All four chambers in each cortical shell nearly equal, subregular. Surface
smooth, without radial spines. Structure of the network in both shells
similar. Pores regular, circular, twice as broad as the bars; six to eight
in the basal semicircle of one inner, ten to twelve in the semicircle of
one outer cupola.
_Dimensions._--Diameter of the outer shell 0.14, of the inner 0.09; pores
0.006, bars 0.003.
_Habitat._--South Pacific, Station 302, surface.
Subgenus 2. _Tholomura_, Haeckel.
_Definition._--Surface of the shell with radial spines.
2. _Tholoma metallasson_,[334] n. sp. (Pl. 10, fig. 13).
Two opposite chambers in each cortical shell larger than the two others;
the larger chambers of the inner shell corresponding to the smaller
chambers of the outer shell. Network in both shells of the same structure,
regular, with circular, hexagonally framed pores of the same breadth as the
bars; eight to ten in the semicircle of an inner, fourteen to sixteen in
the semicircle of an outer cupola. Numerous (twenty to thirty or more)
thin, cylindrical, bristle-shaped, long radial spines, symmetrically
disposed.
_Dimensions._--Major axis of the outer shell 0.26, minor axis 0.2; major
axis of the inner shell 0.16, minor axis 0.13; pores and bars 0.006.
_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.
Genus 295. _Staurotholus_,[335] n. gen.
_Definition._--#Tholonida# with simple cortical shell (without external
veil), composed of four hemispherical cupolas in cross-form, opposite in
pairs on the poles of {673}two axes perpendicular one to another; central
chamber _Larnacilla_-shaped (with enclosed medullary shell).
The genus _Staurotholus_ differs from _Tholostaurus_ in the possession of a
medullary shell in the central chamber, and may be derived from this genus
by its production. But it may also be derived from _Amphitholus_ by
apposition of two secondary opposite cupolas between the two primary
cupolas. The symmetrical position of an increasing number of radial spines
in the different species is remarkable (resembling _Tholostaurus_ as well
as _Amphitholus_).
Subgenus 1. _Staurotholissa_, Haeckel.
_Definition._--Surface of the shell smooth or rough, without radial spines.
1. _Staurotholus quadratus_, n. sp.
Surface of the cortical shell smooth. All four cupolas nearly of the same
size and form; therefore principal and lateral axes equal. Pores regular,
circular, with hexagonal frames, twice as broad as the bars; eight to ten
on the basal semicircle of one cupola. Medullary shell square.
_Dimensions._--Diameter of the cortical shell 0.15; pores 0.01, bars 0.005.
_Habitat._--South Atlantic, Station 323, depth 1900 fathoms.
2. _Staurotholus cruciatus_, n. sp.
Surface of the cortical shell rough. The two principal cupolas somewhat
larger than the two lateral cupolas; therefore the longitudinal axis longer
than the transverse. Pores irregular, roundish, twice to three times as
broad as the bars; twelve to sixteen in the semicircle of one cupola.
_Dimensions._--Major axis of the shell 0.16, minor 0.13; pores 0.005 to
0.009, bars 0.003.
_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.
Subgenus 2. _Staurotholura_, Haeckel.
_Definition._--Surface of the shell with radial spines.
3. _Staurotholus tetrastylus_, n. sp. (Pl. 10, fig. 8).
The two principal cupolas smaller than the two lateral cupolas. Pores
subregular, circular, three times as broad as the bars; six to eight in the
semicircle of one cupola. Medullary shell elliptical. On the surface four
long cylindrical radial spines; two in the principal and two in the lateral
axis.
_Dimensions._--Major axis of the cortical shell 0.15, minor 0.12; pores
0.012, bars 0.004.
_Habitat._--South Pacific, Station 166, surface.
{674}4. _Staurotholus octostylus_, n. sp.
The two lateral cupolas larger than the two principal cupolas. Pores
subregular, circular, twice as broad as the bars; ten to twelve in the
semicircle of one cupola. Medullary shell hexagonal, connected with each
ring-like constriction by eight strong cylindrical radial spines (longer
than the whole shell), lying in two crossed meridian planes, and
corresponding to the eight diagonal wing-spines of _Tetrapyle octacantha_.
_Dimensions._--Major axis of the cortical shell 0.12, minor 0.1; pores
0.008, bars 0.004.
_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.
5. _Staurotholus decastylus_, n. sp.
The two principal cupolas twice as broad and high as the two lateral
cupolas. Pores subregular, circular, four times as broad as the bars; six
to eight in the semicircle of one cupola. Ten long and thin radial spines
with thickened conical bases, about as long as the major axis of the shell,
by inner prolongations connected with the lentelliptical medullary shell;
two polar spines in the principal axis, eight wing-spines in two crossed
diagonal planes.
_Dimensions._--Major axis 0.12, minor 0.1; pores 0.012, bars 0.003.
_Habitat._--Western Tropical Pacific; Station 224, depth 1850 fathoms.
6. _Staurotholus dodecastylus_, n. sp. (Pl. 10, fig. 9).
The two lateral cupolas larger than the two principal cupolas. Pores
subregular, circular, three times as broad as the bars; five to seven in
the semicircle of one cupola. Twelve strong cylindrical radial spines, four
on the poles of the two larger axes (two principal and two lateral), eight
wing-spines in two crossed diagonal planes. Medullary shell hexagonal.
_Dimensions._--Major (lateral) axis 0.11, minor (principal) 0.09; pores
0.009, bars 0.003.
_Habitat._--Tropical Atlantic, Station 348, surface.
7. _Staurotholus polystylus_, n. sp.
The two principal cupolas larger than the two lateral cupolas. Pores
irregular, roundish, twice to three times as broad as the bars; ten to
twelve in the semicircle of one cupola. On the surface numerous thin
bristle-shaped spines (twenty to thirty or more).
_Dimensions._--Major axis 0.14, minor 0.11; pores 0.006 to 0.01, bars
0.003.
_Habitat._--North Pacific, Station 231, surface.
Genus 296. _Staurotholonium_,[336] n. gen.
_Definition._--#Tholonida# with double cortical shell (with external veil),
composed of four hemispherical cupolas in cross-form, opposite in pairs on
the poles of two axes perpendicular one to another; central chamber
_Larnacilla_-shaped (with medullary shell).
{675}The genus _Staurotholonium_ differs from the nearly allied
_Staurotholus_ (its probable ancestral form) only in the duplication of the
cortical shell. The outer shell commonly repeats the cross-form of the
inner, with four corresponding cupolas; but sometimes the four cupolas of
the outer shell alternate in size and form with those of the inner, or the
outer shell forms a simple lenticular envelope around the inner. From the
similar _Tholoma_, _Staurotholonium_ differs in the possession of a
medullary shell in the central chamber.
Subgenus 1. _Staurotholodes_, Haeckel.
_Definition._--Surface of the outer cortical shell smooth or rough, without
radial spines.
1. _Staurotholonium biquadratum_, n. sp.
Outer cortical shell smooth, of the same regular crucial form as the inner,
equidistant from it everywhere. Form and structure of both cortical shells
nearly the same, but the outer about twice as large as the inner; both
connected only by eight diagonal beams. All four cupolas of each cortical
shell regular, of the same size. Pores regular, circular, twice as broad
as the bars; six to eight in the basal semicircle of each cupola. Medullary
shell square. (Similar to _Staurotholus quadratus_, but differs by the
double cortical shell.)
_Dimensions._--Diameter of the outer cortical shell 0.16, of the inner
0.08, of the medullary shell 0.04; pores of the inner cortical shell 0.006,
bars 0.003.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
2. _Staurotholonium bicruciatum_, n. sp.
Outer cortical shell rough, twice as large as the inner, of the same form
and structure, at an equal distance from it. In both shells the principal
cupolas are larger than the lateral. Pores irregular, roundish, in the
outer shell four times, in the inner twice as large as the bars; eight to
ten in the basal semicircle of one cupola. (Similar to _Staurotholus
cruciatus_, but differs mainly in the double cortical shell.) Medullary
shell lentelliptical.
_Dimensions._--Major (longitudinal) axis of the outer cortical shell 0.016,
of the inner 0.08; minor (transverse) axis of the former 0.14, of the
latter 0.07; medullary shell 0.03 to 0.04.
_Habitat._--Pacific, central area, Station 267, depth 2700 fathoms.
3. _Staurotholonium alternatum_, n. sp.
Outer cortical shell smooth, very different from the inner; in the outer
the two principal cupolas are larger than the two lateral; in the inner
inversely smaller. Pores subregular, circular, in the outer shell four
times, in the inner shell twice as broad as the bars; ten to twelve pores
in the basal semicircle of one cupola.
{676}_Dimensions._--Major axis (length) of the outer cortical shell 0.15,
minor (breadth) 0.13; pores 0.012, bars 0.003; major axis (length) of the
inner cortical shell 0.11, minor axis (breadth) 0.09; pores 0.006, bars
0.003.
_Habitat._--Indian Ocean, surface, Madagascar, Rabbe.
4. _Staurotholonium lenticulare_, n. sp.
Outer cortical shell smooth, lenticular, with circular circumference, with
very delicate irregular network and small roundish pores. Its distance from
the inner much greater in the four diagonal points than in the four polar
points. Inner cortical shell regular, cross-like, with four cupolas of
similar size and form. Pores subregular, circular, twice as broad as the
bars; eight to ten in the basal semicircle of one cupola. Medullary shell
lenticular.
_Dimensions._--Diameter of the outer cortical shell 0.16, of the inner
0.12; pores of the inner 0.008, bars 0.004.
_Habitat._--North Atlantic, Station 353, surface.
Subgenus 2. _Staurotholoma_, Haeckel.
_Definition._--Surface of the outer cortical shell with radial spines or
thorns.
5. _Staurotholonium octodoratium_, n. sp.
Outer cortical shell of the same form and structure as the inner, but twice
as large, both principal domes somewhat larger than both lateral. Pores
subregular, circular, of the same breadth as the bars; five to six in the
semicircle of one inner, eight to ten of one outer cupola. Eight thin and
long bristle-like spines, opposite in pairs in two crossed diagonal planes.
_Dimensions._--Major axis of the outer cortical shell 0.15, minor 0.12;
major axis of the inner cortical shell 0.07, minor 0.06; pores and bars
0.005.
_Habitat._--North Pacific, Station 231, surface.
6. _Staurotholonium octodoronium_, n. sp. (Pl. 10, fig. 11).
Outer cortical shell of the same form as the inner, both little distant;
network of the outer irregular and delicate. Pores of the inner regular,
circular, twice as broad as the bars; seven to nine in the basal semicircle
of one cupola. Both lateral domes larger than the principal. Eight long and
thin, cylindrical radial spines opposite in pairs in two crossed diagonal
planes.
_Dimensions._--Major axis of the outer cortical shell 0.2, minor 0.18;
major axis of the inner cortical shell 0.16, minor 0.14; pores 0.008, bars
0.004.
_Habitat._--South Pacific, Station 288, surface.
{677}Subfamily 3. CUBOTHOLIDA, Haeckel.
_Definition._--#Tholonida# with triaxial growth; cupolas lying in pairs on
the six sides of a cubical central chamber, opposite at the poles of three
axes perpendicular one to another. (Shell commonly seven-chambered, with
six domes surrounding the central chamber.)
Genus 297. _Tholocubus_,[337] n. gen.
_Definition._--#Tholonida# with simple cortical shell (without external
veil), composed of six hemispherical cupolas, opposite in pairs on the
poles of three axes perpendicular one to another, covering six sides of the
simple cuboidal central chamber (without medullary shell).
The genus _Tholocubus_ is the most simple form of the Cubotholida, or of
the Tholonida with domes situated in three axes perpendicular one to
another; six hemispherical cupolas lying on the six sides of a cuboidal
central chamber; this latter contains no medullary shell. _Tholocubus_ may
be derived phylogenetically either from _Tholostaurus_ by apposition of two
opposite domes on the flat sides of the cross-shell, or from _Cubotholus_
by loss of the medullary shell.
Subgenus 1. _Tholocubulus_, Haeckel.
_Definition._--Surface of the shell smooth or rough, without radial spines.
1. _Tholocubus tessellatus_, n. sp. (Pl. 10, fig. 12).
Surface of the shell smooth, without radial spines. Pores regular,
circular, hexagonally framed, twice as broad as the bars; eight to twelve
pores on the semicircle of one cupola. Principal cupolas smaller than the
lateral, larger than the sagittal cupolas.
_Dimensions._--Diameter of the shell 0.15; pores 0.01, bars 0.005.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
2. _Tholocubus tesserarius_, n. sp.
Surface of the shell rough, without radial spines. Pores irregular,
roundish, once to three times as broad as the bars; twelve to sixteen pores
in the semicircle of one cupola. All six cupolas nearly of the same size.
_Dimensions._--Diameter of the shell 0.16; pores 0.004 to 0.008, bars
0.003.
_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.
{678}Subgenus 2. _Tholocubitus_, Haeckel.
_Definition._--Surface of the shell with radial spines or thorns.
3. _Tholocubus tesseralis_, n. sp. (Pl. 10, fig. 16).
Surface of the shell with numerous (eight to sixteen) thin and long,
bristle-shaped radial spines (the greater part broken off in the figured
specimen); pores subregular, circular, three to four times as broad as the
bars; ten to twelve in the semicircle of one cupola.
_Dimensions._--Major axis of the shell 0.16, minor axis 0.14; pores 0.01,
bars 0.0027.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
Genus 298. _Tholonium_,[338] n. gen.
_Definition._--#Tholonida# with double cortical shell (with external veil),
composed of six hemispherical cupolas, opposite in pairs on the poles of
three axes perpendicular one to another, covering six sides of the simple
cuboidal central chamber (without medullary shell).
The genus _Tholonium_ (Pl. 10, fig. 17) differs from the preceding
_Tholocubus_ only in the duplication of the cortical shell. The outer
(secondary) shell forms either a simple (spheroidal or ellipsoidal) thin
veil around the inner (primary) shell, or both shells are of the same form,
with six corresponding cupolas. Possibly _Tholonium_ is the offspring of
_Cubotholonium_, having originated by loss of the medullary shell.
