._--Spongy framework everywhere of the same structure; surface armed with radial spines.

4. _Spongurus asper_, Haeckel.

_Haliomma asperum_, Joh. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 40, Taf. ii. fig. 2.

_Haliomma asperum_, Haeckel, 1862, Monogr. d. Radiol., p. 431.

Shell ellipsoidal, one and a third times as long as broad, with thorny surface and twenty symmetrically disposed, thin, bristle-shaped, radial spines, about as long as the shell. Spongy framework everywhere of the same structure, very compact, with small meshes, three to four times as broad as the bars.

_Dimensions._--Length of the shell 0.11, breadth 0.08.

_Habitat._--Mediterranean, Ligurian coast (J. Müller), Portofino (Haeckel).

5. _Spongurus cylindricus_, Haeckel.

_Spongurus cylindricus_, Haeckel, 1862, Monogr. d. Radiol., p. 465, Taf.
xxvii. fig. 1.

Shell cylindrical, four to five times as long as broad, with nearly smooth surface, and twenty to thirty thin, bristle-shaped, radial spines, about half as long as the shell. Spongy framework everywhere of the same structure, very compact, with small meshes, scarcely broader than the bars.

_Dimensions._--Length of the shell 0.2, breadth 0.04 to 0.05.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, and Pacific, surface.

6. _Spongurus tricolus_, n. sp.

Shell nearly cylindrical, with two slight annular transverse strictures; its middle part is somewhat broader. Surface thorny, with numerous (forty to sixty or more) short, thin, radial spines, not longer than the breadth of the shell. Spongy framework everywhere of the same structure, compact, with small meshes, twice to three times as broad as the bars.

_Dimensions._--Length of the shell 0.24, breadth 0.04 to 0.06.

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

Subgenus 3. _Sponguroma_, Haeckel.

_Definition._--Spongy framework in the inner part of the shell very compact, in the outer part very loose; surface armed with radial spines.

{345}7. _Spongurus radians_, n. sp.

Shell ellipsoidal, one and a half times as long as broad, with thorny surface, and eighty to one hundred and twenty (or more) thin, bristle-shaped, radial spines, somewhat longer than the shell. Spongy framework in the inner part very compact, in the outer part very loose, with a gradual transition between the two parts. Meshes in the central part not broader than the bars, in the superficial part ten to twenty times as broad.

_Dimensions._--Length of the shell 0.24, breadth 0.16.

_Habitat._--Mediterranean, Portofino, near Genoa, Haeckel, surface.

8. _Spongurus spongechinus_, n. sp.

Shell ellipsoidal, one and a third times as long as broad, with thorny surface, and thirty to forty thick, conical radial spines, about half as long as the shell. Spongy framework in the inner part of the shell compact, in the outer loose, with a gradual transition between the two parts. Meshes in the central part smaller than the bars, in the superficial part four to eight times as broad.

_Dimensions._--Length of the shell 0.18, breadth 0.14.

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

Genus 146. _Spongocore_,[185] n. gen.

_Definition._--#Spongurida# with ellipsoidal or cylindrical (sometimes three-jointed) shell of solid spongy framework, without internal cavity and without latticed medullary shell. Polar spines absent. An outer lattice-mantle is connected with the spongy shell by radial beams.

The genus _Spongocore_ contains some widely distributed Spongurida, which are distinguished from the nearly related _Spongurus_ by the development of a peculiar veil or mantle of delicate lattice-work, which envelops either the whole shell or only the middle part of it, and is connected with it by numerous radial beams. The distance of the simple fine lattice-lamella from the spongy shell is everywhere the same. Often the cylindrical shell is three-jointed, with two annular strictures, as also in the foregoing _Spongurus._ It is derived from the latter by development of the veil connecting the points of the radial spines.

Subgenus 1. _Spongocorina_, Haeckel.

_Definition._--Shell without distinct annular strictures, not evidently three-jointed.

{346}1. _Spongocore velata_, n. sp.

Shell ellipsoidal, one and a half times as long as broad, without annular strictures. Spongy framework loose, with rather large meshes, four to six times as broad as the bars. The whole spongy shell enveloped by a delicate veil with smooth surface, connected with it by numerous thin radial beams. Breadth of the spongy ellipsoid (or minor axis) six times as large as its distance from the veil.

_Dimensions._--Length of the whole shell (with veil) 0.3, breadth 0.2; distance of the veil from the spongy ellipsoid 0.035.

_Habitat._--South Atlantic, Station 325, surface.

2. _Spongocore diplocylindrica_, n. sp.

