spherical or polyhedral shell exhibits a peculiar porcellanous structure,
possesses a simple mouth, and is particularly distinguished by the constant
character denoted by their name, viz., by circles of pores surrounding the
base of the radial spines. It agrees in these striking peculiarities with
the following family, the Tuscarorida, but differs from them essentially by
the spherical or polyhedral form of the shell, which is never ovate, with
the main axis prolonged. The radial spines, variable in number, are
regularly or symmetrically disposed in all Circoporida, whilst they are
arranged around the poles of the main axis in all Tuscarorida. Whilst the
latter are always extremely large, more than a millimeter in size, the
former are much smaller and never reach the diameter of a millimeter. The
number of genera and species in this family is not large, and the majority
are very rare, but they belong to the most remarkable Radiolaria by the
peculiar structure, as well as by the geometrical regularity of the
polyhedral shell.
The Circoporida may be divided into two different subfamilies, the
Circogonida and the Haeckelinida. The latter are represented by the single
genus _Haeckeliana_ (Pl. 114), and possess a spherical shell with numerous
small dimples between the circles of pores, and numerous simple radial
spines which do not exhibit a regular arrangement. The Circogonida, on the
other hand, comprise all other genera (Pls. 115-117) and possess a panelled
shell with polygonal plates, and a certain number of radial spines, which
are regularly disposed on the corners of the polyhedral shell, and usually
armed with verticillate bristles and terminal forks or spathillæ. Perhaps
the Circogonida and Haeckelinida may be better considered as two separate
families.
The geometrical fundamental form of the shell is in the Circoporida of the
highest interest, since it exhibits regular proportions, which are very
rare in other organic forms, generally some rare forms of regular
polyhedrons. The shell in all members of this family belongs to that group
of geometrical forms which I have called in my General Morphology
"_Polyaxonia_" (vol. i., 1866, pp. 406-416). The shell therefore is
constantly an "endospherical polyhedron," _i.e._, a polyhedron, all the
corners of which lie in a spherical surface. The corners are always
indicated by the bases of the radial spines arising from the surface of the
shell and marking its axes, and it is immaterial whether the shell itself
is a true polyhedron or a sphere; for in the latter case also the radial
spines mark the axes of the polyhedron.
The six genera which we here distinguish among the Circoporida, represent
six different fundamental forms. _Circoporus_ (Pl. 115, figs. 1-3; Pl. 117,
figs. 5, 6) possesses six radial spines, opposite in pairs in three
diameters, perpendicular one to another; it agrees therefore with the
Cubosphærida (p. 169, Pls. 21-25) and {1691}represents the regular
octahedron, with eight congruent triangular faces and six corners. It has
the same form as the well-known antheridia of Chara (Gener. Morphol., vol.
i. p. 412). _Circogonia_ (Pl. 115, figs. 8-10; Pl. 117, fig. 1) exhibits
twelve radial spines, opposite in pairs in six equidistant diameters. The
surface of the shell is divided into twenty equal and equilateral
triangles, and agrees therefore with the regular icosahedron. The same form
appears also in some forms of _Aulosphæra_, and in several Astrosphærida
(Gener. Morphol., vol. i. p. 411). _Circorrhegma_ (Pl. 117, fig. 2)
possesses a regular shell with twelve equal pentagonal faces and twenty
equidistant corners, from which arise twenty regularly disposed radial
spines. It represents therefore the regular "pentagonal dodecahedron," the
same remarkable form which is found in some Astrosphærida, and in the
pollen-grains of some plants, _e.g._, _Bucholzia maritima_, _Fumaria
spicata_, _Polygonum amphibium_, &c. (Gener. Morphol., vol. i. p. 412, Taf.
ii. fig. 18).
The three genera of Circoporida mentioned therefore represent three
different forms of regular polyhedrons, in the exact mathematical sense,
viz., _Circoporus_, the regular octahedron, _Circogonia_, the regular
icosahedron, and _Circorrhegma_, the regular dodecahedron. In each of these
three regular forms all the faces, edges, and corners are equal. The
remaining three genera of Circoporida represent, however, three forms of
subregular or irregular endospherical polyhedra, which are not perfectly
regular. _Circospathis_ (Pl. 115, figs. 4-7; Pl. 117, fig. 3) is a rather
common form, and constantly possesses nine symmetrically disposed radial
spines; the shell is either spherical or polyhedral, with fourteen
triangular faces and thirty edges; the nine spines lie in three meridional
planes, which are crossed at equal angles (three equidistant spines in each
plane). We call this remarkable form the tetradecahedron; it appears also
in some Astrosphærida (_e.g._, in _Haliomma echinaster_, figured in my
Monograph, Taf. xxiv. fig. 1). _Circostephanus_ (Pl. 116, fig. 3) exhibits
a subregular polyhedral shell with a variable number of triangular faces
and of radial spines (twenty-four to forty or more). _Circostephanus
sexagenarius_ possesses sixty triangular equilateral faces, which are
disposed in twelve pentagonal groups (each with five faces), so that the
shell seems to be derived from a regular pentagonal dodecahedron, the
twelve regular faces of which are divided each into five congruent
triangles. From its corners arise thirty-two radial spines (twelve from the
central points of the pentagons, twenty from the meeting corners of every
three pentagons). In other cases the number of faces and radial spines
seems to be larger and their arrangement more irregular. The same may be
said of _Haeckeliana_, in which the dimpled shell is constantly spherical,
and possesses a variable number of radial spines, from sixteen to
fifty-five (usually between thirty and forty).
The structure of the shell in the Circoporida is the same as in the
Tuscarorida, of a peculiar porcellanous nature. The shell-wall is very
thick, more or less opaque, and in direct light whitish or yellowish. Its
surface is dimpled, with numerous small, circular, {1692}roundish or
polygonal dimples in _Haeckeliana_ (Pl. 114, figs. 1-6). In the
Circogonida, however, the surface is panelled, with regular or irregular
polygonal plates, often separated by high prominent crests (Pl. 115, figs.
4-9, &c.). Numerous simple thin needles of silica lie tangentially disposed
and irregularly scattered in the porcellanous or cement-like substance of
the thick shell-wall. Under a strong lens this substance appears finely
punctate, being probably pierced by numerous very fine pores. The surface
of the shell is therefore minutely roughened, and often appears quite black
under the microscope, by the adhesion of innumerable fine air-bubbles. In
all Circoporida, as well is in the Tuscarorida, the porcellanous shell has
not the perfect transparency of the purely siliceous shells of other
Radiolaria; its refractive power is somewhat different from the latter; it
becomes deeply stained by carmine and browned by fire, and seems therefore
to consist of a peculiar carbonic silicate.
The shell in all Circoporida exhibits a simple, excentric mouth, which
corresponds to the main osculum of the central capsule. The excentric
position of this shell-mouth has no influence on the regular form of the
shell. The mouth is either circular or polygonal, usually about as large as
a basal circle of pores. It is always armed with prominent conical or
pyramidal teeth, the number of which is variable and seems to depend partly
upon the number of the shell-faces or the radial spines. _Circoporus_ has
usually four cruciate teeth (Pl. 115, fig. 1; Pl. 117, figs. 4, 5).
_Circorrhegma_ exhibits a pentagonal mouth with five teeth (Pl. 117, fig.
2). _Circogonia_ possesses a hexagonal mouth with six teeth (Pl. 115, fig.
8; Pl. 117, fig. 1). _Circospathis_ has no constant number; some species
have five teeth (Pl. 115, fig. 4), others four (Pl. 115, fig. 10), others
nine (Pl. 117, fig. 3_a_). _Circostephanus_ is also variable; one species
exhibits eight teeth (Pl. 116, fig. 3_a_), another ten, another twelve. In
_Haeckeliana_ (Pl. 114, fig. 3) the teeth are smaller and more numerous.
Usually the teeth arise vertically from the surface of the shell and are
spinulate; more rarely their points are directed towards the centre of the
mouth. Sometimes numerous thin needles arise between the teeth (Pl. 115,
fig. 10).
The radial spines of the Circoporida are tubular, usually cylindrical and
conical at the thickened base, more rarely prismatic or slenderly
pyramidal, with three or more edges; sometimes the edges are spirally wound
around the axis (Pl. 115, fig. 6). In the majority of species their length
is about equal to the diameter of the shell; often they are somewhat
shorter, more rarely longer. Their tubular structure is always the same as
in the Tuscarorida; the wall of the tube is thick, and in the axis of its
cavity lies an axial cord or funicle, which is connected with the wall by
numerous horizontal, simple, or branched threads (Pl. 115, figs. 6, 7). The
axial funicle itself is either a simple thread of silica, or a strand,
composed of three to fifteen or more filaments, which are closely twisted
like a rope around the axis of the spine, and arise separately from the
bridges between the pores of the basal circle (Pl. 115, figs. 7, 9). The
number of {1693}pores in these circles is very variable, commonly from
three to nine, sometimes twelve to fifteen or more; their form is usually
irregularly ovate (Pl. 115, figs. 7, 9). The bridges between the pores
usually bear numerous siliceous threads or bristles, which are curved
downwards or upwards (Pl. 115, figs. 4-6). Sometimes the spines are
entirely covered with similar bristles or cilia (Pl. 117, figs. 2-5), more
rarely with regular verticils of lateral branches (Pl. 117, fig. 6).
The distal ends of the radial spines are simple in _Haeckeliana_ (Pl. 114),
whilst in the other Circoporida they are usually (or perhaps constantly)
either forked or armed with a verticil of terminal branches. When the
spines are simply forked, their two terminal branches lie in certain
meridional planes (Pl. 117, fig. 5). The same is probably the case when
they bear three divergent branches (Pl. 115, figs. 1, 2), or four crossed
branches (Pl. 117, figs. 4, 6). The larger species usually bear a corona of
five curved branches disposed around the distal apex of each spine (Pl.
116, fig. 3; Pl. 117, figs. 1, 2). Sometimes the formation of these coronas
is twice or more often repeated, so that the spines appear verticillate.