Subgenus 1. _Tholonetta_, Haeckel.
_Definition._--Surface of the shell smooth or rough, without radial spines
or thorns.
1. _Tholonium bicubicum_, n. sp.
Outer shell with six hemispherical dome-shaped protuberances, corresponding
in those of the inner shell. Both shells connected by numerous radial
beams. Surface of the outer shell smooth; its network nearly of the same
shape as that of the inner, with subregular, circular pores, twice as broad
as the bars; ten to fifteen pores on the semicircle of one cupola.
_Dimensions._--Diameter of the outer shell 0.14, of the inner 0.12; pores
of the latter 0.006, bars 0.003.
_Habitat._--South Atlantic, Station 325, depth 2650 fathoms.
{679}2. _Tholonium ellipticum_, n. sp.
Outer shell ellipsoidal, without dome-shaped protuberances, with smooth
surface, without radial spines; network delicate, with subregular, circular
pores. Inner shell with regular, circular, hexagonally framed pores, twice
as broad as the bars; ten to twelve pores on the semicircle of one cupola.
_Dimensions._--Major axis of the outer shell 0.16, minor axis 0.14; major
axis of the inner shell 0.14, minor axis 0.12; pores 0.008, bars 0.004.
_Habitat._--Pacific central area, Station 267, depth 2700 fathoms.
3. _Tholonium sphæricum_, n. sp.
Outer shell spherical, without dome-shaped protuberances, with smooth
surface, without radial spines; network very delicate, with very small
subregular, circular pores. Inner shell with regular, circular pores of the
same breadth as the bars; fourteen to sixteen on the basal semicircle of
one cupola.
_Dimensions._--Diameter of the spherical outer shell 0.15, inner shell
0.12; pores and bars of the inner shell 0.005.
_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.
Subgenus 2. _Tholonilla_, Haeckel.
_Definition._--Surface of the outer shell covered with radial spines or
thorns.
4. _Tholonium hexonium_, n. sp. (Pl. 10, fig. 17).
Outer shell ellipsoidal, without dome-shaped protuberances, covered with
numerous (thirty to fifty) thin and long, bristle-shaped radial spines;
network very delicate, irregular, with roundish pores. Inner shell with six
marked hemispherical domes of somewhat different sizes; pores regular,
circular, with prominent hexagonal frames, twice as broad as the bars; ten
to twelve on the basal semicircle of one cupola.
_Dimensions._--Major axis of the outer shell 0.15, minor axis 0.14; major
axis of the inner shell 0.13, minor axis 0.12; pores 0.008, bars 0.004.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
5. _Tholonium sphæronium_, n. sp.
Outer shell very thin walled, spherical, without dome-shaped protuberances,
with smooth surface, excepting eight large radial spines, rising from the
eight corners of the inner cubical central chamber. Pores of the outer
shell very small, subcircular. Inner shell very thick walled, with six
marked hemispherical domes; pores subregular, circular, with prominent
hexagonal frames, twice as broad as the bars; six to eight on the
semicircle of one cupola.
{680}_Dimensions._--Diameter of the spherical outer shell 0.15, inner shell
0.11; pores of the inner 0.01, bars 0.005.
_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.
Genus 299. _Cubotholus_,[339] n. gen.
_Definition._--#Tholonida# with simple cortical shell (without external
veil), composed of six hemispherical cupolas, opposite in pairs on the
poles of three axes perpendicular one to another, covering six sides of the
cuboidal _Larnacilla_-shaped central chamber (with medullary shell).
The genus _Cubotholus_ differs from _Tholocubus_ in the possession of a
medullary shell in the central chamber, and may be derived from this genus
by its production; but it may also be derived from _Staurotholus_ by
apposition of two opposite domes on the flat sides of the cross-shell.
Sometimes all six domes are of the same size and form, but commonly
different in pairs.
Subgenus 1. _Cubotholissa_, Haeckel.
_Definition._--Surface of the shell smooth or rough, without radial spines.
1. _Cubotholus regularis_, n. sp. (Pl. 10, fig. 14).
On the six sides of the cubical central chamber six hemispherical cupolas
of the same size and form. Surface smooth. Pores regular, circular, twice
as broad as the bars; eight in the basal semicircle of each cupola.
Medullary shell apparently spherical (?), connected with the eight corners
of the central chamber by eight radial beams, regularly disposed. (This
species is remarkable for the perfect symmetry of the shell, the six sides
of which appear to be quite similar. It differs from the similar
_Tholocubus regularis_ in the possession of a medullary shell.)
_Dimensions._--Diameter of the cortical shell (equal in all three dimensive
axes) 0.15; pores 0.01, bars 0.005; diameter of the medullary shell 0.04.
_Habitat._--Pacific, central area, Station 273, depth 2350 fathoms.
2. _Cubotholus quadraticus_, n. sp.
Surface of the shell smooth. Both principal cupolas (on the poles of the
longitudinal axis) larger than the four other cupolas, which have the same
size and lie cross-wise in the equatorial plane. (Therefore two of the
three fundamental axes equal, the third larger.) Pores subregular,
circular, three times as broad as the bars; ten to twelve in the semicircle
of each cupola-basis.
_Dimensions._--Major axis 0.16, minor axis 0.12; pores 0.012, bars 0.004.
_Habitat._--Indian Ocean, Zanzibar, Pullen; depth 2200 fathoms.
{681}3. _Cubotholus rhombicus_, n. sp.
Surface of the shell smooth. Both principal cupolas (on the poles of the
longitudinal axis) larger than the two lateral (on the poles of the
transverse axis), and these larger than the two sagittal cupolas (on the
poles of the sagittal axis). Therefore all three fundamental axes unequal.
Pores irregular, roundish, twice to four times as broad as the bars; eight
to twelve in the basal semicircle of each cupola. Medullary shell
lentelliptical.
_Dimensions._--Major (principal) axis 0.16, middle (lateral) axis 0.14,
minor (sagittal) axis 0.12; pores 0.006 to 0.012, bars 0.003.
_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.
Subgenus 2. _Cubotholura_, Haeckel.
_Definition._--Surface of the shell with radial spines or thorns.
4. _Cubotholus octoceras_, n. sp.
All six cupolas in pairs of different sizes. Both principal domes larger
than the lateral domes, and these larger than the sagittal domes. Pores
subregular, circular, twice as broad as the bars; eight to ten in the
semicircle of each cupola. From the surface arise (at the intersecting
points of every three cupolas) eight strong conical radial spines, about as
long as the shell-axis; they lie in two diagonal planes, and are the
external free prolongations of eight inner beams (homologous with the eight
wing-spines of _Tetrapyle octacantha_), which connect the lentelliptical
medullary shell with the eight corners of the cuboidal central chamber.
_Dimensions._--Major axis of the cortical shell 0.15, middle 0.13, minor
0.11; pores 0.008, bars 0.004; diameters of the medullary shell
corresponding to 0.05, 0.04, 0.03.
_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.
Genus 300. _Cubotholonium_,[340] n. gen.
_Definition._--#Tholonida# with double (or sometimes triple) cortical shell
(with external veil), composed of six hemispherical cupolas, opposite in
pairs on the poles of three axes perpendicular one to another, covering six
sides of the cuboidal _Larnacilla_-shaped central chamber (with medullary
shell).
The genus _Cubotholonium_ differs from the nearly allied _Cubotholus_ (its
probable ancestral form) only in duplication of the cortical shell. I have
observed only two species of this rare form, both rather different. In the
first species the outer cortical shell forms a simple spherical thin veil
around the inner, the six cupolas of which are nearly of the same form and
size. In the second species each of the domes of the {682}inner cortical
shell is protected by an outer larger cupola, and besides this the whole
shell is enveloped by a thin ellipsoidal veil (Pl. 10, fig. 15). Therefore
this species may be the representative of a peculiar genus, the most highly
developed of all Tholonida--_Tholothauma_.
1. _Cubotholonium sphæroides_, n. sp.
Outer cortical shell (or veil) spherical, with smooth surface; network very
delicate, with very thin bars and very small irregular, roundish pores.
Inner cortical shell simple, composed of six hemispherical cupolas,
surrounding the six sides of the cubical central chamber, which encloses a
spherical medullary shell (one-third as large as itself). Network of the
inner cortical shell regular, with circular pores of the same breadth as
the bars, twelve to fourteen in the basal semicircle of one cupola.
_Dimensions._--Diameter of the spherical outer shell 0.2, of the inner
cortical shell 0.15; pores and bars of the latter 0.006.
_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.
2. _Cubotholonium ellipsoides_, n. sp. (Pl. 10, fig. 15).
_Tholothauma ellipsoides_, Haeckel, 1883, MS.
Outer cortical shell (or veil) ellipsoidal, with very thin irregular
network and thorny surface. Inner cortical shell double, with six double,
flatly vaulted cupolas, surrounding the six sides of the
_Larnacilla_-shaped central chamber; the double domes of each shell are in
opposite pairs somewhat larger than the alternating pairs. Pores
subregular, circular, about the same breadth as the bars; eight to twelve
in the basal semicircle of one cupola. Central chamber with ellipsoidal
medullary shell. Radial spines short, very numerous.
_Dimensions._--Major axis of the outer cortical shell 0.28, minor 0.24;
major axis of the inner cortical shell 0.16, minor axis 0.14; pores and
bars 0.006; medullary shell 0.03.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
Family XXVIII. #ZONARIDA#, n. fam. (Pl. 50, figs. 9-12).
_Definition._--#Larcoidea# with regular, completely latticed cortical
shell, distinguished by two to four or more annular constrictions, which
lie (all or partly) in the dimensive planes (sagittal, transverse, or
lateral), and by which four to eight or more vaulted cupolas or dome-like
chambers become separated. In the centre of this chambered cortical shell
lies constantly a trizonal or _Larnacilla_-shaped medullary shell.
The family #Zonarida# comprises a small number of peculiar #Larcoidea#,
resembling the Tholonida in the composition of the polythalamous cortical
shell by a number of cupolas or dome-shaped protuberances. But the
disposition and origin of these latter {683}are quite different. Whilst in
the Tholonida the axes of the domes are dimensive axes, and these are
separated by annular constrictions lying in diagonal planes, in the
Zonarida we find the contrary; the axes of the domes are here diagonal
axes, and these are separated by annular constrictions lying in dimensive
planes. However, this definition agrees absolutely only in the
four-chambered _Zonarium_ and in the eight-chambered _Zonidium_, whilst in
the six chambered _Zoniscus_ only four domes are disposed according to this
law, two others, however, in the same manner as in the Tholonida. Therefore
this genus is intermediate between both families.
_The Cortical Shell_ of the Zonarida is in all cases completely latticed
and of regular lentelliptical fundamental form, as in the nearly allied
Larnacida and Tholonida. The three dimensive axes are constantly of
different sizes, each with two equal poles; commonly (as in the human body)
the principal or longitudinal axis is the longest, the sagittal (or
dorso-ventral) axis the shortest; the transverse (or lateral) axis being
intermediate between them. Of the three dimensive planes the lateral plane
is the largest (determined by the principal and transverse axes); the
smallest is the equatorial plane (crossed by the transverse and sagittal
axes); the sagittal plane (determined by the sagittal and principal axes)
being intermediate between them.
The annular constrictions of the cortical shell which produce the
dome-shaped protuberances are different in number in the three known
genera--two, three, or four. To each constriction often (but not always)
corresponds an internal latticed septum, which connects the cortical with
the medullary shell. The number of the cupolas is always double the number
of the annular constrictions by which they are separated, therefore four,
six, or eight.
In all known Zonarida the sagittal septum is quite constant, but derived
from the original axial rod, which lies in the principal axis. By
ramification of this axial beam and reticular connection with the sagittal
girdle arises the sagittal septum, which we found first in _Octopyle_,
halving the four gates of _Tetrapyle_. Whilst this sagittal septum (between
right and left halves of the body) is common to all three known genera of
this family, the number and shape of the other annular constrictions are
different. In _Zonarium_ (Pl. 50, fig. 9) we find only one transverse
constriction (in the equatorial plane), in _Zoniscus_ (figs. 10, 11) two
parallel transverse constrictions (parallel to the equatorial plane, on
both sides of it). _Zonidium_ (fig. 12) is a combination of both foregoing
genera; it has three parallel transverse constrictions (one in the
equatorial plane, and one on each side of it).
_The Latticed Domes_ (cupolas or chambers) of the cortical shell exhibit
correspondingly a different number and disposition in the three known
genera. In _Zonarium_ are found only four crossed chambers, separated by
the sagittal and transverse septa; the axes of the four crossed domes are
diagonal axes, whilst in the similar _Staurotholus_ they are dimensive axes
(principal and transverse axes). In _Zonidium_ we find eight domes, each
cupola of _Zonarium_ being halved by a diagonal septum. _Zoniscus_ is
intermediate {684}between the two foregoing genera, and has six cupolas,
three on each side of the sagittal septum.
The inner communication of the cupolas or chambers is more or less free,
the lattice-work of the separating septa between them commonly remaining
more or less imperfect, or represented only by some isolated beams or
meshes. The outer network of the cupolas is commonly irregular (as in the
majority of #Larcoidea#), but sometimes distinguished by a small number of
regularly disposed larger apertures (similar to the "gates" of the
Pylonida). From the surface radial spines often arise in characteristic
number and symmetrical disposition, commonly as prolongations of the septal
axes or of the constricted edges.
The _Medullary Shell_ in all Zonarida is a true trizonal or
_Larnacilla_-shaped lattice-shell (compare above, p. 600); its perimeter
(or the first lateral girdle) is sometimes more elliptical, at other times
more hexagonal; the hexagon is amphithect; both its lateral sides are often
concave and commonly longer than the four other sides.
The _Central Capsule_ in all Zonarida is in a strict geometrical sense a
true lentellipsis (compare above, p. 599); its principal axis is commonly
one and a third to one and a half times as great as the transverse axis,
and twice to three times as great as the sagittal axis. The lentelliptical
central capsule encloses the trizonal medullary shell, whilst it is
externally enveloped by the chambered cortical shell.