Shell cylindrical, three times as long as broad, without annular strictures. Spongy framework compact, with small meshes, twice to three times as broad as the bars. The whole surface of the spongy cylinder, with exception of both rounded polar faces, enveloped by a delicate cylindrical veil with smooth surface, connected with it by numerous radial beams. Diameter of the spongy cylinder twice as large as its distance from the veil.

_Dimensions._--Length of the shell 0.3, breadth (with veil) 0.1; distance of the veil 0.025.

_Habitat._--South Pacific, Station 302, surface.

Subgenus 2. _Spongocorisca_, Haeckel.

_Definition._--Shell distinctly three-jointed, with two transverse annular strictures.

3. _Spongocore chrysalis_, n. sp.

Spongy shell cylindrical, without the veil six times as long as broad, three-jointed, with two annular strictures; all three joints of the same length. The whole spongy shell enveloped by a thin veil with thorny surface, connected with it by numerous radial beams. Breadth of the spongy cylinder three times as large as its distance from the veil.

_Dimensions._--Length of the shell (with veil) 0.4, breadth 0.1; distance of the veil from the spongy shell 0.02.

_Habitat._--South Atlantic (off Patagonia), Station 318, surface.

4. _Spongocore cincta_, n. sp.

Spongy shell cylindrical, without the veil four times as long as broad, three-jointed, with two annular strictures; all three joints of the same length. Only the middle joint enveloped by a thin veil with smooth surface, connected with it by radial beams. Both terminal joints with long, {347}bristle-shaped, radial spines. Breadth of the spongy cylinder twice as large as its distance from the veil.

_Dimensions._--Length of the shell 0.24, breadth (with veil) 0.12; distance of the veil 0.03.

_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.

5. _Spongocore pupula_, n. sp.

Spongy shell cylindrical, without the veil six times as long as broad, three-jointed, with two annular strictures; the middle joint half as long as either terminal joint. Only the middle joint enveloped by a thin veil with spiny surface, connected with it by twenty to thirty radial beams, which are prolonged on the outside into short radial spines. Breadth of the spongy cylinder about equal to its distance from the veil.

_Dimensions._--Length of the shell 0.2, breadth (with veil) 0.1; distance of the veil 0.033.

_Habitat._--North Pacific, Station 244, surface.

6. _Spongocore puella_, n. sp. (Pl. 48, fig. 6).

Spongy shell cylindrical, without the veil five times as long as broad, three-jointed, with two annular strictures; the middle joint twice as long as either terminal joint. Only the middle joint enveloped by a thin veil with delicate lattice-work and smooth surface; both terminal joints armed with numerous thin, bristle-shaped, radial spines. Breadth of the spongy cylinder twice as large as the distance from the veil.

_Dimensions._--Length of the shell 0.25 to 0.3, breadth (with veil) 0.1 to 0.12; distance of the veil 0.028 to 0.032.

_Habitat._--South Pacific, Stations 295 to 304, surface.

Genus 147. _Spongoprunum_,[186] n. gen.

_Definition._--#Spongurida# with ellipsoidal or cylindrical shell of solid spongy framework, without internal cavity and without latticed medullary shell. On the poles of the axis occur two opposite strong spines.

The genus _Spongoprunum_ differs from the most nearly allied _Spongurus_ by the possession of two strong solid spines, lying in the axis of the ellipsoidal or cylindrical massive spongy shell, on its two opposite poles. _Spongoprunum_ bears therefore the same relation to _Spongurus_ that _Ellipsoxiphus_ does to _Cenellipsis_.

1. _Spongoprunum amphilonche_, n. sp. (Pl. 48, fig. 7).

Shell ellipsoidal, two and a third times as long as broad, with nearly smooth surface. Spongy framework very compact, in the whole solid shell of the same structure, with very small meshes, {348}scarcely broader than the bars. Two polar spines conical, very strong, about half as long as the main axis of the shell and three times as long as broad.

_Dimensions._--Length of the shell (without spines) 0.2, breadth 0.08.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; fossil in the rocks of Barbados.

2. _Spongoprunum atractus_, n. sp.

Shell spindle-shaped, twice as long as broad, with thorny surface. Spongy framework loose, in the whole shell of the same structure, with large meshes, eight to twelve times as broad as the bars. Two polar spines angular, pyramidal, very strong, about one-third as long as the shell, and twice as long as broad.

_Dimensions._--Length of the shell 0.2, breadth 0.11.

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

3. _Spongoprunum amphicylindrus_, n. sp.

Shell nearly cylindrical, four times as long as broad, with rough surface. Spongy framework compact, in the whole shell of equal structure, with small meshes, twice to three times as broad as the bars. Two polar spines cylindrical, very large, longer than the shell, and about one-fourth as thick as its diameter.

_Dimensions._--Length of the shell 0.2, breadth 0.05.