The _central capsule_ of the Circoporida (Pl. 115, fig. 8; Pl. 117, fig. 6)
is usually about half as large as the enclosing shell, and lies
excentrically in that half of its cavity which is remote from the
shell-mouth (Pl. 115, fig. 8). The other half (near the mouth) is filled up
by the cap-shaped, dark phæodium. The proboscis, or the central tubule of
the astropyle, is hidden in the axis of the blackish phæodium, and is
directed towards the mouth of the shell; it is often S-shaped, more or less
curved. The circular radiate operculum of the astropyle, placed on the base
of the proboscis, exhibits numerous branched radial ribs, and closes the
main-opening like the lid of a tea-kettle (Pl. 115, fig. 3). The number of
the parapylæ, or the accessory openings of the capsule, which in the
majority of PHÆODARIA is two, seems to be usually increased in the
Circoporida. In _Circoporus_ the capsule seems to posses six and in
_Circospathis_ nine secondary openings, and therefore there is some
probability that each circle of pores on the base of a radial spine
corresponds to a secondary opening of the capsule. In _Haeckeliana_,
however (Pl. 114), I could observe no parapylæ at all. These accessory
openings are always very small in the Circoporida, and may be easily
overlooked. Furthermore, the number of observations respecting this
difficult point is too small, and their certainty not satisfactory; it
requires therefore further accurate examination, as also does the whole
central capsule of the Circoporida.
The numerous and remarkable characters of shape and structure, which we
have described above as occurring in the Circoporida, are also found in the
following closely allied family, the Tuscarorida; all the species are
inhabitants of great depths. Perhaps it may therefore be more convenient to
separate these two families from the other PHÆOGROMIA as a peculiar order,
under the name PHÆOCALPIA.
{1694}_Synopsis of the Genera of Circoporida._
-------------------------------------------------------------------------
I. Subfamily Circogonida.
Shell spherical or polyhedral with panelled structure and polygonal
plates. A certain number of radial spines are geometrically disposed.
-------------------------------------------------------------------------
Shell octahedral (or
spherical), Six radial spines, 711. _Circoporus_.
Shell tetradecahedral, Nine radial spines, 712. _Circospathis_.
Shell icosahedral, Twelve radial spines, 713. _Circogonia_.
Shell dodecahedral, Twenty radial spines, 714. _Circorrhegma_.
Shell polyhedral, Twenty-four to forty
or more radial spines, 715. _Circostephanus_.
-------------------------------------------------------------------------
II. Subfamily Haeckelinida.
-------------------------------------------------------------------------
Shell spherical, with dimpled structure, and a
variable number of radial spines (without
polygonal plates), 716. _Haeckeliana_.
Subfamily 1. CIRCOGONIDA, Haeckel.
_Definition._--#Circoporida# with panelled shell, composed of polygonal
plates. The shell is usually polyhedral, more rarely spherical, and the
radial spines are usually (or perhaps constantly) branched and regularly
arranged.
Genus 711. _Circoporus_,[328] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Circoporida# with a spherical or regularly octahedral
shell, composed of eight congruent, triangular plates, with six corners
from which arise six radial spines, opposite in pairs in three diameters,
perpendicular one to another.
The genus _Circoporus_, the simplest among the Circoporida, is
distinguished by the regular octahedral form of the shell, with the three
equal axes of the regular crystalline system perpendicular one to another.
Six equal radial spines, arising from the six corners, lie opposite in
pairs in those three dimensive axes. The eight equal triangular faces of
the octahedron are sometimes plane, sometimes concave or convex, and
sometimes the shell becomes spherical. In this case it becomes very similar
to the Hexastylida among the #Sphæroidea#.
1. _Circoporus sexfurcus_, Haeckel (Pl. 117, fig. 5).
_Challengeria_ sp., John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv.
pl. xxiv. fig. 5.
Shell spherical, covered with irregular, polygonal plates. Six radial
spines shorter than the diameter of the shell, covered with thin curved
bristles, in the proximal half cylindrical, in the distal half forked, each
with two equal curved fork-branches. Around the ciliated base of each spine
a {1695}corona of twelve to sixteen pores surrounded by a circle of
numerous, curved, longer bristles. Mouth cruciform, with four triangular,
convergent teeth.
_Dimensions._--Diameter of the shell 0.55, length of the spines 0.4.
_Habitat._--South Pacific, Station 289, depth 2550 fathoms.
2. _Circoporus hexastylus_, n. sp. (Pl. 117, fig. 4).
Shell regularly octahedral, with eight plane, congruent, triangular faces,
which are covered with a very delicate network of small, regular, hexagonal
plates. Six radial spines as long as the radius of the shell, four-sided
pyramidal, simple, in the basal half covered with numerous curved bristles.
Around the base of each spine a corona of four equal pores, surrounded by a
circle of twelve short teeth. Apex with four crossed, curved branches (like
those of _Circospathis tetrodon_). Mouth cruciform, with four smooth teeth.
_Dimensions._--Diameter of the shell 0.24, length of the spines 0.12.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
3. _Circoporus characeus_, n. sp.
Shell spherical, covered with a delicate network of irregular polygonal
plates. Six radial spines longer than the diameter of the shell,
cylindrical, covered with numerous curved bristles, each with eight pores
at the base surrounded by a circle of long bristles. Apex of each spine
with a trident or fuscina, similar to that of the following species.
Similar to an antheridium of Chara.
_Dimensions._--Diameter of the shell 0.32, length of the spines 0.4.
_Habitat._--South Pacific, Station 285, depth 2375 fathoms.
4. _Circoporus sexfuscinus_, n. sp. (Pl. 115, figs. 1-3).
Shell subregular, octahedral, with eight triangular, concave, somewhat
unequal faces, which are covered with an extremely delicate network of
small square dimples, and furrowed by radial crests arising from the bases
of the spines (fig. 2). Six radial spines about as long as the diameter of
the shell, four-sided, prismatic, with rounded edges; each in the basal
half with a verticil of four crossed, curved bristles (fig. 1), sometimes
with two verticils (fig. 2); on the distal apex inflated, armed with a
trident or fuscina. Around the base of each spine four crossed elliptical
pores. Mouth cruciform, with four small teeth (fig. 1).
_Dimensions._--Diameter of the shell 0.2 to 0.25, length of the spines 0.2
to 0.25.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
5. _Circoporus octahedrus_, n. sp. (Pl. 117, fig. 6).
Shell regularly octahedral, with eight plane, or slightly convex,
congruent, triangular faces, which are covered with very small, regular,
triangular plates (like those of _Polypetta tabulata_, Pl. 116, fig. 2).
Six stout radial spines, about as long as the diameter of the shell,
four-sided prismatic, {1696}covered with three or four verticils of four
long curved bristles; at the distal apex inflated, with four crossed,
divergent, stout, curved horns. Around the pyramidal base of each spine a
corona of eight pores (two on each of the four faces). Mouth cruciform,
with four triangular, convergent teeth.
_Dimensions._--Diameter of the shell 0.16, length of the spines 0.18.
_Habitat._--South Pacific, Station 298, depth 2225 fathoms.
Genus 712. _Circospathis_,[329] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Circoporida# with a subregular, spherical, or polyhedral
shell, composed of fourteen triangular, nearly equal plates, with nine
corners, from, which arise nine radial spines, symmetrically disposed.
The genus _Circospathis_ exhibits the remarkable and peculiar form of a
"Tetradecahedron," or a subregular polyhedron with fourteen triangular
faces, thirty edges, and nine corners, from which arise nine radial spines.
These lie in three meridional planes, which are crossed at equal angles
(three equidistant spines in each plane). The same interesting form occurs
also in some Astrosphærida, which bear nine regularly disposed radial
spines, as _Haliomma echinaster_. All four observed species of
_Circospathis_ are South Atlantic.
1. _Circospathis furcata_, n. sp. (Pl. 115, figs. 4-6).
Shell polyhedral or nearly spherical, with nine prominent corners, from
which arise nine radial spines, about as long as the diameter of the shell.
The polygonal plates of the shell are separated by high crests, usually
hexagonal or pentagonal, irregular, about twelve to fifteen on the half
meridian. Radial spines cylindrical, straight, about as long as the
diameter of the shell, with spirally turned edges, covered with numerous
curved bristles, at the distal end forked; the two fork branches curved,
one-third as long as the simple basal part. The inflated base of each spine
is surrounded by a corona of nine to twelve ovate basal pores. Mouth
pentagonal, with five thick, mammillate and spinulate, somewhat convergent
teeth (fig. 5).
_Dimensions._--Diameter of the shell 0.6, length of the spines 0.5.
_Habitat._--South Atlantic (east of Buenos Ayres), Station 325, depth 2650
fathoms.
2. _Circospathis novena_, n. sp. (Pl. 117, figs. 3, 3_a_).
Shell polyhedral (tetradecahedral), with fourteen triangular, plane, or
slightly convex faces, covered with small, irregular, polygonal (usually
hexagonal) plates, and nine prominent corners, from which arise nine radial
spines, shorter than the diameter of the shell. Each spine is surrounded at
the broader base by a circle of twelve to sixteen pores and a corona of
bristles, and bears at the {1697}inflated distal apex a trident or fuscina,
similar to that of _Circoporus sexfuscinus_ (Pl. 115, fig. 2). Mouth with
nine convergent, conical, denticulate teeth (fig. 3_a_).
_Dimensions._--Diameter of the shell 0.6, length of the spines 0.4.
_Habitat._--South Atlantic, Station 318 (east of Patagonia), depth 2040
fathoms.
3. _Circospathis tetradeca_, n. sp.
Shell spherical, covered with irregular, polygonal plates. Nine radial
spines, cylindrical, as long as the radius of the shell, bristly, armed at
the distal apex with a trident. (In one specimen six spines possessed three
terminal branches, two spines two branches, and one spine four branches.)
The broader base of each spine is surrounded by a corona of nine pores and
a circle of curved bristles. Mouth with nine smooth conical teeth.
_Dimensions._--Diameter of the shell 0.55, length of the spines 0.3.
_Habitat._--South Atlantic, Station 332 (west of Tristan da Cunha), depth
2200 fathoms.