_Synopsis of the Genera of Zonarida._
Two annular constrictions and four cupolas, 301. _Zonarium_.
Three annular constrictions and six cupolas, 302. _Zoniscus_.
Four annular constrictions and eight cupolas, 303. _Zonidium_.
Genus 301. _Zonarium_,[341] n. gen.
_Definition._--#Zonarida# with four dome-shaped chambers of the cortical
shell, separated by two annular constrictions (one sagittal and one
transverse).
The genus _Zonarium_ is the most simple form of the Zonarida, and differs
from the nearly allied _Larnacalpis_ by two ring-like constrictions, which
are crossed at right angles, one in the sagittal (or median) plane, and one
in the transverse (or equatorial) plane. By these two annular constrictions
four egg-shaped or kidney-shaped chambers become imperfectly separated,
which correspond to the quadrants of the lateral plane. The first cause of
the marked constrictions may be the formation of the latticed sagittal
septum, which is found first in _Octopyle_, as halving the four gates of
{685}_Tetrapyle_. Between this septum and the constricted narrow transverse
girdle the cortical shell grows out in the form of four vaulted cupolas;
every two opposite domes are congruent, two neighbouring are symmetrically
equal.
1. _Zonarium quadrigatum_, n. sp.
Cortical shell quadrangular, one and a half times as long as broad, with
four rounded corners. Surface thorny, with numerous short radial spines.
Sagittal constriction twice as long as the hexagonal medullary shell. Four
cupolas kidney-shaped.
_Dimensions._--Length of the cortical shell 0.16, breadth 0.11; length of
the medullary shell 0.06, breadth 0.04.
_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.
2. _Zonarium quadrispinum_, n. sp.
Cortical shell quadrangular, nearly rectangular, about twice as long as
broad, with four corners, from which arise four strong, three-sided
pyramidal, radial spines (crossed in two diagonals of the lateral plane).
Surface thorny, only smooth in the transverse constriction. Sagittal
constriction three times as long as the lentelliptical medullary shell.
Four cupolas elliptical or nearly quadrangular.
_Dimensions._--Length of the cortical shell 0.22, breadth 0.1; length of
the medullary shell 0.07, breadth 0.05.
_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.
3. _Zonarium octangulum_, n. sp. (Pl. 50, fig. 9).
Cortical shell octangular, one and a fourth times as long as broad, with
eight strong conical spines on the eight corners; these are separated by
four deep constrictions on the poles of the principal and transverse axes,
and by four truncated planes on the poles of the crossed diagonal axes
between the former. Sagittal constriction twice as long as the hexagonal
medullary shell. Four cupolas kidney-shaped or nearly pentagonal.
_Dimensions._--Length of the cortical shell 0.15, breadth 0.12; length of
the medullary shell 0.07, breadth 0.04.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
4. _Zonarium tetratholium_, n. sp.
Cortical shell quadrangular, with four rounded corners. Surface thorny,
with sixteen stronger radial spines; eight of these lie in the lateral
plane, in the same symmetrical disposition as in the foregoing species;
eight others lie on both sides of the lateral plane, opposite in pairs in
two crossed diagonal planes, in the same symmetrical disposition as in
_Tetrapyle octacantha_. Sagittal {686}constriction three times as long as
the lentelliptical medullary shell. Four cupolas obliquely elliptical.
_Dimensions._--Length of the cortical shell 0.16, breadth 0.12; length of
the medullary shell 0.04, breadth 0.03.
_Habitat._--North Pacific, Station 241, depth 2300 fathoms.
Genus 302. _Zoniscus_,[342] n. gen.
_Definition._--#Zonarida# with six dome-shaped chambers of the cortical
shell, separated by three annular constrictions (one sagittal and two
transverse, parallel to the equatorial plane).
The genus _Zoniscus_ differs from _Zonarium_ as well as from _Zonidium_ by
the development of the transverse girdle, which is not constricted, but on
the contrary prominently vaulted in the equatorial plane. Therefore both
wings of the transverse girdle form here two opposite lateral or
"equatorial cupolas," as in _Amphitholus_. These are separated from four
other domes (the "corner cupolas") by two transverse annular constrictions,
which correspond to the free edges of the original transverse girdle. The
corner domes of each pair are separated from each other by the sagittal
septum.
1. _Zoniscus rectangulus_, n. sp.
Cortical shell nearly rectangular, with rounded corners, nearly one and a
half times as long as broad. Surface thorny, without larger radial spines.
Sagittal constriction scarcely half as long as the hexagonal medullary
shell. Both equatorial cupolas (or wings of the transverse girdle) scarcely
half as large as the four corner cupolas.
_Dimensions._--Length of the cortical shell 0.15, breadth 0.11; length of
the medullary shell 0.07, breadth 0.045.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
2. _Zoniscus hexathalamus_, n. sp.
Cortical shell nearly elliptical, one and a third times as long as broad.
Surface nearly smooth, without radial spines. Sagittal constriction three
times as long as the lentelliptical medullary shell. Both equatorial
cupolas about as large as the four corner cupolas.
_Dimensions._--Length of the cortical shell 0.12, breadth 0.09; length of
the medullary shell 0.035, breadth 0.025.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
{687}3. _Zoniscus tetracanthus_, n. sp. (Pl. 50, fig. 10).
Cortical shell nearly quadrangular, one and a half times as long as broad,
with four prominent corners, from which arise in the lateral plane four
strong, three-sided pyramidal radial spines (opposite in pairs in two
crossed diagonal axes). Surface thorny, with exception of the concave
lateral sides. Sagittal constriction two and a half times as long as the
hexagonal medullary shell. Both equatorial cupolas scarcely half as large
as the four corner cupolas.
_Dimensions._--Length of the cortical shell 0.18, breadth 0.12; length of
the medullary shell 0.07, breadth 0.04.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
4. _Zoniscus octacanthus_, n. sp.
Cortical shell nearly four-sided, prismatic, one and a third times as long
as broad, with spiny surface. Eight longer thin radial spines opposite in
pairs in two crossed diagonal planes (as in _Tetrapyle octacantha_).
Sagittal constriction two and a half times as long as the hexagonal
medullary shell. Both equatorial cupolas somewhat larger than the four
corner cupolas.
_Dimensions._--Length of the cortical shell 0.16, breadth 0.12; length of
the medullary shell 0.055, breadth 0.04.
_Habitat._--Pacific, central area, Station 263, depth 2650 fathoms.
5. _Zoniscus hexatholius_, n. sp. (Pl. 50, fig. 11).
Cortical shell nearly rectangular, with four rounded corners and deep
sagittal constriction, one and a fourth times as long as broad with thorny
surface. Twelve longer edged radial spines; eight opposite in pairs in two
crossed diagonal planes (as in the foregoing species), four others in the
lateral plane, opposite in pairs on both sides of the sagittal
constriction, which is scarcely twice as long as the hexagonal, in the
equatorial plane constricted medullary shell. Both equatorial cupolas
nearly of the same size as the four corner cupolas.
_Dimensions._--Length of the cortical shell 0.16, breadth 0.13; length of
the medullary shell 0.07, breadth 0.04.
_Habitat._--South Pacific, Station 300, depth 1375 fathoms.
Genus 303. _Zonidium_,[343] n. gen.
_Definition._--#Zonarida# with eight dome-shaped chambers of the cortical
shell, separated by four annular constrictions (one sagittal, one
transverse, and two others parallel to the latter).
The genus _Zonidium_ must be regarded as a _Zonarium_, in which the four
cupolas (in the quadrants of the lateral plane) are halved by diagonal
beams or latticed septa, {688}lying opposite in pairs in two crossed
diagonal planes. Therefore the number of the septa (four) and the domes
(eight) is here doubled. Among the eight cupolas we distinguish four median
(on both sides of the sagittal plane) and four lateral (on both sides of
the equatorial plane); both groups are of different size and form. Probably
_Zonidium_ is derived from _Zonarium_ by lattice-connection between the
eight diagonal wing-spines, which in both species of this genus are
present, the same as in _Tetrapyle octacantha_.
1. _Zonidium octostylium_, n. sp.
Cortical shell nearly quadrangular, with rounded corners and thorny
surface. Eight long and thin radial spines on both sides of the lateral
plane opposite in pairs and lying in two crossed diagonal planes (as in
_Tetrapyle octacantha_). Sagittal constriction three times as long as the
lentelliptical medullary shell. Four medial cupolas (on both sides of the
sagittal plane) somewhat larger than the four lateral cupolas (on both
sides of the equatorial plane).
_Dimensions._--Length of the cortical shell 0.15, breadth 0.12; length of
the medullary shell 0.05, breadth 0.03.
_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.
2. _Zonidium octotholium_, n. sp. (Pl. 50, fig. 12).
Cortical shell nearly octangular, with spiny surface; twenty long and stout
radial spines between numerous smaller spines; eight wing-spines opposite
in pairs in two crossed diagonal planes (as in the preceding species);
twelve other strong spines in the lateral plane (four longer opposite in
pairs on the poles of the principal and transverse axes, eight others
smaller, alternating between these and the diagonal spines). Sagittal
constriction twice as long as the hexagonal medullary shell. Four median
cupolas somewhat smaller than the four lateral cupolas.
_Dimensions._--Length of the cortical shell 0.18, breadth 0.15; length of
the medullary shell 0.07, breadth 0.05.
_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.
Family XXIX. #LITHELIDA#, Haeckel (Pl. 49, figs. 1-7).
_Lithelida_, Haeckel, 1862, Monogr. d. Radiol., p. 515.
_Definition._--#Larcoidea# with symmetrical spiral shell, divided by the
spiral plane into two symmetrical halves; all windings of the spiral lie in
this plane. Primordial chamber either simple or _Larnacilla_-shaped.
The family #Lithelida# comprises all those #Larcoidea# in which the growth
of the latticed shell is spirally winding in one plane, _Nautilus_-like.
They agree in the spiral growth with the following family. But in the
Streblonida the spiral is screw-shaped, {689}ascending (like _Helix_).
Therefore in these latter the geometrical fundamental form of the shell is
asymmetrical or "dysdipleural," whereas in the Lithelida
bilateral-symmetrical or "eudipleural." The lentelliptical or nearly
spherical shell may be divided by a median section into two symmetrical
halves; the right half is the mirror image of the left half.
When in 1862 I founded the family Lithelida in my Monograph (p. 515), I
knew only one genus, _Lithelius_, with two species. The rich material of
the Challenger collection contains a great number of similar spirally
constructed #Larcoidea#, so that at the present time we may distinguish at
least six genera. These belong to two different subfamilies, which may
possibly be afterwards better separated as families. The first subfamily,
Spiremida, possess a simple, spherical or subspherical, medullary shell;
the second subfamily, Larcospirida, possess a trizonal or
_Larnacilla_-shaped medullary shell. No doubt these latter must be derived
from Pylonida, as we observe all stages of development starting from a
simple _Trizonium_; but perhaps also the Spiremida have the same origin,
their simple, spherical or subspherical, medullary shell being derived from
a trizonal or _Larnacilla_-shaped medullary shell by reduction.
The general appearance in both subfamilies of the Lithelida is quite the
same, and it requires a careful study of the medullary shell to distinguish
certainly the Spiremida from the Larcospirida. This distinction is often
not easy, particularly in the larger forms; the shell is often very opaque
and difficult to understand. Only in one position, if the spiral axis be
parallel to the axis of the eye of the observer, and the spiral plane be
therefore fully seen in the optical plane of the microscope, the spiral
line (or the axial section of the latticed spiral lamella) is distinctly
observed; in all other positions the figure of the spiral is more or less
indistinct, and the whole microscopical image often quite intricate and
confused. The sufficient study of this family requires therefore the
contemplation of the shell from different sides, and is the more difficult,
as the variability of the Lithelida--as of the Pylonida--is extraordinarily
great.
The description which I gave of _Lithelius_ (1862) in my Monograph is in
some points erroneous, and was afterwards (1879) corrected by R. Hertwig,
who explained particularly the near relation of it to _Tetrapyle_. Indeed
the intermediate forms between the Lithelida and the Pylonida are so
numerous and so evident in all stages of development, that the derivation
of the former (at least of the Larcospirida) from the latter is quite
clear. The analogy between the structure of the Lithelida and the
calcareous (foraminiferous) Alveolinida is not so complete as I supposed it
to be in my Monograph (1862); particularly the formation of the small
chambers between the turnings of the spiral lamella is much more complete
in the Alveolinida than in the Lithelida.
The cortical shell of all Lithelida has the same geometrical fundamental
form as _Nautilus_ or as the nautiloid Polythalamia (_Polystomella_,
_Nummulites_, &c.); therefore the shell is dipleural, being divided by the
median plane into two symmetrical lateral halves. {690}Since the spiral
line lies in the median plane, we will call it the spiral plane; it
separates the right half from the left. The axis of the body, around which
the spiral turns (without touching it), is the spiral axis. The latticed
part of the cortical shell, which turns around them, is the spiral lamella.
Only in one genus of our family, viz., _Tholospira_, are the spiral axis,
the lateral axis, the spiral plane, and the sagittal plane quite as in
_Nautilus_. In all other genera this disposition is different or is
uncertain. This depends on the different part of the cortical shell, from
which the spiral growth begins. In this respect we can distinguish four
different modes.
In the Larcospirida (or the Lithelida with _Larnacilla_-shaped medullary
shell) the spiral growth exhibits four quite different forms. It begins
here with _Larcospira_, in which already the first cortical girdle of the
Diplozonaria determines the spiral growth; one wing of this girdle, the
transverse girdle of _Amphipyle_, grows more swiftly than the other,
overgrows it, and thus turns around the principal axis. In _Pylospira_ the
first or transverse girdle is already perfectly formed (as in _Amphipyle_),
and the spiral growth is introduced by the second or lateral girdle of
_Tetrapyle_; one wing of it (the right or the left) grows more swiftly than
the other, overgrows it, and thus turns around the sagittal axis. In
_Tholospira_ also the second girdle is complete, and the spiral growth
begins from the third or sagittal girdle. One of its wings grows more
swiftly than the other, overgrows it, and thus turns around the transverse
axis. Consequently we see that each of the three dimensive planes of the
lentelliptical Larcoid-body may be the spiral plane: in _Larcospira_ the
transverse plane, in _Pylospira_ the lateral plane, in _Tholospira_ the
sagittal plane. Correspondingly the spiral axis in the first genus is the
principal, in the second the sagittal, in the third the transverse axis of
the central _Larnacilla_-shell. Therefore in these three genera the spiral
plane is the plane of the latticed girdle, which determines the spiral
growth, one of both its wings overgrowing the other.
