_Lonchostaurus_ and _Zygostaurus_. In the former (Pl. 131, figs. 4-6) the
four larger equatorial spines becomes differentiated in pairs, so that the
opposite equal spines of one pair, _c_1, _c_3 (in the longitudinal or
hydrotomical axis), are larger, and often also of another form, than the
opposite equal spines of the other pair, _c_2, _c_4 (in the transverse or
geotomical axis). The most peculiar form is the rather common _Zygostaurus_
(Pl. 131, figs. 7, 8). Here the two opposite spines of one equatorial axis
(of the longitudinal axis) become very different, so that the anterior or
frontal spine (_c_1) is very unequal to the posterior or caudal spine
(_c_3), whereas the two opposite spines, of the other equatorial axis (of
the transverse axis) remain equal (_c_2, _c_4). Therefore the fundamental
forms become here "amphithect," as in the Ctenophora.
The numerous Quadrilonchida may be disposed in two different subfamilies:
in the Acanthostaurida all twenty radial spines are simple, without
apophyses; in the Lithopterida all twenty spines (or only one part of
them) bear two opposite apophyses (or lateral transverse processes). The
former correspond to the Zygacanthida, the latter to the Phractacanthida
among the Astrolonchida. The two opposite apophyses are simple in
_Quadrilonche_ (Pl. 133, fig. 1). In _Xiphoptera_ they are provided on
their distal side with lateral branches which are parallel to the spine
itself. In _Lithoptera_ the spines bear two to four parallel pairs of
transverse apophyses, and these are crossed by perpendicular branches,
parallel to the spine itself, so that there arise fenestrated wings or
latticed plates, comparable to the sails of a wind-mill. The lattice-work
of these plates lies in the same meridian plane with the radial spine
itself, and is therefore not comparable to the fenestrated apophyses of
_Doracantha_, of _Phatnacantha_, and of the Dorataspida; in these the
lattice-plates lie in tangential planes, perpendicular to the radial spine.
The apophyses of the Lithopterida may be developed either on all twenty
spines equally, or only on twelve spines (four equatorial and eight
tropical, whilst the eight polar spines are simple, Pl. 131, fig. 10), or
only on the four equatorial spines (whilst the sixteen others are simple,
Pl. 131, fig. 9).
_The Central Capsule_ of the Quadrilonchida is rarely spherical, commonly
more or {768}less compressed from both poles of the spineless axis,
lenticular or discoidal, sometimes square. It is enveloped by a voluminous
calymma constantly bearing coronals of "Myophrisca" (compare p. 724).
_Synopsis of the Genera of Quadrilonchida._
-------------------------------------------------------------------------
I. Subfamily Acanthostaurida.
All twenty spines simple, without lateral apophyses (sometimes forked,
but neither branched nor latticed).
-------------------------------------------------------------------------
{ Eight tropical and
{ eight polar spines
{ nearly equal, 334. _Acanthostaurus_.
Four equatorial spines of {
equal size and form. { Eight tropical and
{ eight polar spines
{ very different, 335. _Belonostaurus_.
{ Two principal spines
Four equatorial spines of { of equal size and
very different size or { form, 336. _Lonchostaurus_.
form (the two lateral {
constantly equal). { Two principal spines
{ (frontal and caudal)
{ very different, 337. _Zyostaurus_.
-------------------------------------------------------------------------
II. Subfamily Lithopterida.
Either all twenty spines or a part of them provided with two opposite
lateral branches or apophyses.
-------------------------------------------------------------------------
Apophyses simple, neither branched nor latticed, 338. _Quadrilonche_.
Apophyses branched or pinnate, but not latticed, 339. _Xiphoptera_.
Apophyses latticed, with fenestrated network, 340. _Lithoptera_.
Subfamily 1. ACASTHOSTAURIDA, Haeckel, 1881, Prodromus, p. 466.
_Definition._--#Quadrilonchida# with simple radial spines, without
apophyses.
Genus 334. _Acanthostaurus_,[374] Haeckel, 1862, Monogr. d. Radiol., p.
395.
_Definition._--#Quadrilonchida# with four equatorial spines of equal size
and form, which are much larger than the sixteen other spines. Eight
tropical and eight polar spines nearly equal. No apophyses.
The genus _Acanthostaurus_ is the most simple and primitive form of the
Quadrilonchida, and the common ancestral genus of this family; it is at the
same time its most common and widely distributed form. Some species appear
in astonishing numbers in different seas. It has been derived from
_Acanthometron_ by stronger development of the four equatorial spines,
which are all of equal size and much larger than the sixteen others.
{769}Subgenus 1. _Acostaurus_, Haeckel.
_Definition._--All twenty spines separated, in the centre united only by
the triangular faces or the meeting leaf-shaped edges of their pyramidal
bases.
1. _Acanthostaurus aequatorialis_, n. sp.
Spines cylindrical, of nearly equal breadth throughout their whole length.
Apex simple conical. Base with a large leaf-cross. Four equatorial spines
of the same form as the sixteen others, but much longer and about three
times as broad.
_Dimensions._--Length of the four major spines 0.2 to 0.25, breadth 0.008;
length of the sixteen minor spines 0.01 to 0.15, breadth 0.003.
_Habitat._--Equatorial Pacific, Station 271, surface.
2. _Acanthostaurus bipennis_, n. sp.
Spines linear, sword-shaped, strongly compressed, two edged; of nearly
equal breadth in their whole length. Apex bifid. Base with a small
leaf-cross. Four equatorial spines of the same form as the sixteen others,
but twice as long and as broad.
_Dimensions._--Length of the four major spines 0.4 to 0.5, of the sixteen
minor 0.2 to 0.3; breadth of the former 0.02, of the latter 0.01.
_Habitat._--North Pacific, Station 244, surface.
3. _Acanthostaurus conacanthus_, n. sp.
Spines conical, short, gradually tapering from the thick base towards the
simple apex. Base with large leaf-cross. Four equatorial spines more
cylindrical, twice to three times as long and as broad as the sixteen
others.
_Dimensions._--Length of the four major spines 0.15 to 0.2, of the sixteen
minor 0.05 to 0.08; basal breadth of the former 0.03, of the latter 0.012.
_Habitat._--South Atlantic, Station 332, surface.
4. _Acanthostaurus purpurascens_, Haeckel.
_Acanthostaurus purpurascens_, Haeckel, 1862, Monogr. d. Radiol., p. 395,
Taf. xix. figs. 1, 2.
_Acanthostaurus purpurascens_, R. Hertwig, 1879, Organism. d. Radiol.,
Taf. i. figs. 8, 9, Taf. iii. figs. 13, 15.
_Acanthometra purpurascens_, Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 809.
Spines nearly cylindrical, with four blunt (often scarcely visible) edges,
tapering slightly from the central to the distal end. Apex bifid, with two
short parallel teeth. Base with a broad leaf-cross. {770}Four equatorial
spines one and a half times to twice as long and broad as the sixteen
others. Central capsule cruciate, with four arms (enveloping the basal part
of the four large spines); filled up with yellow bodies and purple
granules. Calymma large, with a network of purple granules. The four main
spines are constantly much larger than the sixteen others, but in variable
proportion. The eight polar spines are sometimes rudimentary.
_Dimensions._--Length of the four major spines 0.3 to 0.4, of the sixteen
minor 0.15 to 0.3; breadth of the former 0.012, of the later 0.008 or less.
_Habitat._--Mediterranean (Messina); Atlantic, Stations 348 to 354,
surface.
5. _Acanthostaurus pallidus_, Haeckel.
_Acanthostaurus pallidus_, Haeckel, 1862, Monogr. d. Radiol., p. 396.
_Acanthometra pallida_, Claparède et Lachmann, 1858, Études sur les
Infusoires, &c., p. 461, Taf. xxiv. fig. 6.
Spines four-sided prismatic, with four blunt edges, of nearly equal breadth
throughout their whole length. Apex bifid. Base with a small leaf-cross.
Four equatorial spines much larger than the sixteen others. Central capsule
spherical, transparent, containing some yellow bodies.
_Dimensions._--Length of the four main spines 0.12 to 0.2, of the sixteen
others 0.04 to 0.08; breadth of the former 0.01, of the latter 0.004.
_Habitat._--North Atlantic, west coast of Norway, Claparède; Færöe Channel,
John Murray.
6. _Acanthostaurus forceps_, Haeckel.
_Acanthostaurus forceps_, Haeckel, 1862, Monogr. d. Radiol., p. 396, Taf.
xix. figs. 3, 4.
_Acanthometra forceps_, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, p. 809.
Spines pincer-shaped, linear, compressed, cleft nearly throughout their
whole length into two parallel thin, straight branches, which are united
only at the pyramidal base and by means of a small bridge in the middle
part. Four main spines twice as long and as broad as the sixteen others.
Central capsule square, filled up with red pigment, and containing yellow
bodies. The diagonals of the square are the two equatorial axes.
_Dimensions._--Length of the four main spines 0.1, of the sixteen others
0.05; breadth of the former 0.01, of the latter 0.005.
_Habitat._--Mediterranean (Messina); North Atlantic, Canary Islands,
Station 354, surface.
7. _Acanthostaurus hastatus_, Haeckel.
_Acanthostaurus hastatus_, Haeckel, 1862, Monogr. d. Radiol., p. 397,
Taf. xix. fig. 5.
_Acanthometra hastata_, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, p. 809.
Spines of very different size and form; four equatorial spines cylindrical
in the basal half, spear-shaped or lanceolate in the distal half, with thin
edges, little longer, but five to eight times as {771}broad as the sixteen
smaller spines, which are cylindrical, of equal breadth throughout their
whole length, with bifid apex. Base of all twenty spines pyramidal, without
leaf-cross. Central capsule yellow, spherical, or lenticular.
_Dimensions._--Length of the four major spines 0.066, breadth in the middle
0.005, on the apex 0.008; length of the sixteen smaller spines 0.054,
breadth 0.001.
_Habitat._--Mediterranean (Messina), surface.
Subgenus 2. _Staurolithium_, Haeckel, 1862, Monogr. d. Radiol., p. 401.
_Definition._--All twenty spines in the centre melted and grown together,
forming one single, star-like piece of acanthin.
8. _Acanthostaurus cruciatus_, Haeckel.
_Staurolithium cruciatum_, Haeckel, 1862, Monogr. d. Radiol., p. 401,
Taf. xx. fig. 6.
_Astrolithium cruciatum_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 811.
Spines cylindrical, of equal breadth throughout their whole length. Apex
simple conical. Four equatorial spines twice as long and broad as the
sixteen other spines. All twenty spines in the centre melted and grown
together, forming a single piece of acanthin. Central capsule spherical,
red-brown, opaque.
_Dimensions._--Length of the four equatorial spines 0.12, breadth 0.006;
length of the sixteen smaller spines 0.06, breadth 0.003.
_Habitat._--Mediterranean (Messina), surface.
Genus 335. _Belonostaurus_,[375] n. gen.
_Definition._--#Quadrilonchida# with four equatorial spines of equal size
and form, which are much larger than the sixteen other spines. Eight
tropical and eight polar spines very different. No apophyses.
The genus _Belonostaurus_ differs from the preceding _Acanthostaurus_ in
the unequal size and form of the eight tropical and the eight polar spines;
the latter are much smaller than the former and often quite rudimentary, so
that the skeleton appears composed only of twelve spines, four larger
equatorial and eight smaller tropical spines. The central bases of the
polar spines are constantly preserved. The central capsule is a flattened
square disk.
1. _Belonostaurus quadratus_, n. sp.
Four equatorial spines little compressed, almost cylindrical in the basal
half, lanceolate, broader, with simple apex in the distal half. Eight
tropical spines a little shorter, but only half as broad,
{772}sword-shaped, two-edged, of equal breadth, with simple apex. Eight
polar spines very short, conical, also with simple apex. Base without
leaf-cross, a simple pyramid.
_Dimensions._--Length of the four equatorial spines 0.18, of the eight
tropical spines 0.14, of the eight polar spines 0.04.
_Habitat._--Central Pacific, Station 271, surface.
2. _Belonostaurus bicuspis_, n. sp.
Four equatorial spines compressed, almost lanceolate in the basal half,
bifid, with two large, bent, little divergent horns in the distal half.
Eight tropical spines nearly of the same form, but only half as large, with
much smaller horns. Eight polar spines rudimentary, very short, conical,
with simple apex. Base with a large leaf-cross.
_Dimensions._--Length of the four equatorial spines 0.2, of the eight
tropical spines 0.1, of the eight polar spines 0.02.
_Habitat._--Central Pacific, Station 263, surface.
Genus 336. _Lonchostaurus_,[376] Haeckel, 1862, Monogr. d. Radiol., p. 397
(_sensu emendato_).
_Definition._--#Quadrilonchida# with four equatorial spines of unequal size
and form; the principal spines (in the longitudinal axis) larger than the
lateral spines (in the transverse axis); both opposite spines of each pair
equal. Sixteen other spines much smaller (often the eight tropical larger
than the eight rudimentary polar spines). No apophyses.
The genus _Lonchostaurus_ differs from the two preceding genera in the
unequal size and shape of both equatorial pairs of spines, whilst the two
opposite spines of each pair are equal. Therefore the equatorial plane is
here a rhombus, not a square, as in the preceding genera. We encounter here
for the first time the differentiation of the two equatorial axes, the
longitudinal (or hydrotomical) and the transverse (or geotomical) axis. The
sixteen other spines are constantly smaller (often also the eight polar
more or less rudimentary).
1. _Lonchostaurus rhomboides_, n. sp. (Pl. 131, fig. 6).
Four equatorial spines cylindrical, twice to three times as broad as the
sixteen smaller spines, conical at the distal apex; the two opposite spines
of the longitudinal axis twice as long as those of the transverse axis.
Sixteen smaller spines conical at the base, with simple bristle-shaped
apex. The surface of the rhombical calymma, including the spines, was
covered in the figured specimen with small plates like those of
_Sphærocapsa_.
_Dimensions._--Length of the cross (longitudinal axis) 0.24, breadth
(transverse axis) 0.12.
_Habitat._--South Pacific, Station 302, depth 1450 fathoms.
{773}2. _Lonchostaurus lanceolatus_, n. sp.
Four equatorial spines compressed, lanceolate, tapering equally from the
middle towards the two ends; the two opposite spines of the longitudinal
axis one and a half times as long as those of the transverse axis. Sixteen
smaller spines compressed, linear, two-edged, half as long and only
one-fourth as broad as the two longitudinal spines.
_Dimensions._--Length of the equatorial cross 0.3, breadth 0.2.
_Habitat._--Central Pacific, Station 272, surface.
3. _Lonchostaurus bifidus_, n. sp.