_Habitat._--South Atlantic, Station 333, surface.

Subfamily SPONGODRUPPIDA, Haeckel.

_Definition._--#Spongurida# with latticed medullary shell, enclosed by a spongy cortical shell.

Genus 148. _Spongodruppa_,[187] n. gen.

_Definition._--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a simple, spherical or ellipsoidal, latticed medullary shell. Polar spines absent.

The genus _Spongodruppa_ opens the series of Spongodruppida, or of those Spongurida in which the ellipsoidal spongy cortical shell encloses a simple or double, latticed, medullary shell. In _Spongodruppa_, the simplest and probably the ancestral form of this subfamily, the medullary shell is simple and the polar spines absent. It may be derived from _Druppula_ by a spongy thickening of the simple latticed cortical shell.

{349}Subgenus 1. _Spongodruppula_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial spines.

1. _Spongodruppa terebintha_, n. sp.

Cortical shell one and a third times as long as broad, with smooth surface, three times as broad as the spherical medullary shell. Spongy framework very compact, with small meshes of the same breadth as the bars. Thickness of the spongy wall equal to the radius of the medullary shell.

_Dimensions._--Length of the cortical shell (or major axis of the ellipsoid) 0.16, breadth (or minor axis) 0.12; thickness of its wall 0.02; medullary shell 0.04.

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

2. _Spongodruppa pistacia_, n. sp.

Cortical shell one and a half times as long as broad, with thorny surface, nearly five times as broad as the spherical medullary shell. Spongy framework compact, its thickness equal to the diameter of the medullary shell.

_Dimensions._--Length of the cortical shell 0.2, breadth 0.14; thickness of its wall 0.03; medullary shell 0.03.

_Habitat._--Fossil in the rocks of Barbados.

3. _Spongodruppa lentisca_, n. sp.

Cortical shell twice as long as broad, with rough surface, four times as large as the ellipsoidal medullary shell. Spongy framework loose, with large meshes, its thickness equal to the length of the medullary shell.

_Dimensions._--Length of the cortical shell 0.25, breadth 0.13; thickness of its wall 0.06; length of the medullary shell 0.06, breadth 0.04.

_Habitat._--Pacific, central area, Station 266, surface.

Subgenus 2. _Spongodruppium_, Haeckel.

_Definition._--Surface of the shell armed with radial spines.

4. _Spongodruppa frangula_, n. sp.

Cortical shell one and a third times as long as broad, three times as broad as the spherical medullary shell. Spongy framework loose, with large meshes, its thickness half as large as the diameter of the medullary shell. Surface covered with numerous (forty to fifty) thin, bristle-shaped, radial spines, about as long as the cortical shell.

{350}_Dimensions._--Length of the cortical shell 0.24, breadth 0.18; thickness of its wall 0.035; diameter of the medullary shell 0.06.

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

5. _Spongodruppa elliptica_, Haeckel.

_Acanthosphæra elliptica_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 285, Taf. vii. fig. 4.

Cortical shell nearly twice as long as broad, four times as broad as the ellipsoidal medullary shell. Spongy framework compact, with small meshes. Surface covered with very numerous short radial spines, about as long as the medullary shell.

_Dimensions._--Length of the cortical shell 0.2, breadth 0.11; length of the medullary shell 0.04, breadth 0.03.

_Habitat._--Philippine Sea, Ehrenberg, Station 206, depth 2100 fathoms.

6. _Spongodruppa polyacantha_, Haeckel.

_Haliomma polyacanthum_, J. Müller, 1858, Abhandl., p. 36, Taf. i. figs.
10, 11.

_Haliomma polyacanthum_, Haeckel, 1862, Monogr. d. Radiol., p. 430.

Cortical shell one and a third times as long as broad, twice as broad as the ellipsoidal medullary shell. Spongy framework loose on the surface, with large regular meshes. Surface covered with fifteen to twenty thick, conical spines, about as long as the radius of the shell.

_Dimensions._--Length of the cortical shell 0.12, of the medullary shell 0.09; diameter of the medullary shell 0.05 to 0.06.

_Habitat._--Mediterranean (south coast of France); Atlantic (Canary Islands), Station 354, surface.

Genus 149. _Spongatractus_,[188] n. gen.

_Definition._--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a simple, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur two opposite strong spines.

The genus _Spongatractus_ differs from _Spongodruppa_ by development of two strong spines in the axis of the shell, on its two opposite poles; therefore it bears the same relation to the latter that _Lithatractus_ does to _Druppula_, and can be derived from _Lithatractus_ by a spongy thickening of the cortical shell.

1. _Spongatractus pachystylus_, Haeckel.