In each of the three above mentioned genera the spiral may be simple or
double; it remains simple if only one of both wings of the turning girdle
overgrow the other, and this latter remain a simple half girdle (or
tube-like wing). Whereas the spiral becomes double if the second wing of
the girdle afterwards follow the example of the first wing and now turn
around it in the same direction. As this happens in all three genera, we
can subdivide them into six subgenera.
A quite peculiar form of spiral growth is produced in _Spironium_, in which
the direction of growth in both lateral wings of the transverse girdle is
inverse from the beginning. The left wing grows against the posterior, the
right wing against the anterior pole of the principal axis, turning around
it in crossed, eight-like spirals. The whole shell afterwards assumes a
lentelliptical form.
Commonly between the embracing spiral turnings or convolutions a great
number of radial beams is developed, irregularly disposed and often
branching; they support the {691}thin spiral lamellæ and give to the whole
shell more solidity. Often these beams form imperfect radial septa, by
which the spiral cavity of the turnings is divided into a variable number
of chambers. But these chambers never become so regular and perfect as in
the analogous nautiloid Polythalamia.
In many Lithelida the growth of the shell reaches a certain limit,
concluding with the formation of a superficial latticed lamella of
lentelliptical or nearly spherical form. In many other forms of the family
this seems not to be the case; but these may possibly be younger forms,
afterwards reaching the same limit.
The network of the shell in the Lithelida is commonly quite irregular, and
so variable that its special conformation has usually no value in the
determination of the species. The surface of the shell is often covered
with radial spines, which are sometimes arborescent.
The central capsule seems always to preserve the same lentelliptical form
(or triaxial ellipsoid) as in all other #Larcoidea#. With the increase of
growth it encloses successively a larger part of the spiral cortical shell,
but on the outside is constantly protected by the last turnings of the
spiral, or by the lattice-lamella of the surface.
_Synopsis of the Genera of Lithelida._
-------------------------------------------------------------------------
I. Subfamily Spiremida.
Central medullary shell simple, spherical or lentelliptical.
-------------------------------------------------------------------------
Surface of the cortical shell smooth or thorny,
without radial spines, 304. _Spirema_.
Surface of the cortical shell covered with numerous
simple or branched radial spines, 305. _Lithelius_.
-------------------------------------------------------------------------
II. Subfamily Larcospirida.
Central medullary shell double, trizonal or _Larnacilla_-shaped.
-------------------------------------------------------------------------
The transverse girdle turns around the principal axis, 306. _Larcospira_.
The lateral girdle turns around the sagittal axis, 307. _Pylospira_.
The sagittal girdle turns around the transverse axis, 308. _Tholospira_.
Both wings of the transverse girdle turn around the
principal axis in an opposite diagonal direction, 309. _Spironium_.
Subfamily 1. SPIREMIDA, Haeckel, 1881, Prodromus, p. 464.
_Definition._--#Lithelida# with simple, spherical or subspherical,
medullary shell.
Genus 304. _Spirema_,[344] Haeckel, 1881, Prodromus, p. 464.
_Definition._--#Lithelida# with simple, spherical or subspherical,
medullary shell, and lentelliptical or subspherical, spirally constructed
cortical shell; surface smooth or thorny, without radial spines.
{692}The genus _Spirema_ begins the series of the Spiremida, or of those
Lithelida in which the medullary shell presents a simple latticed sphere or
ellipsoid, never composed of a double, trizonal or _Larnacilla_-shaped
shell. In the present state of our knowledge we cannot say whether this
simple medullary shell be a primary formation, or effected by secondary
means, by reduction of a double _Larnacilla_-shaped medullary shell, which
is constantly found in the Larcospirida. The species of this genus (as of
all Lithelida) are difficult to distinguish, are transformistic, and
incline very much to variations and abnormalities. The spiral may be simple
or double.
Subgenus 1. _Spiremarium_, Haeckel.
_Definition._--Spiral convolutions of the cortical shell simple.
1. _Spirema lentellipsis_, n. sp.
Cortical shell lentelliptical, with smooth surface; proportion of its three
dimensive axes = 4 : 5 : 6. In the median plane are visible four perfect
turnings of the simple spiral, the breadth of which gradually increases
towards the third convolution, finally decreasing; the broadest (third)
turning three times as broad as the simple spherical medullary shell.
_Dimensions._--Length of the lentelliptical cortical shell 0.18, breadth
0.15, height 0.12; diameter of the spherical medullary shell 0.02.
_Habitat._--North Atlantic, Station 353, surface.
2. _Spirema melonia_, n. sp. (Pl. 49, fig. 1).
Cortical shell nearly spherical, with smooth surface; proportion of its
three dimensive axes = 1.4 : 1.5 : 1.6. In the median plane are visible
three perfect turnings of the simple spiral, all of the same breadth as the
simple spherical medullary shell; the breadth of each convolution somewhat
greater at the poles of the principal than at the poles of the sagittal
axis.
_Dimensions._--Length of the shell 0.16, breadth 0.15, height 0.14;
medullary shell 0.018.
_Habitat._--Pacific, central area, Station 271, surface.
3. _Spirema flustrella_, Haeckel.
_Flustrella haliomma_, Ehrenberg (1861), Abhandl. d. k. Akad. d. Wiss.
Berlin, 1872, p. 293, Taf. ii. fig. 6.
Cortical shell egg-shaped, with thorny surface; proportion of its three
axes = 4 : 5 : 6. In the median plane are visible three perfect turnings of
the simple spiral, the first and second of about the same breadth as the
simple spherical medullary shell, the third suddenly increasing, and
finally three to four times as broad. Network of the surface irregular,
with roundish pores.
_Dimensions._--Length of the shell 0.2, breadth 0.17, height 0.14;
medullary shell 0.013.
_Habitat._--North Atlantic, Greenland, 1000 fathoms, Ehrenberg; Færöe
Channel, John Murray.
{693}Subgenus 2. _Spiremidium_, Haeckel.
_Definition._--Spiral convolutions of the cortical shell double.
4. _Spirema diplospira_, n. sp.
Cortical shell lentelliptical, with smooth surface; proportion of its three
dimensive axes = 6 : 7 : 8. In the median plane are visible three perfect
turnings of a double spiral, the breadth of which gradually increases; the
broadest (third) convolution three times as broad as the simple
lentelliptical medullary shell.
_Dimensions._--Length of the shell 0.24, breadth 0.21, height 0.18;
medullary shell 0.02.
_Habitat._--Tropical Pacific, Philippines, Station 200, depth 250 fathoms.
5. _Spirema subglobosum_, n. sp.
Cortical shell nearly spherical, with thorny surface; proportion of its
three axes = 2 : 2.1 : 2.2. In the median plane are visible two perfect
turnings of a double spiral, the breadth of which in the second convolution
is four times as great as that of the first convolution and the simple
spherical medullary shell.
_Dimensions._--Length of the shell 0.22, breadth 0.21, height 0.2;
medullary shell 0.02.
_Habitat._--Tropical Atlantic, off Sierra Leone, Station 348, depth (2450)
fathoms.
Genus 305. _Lithelius_,[345] Haeckel, 1862, Monogr. d. Radiol., p. 519.
_Definition._--#Lithelida# with simple, spherical or subspherical,
medullary shell, and lentelliptical or subspherical, spirally constructed
cortical shell; surface covered with numerous, simple or branched, radial
spines.
The genus _Lithelius_, founded by me in 1862, and represented by two
Mediterranean species, was at that time the only known form of this family,
which now contains six genera and twenty-seven species. It differs from the
foregoing _Spirema_ in the possession of numerous radial spines on the
surface. These may be either simple or branched. The spiral may be simple
or double, and according to this latter modification we distinguish two
different subgenera.
Subgenus 1. _Lithospira_, Haeckel.
_Definition._--Spiral convolutions of the cortical shell simple.
1. _Lithelius spiralis_, Haeckel.
_Lithelius spiralis, Haeckel_, 1862, Monogr. d. Radiol., p. 519, Taf.
xxvii. figs. 6, 7.
Cortical shell lentelliptical, one and a third times as long as broad,
covered with very numerous (one hundred to one hundred and fifty or more)
simple, bristle-shaped radial spines, about as long {694}as the shell.
Spiral turnings simple, all nearly of the same breadth and scarcely broader
than the simple spherical medullary shell.
_Dimensions._--Length of the cortical shell (with six spiral convolutions)
0.15, breadth 0.13; diameter of the medullary shell 0.012.
_Habitat._--Mediterranean, Messina, Haeckel, surface; Atlantic, Stations
348 to 353, surface.
2. _Lithelius primordialis_, R. Hertwig.
_Lithelius primordialis_, R. Hertwig, 1879, Organism. d. Radiol., p. 54,
Taf. vi. figs. 4, 4_a_.
Cortical shell subspherical, covered with numerous simple, bristle-shaped
radial spines, longer than the shell. Spiral turnings simple, with
gradually increasing breadth, so that the beginning of the third spiral is
twice as broad as the first and as the simple spherical medullary shell.
_Dimensions._--Diameter of the cortical shell (with two spiral
convolutions) 0.12; diameter of the medullary shell 0.02.
_Habitat._--Mediterranean, Messina, R. Hertwig, surface.
3. _Lithelius alveolina_, Haeckel, 1862.
_Lithelius alveolina_, Haeckel, 1862, Monogr. d. Radiol., p. 520, Taf.
xxvii. figs. 8, 9.
Cortical shell spherical, covered with simple, very numerous (two hundred
to three hundred or more), short, bristle-shaped radial spines, scarcely
half as long as the radius of the shell. Spiral turnings simple, with
gradually increasing breadth, so that the beginning of the third spiral is
three times as broad as the first and as the simple spherical medullary
shell.
_Dimensions._--Diameter of the cortical shell (with four spiral
convolutions) 0.2; diameter of the medullary shell 0.01.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, on many
Stations, surface.
4. _Lithelius capreolus_, n. sp.
Cortical shell lentelliptical, one and a fourth times as long as broad,
covered with numerous (eighty to one hundred and twenty or more) short,
branched radial spines, about half as long as the radius of the shell; each
spine once or twice dichotomous, with curved divergent branches. Spiral
turnings simple, with gradually increasing breadth, so that the beginning
of the third spiral is twice as broad as the first, and as the simple
spherical medullary shell.
_Dimensions._--Length of the cortical shell (with four spiral convolutions)
0.18, breadth 0.14; diameter of the medullary shell 0.015.
_Habitat._--Pacific, central area, Station 274, surface.
Subgenus 2. _Drymospira_, Haeckel, 1881, Prodromus, p. 464.
_Definition._--Spiral convolutions of the cortical shell double.
{695}5. _Lithelius solaris_, n. sp. (Pl. 49, fig. 2).
Cortical shell spherical, covered with simple, very numerous (two hundred
to three hundred) bristle-shaped radial spines, longer than the diameter of
the shell. Spiral turnings double, both of the same breadth, gradually
increasing with the growth of the shell and several times surpassing the
diameter of the simple spherical medullary shell. (Pl. 49, fig. 2, exhibits
only the first convolutions in the centre of the shell.)
_Dimensions._--Diameter of the cortical shell (with four spiral
convolutions) 0.18; diameter of the medullary shell 0.02.
_Habitat._--Pacific, central area, Stations 266 to 272, surface and in
various depths.
6. _Lithelius arborescens_, n. sp.
Cortical shell lentelliptical, one and a half times as long as broad,
covered with numerous (fifty to eighty or more) branched radial spines,
about as long as the greatest diameter of the shell; each spine with two to
four lateral branches, which are again branched or dichotomous. Spiral
turnings double, both of little different breadth, which increases
considerably with the growth of the shell, so that the third turn is four
times as broad as the simple spherical medullary shell.
_Dimensions._--Length of the cortical shell (with three spiral
convolutions) 0.18, breadth 0.12; diameter of the medullary shell 0.01.
_Habitat._--North Atlantic, Færöe Channel, surface, John Murray.
Subfamily 2. LARCOSPIRIDA, Haeckel.
_Definition._--#Lithelida# with double, trizonal, or _Larnacilla_-shaped
medullary shell.
Genus 306. _Larcospira_,[346] n. gen.
_Definition._--#Lithelida# with double, trizonal, or _Larnacilla_-shaped
medullary shell; cortical shell subspherical or lentelliptical, constructed
of a simple or double spiral of the transverse girdle (or primary cortical
girdle); the spiral lamella revolving around the principal axis.
The genus _Larcospira_ begins the interesting series of the Larcospirida,
or of those Lithelida in which the medullary shell is formed by a trizonal
or _Larnacilla_-shaped lattice-shell, and the cortical shell by spiral
turnings of one of the three girdles, which compose the cortical shell of
the Pylonida. In _Larcospira_, as the oldest and most simple form of
Larcospirida, the spiral is formed by the transverse girdle, or the first
girdle of the Diplozonaria, the only cortical girdle of _Amphipyle_. If in
this genus one of both wings of the transverse girdle grow stronger than
the other and overgrow the latter, turning {696}around the principal axis,
we reach the characteristic form of _Larcospirema_, the first subgenus of
_Larcospira_; but if afterwards the second wing follow the example of the
first, and overgrow it from the other side, we reach the typical form of
the second subgenus, _Larcospironium_. In this latter subgenus the spiral
becomes double, whilst in the former it remains simple.
Subgenus 1. _Larcospirema_, Haeckel.
_Definition._--Spiral convolutions or turns of the cortical shell simple;
only one single wing of the transverse girdle turning around the principal
axis.
1. _Larcospira lentelliptica_, n. sp.