Four equatorial spines compressed, nearly rectangular, forked, with two
long and thin, bent, little divergent horns; the two opposite spines of the
longitudinal axis about one-third longer and broader than those of the
transverse axis. Sixteen smaller spines of the same form, also forked, but
the eight tropical only half as large, and the eight polar spines scarcely
one-fourth as large as the two longitudinal spines.
_Dimensions._--Length of the equatorial cross 0.36, breadth 0.26.
_Habitat._--South-west Pacific, Station 166, surface.
4. _Lonchostaurus bifurcus_, n. sp. (Pl. 131, fig. 4).
Four equatorial spines nearly rhomboidal, about one and a half times as
large as the eight tropical and three times as large as the eight polar
spines; the two opposite spines of the longitudinal axis only with two
large divergent straight horns; the two spines of the transverse axis
somewhat shorter, with four short horns (the two outer horns longer than
the two inner). Eight tropical spines doubly forked, each with four thin
bristle-shaped horns. Eight polar spines very short, each with two thin
bristle-shaped, much divergent horns.
_Dimensions._--Length of the equatorial cross 0.34, breadth 0.28.
_Habitat._--North-west Pacific, Station 236, surface.
5. _Lonchostaurus rhombicus_, n. sp.
Four equatorial spines nearly rhomboidal, tapering from the broader middle
towards the two ends. Leaf-cross of their base very large. The two opposite
spines of the longitudinal axis about one-third larger than the two spines
of the transverse axis. Eight tropical spines of the same form, but only
half as large. Eight polar spines rudimentary, very short, conical.
_Dimensions._--Length of the equatorial cross 0.4, breadth 0.3.
_Habitat._--North Pacific, Station 253, surface.
6. _Lonchostaurus crystallinus_, n. sp. (Pl. 131, fig. 5).
Four equatorial spines lanceolate or rhomboidal, with broad leaf-cross at
the base, of a peculiar crystalline structure and a lamellated surface,
both opposite spines of the longitudinal axis twice as {774}large as the
two spines of the transverse axis. Eight tropical spines of similar form,
but only half as large, and with a very large, extremely prominent,
lamellated leaf-cross. Eight polar spines quite rudimentary, scarcely
prominent.
_Dimensions._--Length 0.36, breadth 0.2.
_Habitat._--Central Pacific, Station 271, surface.
Genus 337. _Zygostaurus_,[377] n. gen.
_Definition._--#Quadrilonchida# with four equatorial spines of unequal size
and form; both lateral spines (in the transverse axis) equal; but both
principal spines (in the longitudinal axis) very different, the frontal
larger than the caudal. Sixteen other spines much smaller (often the eight
tropical larger than the eight rudimentary polar spines). No apophyses.
The genus _Zygostaurus_ differs from all other Staurolonchida in the
peculiar differentiation of the four equatorial spines; the two opposite
spines of the hydrotomical or longitudinal axis being very different in
size and form (the frontal spine forked, the caudal spine simple); whilst
the two opposite spines of the geotomical or lateral axis (perpendicular to
the former) are equal, forked, but different in shape from the former.
Therefore the geometrical fundamental form of the body in this remarkable
genus becomes "amphithect" or "bilateral" in the widest signification of
this term (comp. my General Morphology, vol. i. pp. 480, 482). Of the three
different dimensive axes one (the longitudinal) exhibits unequal poles,
whilst the two other (the sagittal and lateral) axes exhibit equal poles.
1. _Zygostaurus amphithectus_, n. sp. (Pl. 131, fig. 7).
Frontal spine (_c_1) little different from the two lateral spines; each
with two divergent curved horns, which are equal and of about the same
length as the simple broad basal part. Caudal spine (_c_3) simple,
spindle-shaped, about as long as the frontal spine. Tropical spines little
smaller than the three former, and of the same symmetrical forked form.
Eight polar spines much smaller, but also forked, with thin bristle-shaped
branches.
_Dimensions._--Length of the cross (longitudinal axis) 0.5, breadth
(lateral axis) 0.4.
_Habitat._--Central Pacific, Station 272, surface.
2. _Zygostaurus longicornis_, n. sp.
Frontal spine (_c_1) little different from the two lateral spines, each
with two divergent curved horns, which are equal and of about the same
length as the simple broad basal part. Caudal {775}spine (_c_3) simple,
lanceolate, shorter than the frontal spine. Eight tropical spines in the
basal part smaller than the three former, but with much longer
fork-branches, which are prolonged into very thin and long bristles. Eight
polar spines rudimentary, very short.
_Dimensions._--Length of the equatorial cross 0.4, breadth 0.3.
_Habitat._--South Pacific, Station 295, surface.
3. _Zygostaurus cornutus_, n. sp.
Frontal spine (_c_1) little different from the two lateral spines, each
with two divergent straight horns, which are shorter than the basal part.
Caudal spine (_c_3) simple, triangular, shorter than the three former.
Eight tropical spines of equal size and form, doubly forked, each with four
thin, bristle-shaped, little divergent teeth. Eight polar spines short,
simply forked.
_Dimensions._--Length of the equatorial cross 0.5, breadth 0.4.
_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.
4. _Zygostaurus caudatus_, n. sp.
Frontal spine (_c_1) very different from the others, pincer-shaped, with
two long, nearly parallel slightly bent horns. Lateral spines (_c_2 and
_c_4) only half as long, with two short, nearly parallel horns. Caudal
spine (_c_3) very long and stout, spindle-shaped, about twice as long as
the frontal spine. Eight tropical spines of equal size and form,
symmetrical, with two long and thin, divergent horns. Eight polar spines
short and stout, with two divergent horns.
_Dimensions._--Length of the equatorial cross 0.8, breadth 0.3.
_Habitat._--Central Pacific, Station 265, surface.
5. _Zygostaurus frontalis_, n. sp.
Frontal spine (_c_1) very different from the others, with two very long,
divergent, stout branches. Lateral spines (_c_2 and _c_4) only half as
long, each with two stout, nearly parallel horns of equal length. Caudal
spine (_c_3) simple, sword-like, shorter than the three former. Eight
tropical spines of equal size and form, symmetrical, of the same shape as
the two lateral, but only half as large. Eight polar spines very small,
rudimentary, each with two short teeth.
_Dimensions._--Length of the equatorial cross 0.7, breadth 0.5.
_Habitat._--Central Pacific, Station 274, surface.
6. _Zygostaurus sagittalis_, n. sp. (Pl. 131, fig. 8).
Frontal spine (_c_1) very different from the others, with two equal,
strongly divergent, bent horns. Lateral spines (_c_2 and _c_4) little
smaller, but with two very unequal horns (the anterior shorter than the
posterior). Caudal spine (_c_3) simple, sword-like or triangular,
two-edged, longer {776}than the frontal spine. Eight tropical spines
different, the four anterior (_b_1, _b_4, _d_1, _d_4) smaller, with longer
horns; the four posterior (_b_2, _b_3, _d_2, _d_3) broader, with shorter
horns; the anterior horn of each tropical spine is longer than the
posterior. Eight polar spines rudimentary, simple, very short.
_Dimensions._--Length of the equatorial spine-cross 0.6, breadth 0.4.
_Habitat._--Central Pacific, Station 271, surface.
Subfamily 2. LITHOPTERIDA, Haeckel.
_Definition._--#Quadrilonchida# with two opposite transverse apophyses
either on all twenty spines or only on a part of them.
Genus 338. _Quadrilonche_,[378] n. gen.
_Definition._--#Quadrilonchida# with two simple opposite apophyses either
on each radial spine or only on a part of the twenty spines.
The genus _Quadrilonche_ is the ancestral form of the Lithopterida, or of
those Quadrilonchida which bear two opposite apophyses or transverse
processes. In _Quadrilonche_ these apophyses are simple, whilst they are
branched in _Xiphoptera_ and fenestrated in _Lithoptera_. Each of these
three genera may be divided into three subgenera; in the first only the
four equatorial spines are provided with apophyses, in the second twelve
spines (four equatorial and eight tropical), in the third subgenus all
twenty spines.
Subgenus 1. _Quadriloncharium_, Haeckel.
_Definition._--Four large equatorial spines provided with transverse
apophyses; sixteen other smaller spines simple, without apophyses.
1. _Quadrilonche tetrastaura_, n. sp.
Four equatorial spines very large, compressed, two-edged, each crossed in
the distal third by two opposite simple apophyses. Sixteen other spines
also compressed, linear, somewhat shorter than the former and only half as
broad, without apophyses.
_Dimensions._--Length of the four major spines 0.12, breadth 0.02; length
of the sixteen minor spines 0.08, breadth 0.01.
_Habitat._--Central Pacific, Station 266, surface.
{777}2. _Quadrilonche platystaura_, n. sp. (Pl. 131, fig. 2).
Four equatorial spines lanceolate, compressed, with two opposite triangular
simple apophyses in the broadest middle part. Sixteen other spines also
lanceolate, much smaller, of about half the length, but only of one-fourth
the breadth, without apophyses.
_Dimensions._--Length of the four major spines 0.2, breadth 0.018; length
of the sixteen minor spines 0.1, breadth 0.004.
_Habitat._--North Pacific, Station 235, surface.
Subgenus 2. _Quadrilonchidium_, Haeckel.
_Definition._--All twenty spines provided with transverse apophyses.
3. _Quadrilonche mesostaura_, n. sp. (Pl. 131, fig. 1).
Four equatorial spines almost of the some form and length as the sixteen
others, but of double or triple the breadth; each spine in its middle third
with two opposite broad triangular apophyses, in the basal third
rectangular, compressed, in the distal third isosceles triangular, with
simple apex.
_Dimensions._--Length of the four major spines 0.16, breadth 0.01 to 0.015;
length of the sixteen minor spines 0.12, breadth 0.005.
_Habitat._--Tropical Atlantic, Station 345, surface.
4. _Quadrilonche telostaura_, n. sp.
Four equatorial spines one and a half times as long and three times as
broad as the sixteen others; all twenty spines cylindrical, of equal
breadth throughout their whole length, with simple conical apex; each spine
crossed in the distal third by two opposite, simple, conical apophyses.
_Dimensions._--Length of the four major spines 0.3, breadth 0.012; length
of the sixteen minor spines 0.2, breadth 0.004.
_Habitat._--South Atlantic, Station 325, surface.
Genus 339. _Xiphoptera_,[379] Haeckel, 1881, Prodromus, p. 466.
_Definition._--#Quadrilonchida# with two opposite branched (but not
latticed) apophyses, either on each radial spine or only on a part of the
twenty spines.
The genus _Xiphoptera_ differs from the preceding ancestral genus
_Quadrilonche_ in the ramification of the apophyses, which bear
perpendicular branches on their distal side. These are therefore parallel
to the spine itself. If the branches become united by transverse beams then
we get _Lithoptera_.
{778}1. _Xiphoptera tessaractena_, n. sp.
Four equatorial spines in the outer third crossed by two opposite
transverse apophyses, each of which bears on its distal side two to three
branches, perpendicular to the apophysis and parallel to the spine itself.
Sixteen other spines much smaller, in the outer third crossed by two simple
opposite transverse apophyses.
_Dimensions._--Length of the four major spines 0.18, of the sixteen minor
0.05 to 0.1.
_Habitat._--North Pacific, Station 238, surface.
2. _Xiphoptera dodecactena_, n. sp. (Pl. 131, fig. 3).
Four equatorial spines one and a half times to twice as long and broad as
the eight tropical spines. These twelve spines have the same form and are
crossed in their distal third by two large opposite transverse apophyses,
each of which bears on its distal side two to four branches, perpendicular
to the apophysis and parallel to the spine. Eight polar spines much smaller
than the twelve others, simple, without apophyses. The central capsule of
this species exhibited a conical protuberance around the base of each
individual spine.
_Dimensions._--Length of the twelve larger spines 0.1 to 0.2, of the eight
smaller 0.02 to 0.06.
_Habitat._--Central Pacific, Station 272, surface.
3. _Xiphoptera icosactena_, n. sp.
Four equatorial spines about twice as long and four times as broad as the
sixteen other spines. All twenty spines crossed in the outer third by two
large opposite transverse apophyses, each of which bears on its distal side
two to four branches perpendicular to the apophysis and parallel to the
spine itself.
_Dimensions._--Length of the four equatorial spines 0.26, of the sixteen
smaller 0.11 to 0.14.
_Habitat._--South Pacific, Station 288, surface.
Genus 340. _Lithoptera_,[380] J. Müller, 1858, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 155.
_Definition._--#Quadrilonchida# with two opposite branched and latticed
apophyses, either on each radial spine or only on a part of the twenty
spines.
The genus _Lithoptera_, founded by Johannes Müller in 1858 for the first
observed Mediterranean species, _Lithoptera fenestrata_, differs from all
other Quadrilonchida in the fenestrated form of the apophyses, which he
compared to the sails of a windmill. This peculiar fenestration is effected
by two to four parallel pairs of opposite apophyses, which are crossed by
perpendicular branches, parallel to the spine itself. {779}Therefore the
wings or lattice-plates have quadrangular meshes and lie in one meridian
plane of the spine, not in a tangential plane (as in the _Acanthophracta_).
Commonly the lateral ends of the four broad equatorial wings are so crossed
that one lateral corner of each wing lies on the upper, the other corner on
the under side of both its neighbours; but sometimes the meeting corners
have grown together.
Subgenus 1. _Lithopteranna_, Haeckel.
_Definition._--Four equatorial spines with transverse apophyses; sixteen
others (eight tropical and eight polar spines) simple, without apophyses.
1. _Lithoptera tetraptera_, n. sp. (Pl. 131, fig. 9).
Four equatorial spines spindle-shaped, with latticed apophyses, each
crossed by two transverse beams which are connected at equal distances by
four rods parallel to the spine (therefore each wing with four square
meshes in a single row). Lateral corners of the neighbouring wings not
meeting. Sixteen smaller spines (eight tropical and eight polar) simple,
conical, without apophyses.
_Dimensions._--Diagonal of the square body 0.24; length of the inner square
0.16.
_Habitat._--Tropical Atlantic, Station 348, surface.
2. _Lithoptera mülleri_, Haeckel.
_Lithoptera mülleri_, Haeckel, 1862, Monogr. d. Radiol., p. 398, Taf. xx.
figs. 1, 2.
Four equatorial spines four-edged, with large latticed apophyses, each
crossed by three transverse beams, which are connected at irregular
distances by eight to twelve rods parallel to the spine (therefore each
wing with two rows of rectangular meshes). The wings are placed not
perfectly in the equatorial plane, but a little obliquely, so that each
wing lies with one lateral corner on the upper, with the other corner on
the under side of its neighbours. Sixteen smaller spines simple, thin,
cylindrical, without apophyses.
_Dimensions._--Diagonal of the square body 0.3; length of the inner square
0.17.