_Spongosphæra pachystyla_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 82, Taf. xxvi. fig. 3.

Cortical shell one and a half times as long as broad, with rough surface. Spongy framework compact, with small meshes, about as thick as the spherical medullary shell. Polar spines very {351}stout, conical, slightly sulcated, about as long as the breadth of the cortical shell, as broad at the base as the medullary shell.

_Dimensions._--Length of the cortical shell 0.2, breadth 0.13; thickness of the spongy wall 0.045; diameter of the medullary shell 0.04.

_Habitat._--Fossil in the rocks of Barbados, Ehrenberg; living in the Equatorial Atlantic, Station 348, depth (2450) fathoms.

2. _Spongatractus fusiformis_, n. sp.

Cortical shell one and a third times as long as broad, with nearly smooth surface. Spongy framework very compact, with very small meshes, about as thick as the radius of the spherical medullary shell. Polar spines very strong, three-sided pyramidal, about as long as the breadth of the cortical shell, as broad at the base as the medullary shell.

_Dimensions._--Length of the cortical shell 0.16 to 0.18, breadth 0.12 to 0.14; thickness of the spongy wall 0.02; diameter of the medullary shell 0.04.

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

3. _Spongatractus streptacanthus_, n. sp.

Cortical shell twice as long as broad, with thorny surface. Spongy framework loose, with large meshes, about as thick as the ellipsoidal medullary shell. Polar spines very long, three-sided prismatic, with three spirally contorted edges, much longer than the cortical shell, half as broad as the medullary shell.

_Dimensions._--Length of the cortical shell 0.25, breadth 0.13; thickness of the spongy wall 0.03; diameter of the medullary shell 0.03 to 0.04.

_Habitat._--North Atlantic, off Canary Islands, Haeckel.

Genus 150. _Spongoliva_,[189] n. gen.

_Definition._--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a double, spherical or ellipsoidal, latticed medullary shell. Polar spines absent.

The genus _Spongoliva_ differs from the nearest _Spongodruppa_ by duplication of the medullary shell; it bears therefore the same relation to this that _Prunulum_ does to _Druppula_, and can be regarded as a _Prunulum_, in which the simple latticed cortical shell is replaced by a spongy framework.

Subgenus 1. _Spongolivetta_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial spines.

{352}1. _Spongoliva cerasina_, n. sp.

Cortical shell one and a fourth times as long as broad, with smooth surface, four times as broad as the outer spherical medullary shell. Spongy framework very compact, with very small meshes, its thickness equal to the diameter of the outer medullary shell.

_Dimensions._--Length of the cortical shell 0.2, breadth 0.16; thickness of its wall 0.04; diameter of the outer medullary shell 0.04, of the inner 0.014.

_Habitat._--Fossil in the rocks of Barbados.

2. _Spongoliva prunulina_, n. sp.

Cortical shell one and a third times as long as broad, with smooth surface, three times as large as the outer ellipsoidal medullary shell. Spongy framework very compact, with small meshes, its thickness equal to the diameter of the inner medullary shell.

_Dimensions._--Length of the cortical shell 0.24, breadth 0.18; thickness of its wall 0.03; size of the outer medullary shell 0.08 to 0.06, of the inner 0.03.

_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.

3. _Spongoliva persicina_, n. sp.

Cortical shell one and a half times as long as broad, with rough surface, five to six times as large as the ellipsoidal outer medullary shell. Spongy framework loose, with large meshes, its thickness about equal to the outer medullary shell.

_Dimensions._--Length of the cortical shell 0.26, breadth 0.18; thickness of its wall 0.04; size of the outer medullary shell 0.045 to 0.035, of the inner 0.015.

_Habitat._--Equatorial Atlantic, Station 348, depth (2450) fathoms.

4. _Spongoliva amygdalina_, n. sp.

Cortical shell twice as long as broad, with thorny surface, ten times as long as the small spherical outer medullary shell. Spongy framework loose, with large meshes, its thickness one and a half times as large as the outer medullary shell.

_Dimensions._--Length of the cortical shell 0.3, breadth 0.16; thickness of its wall 0.045; size of the outer medullary shell 0.03, of the inner 0.015.

_Habitat._--Fossil in the Tertiary rocks of Sicily (Caltanisetta).

Subgenus 2. _Spongolivina_, Haeckel.

_Definition._--Surface of the shell armed with radial spines.

5. _Spongoliva opuntina_, n. sp.

Cortical shell one and a third times as long as broad, armed with numerous thin, bristle-shaped, radial spines, nearly as long as the shell. Spongy framework loose, with large meshes, its thickness nearly equal to the diameter of the outer spherical medullary shell.