Cortical shell with smooth surface, four times as long as the
lentelliptical medullary shell. Perimeter of the lateral plane elliptical,
one and a half times as long as broad, without constrictions. One lateral
wing of the transverse girdle is more strongly developed and turns around
the other in two to three simple spiral turns.
_Dimensions._--Length of the cortical shell 0.2, breadth 0.16; length of
the medullary shell 0.05, breadth 0.04.
_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.
2. _Larcospira quadrangula_, n. sp. (Pl. 49, fig. 3).
Cortical shell with thorny surface, three times as long as the
lentelliptical medullary shell. Perimeter of the lateral plane nearly
quadrangular, with four rounded corners (on the poles of two crossed
diagonal axes), one and a third times as long as broad, with one sagittal
constriction at the poles of the principal axis. One lateral wing of the
transverse girdle turns around the other in one and a half to two simple
spiral turns.
_Dimensions._--Length of the cortical shell 0.18, breadth 0.14; length of
the medullary shell 0.06, breadth 0.04.
_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.
3. _Larcospira sexangula_, n. sp.
Cortical shell with spiny surface, four times as long as the hexagonal
medullary shell. Perimeter of the lateral plane nearly hexagonal, one and a
half times as long as broad, with six rounded corners (two on the poles of
the principal axis, four on the poles of two crossed diagonal axes), with
three slight ring-like constrictions. One lateral wing of the transverse
girdle turns around the other in two to two and a half simple spiral turns.
_Dimensions._--Length of the cortical shell 0.24, breadth 0.16; length of
the medullary shell 0.06, breadth 0.04.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
{697}Subgenus 2. _Larcospironium_, Haeckel.
_Definition._--Spiral convolutions or turns of the cortical shell double;
both wings of the transverse girdle turning around the principal axis.
4. _Larcospira oliva_, n. sp.
Cortical shell with smooth surface, six times as long as the lentelliptical
medullary shell. Perimeter of the lateral plane elliptical, one and a
fourth times as long as broad, without constrictions. Both lateral wings of
the transverse girdle turn round one another and form one and a half to two
double spiral turns.
_Dimensions._--Length of the cortical shell 0.25, breadth 0.2; length of
the medullary shell 0.04, breadth 0.035.
_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.
Genus 307. _Pylospira_,[347] n. gen.
_Definition._--#Lithelida# with double, trizonal or _Larnacilla_-shaped
medullary shell; cortical shell subspherical or lentelliptical, constructed
of a single or double spiral of the lateral girdle (or second cortical
girdle); the spiral lamella revolving round the sagittal axis.
The genus _Pylospira_ follows after _Larcospira_ as the second genus of
Larcospirida; but in this latter the spiral of the cortical shell is formed
by the transverse girdle (or the first lattice-girdle of the Diplozonaria),
whilst in _Pylospira_ it is produced by the lateral girdle, or the second
lattice-girdle of that group. Therefore _Pylospira_ may be derived
phylogenetically from _Tetrapyle_ in the same manner as _Larcospira_ from
_Amphipyle_. Whilst in this latter the first cause of the spiral turning,
the unequal growth of both girdle-wings, proceeds from the transverse
girdle, in _Pylospira_ it proceeds from the lateral girdle. One of its
wings overgrows the other, turning around the sagittal axis. If the second
wing do not become developed, the spiral remains simple and represents the
subgenus _Pylospirema_; but if afterwards the second wing follow the
example of the first and overgrow it from the other side, we reach the
typical form of the second subgenus, _Pylospironium_, with a double spiral.
Subgenus 1. _Pylospirema_, Haeckel.
_Definition._--Spiral convolutions or turns of the cortical shell simple,
only one single wing of the lateral girdle turning around the sagittal
axis.
{698}1. _Pylospira tetrapyle_, n. sp.
Cortical shell with thorny surface, five times as long as the
lentelliptical medullary shell. Perimeter of the lateral plane elliptical,
one and a half times as long as broad. Four internal gates (as in
_Tetrapyle_, between the complete lateral wings of the transverse girdle)
kidney-shaped. One principal wing of the lateral girdle turns around the
other in one and a half to two simple spiral turns.
_Dimensions._--Length of the cortical shell 0.21, breadth 0.15; length of
the medullary shell 0.04, breadth 0.03.
_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.
2. _Pylospira octopyle_, n. sp. (Pl. 49, fig. 4).
Cortical shell with thorny surface, three times as long as the
lentelliptical medullary shell. Perimeter of the lateral plane elliptical
or nearly hexagonal, with four rounded corners (on the poles of two crossed
diagonal axes), one and a third times as long as broad. Eight internal
egg-shaped gates (as in _Octopyle_), between the complete lateral wings of
the transverse girdle, and two axial beams in the principal axis. One
single wing of the lateral girdle turns around the other in two to three
simple spiral turns.
_Dimensions._--Length of the cortical shell 0.18, breadth 0.14; length of
the medullary shell 0.06, breadth 0.035.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
Subgenus 2. _Pylospironium_, Haeckel.
_Definition._--Spiral convolutions or turns of the cortical shell double;
both wings of the lateral girdle turning around the sagittal axis.
3. _Pylospira cymbium_, n. sp.
Cortical shell with smooth surface, seven times as long as the
lentelliptical medullary shell. Perimeter of the lateral plane elliptical,
one and a third times as long as broad. Four internal kidney-shaped gates
between the complete lateral wings of the transverse girdle (as in
_Tetrapyle_). Both principal wings of the lateral girdle turn round one
another in two to two and a half double spiral turns.
_Dimensions._--Length of the cortical shell 0.22, breadth 0.17; length of
the medullary shell 0.03, breadth 0.025.
_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.
{699}Genus 308. _Tholospira_,[348] n. gen.
_Definition._--#Lithelida# with double, trizonal or _Larnacilla_-shaped
medullary shell; cortical shell subspherical or lentelliptical constructed
of a simple or double spiral of the sagittal girdle (or third cortical
girdle); the spiral lamella revolving around the transverse axis.
The genus _Tholospira_ represents the third genus of Larcospirida. Whilst
the spiral growth of the cortical shell is produced in _Larcospira_ by the
first (transverse) girdle of the Diplozonaria, in _Pylospira_ by the second
(lateral) girdle, in _Tholospira_ it is effected by the third or sagittal
girdle, which we found complete in _Pylonium_. If in this genus one wing of
the sagittal girdle overgrow the other remaining one and turn around the
transverse axis, we get _Tholospirema_, the first subgenus of our genus,
with simple spiral; but if afterwards the second wing follow the example of
the first, and overgrow it from the other side, we get _Tholospironium_,
with double spiral.
Subgenus 1. _Tholospirema_, Haeckel.
_Definition._--Spiral convolutions or turns of the cortical shell simple,
only one single wing of the sagittal girdle turning around the transverse
axis.
1. _Tholospira nautiloides_, n. sp.
Cortical shell with smooth surface, five times as long as the
lentelliptical medullary shell. Perimeter of the lateral plane elliptical,
one and a half times as long as broad. Four internal kidney-shaped gates
(between the lateral wings of the transverse girdle, as in _Tetrapyle_).
One wing of the sagittal girdle turns around the other in two to two and a
half simple spiral turns.
_Dimensions._--Length of the cortical shell 0.24, breadth 0.18; length of
the medullary shell 0.05, breadth 0.04.
_Habitat._--Indian Ocean, between Ceylon and Socotra, Haeckel, surface.
2. _Tholospira spinosa_, n. sp.
Cortical shell covered with numerous (sixty to eighty or more) simple,
bristle-like radial spines, about the length of the shell. Perimeter of the
lateral plane nearly quadrangular, with four rounded corners (on the poles
of two crossed diagonal axes), one and a half times as long as broad. Eight
internal egg-shaped gates (between the lateral wings of the transverse
girdle and two axial {700}beams in the principal axes, as in _Octopyle_).
One wing of the sagittal girdle turns around the other in two to three
simple spiral turns.
_Dimensions._--Length of the cortical shell 0.27, breadth 0.18; length of
the medullary shell 0.04, breadth 0.03.
_Habitat._--South Pacific, Station 288, surface.
3. _Tholospira dendrophora_, n. sp. (Pl. 49, fig. 6).
Cortical shell covered with numerous (forty to fifty or more) branched
radial spines, about half as long as the shell; each spine with two to six
dichotomous branches. Perimeter of the lateral plane elliptical, one and a
third times as long as broad. Eight internal egg-shaped gates, as in the
foregoing species. One single wing of the sagittal girdle turns around the
other in three to four spiral turns.
_Dimensions._--Length of the cortical shell 0.22, breadth 0.17; length of
the medullary shell 0.05, breadth 0.04.
_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.
Subgenus 2. _Tholospironium_, Haeckel.
_Definition._--Spiral convolutions of the cortical shell double; both wings
of the sagittal girdle turning around the transverse axis.
4. _Tholospira hystrix_, n. sp.
Cortical shell covered with numerous (sixty to eighty or more) simple
conical spines, about half as long as the shell. Perimeter of the lateral
plane hexagonal, one and a half times as long as broad. Four internal
kidney-shaped gates, as in _Tetrapyle_. Both wings of the sagittal girdle
turn round one another in two to two and a half double spiral turns.
_Dimensions._--Length of the cortical shell 0.21, breadth 0.14; length of
the medullary shell 0.04, breadth 0.03.
_Habitat._--North Atlantic, Station 354, surface.
5. _Tholospira cervicornis_, n. sp. (Pl. 49, fig. 5).
Cortical shell covered with numerous (forty to fifty or more) branched
radial spines; each spine antler-shaped, about as long as the medullary
_Larnacilla_-shell, with eight to twelve dichotomous branches (similar to
_Cromyodrymus abietinus_, Pl. 30, fig. 6). Perimeter of the lateral plane
elliptical, one and a third times as long as broad. Four internal
kidney-shaped gates, as in _Tetrapyle_. Both wings of the sagittal girdle
turn round one another in one and a half to two double spiral turns.
_Dimensions._--Length of the cortical shell 0.2, breadth 0.15; length of
the medullary shell 0.03, breadth 0.025.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
{701}Genus 309. _Spironium_,[349] n. gen.
_Definition._--#Lithelida# with double, trizonal or _Larnacilla_-shaped
medullary shell; cortical shell subspherical or lentelliptical, constructed
of two crossed spirals, which arise from both lateral wings of one girdle
(commonly the lateral girdle) and revolve in an opposite diagonal direction
around the principal axis.
The genus _Spironium_ differs in a very remarkable manner from all
foregoing Lithelida, and is distinguished by a quite peculiar mode of
growth. It is most nearly allied to _Larcopyle_, and may, like this, be
derived from _Amphipyle_ (or rather from _Larnacilla_, beginning to
transform into _Amphipyle_). But whilst in _Larcopyle_ one of the two wings
of the lateral girdle overgrows the other in the direction of the
transverse axis (turning around the principal axis), here in _Spironium_
both lateral wings begin at the same time to grow out from the lateral
sides of the _Larnacilla_-shaped medullary shell; the most remarkable thing
is, however, that the direction of growth in the wings is diverse from the
beginning: the left wing grows downwards and turns around the lower
(aboral) pole of the principal axis, the right wing grows upwards and turns
around the upper (oral) pole of the same axis. Thus both wings of the
lateral girdle are crossed in diagonal axes, and with increasing growth one
overgrows the other in the direction of these diagonals, so as to resemble
the figure 8 in shape. The open gates remaining between the turnings of the
girdle become afterwards closed on the surface by irregular lattice-work,
and so the whole cortical shell assumes finally a spherical, ellipsoidal,
or lentelliptical form. Its surface sometimes becomes covered with simple
or branched radial spines. In the interior the eight characteristic
egg-shaped gates of _Octopyle_ are commonly (or constantly?) visible, two
strong radial beams in the principal axis arising from the poles of the
lentelliptical medullary shell.
Subgenus 1. _Spironetta_, Haeckel.
_Definition._--Surface of the shell smooth or rough, but not with radial
spines.
1. _Spironium octonium_, n. sp. (Pl. 49, fig. 7).
Cortical shell lentelliptical, its breadth (or transverse axis) surpassing
considerably the length (or the principal axis). Surface thorny and
somewhat hump-backed. The spiral wings of the transverse girdle have about
the same breadth as the eight internal gates between them and the axial
beams.
_Dimensions._--Length of the cortical shell (or principal axis) 0.15,
breadth (or transverse axis) 0.2; length of the medullary shell 0.05,
breadth 0.04.
_Habitat._--South Atlantic, west of Tristan da Cunha, Station 332, depth
2200 fathoms.
{702}2. _Spironium diagonale_, n. sp.
Cortical shell nearly spherical, four times as great as the subspherical
medullary shell. Surface rough. The spiral wings of the transverse girdle
about half as broad as the eight internal gates between them and the axial
beams.
_Dimensions._--Diameter of the cortical shell 0.16, of the medullary shell
0.04.
_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.
Subgenus 2. _Spironilla_, Haeckel.
_Definition._--Surface of the shell covered with simple or branched radial
spines.
3. _Spironium spinosum_, n. sp.
Cortical shell subspherical, five times as great as the subspherical
medullary shell. Surface covered with numerous (sixty to eighty or more)
simple, bristle-like radial spines, longer than the shell. The spiral wings
of the transverse girdle of about the same breadth as the eight internal
gates between them and the axial beams.
_Dimensions._--Diameter of the cortical shell 0.2, of the medullary shell
0.04.
_Habitat._--Pacific, central area, Station 274, surface.
4. _Spironium arbustum_, n. sp.
Cortical shell lentelliptical, its breadth surpassing its length
considerably. Surface covered with numerous (forty to sixty or more) thin
radial spines, about as long as the greatest diameter of the shell; each
spine with two to six lateral branches, which are either simple or again
branched (similar to _Cromyodrymus abietinus_, Pl. 30, fig. 6). The spiral
wings of the transverse girdle only half as broad as the eight internal
gates between them and the strong beams of the principal axis.
_Dimensions._--Length of the cortical shell 0.12, breadth 0.15; length of
the hexagonal medullary shell 0.05, breadth 0.04.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
Family XXX. #STREBLONIDA#, n. fam. (Pl. 49, figs. 8, 9).