_Habitat._--Mediterranean (Messina), surface.
3. _Lithoptera lamarckii_, n. sp.
Four equatorial spines four-edged, with large latticed apophyses; each
crossed by three transverse beams, which are connected at short distances
by twelve to sixteen rods parallel to the spine (therefore each wing with
two rows of hexagonal or nearly elliptical meshes). Wings placed as in
_Lithoptera mülleri_. Sixteen smaller spines simple, thin, prismatic,
without apophyses.
_Dimensions._--Diagonal of the square body 0.35; length of the inner square
0.2.
_Habitat._--Central Pacific, Station 271, surface.
{780}4. _Lithoptera tetragona_, n. sp.
Four equatorial spines compressed, four-edged, with large latticed
apophyses, each crossed by four transverse beams, which are connected at
regular distances by eight to twelve rods parallel to the spine. (Therefore
each wing with three rows of square meshes.) Wings placed in the equatorial
plane and grown together by their meeting lateral ends, forming a square
equatorial girdle of lattice-work. Sixteen smaller spines simple, thin,
prismatic, without apophyses.
_Dimensions._--Diameter of the square body 0.4; length of the inner square
0.22.
_Habitat._--North Pacific, Station 244, surface.
Subgenus 2. _Lithopterella_, Haeckel.
_Definition._--Twelve spines (four equatorial and eight tropical) with
transverse apophyses; the eight polar spines simple, without apophyses.
5. _Lithoptera quadrata_, n. sp. (Pl. 131, fig. 10).
Twelve spines with transverse apophyses; eight (polar) spines simple,
small, without apophyses. Four equatorial spines very large and stout,
compressed, each crossed by four transverse beams, which are connected by
eight to ten rods parallel to the spine (therefore each wing with three
rows of irregular rectangular meshes). Wings placed in the equatorial plane
and grown together by their meeting lateral ends, forming a square
equatorial girdle of lattice-work. Eight tropical spines thin, crossed by a
long and thin transverse beam, which bears on its distal side eight to ten
rods parallel to the spine.
_Dimensions._--Diagonal of the square body 0.35; length of the inner square
0.18.
_Habitat._--South Atlantic, Station 326, surface.
6. _Lithoptera dodecaptera_, n. sp.
Twelve spines with transverse apophyses; eight (polar) spines simple,
small, without apophyses. Four equatorial spines very large, quadrangular;
each crossed by three transverse beams, which are connected by ten to
twelve rods parallel to the spine (therefore each wing with two rows of
square meshes). Wings placed as in _Lithoptera mülleri_. Eight tropical
spines much thinner, crossed each by two transverse beams, which are
connected by six to eight rods parallel to the spine (therefore each wing
with one row of rectangular meshes).
_Dimensions._--Diagonal of the square body 0.4; length of the inner square
0.25.
_Habitat._--Central Pacific, Station 271, surface.
Subgenus 3. _Lithopteromma_, Haeckel.
_Definition._--All twenty spines with transverse apophyses.
{781}7. _Lithoptera darwinii_, Haeckel.
_Lithoptera darwinii_, Haeckel, 1879, Natürl. Schöpfungsgesch., Aufl.
vii. p. 706, Taf. xvi. fig. 12.
All twenty spines with transverse apophyses; these are quite simple in the
eight small cross-shaped polar spines; also simple, but bearing some
perpendicular rods, in the eight thin tropical spines. Four equatorial
spines very large and stout, each crossed by four transverse beams, which
are connected by eight to ten rods parallel to the spine (therefore each
wing with three rows of irregular rectangular meshes). Wings placed in the
equatorial plane and grown partly together by their meeting lateral ends.
_Dimensions._--Diagonal of the square body 0.4; length of the inner square
0.2.
_Habitat._--South-east Pacific, west coast of Patagonia, Station 302,
surface.
8. _Lithoptera icosaptera_, n. sp.
All twenty spines with transverse apophyses, bearing one to three rows of
rectangular meshes; eight polar spines small, each with a single row; eight
tropical spines long and thin, each with two parallel rows. Four equatorial
spines much larger and thicker, each with three parallel transverse rows of
meshes. All twenty wings free, not grown together by their lateral ends.
_Dimensions._--Diagonal of the square body 0.48; length of the inner square
0.24.
_Habitat._--Indian Ocean, Belligemma, Ceylon (Haeckel), surface.
9. _Lithoptera fenestrata_, J. Müller.
_Lithoptera fenestrata_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 154, Taf. xi. fig. 13.
All twenty spines with transverse apophyses, bearing one to three rows of
irregular, rectangular meshes; eight polar and eight tropical spines small,
each with a single row of meshes (between two parallel transverse beams).
Four equatorial spines little larger, each with two rows (between three
parallel transverse beams). Central capsule filled up with green pigment.
_Dimensions._--Diagonal of the square body 0.3; length of the inner square
0.2.
_Habitat._--Mediterranean (Saint Tropez, Nice).
Family XXXVIII. #AMPHILONCHIDA#, Haeckel (Pl. 132).
_Acantholonchida_ (Amphilonchida et Amphilithida), Haeckel, 1881,
Prodromus, p. 466.
_Definition._--ACANTHARIA with twenty radial spines of very unequal size,
disposed according to the law of the Icosacantha; two opposite equatorial
spines (in the longitudinal axis) much larger than the eighteen others. No
lattice-shell.
The family #Amphilonchida# is distinguished from all other #Acanthometra#
by the excessive development of two opposite equatorial spines, which are
much larger {782}than the eighteen other spines. In my Monograph (1862, p.
389) I had united all these Acanthonida in a single genus _Amphilonche_
(with ten species). Some species of it are very common and widely
distributed; but in general the number of different forms in this family is
much smaller than in the two foregoing families.
The two principal spines, which in all Amphilonchida are much larger than
the eighteen other spines, characterise the "hydrotomical axis" or the
larger equatorial axis. The two other equatorial spines or the "geotomical
spines" are much smaller, and commonly of the same size as the eight
tropical and the eight polar spines. In the genera _Amphilonche_ and
_Amphibelone_ these eighteen smaller spines are rather equally developed;
sometimes they are very small or quite rudimentary, so that the skeleton
seems to be represented only by the two very long principal spines (Pl.
132, fig. 4). The genus _Acantholonche_ is distinguished by the unequal
size of the eight tropical and the eight polar spines, the latter being
more or less rudimentary. However, the central bases of all twenty spines,
by which they are united in the centre, are constantly present. The genus
_Amphibelone_ is distinguished by the unequal size and form of the two
principal spines, one of them the "caudal spine," being larger (and often
of another form) than the opposite "frontal spine."
The form of the radial spines is in the Amphilonchida far less varied and
complicated than in the other Acanthonida (the Astrolonchida and
Quadrilonchida). Apophyses or lateral transverse processes are never
developed. The three main forms of spines are the same as in the other
Acanthonida; they are (1) either cylindrical or conical (like
_Acanthometron_), or (2) compressed or two-edged (like _Zygacantha_), or
(3) quadrangular or four-edged (like _Acanthonia_). Often the spines are
angular in the inner or proximal, roundish in the outer or distal part. The
distal apex is commonly simple, conical or pyramidal. The central base is
commonly also pyramidal, as in the majority of the Acanthonida; and the
triangular faces of the neighbouring bases are simply propped one upon
another. More rarely a basal leaf-cross is developed above the basal
pyramid. Very rarely the central bases of the united spines grow together
in the centre, so that the whole skeleton forms a single piece of acanthin.
_The Central Capsule_ is rarely spherical, commonly prolonged in the
direction of the hydrotomical axis; ellipsoidal or cylindrical, sometimes
also four-sided prismatic; it commonly envelops the greater part of the two
principal spines; its structure and contents are the same as in the other
Acanthonida.
_Synopsis of the Genera of Amphilonchida._
{ Two opposite large
{ principal spines
Eighteen smaller spines { (frontal and caudal)
of nearly equal size { equal, 341. _Amphilonche_.
and similar form. {
{ Caudal spine larger than
{ the frontal spine, 342. _Amphibelone_.
Eight tropical and eight polar spines of different
sizes (the latter often rudimentary), 343. _Acantholonche_.
{783}Genus 341. _Amphilonche_,[381] Haeckel, 1862, Monogr. d. Radiol., p.
389.
_Definition._--#Amphilonchida# with two equal principal spines (frontal and
caudal spines not different); the eighteen smaller spines nearly equal.
The genus _Amphilonche_ represents the original and at the same time the
most common form of Amphilonchida; the two opposite principal spines are of
equal size and form, much larger (and often also of another form) than the
eighteen smaller spines; these latter exhibit no marked differences in size
and form.
Subgenus 1. _Amphiloncharium_, Haeckel.
_Definition._--Spines in the centre united by triangular faces of their
pyramidal bases, propped one upon another. No basal leaf-cross.
1. _Amphilonche belonoides_, Haeckel.
_Amphilonche belonoides_, Haeckel, 1862, Monogr. d. Radiol., p. 392, Taf.
xvi. fig. 6, Taf. xviii. fig. 21.
_Acanthometra belonoides_, Haeckel, 1860, Monatsber. d. k. Akad. d. Wiss.
Berlin, p. 808.
Two principal spines cylindrical, of equal breadth throughout their whole
length, with simple conical apex; base a small pyramid, without leaf-cross.
Eighteen smaller spines conical, much shorter, with simple bristle-shaped
apex. Central capsule spindle-shaped or cylindrical, yellow.
_Dimensions._--Length of the two major spines 0.4 to 0.8, of the eighteen
minor 0.05 to 0.2.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
2. _Amphilonche lanceolata_, n. sp. (Pl. 132, fig. 1).
Two principal spines compressed, lanceolate, two-edged, gradually tapering
from the broader middle towards the two ends; apex simple; base a large
pyramid, with broad leaf-cross. Eighteen smaller spines about half as long,
pyramidal, with simple conical or bristle-shaped apex. Central capsule
lentelliptical, pink, opaque.
_Dimensions._--Length of the two major spines 0.2, of the eighteen minor
0.1.
_Habitat._--Tropical Atlantic, Station 343, surface.
3. _Amphilonche diodon_, n. sp. (Pl. 132, fig. 3).
Two principal spines compressed, lanceolate, two-edged, tapering from the
broader middle towards the two ends; apex simple; base a small pyramid,
without leaf-cross. Eighteen smaller spines {784}sword-shaped, only
two-thirds or one-half as long, and one-third or one-fourth as broad, each
with two opposite teeth in the distal part. Central capsule ellipsoidal.
_Dimensions._--Length of the two major spines 0.13, breadth 0.02; length of
the eighteen minor spines 0.1.
_Habitat._--North Atlantic, Station 352, surface.
4. _Amphilonche tenuis_, Haeckel.
_Amphilonche tenuis_, Haeckel, 1862, Monogr. d. Radiol., p. 389, Taf.
xvi. fig. 1, Taf. xviii. fig. 16.
_Acanthometra tenuis_, Haeckel, 1860, Monatsber. d. k. Akad. d. Wiss.
Berlin, p. 807.
Two principal spines quadrangular prismatic, with smooth edges, slightly or
not at all prominent, of equal breadth throughout their whole length; apex
simple or bifid; base a small pyramid, without leaf-cross. Eighteen smaller
spines of the same form, but only one-fourth or one-third as long. Central
capsule spherical or ellipsoidal, colourless.
_Dimensions._--Length of the two major spines 0.2 to 0.3, of the eighteen
minor spines 0.05 to 0.1.
_Habitat._--Mediterranean (Messina); Atlantic, Station 354, Canary Islands,
surface.
5. _Amphilonche denticulata_, Haeckel.
_Amphilonche denticulata_, Haeckel, 1862, Monogr. d. Radiol., p. 390,
Taf. xvi. fig. 2, Taf. xviii. fig. 17.
Two principal spines quadrangular prismatic, with prominent, elegantly
denticulated edges, of equal breadth throughout their whole length; apex
simple or truncated; base a small pyramid, without leaf-cross. Eighteen
smaller spines of the same form, but only one-fourth or one-third as long.
Central capsule ellipsoidal, opaque, yellowish-brown.
_Dimensions._--Length of the two major spines 0.3 to 0.4, of the eighteen
minor 0.1; breadth of the former 0.009, of the latter 0.006.
_Habitat._--Mediterranean (Messina), Haeckel, surface.
6. _Amphilonche heteracantha_, Haeckel.
_Amphilonche heteracantha_, Haeckel, 1862, Monogr. d. Radiol., p. 293,
Taf. xvi. fig. 7.
_Acanthometra heteracantha_, Haeckel, 1860, Monatsber. d. k. Akad. d.
Wiss. Berlin, p. 808.
Two principal spines quadrangular prismatic, very large, with four broad,
prominent, lamellar edges, of equal breadth throughout their whole length.
Apex as well as the base a four-sided pyramid. Eighteen smaller spines very
thin, conical, with bristle-shaped apex; base a small pyramid, without
leaf-cross. Central capsule cylindrical or violin-shaped, opaque yellow.
_Dimensions._--Length of the two major spines 0.2 to 0.3, breadth 0.015 to
0.02; length of the eighteen minor spines 0.1 to 0.15, basal breadth 0.004
to 0.008.
_Habitat._--Mediterranean (Messina); Central Pacific, Station 271, surface.
{785}7. _Amphilonche elongata_, Haeckel.
_Amphilonche elongata_, Haeckel, 1862, Monogr. d. Radiol., p. 392, Taf.
xviii. figs. 22_a_, 22_b_.
_Acanthometra elongata_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 48, Taf. vii. fig. 13.
Two principal spines quadrangular prismatic in the proximal half,
cylindrical or spindle-shaped in the distal half, with simple apex; base a
small pyramid, without leaf-cross. Eighteen smaller spines very thin,
bristle-shaped, conical on the base, with small pyramid. Central capsule
spindle-shaped, transparent, yellow.
_Dimensions._--Length of the two major spines 0.3 to 0.5, breadth 0.01 to
0.03; length of the eighteen smaller spines 0.05 to 0.3.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific,
surface.
Subgenus 2. _Amphilonchidium_, Haeckel.
_Definition._--Spines at the central base with a broad leaf-cross, composed
of four prominent triangular lamellæ; between the meeting edges of the
latter twenty-two pyramidal compartments or basal funnels.
8. _Amphilonche ovata_, Haeckel.
_Amphilonche ovata_, Haeckel, 1862, Monogr. d. Radiol., p. 390.
_Acanthometra ovata_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 47, Taf. vii. fig. 10, Taf. ix. fig. 4.
Two principal spines cylindrical, of equal breadth throughout their whole
length, with simple conical or bifid apex; base with a large leaf-cross of
double the breadth. Eighteen smaller spines of the same form, but thinner
and only half as long. Central capsule ellipsoidal, brown, opaque.