{353}_Dimensions._--Length of the cortical shell 0.18, breadth 0.14; thickness of its wall 0.035; diameter of the outer medullary shell 0.04, of the inner 0.02.

_Habitat._--South Atlantic, Station 325, surface.

6. _Spongoliva daturina_, n. sp.

Cortical shell one and a half times as long as broad, armed with numerous, thick and short, conical radial spines, about as long as the outer medullary shell. Spongy framework compact, with small meshes, its thickness equal to half the length of the outer ellipsoidal medullary shell.

_Dimensions._--Length of the cortical shell 0.24, breadth 0.16; thickness of its wall 0.025; diameter of the outer medullary shell 0.045 to 0.035, of the inner 0.025.

_Habitat._--Pacific, central area, Station 272, surface.

Genus 151. _Spongoxiphus_,[190] n. gen.

_Definition._--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a double, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur two opposite strong spines.

The genus _Spongoxiphus_ differs from _Spongoliva_ by the development of two strong spines in the axis of the shell, on its two opposite poles. From the similar _Spongatractus_ it differs in the duplication of the medullary shell. It may also be regarded as a _Stylatractus_, in which the simple latticed cortical shell is replaced by an irregular spongy framework.

1. _Spongoxiphus sphærococcus_, n. sp.

Cortical shell one and a half times as long as broad, with thorny surface. Spongy framework compact, with small meshes, its thickness equal to the radius of the outer medullary shell. Both medullary shells spherical, the outer three times as broad as the inner. Polar spines very stout, conical, slightly sulcated, about half as long as the cortical shell, as broad at the base as the outer medullary shell. (Differs from _Spongatractus pachystylus_ almost only in the double medullary shell.)

_Dimensions._--Length of the cortical shell 0.18, breadth 0.12; thickness of the spongy wall 0.025; diameter of the outer medullary shell 0.05, of the inner 0.016.

_Habitat._--Fossil in the rocks of Barbados (Haeckel); also living in the Pacific, central area, Station 265, depth 2900 fathoms.

{354}2. _Spongoxiphus prunococcus_, n. sp. (Pl. 17, figs. 12, 13).

_Spongostylus prunococcus_, Haeckel, 1881, Prodromus, p. 455, et Atlas,
pl. xvii. figs. 12, 13.

Cortical shell one and a third times as long as broad, with smooth surface. Spongy framework very compact, with very small meshes, its thickness about equals the breadth of the outer medullary shell. Both medullary shells ellipsoidal, the outer three times as large as the inner. Polar spines very stout, three-sided pyramidal, about half as long as the cortical shell, on the base about as broad as the outer medullary shell. (Differs from the preceding in the ellipsoidal form of both medullary shells, and in the finer structure of the spongy framework.)

_Dimensions._--Length of the cortical shell 0.18 to 0.2, breadth 0.14 to 0.16; thickness of the spongy wall 0.035 to 0.04; length of the outer medullary shell 0.04 to 0.06, breadth 0.03 to 0.04.

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

Family XIV. #ARTISCIDA#, Haeckel (Pl. 39, figs. 9, 10; Pl. 48, fig. 5).

_Artiscida_, Haeckel, 1881, Prodromus, p. 462.

_Definition._--#Prunoidea# with an ellipsoidal twin-shell divided by an equatorial stricture into two communicating hemiellipsoidal or hemispherical chambers, without enclosed medullary shell. Central capsule ellipsoidal, with or without equatorial stricture.

The family #Artiscida# has a simple fenestrated outer shell, like that of the Ellipsida, but differs from these in the presence of an equatorial constriction, by which it assumes a characteristic twin form, somewhat similar to a violin (Pl. 39, figs. 9, 10). From the Cyphinida, which have the same form of the cortical shell, the Artiscida differ in the absence of the medullary shell. It is possible that the Artiscida are descended from the Cyphinida (by loss of the medullary shell), but it is more probable that they arise from the Ellipsida by an annular constriction in the equatorial plane (perhaps the formation of the shell originally took place while the central capsule was undergoing division). Both halves of the twin shell are always of the same size and form. Its outer surface is either smooth or covered with radial spines (_Artiscus_, Pl. 39, fig. 9). Sometimes on the opposite poles of the main axis are developed solid spines (_Stylartus_, Pl. 48, fig. 5) or hollow fenestrated tubes (_Cannartus_, Pl. 39, fig. 10).

_The Central Capsule_ is either simply ellipsoidal, or has also an equatorial constriction, which divides it into two equal halves. It is constantly smaller than the surrounding shell, and separated from its inner surface by a thicker or thinner jelly-mantle, the calymma.

_Synopsis of the Genera of Artiscida._

On the poles of the main axis neither solid spines
nor hollow tubes, 152. _Artiscus_.