_Definition._--#Larcoidea# with asymmetrical, spiral, polythalamous shell,
composed of a variable number of roundish chambers, which form together an
ascending spiral; both halves of the shell unequal. Primordial chamber
either simple or _Larnacilla_-shaped.
The family #Streblonida# comprises those #Larcoidea# in which a number of
chambers is arranged in an ascending spiral, round a simple or trizonal
primordial chamber, like winding stairs. They show the same spiral
structure as in the foregoing {703}family, but whilst in the Lithelida the
spiral line lies in one plane (as in _Nautilus_), in the Streblonida it
ascends like a screw (as in _Helix_). Therefore the former have the same
relation, regarding the spiral structure, to the nautiloid Polythalamia as
the latter to the turbinoid Foraminifera. Indeed the single forms of
Streblemida repeat in their special structure the characteristic genera of
Turbinoida, such as _Globigerina_, _Rosalina_, _Pulvinulina_,
_Hastigerina_, &c. As in these calcareous turbinoid Foraminifera, so also
in the analogous siliceous Streblonida the distinction of species is very
difficult and open to many objections.
The number of species in this family is very small; all are rare and for
the most part very opaque and difficult to understand, so that the
following distinction of a dozen species can have only a provisional value.
To get a complete idea of their peculiar structure, the shell must be
turned and observed from different sides, and thus their full study
requires yet much time and work. There are to be found evident transitional
forms between them and the Lithelida on the one hand and the Soreumida on
the other. Besides this, most species of Streblonida seem to have more
inclination to individual varieties and abnormalities than the majority of
the other Radiolaria.
The general form of the whole shell is in the Streblonida sometimes more
egg-shaped or even subspherical, at other times more top-like or conical,
sometimes nearly discoidal. The height of the shell (or the vertical axis
of the ascending spiral) is occasionally larger, at other times smaller
than the breadth (or the greatest horizontal diameter, perpendicular to the
height). Some very flat forms seem to approach the Lithelida. With regard
to the internal screw-formation, the shell of all Streblonida is
asymmetrical.
The number of the aggregated incomplete chambers is commonly between ten
and twenty, but ascends sometimes to thirty, forty, or more. Sometimes the
size of all the chambers is nearly the same, sometimes they increase
gradually, occasionally also very rapidly. The primordial chamber (or the
first and oldest) seems to be commonly the smallest, and inversely, the
last and youngest chamber, the largest. But sometimes (in _Streblopyle_)
also the contrary may be the case. The form of the single chambers is very
variable, from the spherical or hemispherical through all transitions
leading to irregular roundish or longish forms. The network is commonly
irregular, with small roundish pores of different sizes, but sometimes also
regular, circular. The surface of the shell is commonly smooth or rough,
rarely covered with radial spines. In most species the reticulation and
particularly the separation of the chambers is more or less incomplete.
As in the Lithelida, so also in the Streblonida we can distinguish two
subfamilies. In the Streblacanthida (_Streblonia_, _Streblacantha_) the
primordial chamber is a simple, spherical, subspherical, or lentelliptical
latticed shell. In the Streblopylida (_Streblopyle_) the primordial chamber
is trizonal or _Larnacilla_-shaped, as in the greater number of
#Larcoidea#, composed of three elliptical latticed girdles of unequal size,
perpendicular one to another, and surrounding a simple central chamber. As
in the Lithelida, so also {704}here we cannot certainly say whether the
former have originated from the latter by reduction of the
_Larnacilla_-shell, or whether both groups be of different origin. The
latter is perhaps more probable. This family as well as the foregoing
requires a much more careful study than I could give to it.
_Synopsis of the Genera of Streblonida._
-------------------------------------------------------------------------
I. Subfamily Streblacanthida.
Primordial chamber simple, spherical or lentelliptical.
-------------------------------------------------------------------------
Shell without radial spines, 310. _Streblonia_.
Shell with radial spines, 311. _Streblacantha_.
-------------------------------------------------------------------------
II. Subfamily Streblopylida.
Primordial chamber trizonal or _Larnacilla_-shaped.
-------------------------------------------------------------------------
Shell without radial spines, 312. _Streblopyle_.
Genus 310. _Streblonia_,[350] n. gen.
_Definition._--#Streblonida# with simple, spherical, subspherical, or
lentelliptical primordial chamber, beginning the screw-like series of
spirally ascending chambers. Surface smooth or thorny, without radial
spines.
The genus _Streblonia_ contains those Streblonida in which a variable
number of roundish, subspherical, or longish chambers form a screw-like
aggregate, beginning with a quite simple primordial chamber. The special
order of the complex spiral offers interesting resemblances to different
genera of the calcareous Foraminifera, from which I have taken the
corresponding name of the species. The whole form of the shell is sometimes
more egg-shaped or subspherical, at other times more top-like or conical,
occasionally very flat. Its surface is smooth or rough, but not covered
with radial spines.
1. _Streblonia globigerina_, n. sp.
Shell subspherical, thick walled, clustered, with eight to ten nearly
spherical chambers, of rapidly increasing size, the tenth chamber about
twelve times as broad as the first. Breadth of the shell nearly equal to
the height. Pores subregular, circular, hexagonally formed, of about the
same breadth as the bars; about sixteen on the breadth of the tenth
chamber. (Resembles very much the common _Globigerina_.)
_Dimensions._--Breadth of the shell 0.18, height 0.16.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
2. _Streblonia uvigerina_, n. sp.
Shell nearly egg-shaped, clustered, with eight to eleven subspherical
chambers of gradually increasing size, the tenth chamber about six times as
broad as the first. Breadth of the shell about {705}half its height. Pores
of the shell subregular, circular, about twice as broad as the bars; about
twenty on the breadth of the tenth chamber. (Resembles some species of
_Uvigerina_.)
_Dimensions._--Breadth of the shell 0.11, height 0.23.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
3. _Streblonia polymorphina_, n. sp.
Shell egg-shaped, thin walled, with twelve to fourteen roundish chambers of
rapidly increasing size, the tenth chamber about seven times as broad as
the first. Breadth of the shell about two-thirds of the height. Pores
irregular roundish, twice as broad as the bars; about twenty on the tenth
chamber. (Resembles certain forms of _Polymorphina_.)
_Dimensions._--Breadth of shell 0.22, height 0.14.
_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.
4. _Streblonia bulimina_, n. sp.
Shell nearly egg-shaped, thick walled, clustered, with fourteen to eighteen
egg-shaped chambers of rapidly increasing size, the tenth chamber about
eight times as broad as the first. Breadth of the shell about two-thirds of
the height. Pores irregular, roundish, half as broad as the bars; about
twelve on the breadth of the tenth chamber. (Resembles closely _Bulimina_.)
_Dimensions._--Breadth of the shell 0.17, height 0.24.
_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.
5. _Streblonia rosalina_, n. sp.
Shell top-shaped or flatly conical, with twelve to sixteen chambers of
gradually increasing size, the tenth chamber about four times as broad as
the first. Breadth of the shell twice as large as the height. Pores
subregular, circular, very small, of the same breadth as the bars; about
twelve on the breadth of the tenth chamber. (Resembles some forms of
_Rosalina_.)
_Dimensions._--Breadth of the shell 0.27, height 0.13.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
6. _Streblonia planorbulina_, n. sp.
Shell very flatly conical, nearly lenticular or discoidal, with twenty to
twenty-five chambers of nearly equal size, the tenth chamber a little
broader than the first. Breadth of the shell exceeds five to six times the
height. Pores subregular, circular, very small, half as broad as the bars;
about eight on the breadth of the tenth chamber. (Resembles closely
_Planorbulina_.)
_Dimensions._--Breadth of the shell 0.3 to 0.4, height 0.06 to 0.07.
_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.
{706}7. _Streblonia pulvinulina_, n. sp.
Shell top-shaped or flatly conical, with thirty to forty chambers of slowly
increasing size, the tenth chamber about three times as broad as the first.
Breadth of the shell exceeds three times the height. Pores circular,
subregular, very small, about one-third as broad as the bars; about thirty
in the breadth of the tenth chamber. (Resembles closely _Pulvinulina_.)
_Dimensions._--Breadth of the shell 0.25, height 0.08.
_Habitat._--Pacific, central area, Station 263, depth 2650 fathoms.
Genus 311. _Streblacantha_,[351] n. gen.
_Definition._--#Streblonida# with simple, spherical, subspherical, or
lentelliptical primordial chamber, beginning the screw-like series of
spirally ascending chambers. Surface covered with radial spines.
The genus _Streblacantha_ differs from the nearly allied _Streblonia_ only
in the covering of radial spines, and bears therefore the same relation to
it as _Hastigerina_ has to _Globigerina_ amongst the similar calcareous
Polythalamia.
1. _Streblacantha siderolina_, n. sp. (Pl. 49, figs. 8, 8_a_).
_Streblonia siderolina_, Haeckel, 1883, MS.
Shell flatly conical, with fourteen to sixteen nearly hemispherical
chambers of gradually increasing size, the tenth chamber about six times as
broad as the first. Breadth of the shell nearly equal to the height. Pores
subregular, circular, hexagonally framed, twice as broad as the bars; about
nine pores on the breadth of the tenth chamber. Surface covered with
numerous short conical radial spines, one-fourth to one-sixth as long as
the diameter of the shell.
_Dimensions._--Breadth of the shell 0.15, height 0.17.
_Habitat._--South Pacific, Station 298, depth 2225 fathoms.
2. _Streblacantha calcarina_, n. sp.
Shell conical, with sixteen to eighteen roundish chambers of gradually
increasing size, the tenth chamber about three times as broad as the first.
Breadth of the shell about one and a half times the height. Pores
irregular, roundish. Surface covered with numerous strong conical radial
spines, about half as long as the diameter of the shell.
_Dimensions._--Breadth of the shell 0.24, height 0.17.
_Habitat._--South Pacific, Station 285, depth 2375 fathoms.
{707}3. _Streblacantha hastigerina_, n. sp.
Shell nearly spherical, clustered, with nine to eleven nearly spherical
chambers of rapidly increasing size, the tenth chamber about six times as
broad as the first. Breadth of the shell nearly equal to the height. Pores
subregular, circular, of about the same breadth as the bars. Surface
bristly, covered with numerous very thin and long, needle-shaped radial
spines, longer than the diameter of the shell. (Resembles closely
_Hastigerina_.)
_Dimensions._--Breadth of the shell 0.18, height 0.15.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
Genus 312. _Streblopyle_,[352] n. gen.
_Definition_.--#Streblonida# with trizonal lentelliptical medullary shell
(composed like _Larnacilla_ of three elliptical dimensive girdles
surrounding one simple central primordial chamber). From this begins a
screw-like series of spirally ascending chambers. Surface smooth or thorny,
without radial spines.
The genus _Streblopyle_ presents externally the same appearance and contour
as _Streblonia_, and is composed like this of a variable number of
chambers, ascending screw-like around the axis of the spiral shell. The
first or primordial chamber, however, in which the growth begins, is in
_Streblonia_ a simple spherical shell, but in _Streblopyle_ a trizonal
shell or _Larnacilla_-shell (compare above, p. 600). The chambers are very
incompletely separated, and comparatively much larger, their number much
smaller than in _Streblonia_. The structure in the species of this genus is
difficult to understand.
1. _Streblopyle helicina_, n. sp. (Pl. 49, fig. 9).
Shell helicoid, one and a third times as high as broad, with eight to
twelve incomplete semizonal chambers, ascending spirally from the lateral
half girdle of the lentelliptical medullary shell, octopyle-shaped, and
enveloping it in three to four spiral turnings. The height of the whole
cortical shell equals nearly five times the height of the trizonal
medullary shell. Pores irregular, roundish. Surface of the shell rough or
nearly smooth. (This species seems to be nearly allied to _Spironium
octonium_.)
_Dimensions._--Breadth of the spiral cortical shell 0.18, height 0.24;
breadth of the medullary shell 0.04, height 0.05.
_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.
2. _Streblopyle spirulina_, n. sp.
Shell egg-shaped or nearly spherical, about as high as broad, with eight to
nine semizonal chambers, ascending spirally from the subspherical trizonal
medullary shell, and enveloping it in {708}four to five turnings. The sixth
chamber twice as broad as the trizonal medullary shell. Pores irregular,
roundish. Surface of the shell thorny.
_Dimensions._--Breadth of the spiral cortical shell 0.27, height 0.25;
breadth of the medullary shell 0.05, height 0.06.
_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.
Family XXXI. #PHORTICIDA#, Haeckel (Pl. 49, figs. 10, 11).
_Phorticida_, Haeckel, 1881, Prodromus, p. 464.
_Definition._--#Larcoidea# with quite irregular monothalamous shell,
representing irregular modifications of an original lentelliptical latticed
shell; the irregular cortical shell encloses a regular or subregular,
lentelliptical or trizonal medullary shell.
The family Phorticida comprises a small number of #Larcoidea# in which a
subregular, trizonal, lentelliptical medullary shell is enclosed by an
irregular simple or spongy cortical shell. The lattice-work of the latter
is sometimes simple and complete, at other times incomplete, with open
gates (as in the Pylonida), sometimes also spongy. Its form is always more
or less irregular, roundish, often dimply or tuberous; different from most
other #Larcoidea#.
The medullary shell is constantly a regular or subregular
_Larnacilla_-shell, composed of three elliptical latticed girdles of
different sizes, perpendicular one to another. This leaves no doubt that
the Phorticida are true #Larcoidea#. The connection of it with the cortical
shell is rarely effected by radial beams, commonly by two opposite latticed
wings, which are identical with the lateral halves of the transverse girdle
in the Pylonida diplozonaria (_Amphipyle_, _Tetrapyle_). Often also between
this transverse and a second (lateral) girdle there remain large open
gates, so that the affinity between these Phorticida and the Pylonida
cannot be doubted. In other cases these gates become closed, so that they
more nearly approach the Larnacida. From both families they differ by the
irregularity of the papillate or tuberous cortical shell. The network is
more or less irregular, its surface often thorny, but never covered with
symmetrically disposed radial spines.