_Dimensions._--Length of the two major spines 0.3 to 0.4, breadth 0.008 to
0.012; length of the eighteen minor spines 0.1 to 0.2.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
9. _Amphilonche conica_, n. sp. (Pl. 132, fig. 6).
Two principal spines conical, elongate, with simple apex; base thickened,
with large leaf-cross. Eighteen smaller spines also conical, of about the
same basal breadth, but only one-fourth to one-half as long. Central
capsule ellipsoidal, pellucid.
_Dimensions._--Length of the two major spines 0.15 to 0.2, basal breadth
0.03 to 0.04; length of the eighteen minor spines 0.05 to 0.1.
_Habitat._--Central Pacific, Stations 265 to 274, surface.
{786}10. _Amphilonche lancetta_, n. sp.
Two principal spines compressed, lanceolate, two edged, gradually tapering
from the broader middle towards the two ends; apex simple; base of double
the breadth, with a large leaf-cross. Eighteen smaller spines of the same
form, but shorter and only half as broad. Central capsule lentelliptical,
pellucid.
_Dimensions._--Length of the two major spines 0.2 to 0.3, breadth in the
middle part 0.02 to 0.03; length of the eighteen smaller spines 0.1 to 0.2.
_Habitat._--South Pacific, Station 288, surface.
11. _Amphilonche complanata_, Haeckel.
_Amphilonche complanata_, Haeckel, 1862, Monogr. d. Radiol., p. 390, Taf.
xvi. fig. 3, Taf. xviii. fig. 18, _a_, _b_.
_Acanthometra complanata_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 808.
Two principal spines compressed, two-edged, linear, of equal breadth
throughout their whole length; apex emarginate or bifid; base with a large
leaf-cross of double the breadth. Eighteen smaller spines of the same form,
but only one-fourth to one-half as large. Central capsule ellipsoidal,
yellow, pellucid.
_Dimensions._--Length of the two major spines 0.15 to 0.25, breadth 0.004
to 0.006; length of the eighteen minor spines 0.05 to 0.1.
_Habitat._--Mediterranean (Messina), surface.
12. _Amphilonche messanensis_, Haeckel.
_Amphilonche messanensis_, Haeckel, 1862, Monogr. d. Radiol., p. 391,
Taf. xvi. fig. 4, Taf. xviii. fig. 19.
_Acanthometra messanensis_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 808.
Two principal spines quadrangular prismatic, often a little compressed from
two sides, of nearly equal breadth throughout their whole length; apex
either truncate or emarginate, with two opposite teeth; base with a large
leaf-cross of double the breadth. Eighteen smaller spines of similar form
or more compressed, much shorter. Central capsule spherical or ellipsoidal,
yellow, transparent.
_Dimensions._--Length of the two major spines 0.12 to 0.18, breadth 0.016;
length of the minor spines 0.05 to 0.09.
_Habitat._--Mediterranean (Messina, Corfu), Haeckel, surface.
13. _Amphilonche hydrotomica_, n. sp. (Pl. 132, fig. 2).
Two principal spines quadrangular prismatic, with four broad prominent
lamellar edges or wings, of equal breadth throughout their whole length;
apex pyramidal; base with a large leaf-cross. Eighteen smaller spines
cylindrical or bristle-shaped, only half as long and very thin. Central
capsule cylindrical or spindle-shaped, very long, opaque.
{787}_Dimensions._--Length of the two major spines 0.1 to 0.2, breadth 0.02
to 0.03; length of the eighteen minor spines 0.05 to 0.1.
_Habitat._--Central Pacific, Stations 270 to 274, surface.
14. _Amphilonche violina_, n. sp. (Pl. 132, fig. 5).
Two principal spines quadrangular prismatic, nearly violin-shaped, with
four very broad, prominent, lamellar wings, which are constricted in the
middle part, and broadened towards the two ends; apex truncate pyramidal;
base with a large leaf-cross. Eighteen smaller spines much shorter, of
equal breadth at the base, assuming the form of a quadrangular pyramid,
thin prismatic in the distal half. Central capsule spindle-shaped, opaque.
_Dimensions._--Length of the two major spines 0.15 to 0.18, breadth 0.02 to
0.025; length of the eighteen minor spines 0.04 to 0.08.
_Habitat._--Central Pacific, Station 271, surface.
15. _Amphilonche tetraptera_, Haeckel.
_Amphilonche tetraptera_, Haeckel, 1862, Monogr. d. Radiol., p. 391, Taf.
xvi. fig. 5, Taf. xviii. fig. 20.
_Acanthometra tetraptera_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 808.
Two principal spines four-sided pyramidal, with four broad lamellar
prominent edges; apex simple or bifid; base with a large leaf-cross.
Eighteen smaller spines of similar form, but only half as large. Central
capsule spherical, opaque.
_Dimensions._--Length of the two major spines 0.2, breadth on the base
0.025; length of the eighteen minor spines 0.1.
_Habitat._--Mediterranean (Messina); North Atlantic, Canary Islands,
Stations 352 to 354, surface.
Subgenus 3. _Amphilithium_, Haeckel, 1881, Prodromus, p. 466.
_Definition._--Spines in the basal part grown together, so that the whole
skeleton represents a single piece of acanthin; a star with two larger and
eighteen smaller rays.
16. _Amphilonche concreta_, n. sp. (Pl. 132, figs. 4, 4_a_).
Two principal spines cylindrical, very long, of equal breadth throughout
their whole length, with simple conical apex. Eighteen smaller spines
short, conical or bristle-shaped, scarcely one-fourth or one-tenth as long,
often quite rudimentary. All twenty spines perfectly grown together in the
centre, forming a single piece of acanthin (derived from _Amphilonche
belonoides_ by central concrescence; often the sutures of the concreted
bases are visible, fig. 4_a_).
_Dimensions._--Length of the two major spines 0.1 to 0.4, breadth 0.005 to
0.015; length of the eighteen minor spines 0.005 to 0.15.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
{788}17. _Amphilonche acufera_, n. sp.
Two principal spines thick, four-sided prismatic in the basal half,
cylindrical or spindle-shaped in the distal half, with simple conical apex.
Eighteen smaller spines shorter, thin, bristle-shaped or conical on the
base. All twenty spines in the centre perfectly grown together, forming a
single piece of acanthin. (Derived from _Amphilonche elongata_ by central
concrescence.)
_Dimensions._--Length of the two major spines 0.3 to 0.5, breadth 0.01 to
0.03; length of the eighteen minor spines 0.08 to 0.2.
_Habitat._--Central Pacific, Stations 266 to 274, surface.
Genus 342. _Amphibelone_,[382] Haeckel, 1862, Monogr. d. Radiol., p. 392.
_Definition._--#Amphilonchida# with two unequal principal spines (the
frontal spine very different from the caudal spine); the eighteen smaller
spines nearly equal.
The genus _Amphibelone_ exhibits among the Amphilonchida the same
remarkable differentiation of the two principal or longitudinal spines, as
_Zygostaurus_ among the Quadrilonchida; the frontal spine differs commonly
from the caudal spine not only in its size, but also in its peculiar form;
commonly one pole of the longitudinal axis is much more strongly developed
than the other. The eighteen smaller spines are nearly equal.
Subgenus 1. _Amphibelonium_, Haeckel.
_Definition._--All twenty spines separate, but in contact in the centre and
resting one against another by the triangular sides of their pyramidal
bases, without a prominent basal leaf-cross.
1. _Amphibelone aciculata_, n. sp.
Two principal spines thick, without edges and wings, the frontal spine
short, spindle-shaped, the caudal three to six times as long, cylindrical,
both of equal breadth, with simple conical apex and simple pyramidal base,
without leaf-cross. Eighteen smaller spines very thin, bristle-shaped, of
the same length as the frontal spine. Central capsule cylindrical or
spindle-shaped, enveloping the two principal spines nearly throughout their
whole length.
_Dimensions._--Length of the frontal spine 0.2 to 0.4, of the caudal spine
1.0 to 2.0; breadth of both 0.01; length of the eighteen smaller spines 0.1
to 0.3.
_Habitat._--South Atlantic, Station 325, surface.
{789}2. _Amphibelone cultellata_, n. sp. (Pl. 132, fig. 10).
Two principal spines broad, two-edged, knife-shaped; two opposite in the
equatorial plane, thin and broad wings or lamellæ are developed, and these
enclose the proximal part of both spines, whilst their distal part is free,
cylindrical, with conical apex: the two wings of the longer caudal spine
are lanceolate, twice to four times as broad as the two wings of the
shorter frontal spine; their base is a simple pyramid without leaf-cross.
Eighteen smaller spines conical, with bristle-shaped prolongation,
one-fourth to one-half as long as the frontal spine. Central capsule green,
semitransparent.
_Dimensions._--Length of the frontal spine 0.1 to 0.2, breadth 0.02 to
0.03; length of the caudal spine 0.2 to 0.4, breadth 0.04 to 0.08; length
of the eighteen smaller spines 0.05 to 0.15.
_Habitat._--Indian Ocean, Maldive Islands (Haeckel), surface.
3. _Amphibelone pyramidata_, n. sp. (Pl. 132, fig. 9).
Two principal spines four-winged, with four crossed, very thin and broad
wings, which are somewhat broader in the convex middle part than at either
end; both ends of each spine four-sided pyramidal, with four concave edges
and a very small terminal pyramid; base without leaf-cross. The longer
caudal spine is twice as broad at the distal end as at its proximal end,
and three times as broad as the distal end of the shorter frontal spine.
Eighteen smaller spines bristle-shaped, with four-sided pyramidal bases.
Central capsule pyramidal, enveloping the two principal spines throughout
their whole length; the base of the slender quadrangular pyramid is on the
caudal, the apex on the frontal pole of the longitudinal axis.
_Dimensions._--Length of the frontal spine 0.2 to 0.25, distal breadth
0.01; length of the caudal spine 0.3 to 0.4, distal breadth 0.03; length of
the eighteen smaller spines 0.04 to 0.08.
_Habitat._--Cape of Good Hope, Station 143, depth 1900 fathoms.
4. _Amphibelone anomala_, Haeckel.
_Amphilonche anomala_, Haeckel, 1862, Monogr. d. Radiol., p. 394, Taf.
xvi. fig. 8, Taf. xviii. figs. 23_a_, 23_b_.
_Acanthometra anomala_, Haeckel, 1860, Monatsber. d. k. Akad. d. Wiss.
Berlin, p. 808.
Two principal spines four-winged, nearly prismatic, with four crossed, very
broad and thick wings; both ends of each spine four-sided pyramidal, with
four concave edges and a very small terminal pyramid; base without
leaf-cross. The edges of the four wings are concave on the shorter frontal,
convex on the longer caudal spine. Eighteen smaller spines only one-fourth
to one-half as long, linear, two-edged, with two parallel teeth on the
distal end. Central capsule four-sided prismatic, olive-green, enveloping
almost completely the two principal spines.
_Dimensions._--Length of the frontal spine 0.12, middle breadth 0.016;
length of the caudal spine 0.14, middle breadth 0.024; length of the
eighteen smaller spines 0.04 to 0.06.
_Habitat._--Mediterranean (Messina), surface.
{790}Subgenus 2. _Amphibelithium_, Haeckel.
_Definition._--All twenty spines grown together in the centre, forming a
single star-shaped piece of acanthin.
5. _Amphibelone clavaria_, n. sp.
Two principal spines roundish, without edges and wings; the smaller frontal
spine elongate conical, the larger caudal spine two to four times as long,
cylindrical, in the distal part spindle-shaped or club-shaped, with conical
apex. Central base simple pyramidal, without leaf-cross. Eighteen smaller
spines much shorter, bristle-shaped. Central capsule very long,
club-shaped. All twenty spines perfectly grown together in the centre.
_Dimensions._--Length of the frontal spine 0.12, of the caudal spine 0.4 to
0.8; frontal breadth 0.01, caudal breadth 0.03; length of the eighteen
smaller spines 0.05.
_Habitat._--Central Pacific, Station 272, surface.
Genus 343. _Acantholonche_,[383] Haeckel, 1881, Prodromus, p. 466.
_Definition._--#Amphilonchida# with two equal principal spines (frontal and
caudal spines not different). The eighteen smaller spines are very unequal,
ten of them (eight tropical and two transverse equatorial spines) much
larger than the rudimentary eight polar spines.
The genus _Acantholonche_ differs from its ancestral genus _Amphilonche_ in
the different shape of the eight tropical and the eight polar spines; these
latter are much smaller than the former, which are almost equal to the two
transverse equatorial spines. The two principal spines are equal, but in
size and shape very different from the others.
1. _Acantholonche amphipolaris_, n. sp. (Pl. 132, fig. 7).
Two principal spines stout, quadrangular prismatic in the basal half,
cylindrical or spindle-shaped in the distal half, with simple conical apex;
base a small pyramid without leaf-cross. Two transverse and eight tropical
spines, about half as long as the former, very thin, bristle-shaped,
conical at the basal part. Eight polar spines very small, scarcely
one-eighth or one-fourth as long as the latter, short pyramidal or conical,
often quite rudimentary. Central capsule cylindrical, enveloping the basal
half of the two principal spines.
_Dimensions._--Length of the two principal spines 0.4 to 0.5, of the ten
smaller spines 0.2 to 0.3, of the eight rudimentary polar spines 0.01 to
0.06; breadth of the two large spines 0.02 to 0.03.
_Habitat._--Central Pacific, Stations 266 to 274, surface.
{791}2. _Acantholonche peripolaris_, n. sp. (Pl. 132, fig. 8).
Two principal spines quadrangular prismatic, with four broad prominent
lamellar wings, of increasing breadth towards the pyramidal distal apex.
Both ends of each spine four-sided pyramidal, base without leaf-cross. Two
transverse and eight tropical spines about two-thirds as long as the
former, four-sided pyramidal in the basal half, conical in the distal half,
often curved. Eight polar spines very small, about one-fourth as long as
the latter, short conical or pyramidal. Central capsule four-sided
prismatic, enveloping both principal spines.
_Dimensions._--Length of the two principal spines 0.2, of the ten smaller
spines 0.12, of the eight rudimentary polar spines 0.04.
_Habitat._--Central Pacific, Station 274, surface.
----
Order IV. ACANTHOPHRACTA, Richard Hertwig, 1879.
_Acanthometræ cataphractæ_, Johannes Müller, 1858, Abhandl. d. k.
Akad. d. Wiss. Berlin, pp. 12, 22, 49.
_Dorataspida et Diploconida_, Haeckel, 1862, Monogr. d. Radiol.,
pp. 404, 412.
_Acanthophractida_, Richard Hertwig, 1879, Organismus d. Radiol.,
pp. 25, 137.