4. _Circospathis tetrodonta_, n. sp. (Pl. 115, fig. 10).
Shell subspherical or polyhedral, with fourteen triangular, convex faces,
covered with irregular polygonal plates. Nine radial spines cylindrical,
nearly smooth, about as long as the diameter of the shell; at the distal
apex with four strong curved horns, like those of _Circoporus hexastylus_,
Pl. 117, fig. 4. Each spine is surrounded at the base by a corona of nine
irregular pores. Mouth with four large, prominent, conical teeth, which are
spinulate, with vertical inner edge (fig. 10).
_Dimensions._--Diameter of the shell 0.5, length of the spines 0.45.
_Habitat._--South Atlantic, Station 323 (east of Buenos Ayres), depth 1900
fathoms.
Genus 713. _Circogonia_,[330] n. gen.
_Definition._--#Circoporida# with a regular icosahedral shell, composed of
twenty congruent, triangular plates, with twelve corners, from which arise
twelve radial spines.
The genus _Circogonia_ is remarkable for the regular icosahedral form of
its shell, a geometrical fundamental form, which occurs very rarely in
organised bodies (as in _Aulacantha icosahedra_, and in some Astrosphærida
with twelve regularly disposed radial spines). The shell is composed of
twenty triangular, equilateral and congruent plates, which are sometimes
separated by prominent crests; their surface is panelled by smaller
hexagonal or polygonal secondary plates. The thirty edges between the
plates are sometimes thickened. From the twelve corners of the regular
icosahedron (where every five triangular plates meet), twelve equal radial
spines arise, each of which is surrounded at the base by a corona of nine
to sixteen pores. Two species only of _Circogonia_ have been observed; the
one has smooth spines, forked at the distal end, {1698}the other bears
numerous curved bristles around each spine, and at the distal end a
verticil of five curved branches. The mouth of the shell (placed in the
centre of one of the triangular plates) is in both species armed with six
teeth. Both species are found in the Tropical Atlantic.
1. _Circogonia icosahedra_, n. sp. (Pl. 117, figs. 1, 1_a_).
Shell regularly icosahedral, with twenty equal, triangular, nearly plane
faces, which are separated by thirty prominent, crest-like edges, and
covered by a delicate network of small, subregular, hexagonal plates.
Twelve radial spines nearly conical, one and a half times as long as the
radius of the shell, with five prominent edges. The campanulate base of
each spine is covered with numerous long, curved bristles, surrounded by a
circle of twelve to sixteen ovate, irregular pores, and separated from the
slender distal part by a constriction. The distal apex of the spine is
surrounded by a verticil of five conical, curved branches (corresponding to
the five edges of the spines, and to the five faces, which meet in the
corners where the spine arises). Mouth hexagonal, with six conical,
spinulate teeth, convergent towards its centre (fig. 1_a_).
_Dimensions._--Diameter of the shell 0.75, length of the spines 0.5.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
2. _Circogonia dodecacantha_, n. sp. (Pl. 115, figs. 8, 9).
Shell subregularly icosahedral, with twenty equal, triangular, slightly
convex faces, which are not separated by prominent crests, but covered with
a network of irregular polygonal plates. Twelve radial spines, cylindrical,
smooth, about as long as the diameter of the shell, forked at the distal
end with two divergent, slightly curved branches (similar to _Circospathis
furcata_, Pl. 115, figs. 4-6). The conical base of each spine is surrounded
by a circle of nine to twelve irregular, ovate pores (fig. 9). Mouth
circular, with a corona of six conical, smooth teeth which arise
perpendicularly from the shell (in the upper part of fig. 8, at left).
_Dimensions._--Diameter of the shell 0.6, length of the spines 0.7.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
Genus 714. _Circorrhegma_,[331] n. gen.
_Definition._--#Circoporida# with a regular dodecahedral shell, composed of
twelve congruent, pentagonal plates, with twenty corners, from which arise
twenty radial spines.
The genus _Circorrhegma_ is remarkable for the geometrical regularity of
its shell, which represents a pentagonal dodecahedron. The shell is
therefore composed of twelve equal and regular pentagonal plates, and these
are separated in the only known {1699}species by thirty prominent
crest-like edges. From the corners of the dodecahedron, at which every
three pentagons meet, arise twenty radial spines, opposite in pairs in ten
equidistant axes.
1. _Circorrhegma dodecahedra_, n. sp. (Pl. 117, figs. 2, 2_a_).
Shell dodecahedral, with twelve equal and regular, plane, pentagonal
plates, which are separated by thirty prominent crests, and bear a network
of numerous polygonal (usually also pentagonal), smaller plates. Twenty
radial spines about as long as the radius of the shell, three-sided
prismatic, covered with numerous bristles; each surrounded at the thickened
base by a circle of twelve to sixteen pores, and at the distal apex by a
corona of five curved, terminal branches. Mouth pentagonal, with five
conical, subvertical, spinulate teeth (fig. 2_a_).
_Dimensions._--Diameter of the shell 0.8, length of the spines 0.5.
_Habitat._--Indian Ocean, Madagascar (Rabbe).
Genus 715. _Circostephanus_,[332] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Circoporida# with a subregular, polyhedral or nearly
spherical shell, composed of thirty to sixty or more triangular plates,
with twenty-four to thirty-two or more corners, from which arise radial
spines, symmetrically disposed.
The genus _Circostephanus_ comprises those Circoporida in which the
porcellanous shell is an endospherical polyhedron, with numerous (thirty to
sixty or more) triangular faces, and has a variable number of radial spines
(twenty-four to forty or more), arising from its corners. The number of
faces and corners seems to be variable in this genus, but may perhaps be
typical in some species. _Circostephanus sexagenarius_ has the typical form
of a "Sexagenal-Polyhedron," with sixty equal triangular faces and
thirty-two corners, and may be derived from the "Pentagonal-Dodecahedron"
(_Circorrhegma_) by dividing its twelve pentagonal faces each into five
congruent triangles.
1. _Circostephanus coronarius_, n. sp. (Pl. 116, figs. 3, 3_a_, 3_b_).
Shell polyhedral, with thirty-two to forty triangular, concave faces of
nearly equal size, which are separated by high prominent crests. From the
elevated corners of the polyhedron arise twenty-four to thirty radial
spines, which are three-sided prismatic or nearly cylindrical, about as
long as the radius of the shell, and covered with long curved bristles. The
distal end of each spine is surrounded by a verticil of five stout, curved
branches, its pyramidal base by a corona of five (or {1700}sometimes six)
ovate, basal pores (fig. 3_b_). Mouth armed with a corona of eight short,
conical, vertical, spinulate teeth (fig. 3_a_).
_Dimensions._--Diameter of the shell 0.4 to 0.5, length of the spines 0.2
to 0.25.
_Habitat._--South-Eastern Pacific (off Valparaiso), Station 298, depth 2225
fathoms.
2. _Circostephanus sexagenarius_, n. sp.
Shell polyhedral, with sixty triangular, equilateral congruent faces which
are nearly plane, and separated by high prominent crests. They are disposed
in twelve pentagonal groups, each with five faces, so that they appear as
if derived from a regular pentagonal dodecahedron, the twelve regular faces
of which are each divided into five congruent triangles, meeting in its
centre. From the elevated corners of the polyhedron arise thirty-two radial
spines (twelve in the central points of the pentagons, twenty in the
meeting corners of every three pentagons). The radial spines are nearly as
long as the diameter of the shell, cylindrical, spinulate, and surrounded
at the distal end by a verticil of five stout, curved branches, and at the
pyramidal base by a corona of twelve to sixteen basal pores. Mouth armed
with a corona of twelve conical, vertical, spinulate teeth.
_Dimensions._--Diameter of the shell 0.75, length of the spines 0.6.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
3. _Circostephanus polygonarius_, n. sp.
Shell polyhedral, with sixty to eighty subregular, triangular, concave
faces, which are separated by prominent crests. From the elevated corners
of the polyhedron arise thirty to forty radial spines, which are longer
than the diameter of the shell, densely covered with curved bristles and
three-sided prismatic, with three spirally convoluted edges. Their distal
end is surrounded by a verticil of eight or nine curved branches, and their
pyramidal base by a corona of eight or nine basal pores. Mouth armed with a
corona of ten conical, vertical, spinulate teeth.
_Dimensions._--Diameter of the shell 0.8, length of the spines 0.9.
_Habitat._--South Pacific, Station 288, depth 2600 fathoms.
Subfamily 2. HAECKELINIDA.
_Definition._--#Circoporida# with dimpled spherical shell, not composed of
polygonal plates. The shell is covered with small roundish dimples, never
polyhedral, and the radial spines are simple, not branched, and usually not
regularly arranged.
Genus 716. _Haeckeliana_, John Murray, 1879, _in schedulis_, Chall. Coll.
_Definition._--#Circoporida# with spherical shell of a peculiar dimpled,
porcellanous structure, and with a variable number of simple radial
main-spines which are usually not regularly arranged.
{1701}The genus _Haeckeliana_ comprises the spherical Circoporida, with
dimpled, porcellanous shell, which are widely distributed, but rather rare,
in depths between 2000 and 3000 fathoms. All the known species (six in
number) are very closely related, and though the extreme forms appear very
different in size and structure, they are so connected by a continuous
series of intermediate forms, that they may be regarded as varieties of a
single species, first observed by Dr. John Murray, and called by him
_Haeckeliana porcellana_. The number of radial spines may be from sixteen
to fifty-five, and is usually between thirty and forty. Each is surrounded
by a basal coronet of aspinal pores, usually five, more rarely four or six;
the number, however, is not constant in any one species. Each coronet is
armed with an outer ring of by-spines. The surface of the shell between the
coronets is dimpled. The mouth (Pl. 114, fig. 3) is about as large as a
corona, and also armed with a ring of by-spines. The structure of the thick
porcellanous shell and the radial spines is different from the other
Circoporida.
1. _Haeckeliana porcellana_, John Murray (Pl. 114, fig. 6).