The central capsule is lentelliptical, encloses the medullary shell, and is
enveloped by the cortical shell, as in the nearly allied Pylonida and
Larnacida, of which the Phorticida may be regarded as irregular aberrant
forms.
_Synopsis of the Genera of Phorticida._
Cortical shell simply latticed, 313. _Phorticium_.
Cortical shell spongy, 314. _Spongophortis_.
{709}Genus 313. _Phorticium_,[353] Haeckel, 1881, Prodromus, p. 464.
_Definition._--#Phorticida# with irregular cortical shell of simple
lattice-work, enclosing a lentelliptical _Larnacilla_-shaped medullary
shell.
The genus _Phorticium_ comprises all Phorticida in which the irregular
cortical shell is formed by simple lattice-work, not by spongy framework.
We can divide this genus into two subgenera: in _Phortopyle_ (as in the
_Pylonida_) the lattice-work of the cortical shell exhibits large openings
or gates; in _Phortolarcus_ these gates are perfectly closed by network;
the former may be regarded as abnormal or irregular Pylonida, the latter as
modifications of Larnacida.
Subgenus 1. _Phortopyle_, Haeckel.
_Definition._--Lattice-work of the irregular cortical shell incomplete,
with large openings or gates.
1. _Phorticium pylonium_, n. sp. (Pl. 49, fig. 10).
Cortical shell irregular, roundish, about three times as large as the
enclosed lentelliptical, regular, _Larnacilla_-shell, connected with it by
some radial beams and irregularly latticed girdles; between these remain
four to eight large open gates of irregular roundish form and size; and
these gates are the same as in _Tetrapyle_ and _Octopyle_. This very
variable species may be regarded as a monstrosity of those genera of
Pylonida; it is very common, but all individuals are more or less unequal;
some specimens approach to some common species of _Tetrapyle_. The surface
of the shell is more or less spiny.
_Dimensions._--Diameter of the irregular cortical shell 0.12 to 0.18;
length of the lentelliptical medullary shell 0.05 to 0.06, breadth 0.035 to
0.045.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, &c., common,
surface and in various depths.
2. _Phorticium spironium_, n. sp.
Cortical shell irregular, roundish, tuberous, about four times as large as
the enclosed subregular _Larnacilla_-shell, connected with it by some
irregular radial beams, and by opposite, spirally begining, irregularly
latticed girdles, comparable to those of _Spironium_; between them remain
six to twelve large open gates of irregular size and form. Surface rough.
The resemblance to some forms of _Spironium_ makes it probable that this
species is a deformity or monstrosity of that genus.
_Dimensions._--Diameter of the irregular cortical shell 0.12 to 0.2, of the
lentelliptical medullary shell 0.03 to 0.06.
_Habitat._--Pacific, central area, Stations 270 to 274, surface, and in
various depths.
{710}Subgenus 2. _Phortolarcus_, Haeckel.
_Definition._--Lattice-work of the irregular cortical shell complete,
without large openings or gates.
3. _Phorticium deforme_, n. sp.
Cortical shell irregular, roundish or longish, three times as large as the
enclosed subregular, lentelliptical _Larnacilla_-shell, connected with it
by two opposite latticed wings (the halves of the transverse girdle of
_Tetrapyle_). Network of the cortical shell irregular, dense, perfectly
closed, without larger openings or gates. Surface thorny. (May be regarded
as a monstrous form of _Larnacalpis_.)
_Dimensions._--Diameter of the irregular cortical shell 0.15 to 0.18, of
the medullary shell 0.04 to 0.06.
_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.
4. _Phorticium abnorme_, n. sp.
Cortical shell irregular, roundish, tuberous, with five to ten quite
irregular or nearly hemispherical protuberances, which resemble the cupolas
of Zonarida. The regular lentelliptical _Larnacilla_-shell is one-third to
one-fourth as large as the enclosing cortical shell, and is connected with
it by some irregular radial beams. Lattice-work completely closed, without
gates. Surface spiny. (May be regarded as an anomalous form of _Zonidium_;
as in the other species of this variable genus, the individuals are very
unequal.)
_Dimensions._--Diameter of the irregular cortical shell 0.12 to 0.2, of the
medullary shell 0.03 to 0.05.
_Habitat._--Atlantic and Pacific, tropical zone, surface, and at various
depths.
Genus 314. _Spongophortis_,[354] Haeckel, 1881, Prodromus, p. 464.
_Definition._--#Phorticida# with irregular cortical shell of spongy
framework, enclosing a lentelliptical _Larnacilla_-shaped medullary shell.
The genus _Spongophortis_ differs from _Phorticium_ in the spongy framework
of the cortical shell. This encloses the inner _Larnacilla_-shaped
medullary shell either directly, or both shells are separated by a hollow
interval, and connected either by radial beams or by latticed lamellæ.
Perhaps both these subgenera might be better separated as genera.
{711}Subgenus 1. _Stypophorticium_, Haeckel.
_Definition._--Spongy cortical shell immediately enclosing the
lentelliptical medullary shell, without hollow interval.
1. _Spongophortis spongiosa_, n. sp.
Cortical shell irregular, roundish, rough or tuberous, composed of loose
spongy framework, which immediately envelops the lentelliptical central
_Larnacilla_-shell; the diameter of the former becomes about five to six
times as large as that of the latter.
_Dimensions._--Diameter of the spongy cortical shell 0.15 to 0.25, of the
trizonal medullary shell 0.03 to 0.04.
_Habitat._--Pacific, central area, Station 274, surface.
Subgenus 2. _Spongophorticium_, Haeckel.
_Definition._--Spongy cortical shell separated by a hollow interval from
the lentelliptical medullary shell.
2. _Spongophortis radiosa_, n. sp.
Cortical shell irregular, roundish, four to five times as large as the
enclosed lentelliptical _Larnacilla_-shell, with which it is connected by
ten to twenty irregularly disposed radial beams. Spongy framework compact,
about as thick as the medullary shell. Surface covered with numerous short,
bristle-shaped, radial spines.
_Dimensions._--Diameter of the spongy cortical shell 0.15 to 0.2, of the
trizonal medullary shell 0.035 to 0.045.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
3. _Spongophortis larnacilla_, n. sp. (Pl. 49, figs. 11_a_-11_d_).
Cortical shell irregular, roundish, tuberous, three to four times as large
as the enclosed lentelliptical _Larnacilla_-shell, connected with it by two
opposite latticed wings (the halves of the transverse girdle of
_Tetrapyle_). Spongy framework compact, about half as thick as the
medullary shell. Surface rough. (May be regarded as an abnormal _Tetrapyle_
or _Larnacalpis_, with an irregular spongy cortical shell.)
_Dimensions._--Diameter of the spongy cortical shell 0.16 to 0.2, of the
trizonal medullary shell 0.04 to 0.06.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
{712}Family XXXII. #SOREUMIDA#, Haeckel (Pl. 49, figs. 12, 13).
_Soreumida_, Haeckel, 1881, Prodromus, p. 464.
_Definition._--#Larcoidea# with quite irregular polythalamous shell,
composed of a variable number of chambers, aggregated without any definite
order. Primordial chamber either simple or _Larnacilla_-shaped.
The family #Soreumida# contains a small number of #Larcoidea#, different
from most other #Sphærellaria# in the complete irregularity of the
polythalamous shell, which is composed of a variable number of roundish
chambers or subspherical latticed shells, aggregated in the form of an
irregular heap. We can distinguish in this family only two genera, with
very different structure of the central medullary shell or the first
chamber beginning the growth; and these correspond to the two subfamilies
of the nearly allied Streblonida (p. 704). In _Soreuma_ (as in
_Streblonia_) the first or primordial chamber, from which the growth
begins, is like the others, a simple spherical or irregular roundish
lattice-shell. In _Sorolarcus_, however (as in _Streblopyle_), the first or
primordial chamber is a trizonal or _Larnacilla_-shell. It is not
improbable that the former originated phylogenetically from _Streblonia_,
the latter from _Streblopyle_, by loss of the original spiral order of
growth. But it is also possible that these groups have no nearer relation.
Among the calcareous Foraminifera a very similar form is represented by
_Acervulina_ and its allies.
The general form of the whole shell in the Soreumida is sometimes more
egg-shaped or lentelliptical, at other times even subspherical,
occasionally quite irregular, tuberous, or clustered. The number of the
aggregated chambers is very variable, in _Sorolarcus_ between ten and
thirty, in _Soreuma_ ascending to fifty to eighty, sometimes from one
hundred to one hundred and fifty and more. Their size is sometimes nearly
equal, at other times very different, their form commonly very irregular,
roundish, but sometimes also subspherical or egg-shaped. The network of the
shell is also commonly irregular, with roundish pores of different sizes.
The surface is usually smooth or rough, rarely covered with radial spines.
The central capsule is not known, as I observed only a few skeletons of
this family.
_Synopsis of the Genera of Soreumida._
Primordial chamber of the shell simple, subspherical
or roundish, 315. _Soreuma_.
Primordial chamber of the shell trizonal or
_Larnacilla_-shaped, 316. _Sorolarcus_.
Genus 315. _Soreuma_,[355] Haeckel, 1881, Prodromus, p. 464.
_Definition._--#Soreumida# with numerous chambers, aggregated without any
regularity around one simple, spherical or subspherical, central chamber.
{713}The genus _Soreuma_ contains those Soreumida in which no trace of any
regular structure is found, but all the chambers of the irregular shell are
without any order, aggregated around a simple spherical or subspherical
central chamber or medullary shell. _Soreuma_ may have originated either
from _Sorolarcus_ by loss of the central _Larnacilla_-shell or from
_Cenolarcus_ by irregular apposition of new chambers around the
lentelliptical central chamber or simple Larcoid-shell. Some species seem
to exhibit a transition to _Sorolarcus_. Owing to the absolute irregularity
of the polythalamous shell _Soreuma_ resembles _Acervulina_ among the
Foraminifera.
Subgenus 1. _Soreumium_, Haeckel.
_Definition._--Shell without radial spines.
1. _Soreuma irregulare_, n. sp. (Pl. 49, fig. 12).
Shell irregular, clustered, or tuberous, composed of a large number (one
hundred and twenty to one hundred and fifty or more) of irregular, roundish
chambers of very different sizes, the largest four to five times as broad
as the smallest. Network very delicate, with very small roundish pores, to
five times as broad as the bars. Surface thorny.
_Dimensions._--Diameter of the shell 0.3, of the single chambers 0.02 to
0.08.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
2. _Soreuma acinosum_, n. sp.
Shell irregularly lentelliptical, with different growth in the three
dimensions, composed of a large number (forty to sixty or more) of
irregular, roundish chambers of very different sizes, the largest six to
eight times as broad as the smallest. Pores subregular, circular, twice as
broad as the bars. Surface smooth.
_Dimensions._--Length of the shell 0.21, breadth 0.17, height 0.13;
diameter of the largest chambers 0.03, of the smallest 0.004.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
3. _Soreuma subglobosum_, n. sp.
Shell nearly spherical, composed of a variable number (twelve to fifteen or
more) of irregularly aggregated subspherical chambers of nearly equal size.
Pores subregular, circular, twice as broad as the bars. Surface thorny.
_Dimensions._--Diameter of the shell 0.25, of the largest chambers 0.04, of
the smallest 0.005.
_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.
{714}4. _Soreuma acervulina_, n. sp.
Shell quite irregular, cloddy, or tuberous, composed of twenty to thirty
(or more) roundish chambers of almost uniform size, the largest twice to
three times as broad as the smallest. Pores irregular, roundish. Surface
smooth.
_Dimensions._--Diameter of the shell 0.18 to 0.24, of the largest chambers
0.06, of the smallest 0.02.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
Subgenus 2. _Soreumidium_, Haeckel.
_Definition._--Shell with radial spines.
5. _Soreuma spinosum_, n. sp.
Shell quite irregular, cloddy, or tuberous, composed of thirty to forty
subspherical chambers of nearly the same size. Pores subregular, circular,
twice as broad as the bars; on the equator of each chamber six to eight
pores. Surface thorny, covered with irregularly scattered conical radial
spines, about as long as the diameter of the chambers.
_Dimensions._--Diameter of the shell 0.17 to 0.25, of the chambers 0.04.
_Habitat._--North Pacific, Station 241, depth 2300 fathoms.
6. _Soreuma setosum_, n. sp.
Shell nearly spherical, composed of sixty to seventy (or more) irregular,
roundish chambers of very different sizes, the largest five to six times as
broad as the smallest. Pores irregular, roundish. Surface bristly, covered
with very numerous, long and thin, bristle-shaped radial spines, about as
long as the diameter of the shell.
_Dimensions._--Diameter of the shell 0.28, of the chambers 0.005 to 0.03.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
Genus 316. _Sorolarcus_,[356] n. gen.
_Definition._--#Soreumida# with numerous chambers, aggregated irregularly
around a trizonal medullary shell or _Larnacilla_-shell.
The genus _Sorolarcus_ comprises those Soreumida in which the heap of
irregularly aggregated chambers encloses a central trizonal medullary
shell, by which they demonstrate clearly their descent from Larnacida or
Pylonida. The lentelliptical medullary {715}shell exhibits quite the same
characteristic structure as that of _Larnacilla_, being composed of three
elliptical latticed girdles, perpendicular one to another. In some species
also the beginning of a second system of girdles is clearly indicated, so
that there can be no doubt as to their derivation from _Amphipyle_ or
_Tetrapyle_.
Subgenus 1. _Sorolarcium_, Haeckel.
_Definition._--Shell without radial spines.
1. _Sorolarcus larnacillifer_, n. sp. (Pl. 49, fig. 13).
Shell irregular, clustered, or tuberous, composed of twenty to thirty
irregular, roundish chambers of very different size, the largest four to
eight times as broad as the smallest, aggregated without order around a
central, lentelliptical, _Larnacilla_-shaped medullary shell. Pores
irregular, roundish, twice to four times as broad as the bars. Surface
smooth or a little spiny.
_Dimensions._--Diameter of the whole shell 0.18, of the central
_Larnacilla_-shell 0.05.
_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.
2. _Sorolarcus tetrapylifer_, n. sp.