_Dorataspida, Diploconida, et Sphærocapsida_, Haeckel, 1881,
Prodromus, p. 467.
_Definition._--ACANTHARIA with complete latticed shell.
The order #Acanthophracta#, the fourth order of Radiolaria, comprises all
those ACANTHARIA in which the acanthinic skeleton is a complete latticed or
fenestrated shell, supported by radial spines arising from one common
central point. By the possession of such a complete shell the
#Acanthophracta# differ from their ancestral group, the nearly allied
#Acanthometra#, which represent the older and simpler, first order of
ACANTHARIA. All #Acanthophracta# are Icosacantha (like the #Acanthonida#,
their ancestral group), and possess twenty radial spines disposed according
to the Müllerian law (compare above, p. 717).
Johannes Müller, who first observed five representatives of this order,
called a part of them "_Acanthometræ cataphractæ_," and united these with
the true #Acanthometra# (_Acanthometra costata_ and _Acanthometra
cataphracta_; Abhandl. d. k. Akad. d. Wiss. Berlin, 1858, pp. 12, 49).
Another part was united by him with the true _Haliomma_ (_Haliomma
echinoides_, _Haliomma hystrix_, _Haliomma tabulatum_; Abhandl. d. k. Akad.
d. Wiss. Berlin, 1858, pp. 36, 37). He supposed that these latter formed
the immediate transition from the true #Acanthometra# to the true
_Haliomma_, and that their skeleton was siliceous.
{792}In my Monograph (1862, p. 412) I founded a separate subfamily,
Dorataspida, for the "_Acanthometræ cataphractæ,_" which I considered as
the first subfamily of the "Ommatida." That subfamily contained at that
time only two genera, _Dorataspis_ (with seven species) and
_Haliommatidium_ (with five species). A third genus, _Aspidomma_ (with two
species), was united by me with the Haliommatida (because of its double
shell). For a fourth genus (_Diploconus_) with a single species I founded
the peculiar family of Diploconida. Therefore the whole number of
#Acanthophracta# described in my Monograph amounted only to four genera and
fifteen species. Now the rich collections of the Challenger have added such
a great number of new forms, that we may distinguish here thirty-eight
genera and two hundred and twelve species.
Richard Hertwig in his excellent work (Der Organismus der Radiolarien,
1879, p. 25) separated his "Acanthophractida" perfectly from the "Ommatida"
(or the siliceous #Sphæroidea#), and united them with the "Acanthometrida"
in his order "Acanthometrea." But he separated them also from the nearly
allied Diploconida, following my former arrangement. He distinctly noted
that the skeleton in all these Acanthophractida (as well as in the
Acanthometrida) consists not of silex but of the organic substance
"acanthin."
The astonishing number of new and interesting forms of #Acanthophracta#
which I have found in the rich collection of the Challenger enables me to
distinguish now in this suborder six different families, two of which are
perfectly new (the Sphærocapsida and the Hexalaspida). But the four other
families also are so much enlarged that their interesting morphology
appears in quite a new and clear light. Far the largest and most important
of these six families is that of the true Dorataspida, which embraces
seventeen genera and one hundred and eight species (more than the other
five families together). From this largest and oldest ancestral family four
other families have afterwards arisen, whilst a single family, the
Sphærocapsida, seems to possess no direct phylogenetic connection with the
five other families.
The peculiar and quite new family of Sphærocapsida (Pl. 133, figs. 7-11;
Pl. 135, figs. 6-10) differs from all other #Acanthophracta# in the
singular structure of the spherical acanthinic shell, composed of
innumerable small plates or aglets, each of which is pierced by a very
small porule. This peculiar pavemented shell (enclosing the central capsule
and separated from it by the jelly-like calymma) seems to be produced on
the surface of the spherical calymma, immediately by secretion of the
pseudopodia, and independently from the twenty radial spines, united in the
centre of the sphere. On the twenty points, where the spines perforate the
shell, there are originally eighty larger pores (four around each piercing
spine); but there is no certain indication that the shell is produced by
the meeting apophyses of the twenty spines, as is the case in the five
other families of #Acanthophracta#. Therefore perhaps it is {793}more
natural to unite these latter into another suborder as #Cladophracta#, and
to separate them from the Sphærocapsida, which may be called Capsophractæ.
The Dorataspida (Pls. 134-138), the common ancestral stock of the
#Cladophracta#, in the definition here restricted embraces all those
#Acanthophracta# in which the spherical lattice-shell is simple and
composed of the meeting branches of twenty radial spines united in its
centre. As already pointed out above, this family is probably diphyletic,
and embraces two subfamilies which have been derived originally from two
different forms of #Acanthonida#--the Diporaspida (with two opposite
apophyses on each spine) derived from the Phractacanthida, and the
Tessaraspida (with four crossed apophyses on each spine) derived from the
Stauracanthida; in the former we find originally forty apophyses, in the
latter eighty apophyses, by the meeting branches of which the spherical
lattice-shell originates. The four following families of #Acanthophracta#
have probably been derived from the Diporaspida.
The Phractopeltida (Pl. 133, figs. 1-6) differ from all other
#Acanthophracta# in the possession of a double lattice-shell, composed of
two concentric spheres which are united by the twenty radial spines meeting
in the centre. As all Phractopeltida possess originally only two apophyses
on each radial spine, they must be derived from the Diporaspida
(_Orophaspis_), and bear to them the same relation as the Dyosphærida do to
the Monosphærida. As the spherical central capsule of the Phractopeltida is
enclosed between both shells, smaller than the outer, larger than the inner
shell, the latter may be called "medullary shell," the former "cortical
shell." This family represents among the #Acanthophracta# only the
"Diplophracta," whilst all others are "Haplophracta."
The three families here characterised may be called together
"#Sphærophracta#," as their central capsule and the enveloping shell are
constantly spherical (or the shell sometimes an "endospherical
polyhedron"). On the contrary the following three families of
#Acanthophracta# may be united as "#Prunophracta#," as their central
capsule and shell are never spherical, but either ellipsoidal or lenticular
or of another form. The common ancestral stock of this suborder are the
Belonaspida, in which the form of the central capsule and the enclosing
lattice-shell is ellipsoidal; they are derived from the Dorataspida (and
probably all from the subfamily Diporaspida) by the prolongation of two
opposite radial spines which are larger than the eighteen others; they are
the two equatorial spines of the "hydrotomical axis" (compare above, p.
719, and Pl. 136, figs. 6-9).
The Hexalaspida (Pl. 139) represent a new and very remarkable family,
distinguished from all other #Acanthophracta# by the preponderating
development of six stout radial spines, which are much larger than the
fourteen others. These six principal spines lie in one meridian plane of
the shell (in the "hydrotomical plane," p. 720), and are the two opposite
equatorial spines and the four appertaining polar spines of the same plane.
{794}As the fourteen smaller spines develop their apophyses at smaller
distances from the centre, the shell assumes a peculiar lenticular or
discoidal form, and the margin of this disk bears the six larger spines.
Moreover the enclosed small central capsule is lenticular. The Hexalaspida
may be derived immediately from the Belonaspida.
The Diploconida (Pl. 140) form the last and the most modified family of all
#Acanthophracta#. The remarkable shell exhibits the strange form of a
double cone, bearing in its axis two very large opposite spines; these are
the two equatorial spines of the "hydrotomical axis" (p. 719). The
double-conical or nearly cylindrical shell is composed of three different
parts or segments; the small middle part is the true lattice-shell of the
Hexalaspida and Belonaspida, and bears the eighteen smaller (often quite
rudimentary) radial spines. The two other parts (opposite on both poles of
its hydrotomical axis) are the conical or cylindrical, solid, basal sheaths
of the two large equatorial spines, enveloping their major part. In
consequence of this peculiar metamorphosis of the shell the Diploconida
represent the last and the most aberrant group of all ACANTHARIA.
_Synopsis of the Suborders and Families of_ #Acanthophracta#.
-------------------------------------------------------------------------
Suborder I. SPHÆROPHRACTA.
Twenty radial spines of equal size. Shell spherical (or an
endospherical polyhedron).
-------------------------------------------------------------------------
Shell spherical, simple, pierced by twenty or
eighty aspinal pores and composed of a
pavement of innumerable very small plates
or aglets, each pierced by one porule, 1. SPHÆROCAPSIDA.
Shell spherical, simple, composed of the
meeting branches of two or four apophyses
of the twenty radial spines, 2. DORATASPIDA.
Shell spherical, double, composed of two
concentric lattice-spheres, which are connected
by the twenty radial spines and composed
of the meeting branches of their apophyses, 3. PHRACTOPELTIDA.
-------------------------------------------------------------------------
Suborder II. PRUNOPHRACTA.
Twenty radial spines of unequal size; two or six hydrotomical spines
much larger than the eighteen or fourteen others. Shell not spherical.
-------------------------------------------------------------------------
Shell ellipsoidal, with prolonged hydrotomical
axis, the two spines of which are larger
than the eighteen others, 4. BELONASPIDA.
Shell lenticular or discoidal, with six larger
spines placed in the hydrotomical plane
(fourteen other spines much smaller), 5. HEXALASPIDA.
Shell diploconical or nearly cylindrical, with
two opposite large funnels, the sheaths of
the enlarged two spines of the hydrotomical
axis (eighteen other spines much
smaller or rudimentary), 6. DIPLOCONIDA.
{795}----
Suborder I. SPHÆROPHRACTA, Haeckel.
_Definition._--Shell spherical, with twenty radial beams of equal size.
Family XXXIX. #SPHÆROCAPSIDA#, Haeckel (Pl. 133, figs. 7-11; Pl. 135, figs.
6-10).
_Sphærocapsida_, Haeckel, 1881, Prodromus, p. 469.
_Definition._--ACANTHARIA with simple spherical porous shell, composed of
innumerable very small plates, each of which is pierced by one radial
porule. Twenty radial spines of equal size meeting in the centre of the
shell and disposed according to the Müllerian law of the Icosacantha,
sometimes short and enclosed in the shell, at other times long and piercing
it (rarely rudimentary or quite absent). Shell pierced therefore either by
twenty larger perspinal pores or by eighty smaller aspinal pores. Central
capsule spherical, enclosed in the porous shell.
The family #Sphærocapsida#, founded by me in 1881 for the single genus
_Sphærocapsa_, represents a very peculiar and remarkable group of the
#Acanthophracta#, very different from the five other families of this
suborder, and probably derived, independently of them, directly from the
#Acanthonida#. Whilst the lattice-shell of the five other families is
composed of the meeting branches of lateral apophyses of the twenty spines,
and its meshes are all or partly the intervals between these apophyses, in
the Sphærocapsida the spherical shell has quite another structure, and is
composed of innumerable small plates (each with one pore) which are
secreted on the surface of the spherical calymma, independently of the
twenty radial spines, which do not possess true apophyses.
In all Sphærocapsida the structure of the spherical shell is quite peculiar
and different from that of all other Radiolaria. It is composed everywhere
of innumerable very small plates or aglets, which are connected irregularly
like paving-stones, and form a single continuous layer or pavement on the
surface of the spherical calymma (Pl. 133, fig. 11, _a_; Pl. 135, figs. 8,
10). The small plates or paving-stones, which we will call "aglets," are
connected at their meeting edges by a kind of cement, and form together
with it a continuous thick capsule of acanthin. The form of the aglets is
commonly more or less irregular, roundish or polygonal, sometimes longish
(Pl. 133, fig. 11, _a_), more rarely it becomes rather regular, hexagonal,
square, or roundish (Pl. 135, fig. 8). Usually all aglets of one and the
same individual are of nearly equal size, between 0.01 and 0.02 in
diameter, rarely less or more. The outer face of the aglets is more or less
concave, so that the elevated meeting edges of the neighbouring aglets
commonly form together a prominent network of crests (Pl. 135, figs. 8,
10); rarely the meeting edges partly cover one another like squamules (Pl.
133, fig. 11, _a_). {796}Each small plate or aglet is pierced in its centre
by a single radial canalicule or porule. The dimpled surface, so produced,
resembles somewhat the dimpled plates of _Ceriaspis_, &c. Different from
these innumerable very small dimples of the surface are the twenty larger
"spinal dimples," or the concave larger plates, which are originally
pierced by the twenty radial spines. Before we describe these, we must
examine the spines themselves.
The twenty radial spines of all observed Sphærocapsida (sixteen species)
agree perfectly with those of the genus _Acanthonia_ (p. 749), and
especially with _Acanthonia tetracopa_, _Acanthonia denticulata_, &c. All
twenty spines, regularly disposed according to the Müllerian law of the
Icosacantha, are of equal size, constantly four-edged prismatic, of equal
breadth throughout their whole length. The prominent four edges are
parallel, sometimes smooth, at other times elegantly denticulated. The
central bases of the twenty spines are pyramidal, without leaf-cross, and
propped one upon another with their triangular faces, as in the majority of
the #Acanthonida#.
The relation of the twenty radial spines to the spherical shell exhibits in
the five genera described very peculiar and important differences. In the
first described genus, in _Sphærocapsa_, the spines are exactly as long as
the shell-radius, and therefore are not prominent over the surface of the
shell, with which they are firmly connected; the truncated distal end of
the spine lies therefore here in the surface of the shell itself, and is
connected with it by its four edges, between which four open aspinal pores
remain, as in _Tessaraspis_, &c. (Pl. 135, figs. 6-10). In the next allied
genus, _Astrocapsa_ (Pl. 133, figs. 9, 10), the spines are longer than the
shell-radius, and therefore more or less prominent over its surface; the
piercing part of each spine is also surrounded by four aspinal pores. In
the two following genera, _Porocapsa_ and _Cannocapsa_ (Pl. 133, figs. 7,
8), the radial spines are shorter than the shell-radius and therefore quite
hidden and withdrawn inside the shell, which they do not reach. But in the
ideal prolongation of each spine the shell is pierced by a single large
opening, the "perspinal pore" or "perspinal hole," composed of the four
united aspinal pores. Whilst in _Porocapsa_ the perspinal pores are simple,
they are prolonged in _Cannocapsa_ into cylindrical tubes, open at both
ends. The twenty perspinal holes of these Porocapsida are therefore derived
by confluence of the eighty original aspinal pores of the Astrocapsida and
preserve the same regular disposition, according to the Müllerian law of
the Icosacantha. Finally, the same law as is valid also in the last genus
is found in _Cenocapsa_; here the radial spines have completely
disappeared, and the whole skeleton is a simple sphere, but of the same
structure, and with the same twenty perspinal pores as in _Porocapsa_. It
is very interesting that this spineless _Cenocapsa_ among the ACANTHARIA
exhibits the same shell (a simple hollow sphere) as a last reduced form,
which _Cenosphæra_ among the #Sphærellaria# produces as a primitive
ancestral form of numerous genera.