On the poles of the main axis two solid spines (or
bunches of spines), 153. _Stylartus_.

On the poles of the main axis two hollow fenestrated
tubes, 154. _Cannartus_.

{355}Genus 152. _Artiscus_,[191] Haeckel, 1881, Prodromus, p. 462.

_Definition._--#Artiscida# without peculiar polar appendages (without strong solid spines or hollow fenestrated tubes on the poles of the main axis).

The genus _Artiscus_ represents the most simple and primitive form of the Artiscida, and may therefore be regarded as the ancestral form of this subfamily. It resembles an ordinary double loaf, composed of two equal, nearly ellipsoidal fenestrated shells separated by the stricture in the equatorial plane. _Artiscus_ can be derived from _Cenellipsis_ simply by this equatorial constriction. But it can also be derived from _Cyphanta_ by loss of the medullary shell.

Subgenus 1. _Artiscium_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial rods or spines.

1. _Artiscus paniscus_, n. sp.

Pores of the shell regular, hexagonal, four times as broad as the bars; ten to twelve pores on the half meridian, eight to nine on the half equator. Surface smooth. (The network of this species is quite the same as that of the proximal cameræ of _Panartus diploconus_, Pl. 40, fig. 1.)

_Dimensions._--Main axis of the shell 0.12, equatorial axis 0.07; meshes 0.013, bars 0.003.

_Habitat._--Pacific, central area, Station 271, depth 2425.

2. _Artiscus facetus_, n. sp.

Pores of the shell regular, circular, with prominent hexagonal frame, twice as broad as the bars; twenty-two to twenty-four pores on the half meridian, fourteen to fifteen on the half equator. Surface a little thorny. (The shell of this species exhibits nearly the same formation as that of _Cyphonium virgineum_, Pl. 39, fig. 12, but without enclosed medullary shells.)

_Dimensions._--Main axis of the shell 0.15, equatorial axis 0.09; meshes 0.01, bars 0.005.

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

3. _Artiscus paniculus_, n. sp.

Pores of the shell regular, circular, without hexagonal frame, as broad as the bars; fourteen to sixteen pores on the half meridian, ten to eleven on the half equator. Surface quite smooth.

_Dimensions._--Main axis of the shell 0.13, equatorial axis 0.06; meshes 0.01, bars 0.01.

_Habitat._--Fossil in the Tertiary rocks of Barbados (Haeckel).

{356}4. _Artiscus panarius_, n. sp.

Pores of the shell irregular, roundish, twice to four times as broad as the bars; sixteen to eighteen pores on the half meridian, twelve to thirteen on the half equator. Surface smooth.

_Dimensions._--Main axis of the shell 0.11, equatorial axis 0.06; meshes 0.005 to 0.02, bars 0.001 to 0.004.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.

Subgenus 2. _Artidium_, Haeckel, 1881, Prodromus, p. 462.

_Definition._--Surface of the shell covered with radial rods or spines.

5. _Artiscus elegans_, n. sp.

Pores of the shell regular, circular, with hexagonal frames, twice as broad as the bars; fourteen pores on the half meridian, eight to nine on the half equator. From every corner of the hexagonal frames (between every three pores) starts a thin, three-sided pyramidal spine, twice as large as a pore.

_Dimensions._--Main axis 0.13, equatorial axis 0.08; meshes 0.007, bars 0.004; spines 0.015 long.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

6. _Artiscus nodosus_, n. sp. (Pl. 39, fig. 9).

Pores of the shell subregular, circular, without hexagonal frame, three times as broad as the bars; sixteen to eighteen on the half meridian, ten to twelve on the half equator. Irregularly scattered on the whole surface a variable number (twenty-five to thirty in all) of stout short radial spines or rather blunt rods; the length and thickness of these is the same, and equals the size of two to three meshes; its form resembles a truncated six-sided pyramid.

_Dimensions._--Main axis 0.11, equatorial axis 0.08; meshes 0.01, bars 0.003; length and thickness of the radial sticks 0.02.

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

7. _Artiscus hystrix_, n. sp.

Pores of the shell irregular, roundish, of very unequal size and dissimilar form, twice to eight times as broad as the bars; ten to fifteen on the half meridian, seven to nine on the half equator. Irregularly scattered on the whole surface a large number of thin conical spines, about as large as the meshes, partly directed radially, partly obliquely. (The shell of this species resembles very much that of _Cyphonium ceratospyris_ (p. 366) = _Didymocyrtis ceratospyris_, Monogr. d. Radiol., 1862, Taf. xxii. fig. 14, but is without the enclosed inner shells.)