_Haeckeliana porcellana_, John Murray, 1879, _in schedulis_, Chall. Coll.
Shell with forty to forty-five coronets, the majority of which have five
pores (more rarely four or six). Coronets broader than their intervals, and
twice as broad as the length of the by-spines. Dimples subcircular, of the
same breadth as the pores. Main-spines about as long as the radius.
_Dimensions._--Diameter of the shell 0.37 to 0.42, of the coronets 0.06 to
0.07.
_Habitat._--South Pacific, Stations 289 to 293, depth 2025 to 2550 fathoms.
2. _Haeckeliana maxima_, n. sp. (Pl. 114, fig. 5).
Shell with fifty to fifty-five coronets, the majority of which have six
pores (more rarely five or seven). Coronets broader than their intervals,
and eight to ten times as broad as the length of the by-spines. Dimples
irregularly polygonal, of about the same breadth as the pores. Radial
main-spines about as long as the diameter of the shell.
_Dimensions._--Diameter of the shell 0.5 to 0.52, of the coronets 0.08 to
0.09.
_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.
3. _Haeckeliana lamarckiana_, n. sp. (Pl. 114, fig. 4).
Shell with thirty-five to forty coronets, the majority of which have five
pores (more rarely six or four). Coronets broader than their intervals;
each funnel-shaped pore on the inside with a circle of small conical
thorns. By-spines rudimentary or wanting. Dimples irregularly polygonal,
half as broad as the pores. Radial main-spines shorter than the radius.
_Dimensions._--Diameter of the shell 0.38 to 0.45, of the coronets 0.06 to
0.07.
_Habitat._--South Atlantic, Stations 318 to 333, depth 2000 to 2900
fathoms.
{1702}4. _Haeckeliana murrayana_, Haeckel.
_Challengeria_ sp., John Murray, 1876, Proc. Roy. Soc., vol. xxiv, pl.
xxiv. fig. 6.
Shell with twenty to twenty-five coronets, the majority of which have five
pores (more rarely four or six). Coronets of about the same breadth as
their intervals, and twice as broad as the by-spines. Dimples subcircular,
of about the same breadth as the pores. Radial main-spines about as long as
the radius.
_Dimensions._--Diameter of the shell 0.35 to 0.4, of the coronets 0.06 to
0.07.
_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750
fathoms.
5. _Haeckeliana goetheana_, n. sp. (Pl. 114, fig. 3).
Shell with sixteen to twenty coronets, the majority of which have four
pores (more rarely five and very rarely six). Coronets smaller than their
intervals. By-spines very short or rudimentary. Dimples subcircular, half
as broad as the pores. Radial main-spines shorter than the radius.
_Dimensions._--Diameter of the shell 0.25 to 0.3, of the coronets 0.04 to
0.05.
_Habitat._--North Pacific (south of Japan), Station 231, depth 2250
fathoms.
6. _Haeckeliana darwiniana_, n. sp. (Pl. 114, figs. 1, 2).
Shell with twenty-six to thirty-two coronets, the majority of which have
five pores (rarely four or six). Coronets smaller than their intervals and
than the length of the by-spines. Dimples subcircular, half as broad as the
pores, Radial main-spines longer than the radius.
_Dimensions._--Diameter of the shell 0.30 to 0.42, of the coronets 0.07 to
0.08.
_Habitat._--North Pacific (east of Japan), Stations 241 to 245, depth 2300
to 2900 fathoms.
Family LXXXII. #TUSCARORIDA#, n. fam. (Pl. 100).
_Definition._--PHÆODARIA with an ovate, spindle-shaped, or nearly spherical
shell exhibiting a peculiar solid porcellanous structure; with a few radial
pores around the base of the hollow tubules, which are symmetrically
arranged around the main axis and the mouth. Surface of the shell smooth or
spiny, not tabulate nor panelled. Central capsule excentric, placed in the
aboral half of the shell-cavity.
The #Tuscarorida#, and the preceding closely allied family, the
Circoporida, represent together a peculiar small group, which differs from
the other PHÆODARIA in the singular porcellanous structure of the
shell-wall, and may be called #Phæocalpia#; their hollow radial spines are
distinguished by peculiar basal pores, forming a circle around their base.
The shell of the Tuscarorida is monaxonian, ovate, spindle-shaped {1703}or
nearly spherical, whilst in the Circoporida it is polyaxonian, spherical or
polyhedral; the hollow radial spines are arranged in the former around the
main axis, in the latter around the common central point. All #Phæocalpia#
(the Tuscarorida as well as the Circoporida) are inhabitants of great
depths, usually between 2000 and 3000 fathoms.
Though the number of Tuscarorida at present known is small (only three
genera, with ten species), they represent a very distinct and remarkable
family of PHÆODARIA, as well by their considerable size, as by the peculiar
arrangement of the radial spines and the structure of the shell-wall, which
in some species is more solid and thicker than in any other Radiolaria. The
diameter of the shell is always more than 1 mm., usually between 1 and 2,
and sometimes more than 3 mm.
The dry shell of the Tuscarorida is not hyaline and transparent as is usual
in the other Radiolaria, but perfectly opaque, milk-white or
yellowish-white. This opacity is caused by innumerable very fine pores,
which everywhere pierce the thick, apparently solid, fundamental substance
of the shell-wall. Besides those very small pores, it is also pierced by a
certain number of larger pores, which are scattered at wide distances
(Narr. Chall. Exp., vol. i. pl. A, fig. 15_b_). These larger pores or
pore-channels have a diameter of about 0.01 mm., and pierce the shell-wall
either in a perpendicular or in an oblique direction. Very numerous
straight, simple, and thin needles, usually 0.1 to 0.2 mm. in length,
similar to the thin tangential needles of the Aulacanthida, are everywhere
scattered tangentially in the cement-like fundamental substance, which
seems to be a peculiar carbonic silicate; their axis is parallel to the
shell-surface.
The general form of the shell is somewhat different in the three genera of
Tuscarorida; ovate or spherical in _Tuscarora_ and _Tuscarusa_, which bear
no caudal axial spine (Pl. 100, figs. 1-7), or sometimes three-sided
pyramidal (fig. 4); it is spindle-shaped in _Tuscaridium_, which bears on
the aboral pore an axial caudal spine (Pl. 100, fig. 8). In every case the
main axis of the shell, determining its monaxonian fundamental form, is
indicated by the mouth, which is placed in the oral pole of the main axis
and prolonged into a short tube or proboscis.
The hollow apophyses, arising from the shell of the Tuscarorida, are always
cylindrical, long and thin tubules, the narrow cavity of which communicates
directly with the large shell-cavity. In the axis of the tubules lies a
thin axial chord or funicle, composed of a few (usually three or four)
siliceous threads which arise from bridges between the basal pores of the
apophyses, and are twisted together like the strands of a rope. The axial
funicle is connected with the thin wall of the tubular apophyses by
innumerable very thin radial beams, perpendicular to the axis (Pl. 100,
fig. 3_a_, 5_b_). The surface of the apophyses is almost constantly covered
with numerous small bristles or spines, which are usually curved and
directed towards their distal ends.
_Tuscarora_ (Pl. 100, figs. 1-6) exhibits two different groups of
apophyses, which may be distinguished according to their different position
and direction as "circoral {1704}teeth" and "aboral feet"; the teeth
immediately surround the opening of the mouth, whilst the feet are remote
from it and usually placed in the aboral half of the body, more rarely in
the equator or in the oral half. The general form and structure are the
same in both groups of apophyses, but their position and direction is
different; the circoral teeth are directed forwards, often parallel (at the
base at least), while the aboral feet are either divergent and directed
backwards, or they diverge forwards in the basal part, then form a large
arch, and finally curve backwards.
The number of the aboral feet, and their position relative to the circoral
teeth, are different but probably constant in each single species, and
serve, in the first place, for the distinction of genera and species.
_Tuscarora_ (in restricted sense) (Pl. 100, figs. 1-6), has constantly
three feet (comparable to the three cortinar feet of the tripodal
NASSELLARIA); _Tuscarusa_ (Pl. 100, fig. 7) has four feet, opposite in
pairs and forming a regular cross; _Tuscaridium_, finally (Pl. 100, fig.
8), has only one foot, which is situated in the main axis, on its aboral
pole, and may therefore be called a caudal spine.
The number of the circoral teeth varies from two to four, and is usually
three. Originally these three teeth alternate regularly with the three
aboral feet, so that the latter may be regarded as perradial, the former as
interradial (Pl. 100, figs. 1-4). The proportion of the number of each
group of apophyses in the different species is synoptically shown in the
following table:--
a = Depth in Fathoms.
b = Challenger Station.
c = Length of the Shell.
d = Breadth of the Shell.
e = Number of Feet.
f = Number of Pedal Pores.
g = Number of Teeth.
h = Number of Dental Pores.
+------------------------------+------+-----+-----+-----+---+---+---+---+
| | a | b | c | d | e | f | g | h |
+------------------------------+------+-----+-----+-----+---+---+---+---+
| 1. _Tuscarora bisternaria_, | 3000 | 264 | 2.0 | 1.5 | 3 | 8 | 3 | 8 |
| 2. " _murrayi_, | 2000 | 295 | 2.5 | 1.5 | 3 | 3 | 3 | 3 |
| 3. " _wyvillei_, | 2250 | 291 | 1.5 | 1.4 | 3 | 4 | 3 | 4 |
| 4. " _tetrahedra_, | 2450 | 348 | 2.5 | 2.0 | 3 | 4 | 3 | 3 |
| 5. " _tubulosa_, | 3000 | 249 | 1.4 | 1.2 | 3 | 4 | 2 | 3 |
| 6. " _porcellana_, | 2650 | 325 | 1.5 | 1.3 | 3 | 4 | 2 | 4 |
| 7. " _belknapii_, | 2025 | 293 | 2.5 | 1.5 | 3 | 3 | 4 | 2 |
| 8. _Tuscarusa medusa_, | 3125 | 253 | 1.2 | 1.0 | 4 | 4 | 2 | 2 |
| 9. _Tuscaridium cygneum_, | 3050 | 250 | 3.2 | 1.6 | 1 | 2 | 4 | 4 |
|10. " _lithornithium_, | 3000 | 264 | 3.6 | 1.8 | 1 | 4 | 4 | 6 |
+------------------------------+------+-----+-----+-----+---+---+---+---+
The base of the apophyses in all Tuscarorida is inflated, conical, and
pierced by a small number of large ovate pores, the typical "basal pores,"
which occur also in the closely allied Circoporida. The number of these
basal pores varies from two to eight, and is usually three or four; it
never becomes in this family so great as in the Circoporida, where each
circle of pores is often composed of sixteen to twenty-four or more basal
pores. The number seems to be rather constant in each single species, as
may be seen in the preceding Table. The pedal pores (on the base of the
aboral feet) are usually larger than the dental pores (on the base of the
circoral teeth). Their form is {1705}usually irregularly ovate or
triangular; their outer aperture is armed with spines or bristles, which
are commonly larger than in the other parts of the apophyses.