Shell irregularly roundish, clustered, composed of ten to twelve irregular
rather long chambers of almost uniform size, the largest twice as broad as
the smallest, aggregated without order around a central shell of the
structure of _Tetrapyle_, which encloses an inner trizonal
_Larnacilla_-shell of half the size. Pores irregular, roundish, twice to
four times as broad as the bars. Surface spiny.
_Dimensions._--Diameter of the whole shell 0.25, of the outer
(_Tetrapyle_-like) medullary shell 0.12, of the inner (_Larnacilla_-like)
shell 0.06.
_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.
Subgenus 2. _Sorolarcidium_, Haeckel.
_Definition._--Shell with radial spines.
3. _Sorolarcus terminalis_, n. sp.
Shell nearly spherical, composed of fifteen to eighteen irregularly
aggregated roundish chambers of nearly equal size; in the centre a
lentelliptical _Larnacilla_-shell. Surface covered with numerous thin,
bristle-like radial spines, somewhat longer than the shell.
_Dimensions._--Diameter of the whole shell 0.21, of the central
_Larnacilla_-shell 0.05.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
{716}----
LEGION II. #ACANTHARIA#,
VEL ACTIPYLEA, VEL ACANTHOMETREA (PLS. 129-140).
_Acantharia_, Haeckel, 1881.
_Actipylea_, Haeckel, 1882.
_Acanthometrea_, Hertwig, 1879.
_Panacantha_, Haeckel, 1878.
_Definition._--Radiolaria with simple membrane bounding the central
capsule, which is everywhere perforated by innumerable fine pores (disposed
either equally or symmetrically). Extracapsulum without phæodium. Skeleton
centrogenous (its growth proceeding from the centre), acanthinic (organic,
not siliceous). Fundamental form originally spherical.
The legion ACANTHARIA vel ACTIPYLEA, to the extent here defined, was
constituted by me, 1878, in my Protistenreich (p. 102) under the name
"PANACANTHA." A more accurate definition of this group was given in 1879 by
Hertwig under the name ACANTHOMETREA. Both names were replaced by me, 1881,
in my Prodromus (pp. 421, 465) by the more convenient name ACANTHARIA. This
legion comprises all those Radiolaria which were first described by
Johannes Müller, 1858, as _Acanthometrae_, and also an important part of
his _Haliomma_. In my Monograph (1862, pp. 371-424) I disposed them in
three families, Acanthometrida, Diploconida, and Dorataspida.
Although the number of genera and species in this legion is much increased
by the rich collection of the Challenger, we can divide all ACANTHARIA into
two different orders: #Acanthometra# (without complete lattice-shell) and
#Acanthophracta# (provided with a complete lattice-shell).
The ACANTHARIA agree with the SPUMELLARIA in the structure of the simple
capsule-membrane, which is perforated by numerous small pores (but
constantly devoid of the large main opening, which the NASSELLARIA and
PHÆODARIA possess, being hence united as "Merotrypasta"). We can therefore
unite both former legions as "Holotrypasta" (compare above, pp. 5, 6); but
in many ACANTHARIA (if not in all?) the numerous small pores of the
capsule-membrane exhibit a certain peculiar arrangement not observed in the
SPUMELLARIA; therefore the latter can be regarded as true "Peripylea" in
opposition to the former as "Actipylea."
The peculiar main character of all ACTIPYLEA or ACANTHARIA is determined by
the chemical constitution of their skeleton, which is not silex, but a
peculiar organic substance, called by me in 1862 "acanthin" (Monogr. d.
Radiol., pp. 30, 32). In all other Radiolaria the skeleton is composed of
silex or of a silicate. But besides this {717}chemical difference, an
important morphological character of the skeleton also separates the
ACANTHARIA from all other Radiolaria: in the latter the skeleton is never
centrogenous or arising from the centre of the capsule; in strict
opposition to this general fact the skeleton of all ACANTHARIA is
centrogenous, composed of radial spines, which arise from the central point
of the capsule and pierce its membrane. These characteristic "radial spines
of acanthin," arising from the centre, are never hollow (as formerly was
supposed), but constantly solid. Their form is extremely variable, and most
important for the distinction of genera and species; but more interesting
from a general point of view is their peculiar arrangement or disposition.
The regular disposition of twenty radial spines has general value almost
for all ACANTHARIA, with the exception only of the small group of
#Actinelida#. In this latter group the number of radial spines is either
more or less than twenty, and their disposition is either quite irregular
or follows a peculiar rule. The number of individuals of these
#Actinelida#, compared with that of the other ACANTHARIA, may be scarcely 1
per cent., whilst the latter have more than 99 per cent.; the number of
observed species is in the former about 5 per cent., in the latter about 95
per cent. Nevertheless the small group of #Actinelida# is very important,
being probably the ancestral group from which all other ACANTHARIA have
been phylogenetically derived. These other ACANTHARIA, with twenty
regularly disposed radial spines, represent the two large groups of
#Acanthonida# and #Acanthophracta#. For short and clear distinction of
these two groups of ACANTHARIA, we will call the #Actinelida# (with
irregular number and disposition of radial spines) Adelacantha, in
opposition to the Icosacantha (#Acanthonida# and #Acanthophracta#), which
all possess twenty regularly disposed radial spines.
Johannes Müller, the great zoologist, to whom we are indebted for the first
detection and accurate knowledge of the #Acanthometra#, already recognised
the regularity in the peculiar disposition of their twenty radial spines
(Abhandl. d. k. Akad. d. Wiss. Berlin, 1858, pp. 12, 37). In honour of my
great master I have called this regular disposition the "Müllerian law of
spine disposition," and have given a full explanation of it in my Monograph
(1862, pp. 40-45, 371, 372). With regard to its general value for all
Icosacantha (#Acanthonida# and #Acanthophracta#), we might also call this
promorphological Müllerian law "the Icosacanthan law."
In 1862 I had already given the following precise definition of this
"Icosacanthan law" (_loc. cit._, p. 40):--"Between two poles of a spineless
axis are regularly disposed five parallel zones, each with four radial
spines; the four spines of each zone are equidistant one from another, and
also equidistant from each pole; and the four spines of each zone are so
alternating with those of each neighbouring zone, that all twenty spines
together lie in four meridian planes, which intersect one another at an
angle of 45°." For the clear conception of this remarkable Müllerian law,
and for the complete understanding of its high value for the complicated
{718}morphology of all Icosacantha, it is the most profitable way to retain
constantly in mind for comparison the figure of a terrestrial globe with
its axis and zones. The axis of the globe is the spineless axis of all
Icosacantha, around which all twenty spines are symmetrically disposed; it
is perpendicular to the bisecting equatorial plane, in which lies the
middle of the five parallel zones; therefore the four spines, crossed
perpendicularly in this equatorial plane, are called the equatorial spines
(_c_1 to _c_4 in the figures of Pls. 131-140); often, and mainly in the
family Quadrilonchida (Pl. 131), these four equatorial spines are much
larger or of a peculiar form, different from that of the sixteen other
spines. Each pair of the four equatorial spines lies in one equatorial
axis, and this latter is perpendicular to the crossing axis, in which lies
the other pair of opposite spines. We may regard these two equatorial
diameters, perpendicular one to another and to the spineless axis, as the
two perradial axes or primary axes. Correspondingly the two meridian
planes, which are determined by one perradial axis and the spineless axis,
may be called the two primary or perradial meridian planes.
The globe is divided by the equatorial plane into two equal halves, the
northern and the southern hemisphere. In each hemisphere there are disposed
quite symmetrically eight radial spines, the distal ends of which fall in
two parallel circles, a larger tropical circle (nearer to the equator) and
a smaller polar circle (nearer to the pole of the spineless axis).
Therefore we call the four spines of the former the "tropical spines" and
the four spines of the latter the "polar spines." The angle between the
former and the equatorial plane is about 30°, the angle between the latter
and that plane about 60°.
The eight polar spines (four northern and four southern) lie in the same
two meridian planes as the four equatorial spines. Therefore in each of
these two perradial planes lie six radial spines, opposite in pairs; two
equatorial and four polar spines. Commonly all eight polar spines are of
the same size and form; and often they are also equal to the eight tropical
spines; but in some cases (e.g., in some species of Quadrilonchida) they
are much smaller than the twelve other spines, and sometimes even
rudimentary. In all figures of the Pls. 131-140 (and also in my Monograph,
1862, Taf. xv.-xxii.) the polar spines of the northern circle are marked by
the characters _a_1 to _a_4, the polar spines of the southern circle by the
characters _e_1 to _e_4. In the first perradial meridian plane lie _a_1 and
_a_3, _e_1 and _e_3, in the second _a_2 and _a_4, _e_2 and _e_4.
The eight tropical spines lie between the eight polar and the four
equatorial spines, four in each hemisphere; their distal points fall in two
parallel circles, which correspond exactly to the two tropics of the globe.
Therefore the four northern tropical spines may be called "canceral spines"
(as their ends fall in the Tropic of Cancer) and the four southern
correspondingly "capricornal spines" (as their points lie {719}in the
Tropic of the Capricorn). In the figures of the Pls. 131-140 (as well as in
my Monograph, 1862, Taf. xv.-xxii.) the four northern or canceral spines
are marked by the characters _b_1 to _b_4, and the four southern or
capricornal spines by the characters _d_1 to _d_4. Also the eight tropical
spines lie (crossed in pairs) in two meridian planes; they do not lie,
however, in those perradial planes, in which are placed the twelve other
spines; but in two different meridian planes, crossing the former at angles
of 45°; we call these the "secondary" or "interradial" meridian planes.
Each of these planes is determined by the spineless axis and by two crossed
interradial or secondary axes; in each of the latter lie two opposite
tropical spines. In the first interradial meridian plane lie _b_1 and _b_3,
_d_1 and _d_3, in the second _b_2 and _b_4, _d_2 and _d_4.
It is a most interesting and important fact, that in all Icosacantha
(#Acanthonida# and #Acanthophracta#) this regular disposition of the twenty
spines (in five parallel zones and four meridian planes) becomes constantly
preserved by heredity, whilst the form and size of the different spines are
extremely varied by adaptation.
Only in a minority of the Icosacantha are all twenty spines perfectly
equal or nearly equal in size and form; and then it is often very difficult
to distinguish the different zones in their disposition. But in far the
greater part the size or the form of the twenty spines becomes different in
different zones; and then we can commonly distinguish easily the five
different zones. Firstly, in all Quadrilonchida and Dorataspida, the four
equatorial are distinguished from the sixteen other spines either by form
or by size, and often in a very remarkable degree. As soon as these four
principal spines are recognised, it is easy to determine also the sixteen
others; for the eight polar spines lie in the same two (perradial) meridian
planes as the former, whilst the eight tropical spines lie in two different
(interradial) meridian planes, intersecting the two former at angles of
45°. Commonly, therefore, this distinction is rather easy.
In the majority of the Icosacantha all four equatorial spines are exactly
of the same form and size. But in four families the two opposite spines of
one equatorial axis are much larger, or of another form, than those of the
crossing axis. This is the case in the Amphilonchida, Belonaspida,
Hexalaspida, and Diploconida. Therefore we here call the major equatorial
axis (with larger spines) the "hydrotomical axis," and the minor axis (with
smaller spines) the "geotomical axis." Correspondingly, the meridian plane,
in which the two larger equatorial spines are placed (_c_1, _c_3) and the
appertaining four polar spines (_a_1, _a_3, _e_1, _e_3) may be called the
"hydrotomical plane"; in the remarkable family of Hexalaspida (Pl. 139) all
six spines of this hydrotomical plane are much larger than the other
fourteen. Perpendicular to this plane is the second perradial meridian
plane, which we call the "geotomical plane"; in it lie the two smaller
equatorial spines (c2, c4) and the corresponding four polar spines (_a_2,
_a_4, _e_2, _e_4). In some Hexalaspida (_Hexonaspis_ and _Hexacolpus_) the
six spines of the hydrotomical plane become so preponderant that {720}the
other fourteen spines appear rudimentary; and in some of them the two
equatorial spines of the hydrotomical plane are much larger than the four
polar spines of the same plane. This curious relation reaches its maximum
in the Diploconida (Pl. 140).
The different development of the two equatorial axes (of the larger
hydrotomical and the smaller geotomical axis) is the first and most
important cause of the peculiar forms, which are produced in the four cited
families. We derive these terms also from the metaphor of the terrestrial
globe. The hydrotomical plane is that meridian plane of the globe which
intersects almost only the water-hemisphere (the island of Ferro in the
Atlantic, the island of Pandora in the Pacific). Perpendicular to this is
the geotomical plane, the meridian of which intersects great land-masses in
both hemispheres (Bombay in India, Athabasca in Canada). Both poles of the
smaller geotomical axis are everywhere equal (the East Indian and the
Western American). However, both poles of the larger hydrotomical axis (the
eastern Atlantic and the western Pacific) are in some genera very
different, _e.g._, in _Amphibelone_ among the Amphilonchida, and in
_Zygostaurus_ among the Quadrilonchida. In this case we call the anterior
(commonly more developed) pole of the hydrotomical axis the frontal pole,
the opposite posterior (commonly smaller) the caudal pole (Pl. 131, figs.
7, 8; Pl. 132, figs. 9, 10). On both sides of these (right and left) lie
symmetrically the two equal poles of the geotomical lateral axis.
The promorphology of the ACANTHARIA demonstrates that the geometrical
fundamental form in those groups is different. In the majority of the
ACANTHARIA, where the two equatorial axes are equal, that form is a double
square-pyramid or a "quadrate octahedron"; the four equal equatorial spines
indicate the two diagonals of the square, which is the common base of the
united regular four-sided pyramids; their common axis is the spineless axis
of the body; the ends of the polar spines fall on the edges of the
pyramids, while the ends of the tropical spines fall on the halving lines
of their faces. However, in those ACANTHARIA in which the two equatorial
axes become different, the square double pyramid becomes changed into a
rhombic double pyramid; the common base of the united pyramids is thus a
rhombus; the hydrotomical axis is the larger, the geotomical axis the
smaller diagonal of the rhombus.