{357}_Dimensions._--Main axis 0.12, equatorial axis 0.07; meshes 0.004 to 0.02, bars 0.002 to 0.005; spines 0.01 to 0.02.

_Habitat._--Atlantic, Eastern Tropical part, Station 346, surface.

Genus 153. _Stylartus_,[192] Haeckel, 1881, Prodromus, p. 462.

_Definition._--#Artiscida# with two strong, solid, polar spines, or two bunches of polar spines, opposite on the two poles of the main axis.

The genus _Stylartus_ differs from _Artiscus_ by the production of two large opposite spines in the main axis, starting from both poles of it; sometimes every spine is surrounded by a group of smaller radial spines. The genus is nearly allied to _Ellipsoxiphus_ (p. 295), and differs from it only in the equatorial stricture of the ellipsoidal shell. But it may also be derived from the similar _Cyphinus_ (Pl. 39, fig. 14) by loss of the medullary shell.

Subgenus 1. _Stylartella_, Haeckel.

_Definition._--On each pole of the main axis only one single large spine.

1. _Stylartus bipolaris_, n. sp. (Pl. 48, fig. 5).

Shell thick walled, rough; both its chambers nearly spherical, with irregular, roundish pores, twice to four times as broad as the bars; eight to ten on the half equator of each chamber. Polar spines very strong, conical, as long as the greatest breadth.

_Dimensions._--Length of the shell (without spines) 0.18, greatest breadth 0.13; length of the polar spines 0.13, basal breadth 0.03.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.

2. _Stylartus bicuspis_, n. sp.

Shell thin walled, smooth, with regular, circular pores, twice as broad as the bars; twelve to fourteen on the half equator of each chamber. Polar spines very stout, straight, three-sided pyramidal, half as long as the shell.

_Dimensions._--Length of the shell 0.16, greatest breadth 0.12; length of the polar spines 0.08, basal thickness 0.025.

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

Subgenus 2. _Stylartura_, Haeckel.

_Definition._--On each pole of the main axis a bunch of several spines.

{358}3. _Stylartus palatus_, n. sp.

Shell thick walled, thorny, with irregular, roundish pores, twice to three times as broad as the bars; fifteen to eighteen on the half equator of each chamber. On each pole of the main axis a large conical spine, surrounded by a group of ten to fifteen smaller spines, one-third to two-thirds as long as the breadth of the deep equatorial stricture.

_Dimensions._--Length of the shell 0.14, greatest breadth 0.09; length of the polar spines 0.03 to 0.06, basal breadth 0.005 to 0.015.

_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.

4. _Stylartus penicillus_, n. sp.

Shell thin walled, smooth, with irregular, roundish pores, three to four times as broad as the bars; ten to twelve on the half equator of each chamber. On each pole of the main axis a brush-like bunch of twenty to thirty thin conical radial spines, half as long as the shell.

_Dimensions._--Length of the shell 0.15, greatest breadth 0.1; length of the polar spines 0.08, basal breadth 0.005.

_Habitat._--Equatorial Atlantic, Station 347, surface.

Genus 154. _Cannartus_,[193] Haeckel, 1881, Prodromus, p. 462.

_Definition._--#Artiscida# with two hollow polar tubes (fenestrated cylindrical or conical tubuli, opposite on the two poles of the main axis).

The genus _Cannartus_ differs from _Artiscus_ by the production of two opposite hollow tubes on both poles of the main axis. The cavity of the conical or cylindrical fenestrated tubes communicates freely with that of the shell; the network in both is the same. The distal end of the tubes is nearly always broken off, sometimes closed, with a conical apex. _Cannartus_ can be derived either from _Pipettella_ by a transverse equatorial constriction, or from _Cannartiscus_ by the loss of the medullary shell, or from _Artiscus_ by the production of the polar tubes.

1. _Cannartus violina_, n. sp. (Pl. 39, fig. 10).

Pores of the shell subregular, circular, twice to three times as broad as the bars; eighteen to twenty on the half meridian, fourteen to sixteen on the half equator. Shell-wall in the "tropical zone" of both halves thickened. Polar tubes nearly cylindrical, about as long as the main axis, distal ends broken off.

_Dimensions._--Main axis 0.14, equatorial axis 0.09; meshes 0.008, bars 0.003; length of the polar tubes 0.12, breadth 0.02 to 0.03.

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

{359}2. _Cannartus bitubulus_, n. sp.

Pores of the shell regular, circular, hexagonally framed, of the same breadth as the bars; fourteen to sixteen on the half meridian, ten to twelve on the half equator. Polar tubes cylindrical, longer than the main axis, sulcated, distal ends broken off. (Similar to _Pipetta tuba_, Pl. 39, fig. 7, but with equatorial stricture and without medullary shell.)