{797}_The Central Capsule_ of the Sphærocapsida is spherical, constantly
smaller than the enclosing concentric shell, and separated from it by the
calymma. Its structure seems to be the same as in the #Acanthonida#, and
specially in the Astrolonchida. The pseudopodia (not yet observed) are
probably protruded only through the twenty perspinal holes or the eighty
aspinal pores.
_Synopsis of the Genera of Sphærocapsida._
-------------------------------------------------------------------------
I. Subfamily Astrocapsida.
Radial spines connected with the porous shell, as long or longer than
its radius. Eighty aspinal pores.
-------------------------------------------------------------------------
Spines as long as the radius,
without external prolongation, 344. _Sphærocapsa_.
Spines longer than the radius,
with external prolongation, 345. _Astrocapsa_.
-------------------------------------------------------------------------
II. Subfamily Porocapsida.
Radial spines not connected with the porous shell, shorter than its
radius. Twenty perspinal pores.
-------------------------------------------------------------------------
Perspinal holes of the shell
simple, without external
prolongation, 346. _Porocapsa_.
Perspinal holes of the shell
prolonged into radial
centrifugal tubuli, 347. _Cannocapsa_.
-------------------------------------------------------------------------
III. Subfamily Cenocapsida.
Radial spines disappeared.
-------------------------------------------------------------------------
Twenty perspinal holes of the
shell simple, without tubular
prolongation, 348. _Cenocapsa_.
Subfamily 1. ASTROCAPSIDA, Haeckel.
_Definition._--Radial spines connected with the porous shell, as long as or
longer than its radius. Therefore the shell pierced by eighty aspinal pores
(four around each spine).
Genus 344. _Sphærocapsa_,[384] Haeckel, 1881, Prodromus, p. 469.
_Definition._--#Sphærocapsida# with twenty radial spines as long as the
radius of the shell, without external prolongation; therefore their distal
ends inserted in the perspinal holes, each of which is composed of four
aspinal pores.
The genus _Sphærocapsa_ is the most common form of the Sphærocapsida, and
comprises those species in which the radial spines are as long as the
radius of the shell, and therefore are connected with the margin of its
aspinal holes, but not prolonged beyond its surface.
{798}1. _Sphærocapsa cruciata_, n. sp. (Pl. 135, figs. 6, 7).
Aspinal holes nearly circular, with flat radially striated margin. Four
aspinal pores of each hole rounded equilateral triangular. Porules of the
shell simple, without ring and dimple. Four edges of the spines smooth.
_Dimensions._--Diameter of the shell 0.4 to 0.5, of the central capsule 0.3
to 0.4.
_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), 1880, John Murray,
surface.
2. _Sphærocapsa dentata_, n. sp. (Pl. 135, fig. 9).
Aspinal holes four-lobed, with broad concave margin denticulated on the
periphery. Four aspinal pores of each hole pear-shaped, oblong, elevated in
the centre. Porules of the shell simple, without ring and dimple. Four
edges of the spines denticulate.
_Dimensions._--Diameter of the shell 0.3 to 0.4, of the central capsule 0.2
to 0.3.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
3. _Sphærocapsa quadrata_, n. sp. (Pl. 135, fig. 8).
Aspinal holes square, with concave umbilicus in the centre, surrounded by a
convex denticulated margin. Four aspinal pores of each hole nearly square.
Shell-porules with a polygonal elevated smooth ring, in the bottom of a
shallow dimple. Four edges of the spines smooth.
_Dimensions._--Diameter of the shell 0.22, of the central capsule 0.17.
_Habitat._--Indian Ocean, south of Australia, Station 159, surface.
4. _Sphærocapsa pavimentata_, n. sp. (Pl. 135, fig. 10).
Aspinal holes four-lobed, with broad concave, irregularly crenated and
figured margin. Four aspinal pores of each hole violin-shaped. Porules of
the shell surrounded by an irregularly oblong ring with thick elevated,
elegantly crenated margin. Four edges of the spines smooth.
_Dimensions._--Diameter of the shell 0.36, of the central capsule 0.3.
_Habitat._--South-east Pacific (off Valparaiso), Station 298, surface.
Genus 345. _Astrocapsa_,[385] n. gen.
_Definition._--#Sphærocapsida# with twenty radial spines longer than the
radius of the shell, piercing its perspinal holes, with free external
prolongation; therefore with four aspinal pores around each spine.
The genus _Astrocapsa_ differs from the preceding _Sphærocapsa_ in the
external prolongation of the radial spines piercing the perspinal holes; it
assumes therefore the common shape of the Dorataspida more than the other
Sphærocapsida do.
{799}1. _Astrocapsa tritonis_, n. sp.
Aspinal holes circular, with smooth convex margin and four circular aspinal
pores. Porules of the shell simple, without ring and dimple. Four edges of
the spines smooth, their outer free part about as long as the diameter of
the shell.
_Dimensions._--Diameter of the shell 0.25; outer length of the spines 0.3.
_Habitat._--North Atlantic, Færöe Channel, Gulf Stream (expedition of H.M.S
"Triton," August, 1882), John Murray, surface.
2. _Astrocapsa stellata_, n. sp. (Pl. 133, fig. 10).
Aspinal holes cruciform, with high crenated margin. Four aspinal pores of
each hole egg-shaped. Porules of the shell simple, without ring and dimple.
Four edges of the spines denticulate; their outer free part twice to three
times as long as the diameter of the shell.
_Dimensions._--Diameter of the shell 0.36; outer length of the spines 0.5
to 0.8.
_Habitat._--Antarctic Ocean (near Kerguelen), Station 152, surface.
3. _Astrocapsa quadrifida_, n. sp.
Aspinal holes four-lobed, with four prominent teeth between the four
roundish aspinal pores. Porules of the shell surrounded by a high polygonal
smooth ring. Four edges of the spines denticulate; their outer free part
about as long as the radius of the shell.
_Dimensions._--Diameter of the shell 0.28; outer length of the spines 0.15.
_Habitat._--North Pacific, Station 241, surface.
4. _Astrocapsa coronata_, n. sp. (Pl. 133, fig. 9).
Aspinal holes circular, with a coronet of numerous thin parallel teeth.
Porules of the shell in dimples on irregular polygonal small plates, with
coronated ring. Four edges of the spines denticulate; their outer free part
about twice as long as the diameter of the shell.
_Dimensions._--Diameter of the shell 0.4 to 0.5 ; outer length of the
spines 1.0 to 1.2.
_Habitat._--North Atlantic, Færöe Channel, Gulf Stream (expedition of the
"Knight Errant," 1880), John Murray, surface and at depths varying from 10
to 200 fathoms.
Subfamily 2. POROCAPSIDA, Haeckel.
_Definition._--Radial spines not connected with the porous shell, shorter
than its radius; therefore the shell pierced by twenty perspinal pores
(each one in the ideal radial prolongation of one spine).
{800}Genus 346. _Porocapsa_,[386] n. gen.
_Definition._--#Sphærocapsida# with twenty radial spines shorter than the
radius of the shell; therefore their distal ends not connected with the
twenty perspinal holes, which are simple, not prolonged into radial tubes.
The genus _Porocapsa_ and the following _Cannocapsa_ form together the
small sub-family of Porocapsida, distinguished by the peculiar reduction or
retrograde development of the twenty radial spines; all these twenty are
present and disposed according to the Müllerian law of the Icosacantha, but
they are shorter than the radius of the shell and therefore do not reach
it. In the ideal prolongation of the spines the shell is pierced by twenty
simple quadrangular or circular perspinal holes.
1. _Porocapsa murrayana_, n. sp. (Pl. 133, fig. 7).
Perspinal holes cruciform, with smooth thickened margin or with four short
teeth between the four lobes. Porules of the shell simple, without ring and
dimple. Four edges of the spines smooth. (Differs from _Sphærocapsa
cruciata_, Pl. 135, figs. 6, 7, living in the same locality, mainly in the
reduction of the radial spines, which do not reach the shell.)
_Dimensions._--Diameter of the shell 0.28; length of the spines 0.2.
_Habitat._--North Atlantic, Færöe Channel, Gulf Stream (expedition of
H.M.S. "Triton," August 1882), John Murray, surface and in depths from 40
to 640 fathoms.
2. _Porocapsa tetrodon_, n. sp.
Perspinal holes cruciform, with four triangular prominent teeth between the
four lobes of the cross. Porules of the shell with an elevated polygonal
ring, in the bottom of a dimple. Four edges of the spines elegantly
denticulate.
_Dimensions._--Diameter of the shell 0.36; length of the spines 0.12.
_Habitat._--North Pacific, Station 253, surface.
3. _Porocapsa octodon_, n. sp.
Perspinal holes square, with four larger prominent teeth on the sides of
the square, and four smaller teeth on its corners. Porules of the shell
surrounded by an elevated ring with elegantly crenated irregular margin.
Four edges of the spines smooth.
_Dimensions._--Diameter of the shell 0.48; length of the spines 0.18.
_Habitat._--Arctic Ocean (Greenland), in the contents of the stomach of the
Peromedusa, _Periphylla hyacinthina_.
{801}4. _Porocapsa coronodon_, n. sp.
Perspinal holes circular, with ciliated margin, which forms a crown of
sixteen to twenty-four thin parallel teeth. Poruli of the shell surrounded
by an elevated ring with high crenated margin. Four edges of the spines
denticulate.
_Dimensions._--Diameter of the shell 0.55; length of the spines 0.15.
_Habitat._--Antarctic Ocean, Station 154, surface.
Genus 347. _Cannocapsa_,[387] n. gen.
_Definition._--#Sphærocapsida# with twenty radial spines shorter than the
radius of the shell; therefore their distal ends not connected with the
twenty perspinal holes, which are prolonged outside into radial tubes (each
one in the radial ideal prolongation of one inner spine).
The genus _Cannocapsa_, exhibits the same peculiar reduction of the radial
spines as the foregoing _Porocapsa_; the spines are also here shorter than
the shell-radius and do not therefore reach the perspinal holes of the
shell. But whilst these latter are simple in _Porocapsa_, they are
prolonged into radial tubules in _Cannocapsa_; the outer surface bears
therefore twenty such cylindrical tubules, separated by a short distance
from the inner enclosed spines, but disposed quite regularly according to
the law of Icosacantha.
1. _Cannocapsa osculata_, n. sp.
Perspinal holes prolonged into short cylindrical tubuli, the length of
which about equals their diameter. Both ends of the tubuli with smooth
thickened margin. Poruli of the shell simple, without ring and dimple. Four
edges of the spines smooth; their length equals about four-fifths of the
shell-radius.
_Dimensions._--Diameter of the shell 0.24; length of the spines 0.09, of
the tubuli 0.01.
_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), surface, John
Murray.
2. _Cannocapsa stethoscopium_, n. sp. (Pl. 133, fig. 8).
Perspinal holes prolonged into cylindrical tubuli, half as long as the
shell radius. Both ends of the tubuli with smooth thin trumpet-shaped
margins. Poruli of the shell simple, without ring and dimple. Four edges of
the spines smooth; their length about equals three-fourths of the
shell-radius.
_Dimensions._--Diameter of the shell 0.2; length of the spines 0.08, of the
tubuli 0.05.
_Habitat._--South Atlantic (west of Tristan da Cunha), Station 333,
surface.
3. _Cannocapsa tubulosa_, n. sp.
Perspinal holes prolonged into cylindrical tubuli, which are as long as or
longer then the shell-radius. Both ends of the tubuli with smooth thickened
margin. Poruli of the shell simple, {802}without ring and dimple. Four
edges of the spines smooth; their length scarcely equals half the
shell-radius.
_Dimensions._--Diameter of the shell 0.15; length of the spines 0.03, of
the tubuli 0.08.
_Habitat._--South Atlantic (east coast of Patagonia), Station 318, surface.
Subfamily 3. CENOCAPSIDA, Haeckel.
_Definition._--Radial spines completely reduced and absent; shell cavity
therefore simple; shell pierced by twenty perspinal pores (each placed in
the direction of one radial spine which has disappeared).
Genus 348. _Cenocapsa_,[388] n. gen.
_Definition._--#Sphærocapsida# without radial spines, with simple cavity of
the spherical shell, which is pierced by twenty perspinal holes (each one
placed in the radial direction of one spine which has disappeared).
The genus _Cenocapsa_ comprises only a single species, but is very
remarkable in that it is the most reduced form among all Sphærocapsida. The
twenty radial spines of the Icosacantha have perfectly disappeared by
complete retrograde metamorphosis, and the only evidence of their former
existence (in the ancestral genus _Porocapsa_) are the twenty perspinal
holes remaining in the shell. _Cenocapsa_ is the only form of ACANTHARIA
which possesses no radial spines.
1. _Cenocapsa nirvana_, n. sp. (133, fig. 11, 11_a_, 11_c_).
Perspinal holes four-lobed, cruciform, with four short triangular teeth
between the four lobes of the cross. Poruli of the shell in the bottom of
an elliptical dimple surrounded by an elevated ring.
_Dimensions._--Diameter of the shell 0.2 to 0.3, of the aspinal holes 0.02.
_Habitat._--North Pacific, Station 248, surface.
Family XL. #DORATASPIDA#, Haeckel (Pls. 134-138).
_Dorataspida_, Haeckel, 1862, Monogr. d. Radiol., p. 412.
_Definition._--ACANTHARIA with simple spherical lattice-shell, composed of
the branched apophyses of twenty equal radial spines meeting in its centre
and disposed according to the Müllerian law of Icosacantha. Central capsule
spherical, enclosed in the fenestrated shell.
The family #Dorataspida# is the most important family of the
#Acanthophracta#, or of those ACANTHARIA in which the radial spines are
connected by a complete extracapsular lattice-shell. The Dorataspida
represent probably the ancestral {803}stock of this whole order, with the
exception of the Sphærocapsida. The four following families of the order
may be easily derived from the Dorataspida. The number of genera
(seventeen) and of species (one hundred and eight) is in this family
greater than in the other five families together. When I constituted that
family in my Monograph 1862, it comprised only one genus, _Dorataspis_,
with seven species. The nearly allied genus _Haliommatidium_ (_Phatnaspis_)
belongs to the Belonaspida.
The Dorataspida differ from the other #Acanthophracta# in the simple
spherical lattice-shell, which is composed of the meeting apophyses of the
twenty radial spines. In three other families of the suborder the shell is
not spherical, but ellipsoidal (Belonaspida), discoidal (Hexalaspida), or
diploconical (Diploconida). In the Phractopeltida the spherical shell is
double, composed of two concentric lattice-spheres. In the Sphærocapsida
the simple spherical shell is not composed of the apophyses of the spines,
but of innumerable small plates.