The mouth of the shell varies in form, according to the number and
arrangement of the teeth on its corners. It is therefore a narrow
transverse fissure, with two broad opposite lips and two corners, in the
bidental forms (Pl. 100, figs. 5, 7), triangular in the tridental species
(figs. 1-4), quadrangular or square in the quadridental species, _Tuscarora
belknapii_ (Narr. Chall. Exp., _loc. cit._, pl. A, fig. 15). The singular
genus _Tuscaridium_ (fig. 8) exhibits four teeth, which are nearly
horizontally divergent in two pairs, a dorsal and a ventral pair
(corresponding in position to the four feet of _Tuscarusa_, fig. 7); the
mouth is here prolonged into a cylindrical, spinulate proboscis, which is
curved towards the ventral face of the shell (fig. 8).
The _central capsule_ of the Tuscarorida is kidney-shaped or spheroidal,
scarcely half as large as the dark olive-green phæodium, which surrounds
its anterior (oral) face. Usually the capsule and the phæodium together
fill up the aboral half of the shell-cavity, and are separated from its
walls by the calymma. The latter is pierced by numerous branched and
reticulately anastomosing pseudopodia, which arise from the matrix
enveloping the capsule, and pass over into a thin layer of sarcode,
adjacent to the inner surface of the shell. The astropyle or the
main-opening of the central capsule exhibits the usual radiate operculum
and tubular proboscis of the PHÆODARIA (Pl. 115, fig. 3), and is directed
towards the mouth of the shell. The number of the parapylæ or accessory
openings seems to be variable in this family, and to correspond to the
number of radial feet which arise from the shell. Therefore _Tuscaridium_
possesses only one parapyle, which is diametrically opposite to the mouth,
lies on the aboral pole of the capsule, and is directed towards the single
caudal tube. _Tuscarora_ seems to have three parapylæ, corresponding to the
three radial feet, and _Tuscarusa_ probably has four parapylæ, directed
towards its four radial feet; in the latter genus, however, the capsule was
not observed (the shell being empty); and in the other Tuscarorida this
important and difficult anatomical question must be solved by further
accurate examinations.
The nucleus is nearly half as large as the central capsule, ellipsoidal,
and contains numerous nucleoli. In one specimen of _Tuscarora belknapii_ I
observed two nuclei in the central capsule, and in another specimen of the
same species John Murray observed two central capsules (figured by him in
the Narr. Chall. Exp., vol i. pl. A, fig. 15).
_Synopsis of the Genera of Tuscarorida._
Three equidistant aboral radial feet, 717. _Tuscarora_.
Four equidistant aboral radial feet, 718. _Tuscarusa_.
One single aboral foot or terminal spine, 719. _Tuscaridium_.
{1706}Genus 717. _Tuscarora_,[333] John Murray, 1876, _in schedulis_,
Chall. Coll.
_Definition._--#Tuscarorida# with three radial aboral feet, and a variable
number of circoral teeth.
The genus _Tuscarora_ comprises seven of the ten observed species of
Tuscarorida, all seven agreeing in the possession of three perradial feet,
which alternate originally (in four species), with three interradial teeth
surrounding the mouth. The latter is armed in two other species with two
teeth, and in one species with four teeth (compare above, p. 1704). The
three perradial feet have a similar position as in the tripodal
NASSELLARIA, so that they may be distinguished as an odd caudal foot and
two paired lateral feet.
Subgenus 1. _Tuscarantha_, Haeckel.
_Definition._--Shell with three perradial equidistant feet and three
interradial equidistant circoral teeth, alternating regularly with the
former.
1. _Tuscarora bisternaria_, John Murray (Pl. 100, figs. 1, 1_a_).
_Tuscarora bisternaria_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, figs. 16, 16_a._
Shell subspherical, with three lateral perradial feet in the equatorial
zone, and three basal interradial teeth around the mouth, alternating
regularly with the former. The three lateral feet arise either in the
equator itself or a little above it, and are nearly horizontally expanded,
descending a little towards the aboral pole. They are straight,
cylindrical, twice to four times as long as the shell, geniculate at the
inflated base, and covered with small thorns. A circle of six to eight
basal pores in the base of each foot. The narrow mouth is triangular,
surrounded by the thorny, inflated, subspherical bases of the three long,
cylindrical, diverging, thorny teeth, which ascend obliquely and are longer
than the shell; each tooth exhibits in the upper part of the inflated base
a corona of eight to ten ovate holes.
_Dimensions._--Length of the shell 2.0, breadth 1.5.
_Habitat._--Central Pacific, Station 264, depth 3000 fathoms.
2. _Tuscarora murrayi_, n. sp. (Pl. 100, fig. 2). John Murray, 1876, L. N.
27, pl. 24, fig. 4.
Shell pear-shaped, with three circoral perradial feet in the upper third
and three basal interradial teeth around the mouth. The three lateral feet
are thin, cylindrical, arcuate, very bristly, arise immediately beyond the
narrow tubular peristome, and ascend obliquely nearly to the height of the
mouth; then they are curved downwards in a large arc, three to four times
as long as {1707}the shell. The tubular peristome is about half as long as
the shell, bottle-shaped, nearly three-sided prismatic, and bears three
very long spinulate teeth, which in the lower half are parallel, in the
upper slightly curved and diverging, at the base pear-shaped. Three ovate
basal pores in the inflated base of each foot and each tooth.
_Dimensions._--Length of the shell 2.5, breadth 1.5.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
3. _Tuscarora wyvillei_, n. sp. (Pl. 100, figs. 3, 3_a_-3_c_).
Shell subspherical, pellucid, thinner and more fragile than in the other
species of the genus, with three aboral perradial feet in the lower third,
and three interradial teeth around the wide mouth. The three feet are
straight, conical, widely divergent, shorter than the shell, and arise from
its lower third; on the inflated base of each four small ovate pores. The
three teeth, alternating with them, are straight, cylindrical, arise from
the margin of the mouth and diverge obliquely upwards. On the base of each
foot four opposite cordate pores of very unequal size.
_Dimensions._--Length of the shell 1.5, breadth 1.4.
_Habitat._--South Pacific, Station 291, depth 2250 fathoms.
4. _Tuscarora tetrahedra_, John Murray (Pl. 100, figs. 4, 4_a_).
_Tuscarora tetrahedra_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 19.
Shell tetrahedral or three-sided pyramidal, with three perradial basal
feet, and three alternate, interradial, circoral teeth. The three rounded
edges of the pyramid are prolonged directly over the aboral base into the
three short, divergent, conical, basal feet, which are smooth and scarcely
one-fourth as long as the shell. The base of each foot is pierced by four
small crossed pedal pores. The narrow mouth, on the apex of the pyramid, is
surrounded by three short and broad, triangular, spinulate teeth, each of
which bears three slender, triangular, dental pores.
_Dimensions._--Length of the shell 2.5, breadth 2.0.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
Subgenus 2. _Tuscaretta_, Haeckel.
_Definition._--Shell with three perradial equidistant feet, and with two
circoral teeth, which are opposite in the radius of the odd dorsal foot;
therefore a dorsal and a ventral tooth.
5. _Tuscarora tubulosa_, John Murray (Pl. 100, figs. 5, 5_a_, 5_b_).
_Tuscarora tubulosa_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 17.
Shell subspherical, with three lateral perradial feet on the upper half of
the shell (above the equator), and two parallel vertical teeth on the
mouth. The three feet arise between the upper and {1708}the middle third of
the shell, diverge upwards, and are slightly arcuate, covered with numerous
curved spines. Their base is pierced by four pedal pores. The peristome is
a narrow sagittal fissure, placed in the radius of the odd or dorsal foot,
and bears two opposite teeth on its two corners. The teeth are cylindrical,
longer than the shell, covered with curved spines, and ascend in a parallel
and vertical manner; each is perforated at the base by three large dental
pores.
_Dimensions._--Length of the shell 1.4, breadth 1.2.
_Habitat._--North Pacific, Stations 244 to 250, depth 2050 to 3050 fathoms.
6. _Tuscarora porcellana_, John Murray (Pl. 100, figs. 6_a_, 6_b_).
_Tuscarora porcellana_, John Murray, 1819, _in litteris_, Narr. Chall.
Exp., pl. A, fig. 18.
Shell pear-shaped, with three lateral perradial feet in the lower half of
the shell, and two parallel vertical teeth on the mouth. The three lateral
feet arise between the middle and the lower third of the shell, are
straight, cylindrical, spinulate, about as long as the shell and diverge
downwards; their base is pierced by four ovate pedal pores. The two
parallel and vertical teeth are straight, shorter than half the shell, and
opposite in the sagittal plane, on the two corners of the narrow mouth, in
the radius of the dorsal odd foot. The base of each tooth exhibits four
cordate dental pores.
_Dimensions._--Length of the shell 1.5, breadth 1.3.
_Habitat._--South Atlantic, Station 325, depth 2650 fathoms.
Subgenus 3. _Tuscarilla_, Haeckel.
_Definition._--Shell with three perradial equidistant feet, and with four
crossed equidistant teeth around the mouth.
7. _Tuscarora belknapii_, John Murray.