_Dimensions._--Main axis 0.16, equatorial axis 0.12; meshes and bars 0.006; length of the polar tubes 0.2, breadth 0.025.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

3. _Cannartus biscottus_, n. sp.

Pores of the shell irregular, roundish, twice to three times as broad as the bars; ten to twelve on the half meridian, six to eight on the half equator. Polar tubes conical, shorter than the main axis, with closed apex. (Similar to _Cannartidium bicinctum_, Pl. 39, fig. 18, but without enclosed medullary shell.)

_Dimensions._--Main axis 0.11, equatorial axis 0.07; meshes 0.005 to 0.01, bars 0.003; length of the polar tubes 0.08, breadth on the base 0.03.

_Habitat._--Equatorial Atlantic, Station 348, depth 2450 fathoms.

Family XV. #CYPHINIDA#, Haeckel (Pl. 39, figs. 11-19).

_Cyphinida_, Haeckel, 1881, Prodromus, p. 462.

_Definition._--#Prunoidea# with ellipsoidal twin-shell, divided by an equatorial stricture into two communicating hemiellipsoidal or hemispherical chambers; this external twin-shell (cortical shell) is either simple or double, and encloses one or more internal concentric shells (medullary shells). Central capsule ellipsoidal, commonly with an equatorial constriction.

The family #Cyphinida# have the same characteristic twin-form of the cortical shell as the Artiscida, but differ from them in the presence of a simple or double internal medullary shell, connected with the cortical shell by radial beams. The fenestrated shell is therefore composed of two or more concentric shells as in the Druppulida, but differs from these in the ring-like equatorial constriction.

_The Medullary Shell_, in the middle of the central capsule, is either single or double, composed of two concentric shells. As in the Druppulida, the form of the medullary shells is either spherical (Pl. 39, fig. 12_a_) or lenticular, compressed from both poles of the main axis (Pl. 39, fig. 18_a_); sometimes the inner medullary shell is spherical, the outer lenticular.

_The Radial Beams_, which connect the medullary shell with the equatorial constriction of the cortical shell, lie either all in the equatorial plane (Pl. 39, fig. 11) or near it on both sides (Pl. 39, figs. 12_a_, 18_a_).

{360}The _Cortical Shell_ is commonly simple (Pl. 39, figs. 12, 18), sometimes composed of two concentric shells (Pl. 39, fig. 13), rarely of three. As in the Artiscida, also in the Cyphinida, from both poles of the main axis solid spines or hollow fenestrated tubes are often developed (Pl. 39, figs. 14, 16-18).

_The Central Capsule_ of the Cyphinida (Pl. 39, fig. 13) is of the same form as in the Artiscida, generally ellipsoidal, but with an equatorial ring-like stricture, which divides it into two equal halves. It encloses the simple or double medullary shell, and is perforated by the radial beams starting from this. From the inner surface of the surrounding cortical shell it is separated by a thicker or thinner jelly-layer, the calymma. (Compare also Taf. xxii. fig. 14 of my Monograph, 1862.)

_Synopsis of the Genera of Cyphinida._

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Cortical shell without peculiar spines or hollow fenestrated tubes on
both poles of the main axis.
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Cortical twin- {Medullary shell
shell simple { simple, 155. _Cyphanta_.
{
{Medullary shell
{ double, 156. _Cyphonium_.

Cortical twin- {Cortical shell
shell double { double, 157. _Cypassis_.
or triple; {
medullary {Cortical shell
shell double. { triple, 158. _Cyphocolpus_.
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Cortical shell simple, with peculiar spines or hollow fenestrated tubes
on both poles of the main axis.
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Two opposite {Medullary shell
polar spines { simple, 159. _Cyphinus_.
(or bunches {
of spines). {Medullary shell
{ double, 160. _Cyphinidium_.

Two opposite {Medullary shell
hollow { simple, 161. _Cannartiscus_.
fenestrated {
polar tubes. {Medullary shell
{ double, 162. _Cannartidium_.

Genus 155. _Cyphanta_,[194] n. gen.

_Definition._--#Cyphinida# with simple cortical shell and simple medullary shell, without polar spines or tubes.

The genus _Cyphanta_ is the most simple of all Cyphinida, and can be regarded as the common ancestral form of this family. It may be derived phylogenetically from _Druppula_ by a ring-like constriction in the equatorial plane of the ellipsoidal cortical shell, or from _Artiscus_ by secondary formation of a central (spherical or ellipsoidal) medullary shell.

Subgenus 1. _Cyphantella_, Haeckel.

_Definition._--Surface of the cortical shell smooth, without spines or thorns.

{361}1. _Cyphanta colpodes_, n. sp.