The family Dorataspida may be divided into two very different subfamilies,
which are probably derived, independently of one another, from two
different subfamilies of the Astrolonchida. The first subfamily,
Diporaspida, exhibits on each radial spine two opposite apophyses, like its
ancestral group, the Phractacanthida (p. 753); whereas the second
subfamily, Tessaraspida, possesses on each radial spine four crossed
apophyses (opposite in pairs), like its ancestral group, the Stauracanthida
(p. 758). Therefore the composition of the spherical shell, produced by the
meeting branches of the tangential apophyses, is essentially different in
the two subfamilies: in the Diporaspida each radial spine is surrounded by
two opposite primary aspinal meshes, in the Tessaraspida by four crossed
primary aspinal meshes.
Another principle of division may be established for the whole family by
the different mode of composition of the shell, and regarding this
important difference we may distinguish also two different subfamilies as
#Cladophracta# and #Peltophracta#. In the first and simpler subfamily, the
#Cladophracta#, the shell is composed totally (or sometimes partially) of
the meeting branches of the apophyses of the neighbouring spines; but in
each single spine (or in the most part of them) the branches of the
apophyses are not united, and form no lattice-plate (Pl. 137, figs. 1 to
8). Whereas in the #Peltophracta# the shell is composed constantly of
twenty perforated plates, as in each single spine the branches of its
apophyses are united and form a fenestrated shield with two or four (and
sometimes numerous) pores (Pls. 135, 136, 138).
In the Diporaspida as well as in the Tessaraspida we find numerous
representatives of the two groups of the #Cladophracta# and of the
#Peltophracta#; therefore the whole family of Dorataspida may be divided
into four different tribes. The Diporaspida (with two opposite apophyses on
each spine) are partly #Cladophracta# (the Phractaspida, Pl. 137, figs.
1-4), partly #Peltophracta# (the Ceriaspida, Pl. 138). On the other hand
the Tessaraspida (with four crossed apophyses on each {804}spine) are also
partly #Cladophracta# (the Stauraspida, Pl. 137, figs. 5-8), partly
#Peltophracta# (the Lychnaspida, Pls. 135-136). The differences and
relations of these tribes are placed synoptically in the following table:--
------------------------+------------------------+-----------------------
| A. Diporaspida. | B. Tessaraspida.
Synopsis of the four |Two opposite apophyses |Four crossed apophyses
tribes of Dorataspida.| on each radial spine. | on each radial spine.
| Two primary aspinal | Four primary spinal
| meshes. | meshes.
------------------------+------------------------+-----------------------
a. Cladophracta |1. Tribe Phractaspida. |3. Tribe Stauraspida.
All twenty spines (or a | |
part of them) without | |
lattice-plates. | |
| |
b. Peltophracta |2. Tribe Ceriaspida. |4. Tribe Lychnaspida.
All twenty spines with | |
lattice-plates. | |
------------------------+------------------------+-----------------------
All Dorataspida are true Icosacantha, and the twenty spines, composing the
spherical shell, are equally developed, regularly disposed according to the
Müllerian law, and of equal size; also the distance of their plates from
the common centre is equal. Nevertheless they are never of perfectly the
same form; in consequence of their peculiar disposition in five zones (each
with four spines) certain slight differences are effected, so that with
accurate knowledge of the peculiar shell-composition it is generally not
difficult to distinguish the spines of the equatorial, the two tropical,
and the two polar zones.
Already the central bases, by which the twenty spines are united in the
centre of the sphere, exhibit certain differences in the five zones.
Commonly these bases are small pyramids, all meeting with their apex in the
centre, and the triangular faces of the neighbouring pyramids are supported
one upon another. The four equatorial pyramids are commonly six-sided, the
other sixteen five-sided; but sometimes there are eight six-sided and
twelve five-sided basal pyramids; two opposite polar spines on each pole
having a six-sided base (like the four equatorial), the other two polar
spines on each pole having a five-sided base (like the eight tropical).
Rarely the central bases are perfectly grown together, forming a single
spherical central piece of acanthin.
The three different fundamental forms of radial spines, which are found in
all ACANTHARIA, the cylindrical, the two-edged, and the four-edged (spines
with circular, with elliptical, and with square transverse section
respectively) occur also in the different groups of Dorataspida; but
commonly the two-edged or compressed form is prevalent in the Diporaspida,
the four-edged or quadrangular form in the Tessaraspida. In the majority of
species the spines are thickened in the shell-face, where the apophyses
arise, and thinner towards the two ends. Usually the outer or distal part
of the spine (outside the shell) is longer than the inner or proximal part
(inside {805}the shell). The distal apex is commonly simple, conical or
pyramidal, rarely bifid or truncate. The edges of the spines are commonly
smooth, rarely denticulate or serrate.
The apophyses, or the lateral transverse processes of the radial spines, in
the Dorataspida assume the greatest variety and complexity in form, size,
mode of ramification, and in composition of the shell. An expert and
practised observer may determine easily the range of each spine, whether it
be an equatorial (_c_), or a tropical (_b_, _d_), or a polar spine (_a_,
_e_, Pls. 133-138). The two opposite apophyses of the Diporaspida, as well
as the four crossed apophyses of the Tessaraspida, lie constantly in
certain meridian planes of the spine, which have a legitimate signification
for each of the five zones. The comparative morphology of this regular
disposition of the apophyses and the regular meeting of their branches is
of the greatest interest, and necessary for the complete understanding of
the complicated structure of these wonderful shells.
The pores or meshes of the spherical shell, offering the most varied forms,
may generally be divided into two different groups, into sutural and parmal
meshes. The sutural pores are bordered by the meeting branches of the
apophyses of two, three, or four neighbouring spines, and therefore also by
the sutures in which they meet. The parmal pores on the other hand are
bordered only by the united branches of the apophyses of a single spine and
pierce the shield or lattice-plate formed by them. Therefore the
shell-meshes of the #Cladophracta# are all sutural pores (Pl. 137, figs.
1-8; rarely and only in a part of the spines parmal pores also: _Zonaspis_,
_Dodecaspis_); whereas the shell-meshes of the #Peltophracta#, piercing the
shields or lattice-plates of all twenty spines, are always partly sutural,
partly parmal pores (Pls. 135, 136, 138). The parmal pores again may be
divided into two different groups--aspinal and coronal pores. Aspinal pores
("ad spinam") are those which lie immediately on the sides of the radial
spine and are bordered by the primary branches of its apophyses; therefore
constantly only two in the Diporaspida, four in the Tessaraspida. Coronal
pores on the contrary are those which lie in the periphery of the
lattice-plates, surrounding in a circle or crown the aspinal pores and not
touching the spine itself. In _Dorataspis_, _Ceriaspis_, _Tessaraspis_,
_Lychnaspis_, &c., all parmal meshes are only aspinal pores (Pl. 135, figs.
2-5; Pl. 136); whilst in _Coscinaspis_, _Acontaspis_, _Icosaspis_,
_Hylaspis_, &c., one part of the parmal pores is aspinal, one part coronal
(Pl. 136). The number, form, and size of the coronal pores is very variable
and often very large (sometimes more than a hundred in one plate).
The #Cladophracta# exhibit a comparatively simple shell-formation; either
all twenty spines or at least a part of them not forming lattice-plates.
The most primitive form among these is _Phractaspis_ (Pl. 137, figs. 1, 2).
The forty apophyses of its twenty spines are simply forked, and their
eighty fork-branches united by forty sutures, enclosing twenty-two sutural
meshes: two square polar meshes (between the four polar spines on the poles
of the spineless axis, _a a a a_ and _e e e e_); eight triangular
{806}circumpolar meshes (each between two polar and one tropical spine, _a
b a_ and _e d e_); eight quadrangular tropical meshes (each between one
polar, one equatorial, and two tropical spines, _a b c b_ and _e d c d_);
and four rhomboidal equatorial meshes (between two tropical and two
equatorial spines, _c b c d_). If the fork-branches be again forked
(_Phractaspidium_, Pl. 137, fig. 3), the number of the sutures and sutural
meshes is doubled, and the same is the case in _Stauraspis_, the most
simple form of the Tessaraspida.
A peculiar small group, and an interesting transition for the
#Cladophracta# to the #Peltophracta#, is presented by the Zonaspida among
the Tessaraspida (_Zonaspis_ and _Dodecaspis_). Here only one part of the
radial spines bears lattice-plates, the other part not. In _Zonaspis_ the
four equatorial spines bear lattice-plates, the sixteen other only free
branches of the apophyses. In _Dodecaspis_ twelve spines are provided with
lattice-plates (four equatorial and eight polar spines), whilst the eight
other (tropical) spines are devoid of them.
The #Peltophracta# exhibit a great variety in the form and composition of
their twenty lattice-plates or fenestrated shields. In the most simple case
(a part of _Dorataspis_ and _Diporaspis_) the shell is composed of four
(equatorial) hexagonal plates, and sixteen pentagonal plates (four tropical
and four polar); in this case the four polar plates meet on each pole in
one common point. More commonly, however, the shell seems to be composed of
eight hexagonal plates (four equatorial and the four polar spines of the
hydrotomical plane) and twelve pentagonal plates (eight tropical and the
four polar spines of the geotomical plane); in this case only two
(hexagonal) polar plates meet on each pole in a suture which separates the
two other (pentagonal) polar plates (Pl. 138, fig. 4). In the majority of
the Dorataspida the composition of the shell is much more complicated and
often very difficult to understand. Often the surface of the plates is
covered with a network of elevated crests, by which concave blind dimples
are separated (_Ceriaspis_, _Hystrichaspis_, Pl. 138); and sometimes these
dimples become pierced by coronal pores (Pl. 138, fig. 11, &c.).
Peculiar by-spines or "accessory spines" cover the outer surface of the
shell in a great part of Dorataspida, and commonly these most
characteristic by-spines are not placed radially, but parallel to the
radial spine, from the lattice-plate of which they arise (Pl. 135, figs. 1,
5; Pl. 137, figs. 4-8; Monogr. d. Radiol., 1862, Taf. xxi. figs. 8, 9).
They are commonly placed perpendicular to the sutural condyles, or the
branch-ends of the apophyses; so that close to each suture arises a pair of
divergent by-spines, belonging to the meeting apophyses of the two
neighbouring spines, which meet in the suture (Pl. 137, fig. 4). Rarely
these thin, bristle-shaped by-spines are quite simple and straight,
commonly they undulate or are zigzag and often armed with recurved hooks.
Sometimes they are also forked or arborescent (Pl. 138, fig. 7).
_The Central Capsule_ of the Dorataspida is constantly spherical and about
one-third smaller than the enclosing shell, from which it is separated by
the spherical calymma. {807}The membrane of the central capsule is commonly
rather thin, and pierced by the twenty radial spines, meeting in the centre
of the capsule. Between these lie innumerable small pores for the radiating
pseudopodia; however, in many cases (and perhaps constantly) these pores
exhibit a certain regular disposition. In many species the central capsule
encloses Xanthellæ or symbiotic yellow unicellular Algæ. The nucleus
becomes cleft very early in the majority of Dorataspida.
_Synopsis of the Genera of Dorataspida._
-------------------------------------------------------------------------
I. Subfamily Diporaspida.
Each radial spine with two opposite primary apophyses; therefore the
whole shell with forty primary apophyses.
--------------------
I. Tribe Phractaspida.
Twenty radial spines without lattice-plates; no normal pores.
-------------------------------------------------------------------------
No by-spines, 349. _Phractaspis_.
With by-spines, 350. _Pleuraspis_.
-------------------------------------------------------------------------
II. Tribe Ceriaspida.
Twenty radial spines all with lattice-plates produced by union of the
branched apophyses of each plate.
-------------------------------------------------------------------------
{ { No by-spines, 351. _Dorataspis_.
{ Plates not {
Forty parmal { dimpled, { With by-spines, 352. _Diporaspis_.
pores (two { without {
in each { network { No by-spines, but
plate)--no { of crests. { free apophyses, 353. _Orophaspis_.
coronal {
pores in { Plates dimpled, } No by-spines, 354. _Ceriaspis_.
the plates. { with a network }
{ of crests. } With by-spines, 355. _Hystrichaspis_.
Eighty to two hundred or more } No by-spines, 356. _Coscinaspis_.
(in each plate two aspinal }
and two to ten or more } With by-spines, 357. _Acontaspis_.
coronal pores). }
-------------------------------------------------------------------------
II. Subfamily Tessaraspida.
Each radial spine with four crossed primary apophyses; therefore the
whole shell with eighty primary apophyses.
--------------------
III. Tribe Stauraspida.
Twenty radial spines all or partly without lattice-plates.
-------------------------------------------------------------------------
{ No by-spines, 358. _Stauraspis_.
All twenty spines without {
lattice-plates. { With by-spines, 359. _Echinaspis_.
Four plates with, sixteen }
without, lattice-plates. } With by-spines, 360. _Zonaspis_.
Twelve plates with, eight }
without, lattice-plates. } With by-spines, 361. _Dodecaspis_.
-------------------------------------------------------------------------
IV. Tribe Lychnaspida.
Twenty radial spines all with lattice-plates (produced by union of
the branched apophyses of each plate).
-------------------------------------------------------------------------
Eighty parmal pores (four } No by-spines, 362. _Tessaraspis_.
on each plate)--no coronal }
pores in the plates. } With by-spines, 363. _Lychnaspis_.
One hundred and sixty to three }
hundred or more parmal pores } No by-spines, 364. _Icosaspis_.
(in each plate four aspinal }
and four to twelve or more } With by-spines, 365. _Hylaspis_.
coronal pores). }
{808}Subfamily 1. DIPORASPIDA, Haeckel.
_Definition._--#Dorataspida# with twenty radial spines, each of which bears
two opposite apophyses. The spherical shell is composed either of the
meeting branches of these apophyses (Phractaspida), or of twenty perforated
plates, produced by concrescence of their branches (Ceriaspida).
A. Tribe I. #Phractaspida#, Haeckel.
_Definition._--#Dorataspida# without perforated plates; the spherical shell
is composed only of the meeting branches of the two opposite apophyses,
which arise from each radial spine. Therefore the meshes of the shell are
all sutural.
Genus 349. _Phractaspis_,[389] Haeckel, 1881, Prodromus, p. 467.
_Definition._--#Dorataspida# without perforated plates; shell composed only
of the meeting branches of the two opposite apophyses, which arise from
each radial spine. Condyles of the branch-ends without by-spines.