_Tuscarora belknapii_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, figs. 15, 15_a_-15_d._
Shell pear-shaped, with three lateral perradial feet in the upper third,
and four crossed teeth around the mouth. The three arcuate feet are thin,
cylindrical, covered with small curved thorns, and arise at the base of the
peristome, between the upper and middle third of the shell; they ascend
diverging to the height of the mouth, and are then curved downwards in a
large arc, twice to three times as long as the shell. The base of each foot
is dilated and pierced by three pedal pores. The four thin and long teeth
of the peristome are similar to the feet, ascend in a slightly diverging
manner, and are so placed that two opposite lie in the sagittal plane (or
in the radius of the dorsal odd foot), whilst the two others are opposite
in the frontal plane (perpendicular to the former). The base of each tooth
exhibits two large ovate dental pores.
_Dimensions._--Length of the shell 2.5, breadth 1.5.
_Habitat._--South Pacific, Station 293, depth 2025 fathoms.
{1709}Genus 718. _Tuscarusa_,[334] n. gen.
_Definition._--#Tuscarorida# with four radial aboral feet and a variable
number of circoral teeth.
The genus _Tuscarusa_ differs from the preceding closely allied _Tuscarora_
in the possession of four radial feet instead of three. The mouth of the
single observed species is a narrow sagittal fissure, and armed with two
opposite teeth (a dorsal and a ventral, as in the subgenus _Tuscaretta_).
The four lateral feet form a cross, and lie opposite in pairs, in two
diagonals of the square, which is bisected by the sagittal mouth.
1. _Tuscarusa medusa_, n. sp. (Pl. 100, figs. 7, 7_a_).
Shell ovate, with four crossed lateral feet in the upper third, and with
two opposite teeth around the mouth. The four feet are opposite in pairs in
two diameters of the shell, perpendicular one to another, and arise between
the upper and middle third of the shell; they are thin, cylindrical,
spinulate, arcuate, and ascend to the height of the mouth diverging
upwards; then they are curved downwards in a large arc. They lie in the
diagonals of the square, which is halved by the narrow and long fissure of
the mouth. This lies in the original sagittal plane, and from its two
corners arise the two opposite teeth (a dorsal and a ventral), diverging
upwards, cylindrical and slightly curved. The base of each foot is pierced
by four pedal pores, of each tooth by two dental pores.
_Dimensions._--Length of the shell 1.2, breadth 1.0.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
Genus 719. _Tuscaridium_,[335] n. gen.
_Definition._--#Tuscarorida# without radial aboral feet, but with a
terminal axial caudal foot, and a variable number of circoral teeth.
The genus _Tuscaridium_, comprising two closely allied species, differs
from the two preceding genera of Tuscarorida in the absence of lateral
radial feet, which are represented by a single large caudal spine placed in
the main axis of the shell, at its aboral pole. The shell is therefore
spindle-shaped, and not ovate or subspherical, as in the two other genera.
It reaches in the two observed species a length of more than 3 mm.
1. _Tuscaridium cygneum_, Haeckel.
_Tuscarora cygnea_, John Murray, 1879, in litteris, Narr. Chall. Exp.,
vol. i. p. 226, pl. A, fig. 20.
Shell spindle-shaped, twice as long as broad (in the transverse section
circular), equally tapering towards both poles of the main axis. The aboral
pole bears a thin, cylindrical, straight, caudal {1710}spine, placed in the
prolongation of the main axis, and about half as long as the shell. Its
base is pierced by two large opposite pedal pores. The anterior or oral
pole bears a cylindrical peristome, similar to a bird's head, and curved
towards the ventral face; on both sides of its neck (at right and left) a
series of three or four irregular, ovate, buccal holes. The neck bears four
cylindrical, spinulate, radial tubes (two on each side), crossed nearly
horizontally, and placed in two diagonal planes perpendicular one to
another; these planes correspond to those in which the four feet of
_Tuscarusa medusa_ lie. The base of each tube is pierced by four dental
pores.
_Dimensions._--Length of the shell 3.2, breadth 1.6.
_Habitat._--North Pacific, Station 250, depth 3050 fathoms.
2. _Tuscaridium lithornithium_, n. sp. (Pl. 100, figs. 8, 8_a_, 8_b_).
Shell spindle-shaped, twice as long as broad, very similar to the preceding
closely allied species. It differs from the latter in the following
characters:--The curved proboscis of the peristome is broader and more
spiny. The four radial tubes of the mouth and the terminal caudal spine are
very spiny (in the preceding species nearly smooth). The number of buccal
holes (six to eight on each side of the mouth) is twice as great as in the
former. Each circoral tube is pierced at the base by six or eight (in the
former by four pores), and the base of the caudal spine exhibits a cross of
four pores (in _Tuscaridium cygneum_ only two pores).
_Dimensions._--Length of the shell 3.6, breadth 1.8.
_Habitat._--North Pacific, Station 264, depth 3000 fathoms.
----
Order IV. PHÆOCONCHIA, Haeckel, 1879.
_Definition._--PHÆODARIA with a bivalved lattice-shell, composed of two
free opposite valves (a dorsal and a ventral), between which the central
capsule is enclosed.
Family LXXXIII. #CONCHARIDA#, Haeckel, 1879 (Pls. 123-125).
_Concharida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec.
12, p. 6.
_Definition._--PHÆODARIA with a bivalved lattice-shell, which is spherical
or lenticular, and composed of two equal or unequal boat-shaped valves, a
dorsal and a ventral. The valves bear neither an apical latticed cupola or
galea, nor hollow radial tubes. The central capsule is placed in the aboral
half of the shell-cavity, and so enclosed between both valves, that its
three openings lie in the open frontal fissure between them (the astropyle
on the oral pole of the main axis, the two parapylæ on both sides of its
aboral pole, at right and left).
{1711}The family #Concharida# and the two following closely allied
families, the Coelodendrida and Coelographida, compose together the most
remarkable and interesting suborder of #Phæoconchia# (or "PHÆODARIA
bivalva"), differing from all the other Radiolaria in the possession of a
bivalved lattice-shell, composed of two separate valves, like the shell of
a Brachiopod. The central capsule is so enclosed between the two
fenestrated valves that its three openings lie in the horizontal open
(frontal) fissure between them, the astropyle or main-opening on the oral
pole of the main axis; the two secondary openings or parapylæ on the two
sides of its aboral pole, at right and left. The plane in which the three
openings lie is therefore the frontal plane, dividing the entire body into
a dorsal and a ventral half. The two valves, accordingly, must be
considered as dorsal and ventral valves (as in the Brachiopoda), and the
symmetrical halves of each valve as right and left. These halves may be
always easily distinguished, since the oral pole of each valve is
constantly different from the aboral pole. The voluminous phæodium always
lies in the oral half, and the central capsule in the aboral half of the
shell-cavity, whilst the calymma encloses the whole shell.
The Concharida differ from the other two families of bivalved PHÆODARIA in
the absence of the apical galeas, and the branched hollow tubes arising
from them. Each of these two cupolas, which are at the opposite poles of
the sagittal axis (one cupola on the apex of each valve), is in the
Coelographida connected by a simple or double frenulum with a peculiar
rhinocanna, or an open nasal tube directed towards the mouth; whilst the
cupolas of the Coelodendrida possess neither a rhinocanna nor a frenulum.
The three families of #Phæoconchia# may therefore represent a
phylogenetical series, the common root of which are the Concharida. From
these are developed the Coelodendrida by development of an apical cupola or
galea on each valve, and of hollow radial tubes arising from it; whilst the
Coelographida are developed from the latter by production of a rhinocanna
on the base of each cupola, and of one or two frenula connecting the former
with the latter.
All the Concharida described in the following pages (seven genera and
thirty species), are perfectly new to science, and not a single form of
this interesting family was known before the explorations of the
Challenger. Some species (mainly of the genera _Conchidium_ and
_Conchopsis_) are by no means rare, and are found in great numbers at some
stations of the tropical seas (in the Pacific as well as in the Atlantic).
All described species are closely allied, agree in the majority of
characters, and are easy to distinguish from all the other Radiolaria. Some
few forms of Concharida, however, form a direct passage to the
Coelodendrida.
Regarding the probable origin of the Concharida (and therefore also of all
other #Phæoconchia# derived from the latter), two different hypotheses are
possible. They have either been derived directly from the skeletonless
_Phæodina_, by development of a bivalved lattice-shell; or they may be
derived from PHÆODARIA with a simple {1712}spherical lattice-shell
(Castanellida), by the halving of this latter, or its splitting into two
hemispherical valves; the former hypothesis is more probable than the
latter.
The two valves of the lattice-shell (Pls. 123-126) must in the Concharida
(as in all other #Phæoconchia#) be distinguished as dorsal and ventral, and
may therefore be compared with the two valves of the Brachiopoda, not with
those of the Lamellibranchia. This important morphological distinction is
expressed by the constant position of the central capsule within the
shell-cavity. The capsule always exhibits the character of the "TRIPYLEA"
and has three tubular openings, placed in the frontal or lateral plane of
the unicellular body. In the same plane lies the open frontal fissure
between the two valves, and the three openings are so disposed in it that
the large anterior main-opening (or the astropyle) is placed on the oral
pole of the main axis, whilst the two accessory small lateral openings or
parapylæ are placed on both sides of the aboral pole, at the right and
left. Therefore in a dorsal or ventral view all three openings are visible
(Pl. 123, figs. 1, 8_a_); in the usual lateral view, however, from the
right or left side, only two openings are visible, the astropyle on the
anterior, and one parapyle (right or left) near the posterior pole of the
main axis (Pl. 123, figs. 8, 9; Pl. 124, figs. 6, 10). The posterior view
(from the aboral pole) shows the two parapylæ, at right and left; in the
anterior view (from the oral pole) the astropyle may be visible, but
usually it is completely hidden in the dark voluminous phæodium. This
latter envelops sometimes nearly the whole capsule as an opaque
conglomeration of green or brown phæodella (Pl. 123, figs. 8, 9); but
usually the phæodium fills up the anterior (oral) half of the shell-cavity,
whilst the capsule occupies the posterior (aboral) half (Pl. 124, figs. 6,
10).