The genus _Phractaspis_ is the most simple and primitive form among all
Dorataspida, and may be regarded as the common ancestral form either of
this whole family, or at least of its first subfamily, the Diporaspida. In
all members of this subfamily the spherical shell is composed of twenty
radial spines, each of which bears two opposite apophyses; but the mode of
composition is different in the two tribes of the subfamily, in the
Phractaspida and Ceriaspida. In the simpler tribe, the Phractaspida, the
shell is composed only of the meeting branches of the apophyses of
neighbouring spines; there are no peculiar perforated plates or shields. In
the Ceriaspida, however, both apophyses of each single spine form a
perforated plate or shield by union of their branches, and the shell is
formed of the meeting edges of these shields. Of course the Ceriaspida must
be derived from the simpler Phractaspida. _Phractaspis_, as the common
ancestral form of both, exhibits a very simple structure of the shell (Pl.
137, figs. 1, 2). Commonly, if the fork-branches of each apophysis be not
again branched, the shell possesses only twenty-two large meshes and forty
sutures. More rarely their number increases, the fork-branches of the
apophyses being again branched (_Phractaspidium_, Pl. 137, fig. 3).
Subgenus 1. _Phractasparium_, Haeckel.
_Definition._--Shell with twenty-two meshes, and forty sutures, each spine
with only four branches, its two apophyses being simply forked.
{809}1. _Phractaspis prototypus_, n. sp. (Pl. 137, fig. 2).
Radial spines cylindrical, thin, pointed; the outer and inner halves of
nearly equal size. Each spine bears in its middle part two opposite
apophyses, which are simply forked; the four condyles of each spine (or the
thickened ends of the fork-branches) are united with the meeting condyles
of the neighbouring spines by sutures. Therefore the network of the
spherical shell is composed of twenty-two large meshes: two square polar
meshes on each pole (_a a a a_ and _e e e e_); eight triangular circumpolar
meshes (each between two polar and one tropical spine, _a b a_ and _e d
e_); eight tropical rhomboidal meshes (each between one polar, one
equatorial, and two tropical spines: _a b c b_ and _e d c d_); and four
rhomboidal equatorial meshes (each between two tropical and two equatorial
spines _c b c d_).
_Dimensions._--Diameter of the shell 0.1, of the meshes 0.03 to 0.04;
breadth of the spines and bars 0.005.
_Habitat._--Cosmopolitan; Mediterranean (Corfu), Atlantic (Stations 348,
354), Indian Ocean (Ceylon), Pacific (Stations 253, 265, 274), &c.,
surface.
2. _Phractaspis complanata_, n. sp. (Pl. 137, fig. 1).
Radial spines leaf-shaped, strongly compressed, two-edged, pointed; their
outer part longer than the inner. Each spine with two opposite apophyses
which are simply forked, therefore with four condyles. The network with
forty sutures and twenty-two large meshes, as in the foregoing species. The
broad faces of the eight polar spines lie in two meridian planes, of the
four equatorial spines in the equatorial plane, of the eight tropical
spines in two planes parallel to the latter. The planes of the leaf-shaped
fork-branches lie in the spherical face.
_Dimensions._--Diameter of the shell 0.1, of the meshes 0.02 to 0.03;
breadth of the fork-branches 0.012.
_Habitat._--South Atlantic, Station 343, surface.
3. _Phractaspis condylophora_, n. sp.
Radial spines quadrangular, thin; their outer pyramidal part shorter than
the inner. Each spine with four branches, its two opposite apophyses being
simply forked. The eighty condyles (or sutural ends of the branches) much
thickened, twice to four times as broad as the branches themselves. Network
with forty sutures and twenty-two large meshes, as in both foregoing
species.
_Dimensions._--Diameter of the shell 0.12, of the meshes 0.03 to 0.04;
breadth of the condyles 0.01.
_Habitat._--South Pacific, Station 288, surface.
4. _Phractaspis bipennis_, Haeckel.
_Dorataspis bipennis_, Haeckel, 1862, Monogr. d. Radiol., p. 413, Taf.
xxi. figs. 1, 2.
_Phractasplenium bipenne_, Haeckel, 1882, Manuscript.
Radial spines very thin, quadrangular; their outer pyramidal part shorter
than the inner. Each spine with four bent branches, its two opposite
apophyses being simply forked. Eighty {810}condyles, very thin, pointed. In
the specimens of this remarkable species, which I first observed in
Messina, two opposite equatorial spines had quite free apophyses, not
connected with the neighbouring spines; therefore the thin lattice-work of
the shell exhibited only thirty-six sutures and twenty meshes (two meshes
with six sutures, six meshes with four sutures, and twelve meshes with
three sutures). In similar specimens, which I afterwards observed in the
Canary Islands, all four equatorial spines were connected in the same
manner with the neighbouring spines; therefore they possessed forty sutures
and twenty-two meshes, like _Phractaspis prototypus_ (Pl. 137, fig. 2).
Perhaps the Mediterranean species represents a peculiar genus,
_Phractasplenium bipenne_.
_Dimensions._--Diameter of the shell 0.1, of the meshes 0.03 to 0.05;
breadth of the spines 0.002.
_Habitat._--Mediterranean (Messina), Canary Islands (Lanzerote), surface.
Subgenus 2. _Phractaspidium_, Haeckel.
_Definition._--Shell with forty to eighty or more meshes, and eighty to one
hundred or more sutures. Each spine with six to eight or more branches, its
two apophyses being doubly forked or more ramified.
5. _Phractaspis constricta_, n. sp. (Pl. 137, fig. 3).
Radial spines strongly compressed, two-edged, pointed; their outer half
twice constricted and somewhat longer than the inner half. Each spine with
two opposite forked apophyses, the branches of which are again forked;
therefore eight condyles on each spine. The network of the spherical shell
with eighty sutures and sixty-two meshes (twenty-two large primary meshes
and forty smaller secondary meshes, the latter between the distal
fork-branches).
_Dimensions._--Diameter of the shell 0.11, of the large meshes 0.04 to
0.05, of the small meshes 0.01; breadth of the spines 0.01.
_Habitat._--South Atlantic, Station 348, depth 2450 fathoms.
6. _Phractaspis cataphracta_, Haeckel.
_Acanthometra cataphracta_, J. Müller, 1858, Abhandl. d. k. Akad. d.
Wiss. Berlin, p. 49, Taf. x. figs. 7, 8.
_Dorataspis cataphracta_, Haeckel, 1862, Monogr. d. Radiol., p. 415.
Radial spines thin, quadrangular; their outer pyramidal part shorter than
the inner. Each spine with six to eight condyles, the fork-branches of
their two opposite apophyses being (all or partly) again forked. The
network with sixty to eighty sutures and meshes: sometimes as regular as in
the preceding species, at other times more or less irregular.
_Dimensions._--Diameter of the shell 0.1, of the meshes 0.02 to 0.04;
breadth of the bars 0.004 to 0.008.
_Habitat._--Mediterranean (Cette), Müller (Messina), Haeckel; North
Atlantic, Station 353, surface.
{811}Genus 350. _Pleuraspis_,[390] Haeckel, 1881, Prodromus, p. 467.
_Definition._--#Dorataspida# without perforated plates; shell composed only
of the meeting branches of the two opposite apophyses, which arise from
each radial spine. Condyles of the branch ends bearing by-spines.
The genus _Pleuraspis_ has quite the same structure of the shell as the
foregoing _Phractaspis_, and differs from it only in the development of
external by-spines; commonly each condyle of the branch end of the
apophyses bears one zigzag by-spine, which is directed parallel to the
radial main-spine from which the apophyses arise. Therefore each suture of
the shell is armed with two divergent by-spines (Pl. 137, fig. 4).
Subgenus 1. _Pleurasparium_, Haeckel.
_Definition._--Shell regularly developed with twenty-two meshes and forty
sutures (sometimes twenty to twenty-four meshes and thirty-six to
forty-eight sutures); each spine commonly with four branches, its two
apophyses being simply forked.
1. _Pleuraspis horrida_, n. sp. (Pl. 137, fig. 4).
Radial spines roundish, somewhat compressed, very thick, conical, pointed
at both ends, outer part nearly twice as long as the inner. Two apophyses
of each spine simply forked, with short and broad branches and thickened
condyles. Forty sutures, very broad. Twenty-two large meshes three to
four times as broad as the bars. By-spines much developed, as long as the
radius, zigzag, with alternating recurved hooks.
_Dimensions._--Diameter of the shell 0.15, of the meshes 0.04 to 0.06;
breadth of the bars 0.01 to 0.015.
_Habitat._--Tropical Pacific (east of Philippines), Station 215, surface.
2. _Pleuraspis amphithecta_, n. sp.
Radial spines two-edged, leaf-shaped, strongly compressed, pointed at both
ends; outer half longer than the inner. Two apophyses of each spine simply
forked, with short and very broad branches; condyles not thickened. Forty
sutures, broad. Twenty-two large meshes twice to three times as broad as
the bars. By-spines zigzag, half as long as the radius. (Resembles
_Phractaspis complanata_, Pl. 137, fig. 1.)
_Dimensions._--Diameter of the shell 0.12, of the meshes 0.02 to 0.03; bars
0.012.
_Habitat._--Central Pacific, Station 274, surface.
{812}3. _Pleuraspis costata_, Haeckel.
_Acanthometra costata_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 49, Taf. ii. fig. 1, Taf. x. figs. 4-6.
_Dorataspis costata_, Haeckel, 1862, Monogr. d. Radiol., p. 414, Taf.
xxiii. fig. 1.
Radial spines roundish, conical, pointed at both ends; outer and inner
halves of nearly equal length. Two apophyses of each spine simply forked,
with broad branches and thickened condyles. Forty sutures, broad.
Twenty-two large meshes, four to five times as broad as the bars. By-spines
straight, denticulate, half as long as the radius. (This common species is
rather variable in size and details.)
_Dimensions._--Diameter of the shell 0.1 to 0.13, meshes 0.03 to 0.06, bars
0.005 to 0.01.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
4. _Pleuraspis pyramidalis_, n. sp.
Radial spines quadrangular, their outer part pyramidal, very thick, about
half as long as the prismatic inner part. Two apophyses of each spine
simply forked, with very short and broad branches. Condyles much thickened.
Forty sutures, very broad. Twenty-two meshes small, the largest twice as
broad as the bars; the smaller only half as broad. By-spines short,
straight, denticulate, half as long as the radius.
_Dimensions._--Diameter of the shell 0.14, meshes 0.005 to 0.03.
_Habitat._--Western Tropical Pacific, Station 222, surface.
Subgenus 2. _Pleuraspidium_, Haeckel.
_Definition._--Shell with forty to eighty or more meshes and eighty to one
hundred or more sutures; each spine with six to eight or more branches, its
two apophyses being forked twice or oftener.
5. _Pleuraspis ramosa_, n. sp.
Radial spines roundish, stout, somewhat compressed; their inner and outer
half nearly of equal length. Two apophyses of each spine doubly forked or
more irregularly branched; therefore commonly eight (sometimes six, seven,
nine, or ten to twelve) thickened condyles on each spine. Sutures eighty to
one hundred, broad. Irregular meshes sixty to eighty; three to five times
as broad as the bars. By-spines zigzag, ramified, half as long as the
radius.
_Dimensions._--Diameter of the shell 0.15, of the meshes 0.007 to 0.014,
breadth of the bars 0.003.
_Habitat._--Central Pacific, Station 272, surface.
{813}B. Tribe II. #Ceriaspida#, Haeckel.
_Definition._--#Dorataspida#, the spherical shell of which is composed of
twenty perforated plates, produced by union of the branches of the two
opposite apophyses, which arise from each radial spine. Therefore the
meshes of the shell are partly sutural, partly parmal.
Genus 351. _Dorataspis_,[391] Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 811.
_Definition._--#Dorataspida# with twenty plates, which are perforated by
forty aspinal pores (two pores in each plate). Surface of the shell without
combs, dimples, and by-spines.
The genus _Dorataspis_ opens the long series of the Ceriaspida, or of those
Dorataspida in which the shell is composed of twenty plates, each of which
is perforated by two primary aspinal pores. This tribe has arisen from the
simpler Phractaspida by reunion of the branches of the apophyses in each
single spine. If in _Phractaspis_, their common ancestral form (Pl. 137,
figs. 1, 2), the neighbouring fork-branches of both opposite apophyses in
each radial spine become recurved and united, they will produce a shield,
which is perforated by two pores and between them by the spine itself.
These two "primary aspinal pores" are characteristic of all Ceriaspida;
among these _Dorataspis_ itself is the most simple form. Its shell exhibits
therefore constantly forty aspinal pores, and besides these a variable
number of "sutural pores" (in the sutures between the twenty plates). If in
each suture there be only a single pore, we get on the whole fifty-two or
fifty-four pores; if in each suture there be two or three pores, that
number becomes doubled or tripled.
Subgenus 1. _Doratasparium_, Haeckel.
_Definition._--Shell with fifty-two sutures; four polar plates on each pole
of the main axis meeting in one point (in the pole itself); therefore all
eight polar plates pentagonal and of equal size. Spherical shell therefore
composed of four (equatorial) hexagonal plates and of sixteen pentagonal
(eight tropical and eight polar plates).
1. _Dorataspis fusigera_, n. sp. (Pl. 138, fig. 2).
Shell with fifty-two sutures and fifty-two sutural meshes, with four
hexagonal and sixteen pentagonal plates. Both aspinal meshes of each plate
elliptical, twice to four times as broad as the {814}sutural meshes. Radial
spines in the outer half fusiform, somewhat longer than the inner
cylindrical half.
_Dimensions._--Diameter of the shell 0.08 to 0.09, of the parmal meshes 0.1
to 0.2, of the sutural meshes 0.004 to 0.01.
_Habitat._--Central Pacific, Station 271, surface.
2. _Dorataspis macracantha_, n. sp.
Shell with fifty-two sutures and fifty-two sutural meshes; with four
hexagonal and sixteen pentagonal plates. Both aspinal meshes of each plate
circular, small, twice as broad as the small sutural meshes. Radial spines
quadrangular, prismatic, their outer half twice to three times as long as
the inner half.
_Dimensions._--Diameter of the shell 0.12, of the parmal pores 0.008, of
the sutural meshes 0.004.
_Habitat._--South Pacific, Station 288, surface.
3. _Dorataspis macropora_, n. sp.
Shell with fifty-two sutures and one hundred to one hundred and fifty
sutural meshes, with four hexagonal and sixteen pentagonal plates. Both
aspinal meshes nearly circular, very large, five to ten times as broad as
the small circular sutural meshes; the number of the latter is in this
species multiplied, in each suture being two to three (commonly three)
small pores. Radial spines in the outer half leaf-shaped, compressed,
nearly lanceolate, longer than in the inner cylindrical half.
_Dimensions._--Diameter of the shell 0.16, of the parmal pores 0.03 to
0.04, of the sutural pores 0.004 to 0.006.
_Habitat._--Indian Ocean (Madagascar), Rabbe, surface.