The dorsal shell-valve is in almost all PHÆODARIA smaller or somewhat
different in shape from the ventral valve, and this difference is often
very striking (Pl. 124, figs. 3-16); but in a few species both valves are
so similar, that I could not discover any certain difference. This equality
of the two valves occurs mainly in those Concharida which pass over into
the Coelodendrida; in these latter as well as in the Coelographida, both
valves are usually equal in size and form. Whilst the main axis (or the
longitudinal axis of the body) in the two latter families of #Phæoconchia#
seems to be normally vertical (in the living and freely floating body), in
the living Concharida it is probably horizontal, so that the larger and
heavier ventral valve lies below the smaller and lighter dorsal valve.
The geometrical fundamental form of the body is therefore in the Concharida
dipleural or bilaterally symmetrical, and we distinguish in it the same
three dimensive axes, as in all other dipleural forms. On the anterior or
oral pole of the main axis (or longitudinal axis) lies the mouth of the
shell, and behind it the phæodium; on the opposite posterior or aboral pole
lies the hinge of the shell (comparable to the shell-hinge of the
Brachiopoda) and in front of it the central capsule. The sagittal (or
{1713}dorso-ventral) axis, determining the height of the shell, has on its
dorsal (or upper) pole the apex or highest point of the dorsal valve, on
its ventral (or lower) pole the apex or lowest point of the ventral valve.
The two poles of the frontal (lateral or transverse) axis are equal and are
determined by the two parapylæ of the capsule, and the corresponding points
of the shell-fissure between both valves. Usually the main-axis is the
longest, the frontal axis the shortest, and between both the sagittal axis.
In regard to the three dimensive planes which are determined by these three
axes, perpendicular to one another, they are rarely of nearly equal size
(as in some subspherical species), usually the sagittal plane (separating
the right and left halves of the body) is the largest; the cinctural or
equatorial plane (separating oral and aboral halves) is the smallest, and
the frontal or lateral plane (separating dorsal and ventral halves) is
intermediate in size. The relation of the three perimeters of these three
planes corresponds to that proportion; the sagittal perimeter (in which the
keel of the compressed valves lies) is the largest; the cinctural or
equatorial perimeter (separating the anterior phæodium and the posterior
central capsule) is the smallest, and the frontal or lateral perimeter (in
which the fissure between the valves lies) is intermediate in size.
The general form of the single valves is very varied in the different
species, in the majority boat-shaped or hat-shaped, more or less laterally
compressed, in a few forms hemispherical. In _Conchopsis_ (Pl. 125) and
_Conchoceras_ (Pl. 124, figs. 15, 16) the lateral parts of the valves
(right and left) are vaulted, whilst their median parts are so strongly
compressed that they form a sharp sagittal keel, and then the shell in the
dorsal or ventral view appears spindle-shaped (Pl. 123, fig. 8_a_; Pl. 125,
fig. 8). Often the frontal margins of the valves are somewhat constricted
(Pl. 124, fig. 7).
The junction between the two valves of the shell is always loose, but not
so loose as in the two following families. In the Coelodendrida and
Coelographida the two valves are either perfectly free and separated by a
frontal zone of jelly, or in very loose contact on the frontal margins. In
the Concharida, however, the margins of both valves seem to be usually in
contact, and their connection is effected in a double way. In the subfamily
Conchasmida (comprising the genera _Concharium_ and _Conchasma_, Pl. 123,
figs. 1-6) the lateral margins of both valves are smooth, not dentated, and
fit one into another like the two parts of a box, or like the two valves of
a Diatom (_Navicula_). In the second subfamily, however, Conchopsida
(comprising the five other genera, Pls. 124, 125), the lateral margins of
the valves are dentate, usually provided with a series of numerous strong
conical teeth, and the teeth of both valves so catch into one another, that
their union is rather firm (like the margin of the shells of _Tridacna_,
_Pecten_, and other Lamellibranchiata). Besides, a more solid junction is
often effected on the posterior or aboral part of the margins, which we
shall call the hinge. Here often peculiar strong teeth catch one into
another, and in the majority of species {1714}two aboral spines are
developed, the caudal horns (a dorsal and a ventral); these are very large
in _Conchoceras_ (Pl. 124, figs. 15, 16). But a peculiar and most
interesting kind of junction is effected in some Concharida by a true
ligament between the valves (Pl. 123, figs. 8, 9; Pl. 125, fig. 2). This
ligament is always placed on the aboral hinge, is of dark brown colour, and
is not dissolved by mineral acids unless long applied. It may preserve the
connection of the posterior parts of both valves, when their anterior parts
are removed one from another, just as in the Brachiopoda. I observed this
interesting ligament mainly in the genus _Conchopsis_, but not in all
species, and it is not yet certain whether it is a constant organ in these
and some other Concharida.
In the majority of Concharida the lateral margins of the two valves project
slightly inwards into the cavity, and in some species of _Conchopsis_ these
inner borders are so broadened that they form a broad, horizontal,
fenestrated inner shelf, comparable to the deck of a boat or to the velum
of the Hydromedusæ or Craspedotæ (Pl. 125, fig. 9). In this case the velum
surrounds the ovate aperture through which the two lobes of the central
capsule (dorsal and ventral) enter into the cavity of both valves.
The mouth of the shell lies on the oral pole of the main axis, and is
therefore opposed to the aboral hinge. The two valves are here usually more
or less emarginate, so as to form a transverse mouth with an upper and a
lower lip (Pl. 124, figs. 6, 7, 11). The form of these two lips is often
very different and characteristic of particular species (Pl. 124, figs. 3,
15, 16). The mouth remains in many species constantly open, even when the
frontal fissure is closed (figs. 7, 16). Since the centre of the shell
mouth lies in the prolongation of the proboscis arising from the operculum
of the central capsule, probably the main stream of sarcode, issuing from
the latter, becomes protruded by the former.
Apophyses of the shell (besides the teeth of the margins) are completely
wanting in three genera, _Concharium_, _Conchellium_, and _Conchopsis_ (Pl.
123, figs. 1-4, 7; Pl. 125). The four other genera possess free apophyses
or spines, which we call horns. They are probably important as the
beginnings of those large hollow tubes which are characteristic of the two
following families, Coelodendrida and Coelographida. We distinguish two
different forms of horns, apical horns on the poles of the sagittal axis,
and caudal horns on the aboral pole of the main axis; the former probably
correspond to the sagittal tubes and the latter to the caudal tubes of the
two following families. Apical horns are found in a single genus only,
_Conchonia_ (Pl. 124, figs. 10-14). Here either on one pole or on poles of
the sagittal axis a horn is developed, usually curved backwards. Sometimes
the base of this conical horn is inflated and fenestrated, and may
represent the beginning of the formation of the galea or apical cupola of
the Coelodendrida.
The two caudal horns are opposite on the aboral hinge of the shell, one
arising from the posterior end of each valve. Usually they are short and
thick, pyramidal, the {1715}ventral horn larger than the dorsal (Pl. 124,
figs. 3, 6). Rarely the two caudal horns are fenestrated at the base and
reach a considerable size, as in _Conchoceras_ (Pl. 124, figs. 15, 16).
The walls of the bivalved shell usually exhibit in the Concharida a rather
solid shape and regular structure, with an elegant network of regularly
arranged pores. But in some species the walls of the shell become very thin
and fragile, and assume the same shape (with very irregular network), as in
the Coelodendrida and Coelographida. The pores are usually small and
numerous, circular, often hexagonally framed (Pl. 125, figs. 4-6). They
pierce the thick shell-wall either in a radial or in an oblique direction.
Sometimes each pore is armed with six radial teeth (Pl. 123, fig. 7_a_). At
other times each pore represents an oblique ampullaceous canal, dilated in
its middle part, with two narrow openings (Pl. 125, figs. 5_a_, _b_, _c_,
6). The pores are so arranged in the majority of species that they form
regular curved series, which are separated by prominent crests, and
converge towards the poles of the main axis. Usually the marginal pores
(along the frontal margin of the valves) are much smaller (compare Pls.
123-125).
The _central capsule_ of the Concharida, very well preserved in numerous
specimens of the Challenger collection, constantly possesses the same
situation and structure. It is always enclosed in the aboral or posterior
half of the shell-cavity, whilst the oral or anterior half is filled up by
the phæodium. The free spaces between both and between the inner surface of
the shell are completely filled up by the jelly of the calymma, which also
covers the whole shell as a thin outer jelly-envelope. The form of the
central capsule is sometimes nearly spherical, usually somewhat compressed
in the direction of the main axis, and sometimes also in the direction of
the frontal axis (Pl. 123, figs. 1-9). In some species it becomes bilobed,
with an upper dorsal and a lower ventral lobe, and in some others it
becomes triangular (Pl. 125, fig. 7). Its two membranes (inner and outer)
are often separated by a broad colourless interval, containing a clear
fluid or jelly (Pl. 123, figs. 8, 9). The nucleus is usually about half as
large as the central capsule and ellipsoidal, its longer axis lying in the
sagittal diameter of the body. Several specimens (of different genera)
contained two separate nuclei, one placed in the dorsal, the other in the
ventral half of the capsule (Pl. 124, fig. 6). This duplication of the
nucleus is probably the preparation for the division of the capsule. The
division will be probably effected in the frontal plane, so that each half
of the bisected capsule gets one nucleus and one valve, and the other valve
becomes newly formed (in a way similar to that in the bivalved Diatomaceæ).
The astropyle, or the main-opening of the capsule, is closed by a radiate
operculum, from which arises a tubular proboscis; this lies in the main
axis of the body, is directed towards the anterior mouth of the shell, and
surrounded by the phæodium. The two shorter tubes of the paired parapylæ,
or the accessory lateral openings, lie on the posterior or caudal side of
{1716}the capsule, at right and left, and are directed half backwards, half
outwards (towards the frontal fissure between the valves, Pl. 123, figs. 1,
8_a_).
The phæodium exhibits in all Concharida the same characteristic shape, and
represents a dark conglomeration of phæodellæ, filling up the anterior or
oral half of the shell-cavity. Usually it is bilobed, divided into a dorsal
and a ventral lobe or wing, which fills up the corresponding valve of the
shell (Pl. 123, figs. 8, 9). The phæodium is commonly more voluminous than
the capsule, and surrounds its anterior half, more rarely it encloses
nearly the entire capsule (Pl. 124, figs. 6, 10). Its colour is usually
olive, sometimes more greenish, at other times more brownish, in some
species nearly black. The phæodellæ, or the roundish granules which compose
the phæodium, exhibit the same shape as in all other PHÆODARIA (compare
above, p. 1535). Sometimes peculiar rather oblong nucleated cells are
scattered in great numbers between the phæodellæ, probably parasites or
symbiontes (Pl. 123, figs. 7-9, 9_a_).
_Synopsis of the Genera of Concharida._
-------------------------------------------------------------------------
I. Subfamily Conchasmida.
Lateral edges of the two valves smooth, without teeth.
-------------------------------------------------------------------------
{ Aboral hinge without
Valves without sagittal { horns, 720. _Concharium_.
keel, nearly hemispherical {
or slightly compressed. { Aboral hinge with two
{ horns (one on each
{ valve), 721. _Conchasma_.
-------------------------------------------------------------------------
II. Subfamily Conchopsida.
Lateral edges of the two valves dentate, with a series of prominent
teeth on both sides. The teeth of both valves catch one into another.
-------------------------------------------------------------------------
{ Aboral hinge without
{ horns, 722. _Conchellium_.
{
Valves without sagittal { Aboral hinge with two
keel, nearly hemispherical { horns. No apical horn, 723. _Conchidium_.
or slightly compressed. {
{ Aboral hinge with two
{ horns. Apex also with
{ a horn, 724. _Conchonia_.
{ Aboral hinge without
Valves with a sharp { horns, 725. _Conchopsis_.
sagittal keel, strongly {
compressed on both sides, { Aboral hinge with two
boat-shaped. { horns (one on each
{ valve). 726. _Conchoceras_.
Subfamily 1. CONCHASMIDA, Haeckel.
_Definition._--#Concharida# with the lateral margins of the two valves
smooth, without interlocking teeth.
Genus 720. _Concharium_,[336] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 6.
_Definition._--#Concharida# with the lateral margins of the valves smooth,
without sagittal keel and without horns on the hinge.
{1717}The genus _Concharium_ is the simplest and the most primitive form of
all Concharida; it may be regarded as the common ancestral form of the
whole family. The entire shell is usually almost spherical, without horns
or teeth, and may be regarded as a _Castanella_ which is bisected or broken
into two equal hemispherical halves. The lateral margins of the two
hemispherical valves are smooth, without teeth, and catch one into the
other like the two valves of a Diatom, or the two halves of a bivalved box.
_Concharium_ agrees in this simple shape of the frontal margins with the
following genus _Conchasma_, and represents with it the small subfamily
Conchasmida.
1. _Concharium bivalvum_, n. sp. (Pl. 123, figs. 2, 2_a_).
Shell spherical, smooth. Diameter in all directions nearly the same.
Borders of the two hemispherical valves circular, smooth, about twice as
broad as the pores. In the half frontal perimeter of the shell (along the
right and the left border of each valve) twenty-two to twenty-four pores,
in the half sagittal perimeter (in the middle line of each valve) eighteen
to twenty-two pores, in the half equator (in the cinctural perimeter of
each valve) twenty to twenty-two pores. All pores circular, of the same
size, twice as broad as their bars.
_Dimensions._--Length of the shell (longitudinal diameter) 0.35, height
(sagittal diameter) 0.34, breadth (lateral diameter) 0.33.
_Habitat._--North Atlantic, west of Madeira, Station 354, depth 1675
fathoms.
2. _Concharium nucula_, n. sp. (Pl. 123, fig. 3).
Shell pear-shaped, with costate surface. Oral face somewhat truncated,
broader than the aboral face. Its longitudinal diameter about one-fifth
longer than the two other diameters. Borders of the two valves ovate,
smooth, about as broad as the pores. In the half frontal perimeter of the
shell twenty-two to twenty-four pores, in the half sagittal perimeter
eighteen to twenty, in the half equator sixteen to eighteen. Pores
irregularly roundish, three to four times as broad as the bars. The pores
are so disposed in meridional rows that the crests between the rows
converge towards the two poles of the sagittal axis.
_Dimensions._--Length of the shell 0.2, height 0.18, breadth 0.16.
_Habitat._--South Atlantic (west of Tristan da Cunha), Station 332, depth
2200 fathoms.
3. _Concharium diatomeum_, n. sp. (Pl. 123, fig. 1).
Shell nearly spherical, slightly lenticular, somewhat compressed in
dorso-ventral direction; the sagittal diameter therefore somewhat shorter
than the two others. Borders of the two hemispherical valves nearly
circular, quite smooth, about as broad as the length of the largest pores.
In the half frontal perimeter of the shell forty-four to fifty pores; in
the half sagittal perimeter twenty to twenty-four; in the half equator
thirty to thirty-three. Pores different in form and size; the
{1718}marginal pores small, nearly circular; the dorsal and ventral pores
oblongish-hexagonal, twice as long as broad, about four to six times as
long as the bars, regularly arranged in transverse rows.
_Dimensions._--Length of the shell 0.22, height 0.21, breadth 0.2.
_Habitat._--Tropical Atlantic, near Sierra Leone, Station 348, depth 2450
fathoms.
4. _Concharium bacillarium_, n. sp. (Pl. 123, fig. 4).
Shell walnut-shaped, with panelled surface; oral and aboral face of the
same form. Its longitudinal diameter about one-fifth longer than the two
other diameters. Borders of the two cup-shaped valves elliptical, smooth,
with a prominent edge, about as broad as the larger pores. In the half
frontal perimeter of the shell fifty to fifty-five pores, in the half
sagittal perimeter thirty-six to forty, in the half equator also thirty to
forty. Pores hexagonally framed. The pores are tapering in size from the
sagittal plane towards the valve-margins, and so regularly arranged in
meridional rows that the crests between the latter converge towards both
poles of the longitudinal axis.
_Dimensions._--Length of the shell 0.2, height 0.15, breadth 0.15.
_Habitat._--Tropical Atlantic, off St. Helena, Station 340, depth 1500
fathoms.
5. _Concharium fragilissimum_, n. sp.
Shell subspherical, very thin-walled and fragile. Diameter in all
directions nearly the same. Oral and aboral face scarcely different.
Margins of the hemispherical valves extremely thin and hyaline. Pores
irregularly roundish, of very different sizes and unequal forms. The
fragile shell of this species differs in general shape from that of all
other Concharida, and is like that of the Coelodendrida (Pl. 121, fig. 3),
but exhibits neither an apical cupola or galea, nor radial tubes arising
from it. It may be perhaps a young specimen of _Coelodendrum_.
_Dimensions._--Diameter of the shell 0.22, of the pores 0.002 to 0.02.
_Habitat._--Mediterranean, Portofino (Haeckel), surface.
Genus 721. _Conchasma_,[337] n. gen.
_Definition._--#Concharida# with the lateral margins of the valves smooth,
without sagittal keel, but with two caudal horns on the hinge (a dorsal and
a ventral).
The genus _Conchasma_ is closely allied to the preceding _Concharium_, and
has the same hemispherical valves with smooth margins, without teeth; but
it differs from the latter in the development of two caudal horns or
posterior spines on the aboral hinge, one horn on the aboral end of each
valve. The three species of this genus were all found in great depths of
the Antarctic Ocean, in Diatom ooze, between 1260 and 1975 fathoms, at
Stations 152 to 157.
{1719}1. _Conchasma radiolites_, n. sp. (Pl. 123, fig. 5).
Shell nearly spherical, somewhat compressed on both sides; the dorsal valve
smaller, flatter and shorter than the ventral valve. In the half sagittal
perimeter of the shell twenty to twenty-two pores, in the half frontal
perimeter twelve to fourteen, in the half equator eighteen to twenty. All
pores nearly of the same size, circular, hexagonally framed, scarcely as
broad as the bars. The two horns of the hinge are four-sided pyramidal, of
different sizes; the ventral horn (of the larger valve) two to three times
as long as the dorsal horn (of the smaller valve); the latter twice as long
as a pore.
_Dimensions._--Length of the shell 0.16, height 0.15, breadth 0.14.
_Habitat._--Antarctic Ocean, Station 154, depth 1800 fathoms.
2. _Conchasma sphærulites_, n. sp. (Pl. 123, fig. 6).
Shell nearly spherical, somewhat compressed on both sides, the frontal
diameter therefore somewhat shorter than the two others. Both valves nearly
of the same size, hemispherical, their borders smooth, twice as broad as
the largest pores. In the half sagittal perimeter of the shell twenty-eight
to thirty pores, in the half frontal perimeter twenty to twenty-two, in the
half equator twenty-four to twenty-six. Size of the pores increasing from
the borders towards the top of the valves. One series of very small pores
along the frontal free margin of each valve. Pores roundish-polygonal,
three to four times as broad as the bars. The two horns of the hinge are of
equal size, four-sided pyramidal, and twice as long as the larger pores.
_Dimensions._--Length of the shell 0.18, height 0.18, breadth 0.16.
_Habitat._--Antarctic Ocean, Station 152, depth 1260 fathoms.
3. _Conchasma hippurites_, n. sp.
Shell nearly spherical, scarcely compressed. The frontal diameter equal to
the two others. Both valves equal. In the half sagittal perimeter of the
shell thirty-two to thirty-four pores, in the half frontal perimeter
twenty-four to twenty-six, in the half equator twenty-six to twenty-eight.
All pores of nearly equal size, circular, polygonally framed, twice as
broad as the bars. The two horns of the hinge are large, three-sided
pyramidal, the ventral horn twice as long as the dorsal, and four to six
times as long as one pore.
_Dimensions._--Length of the shell 0.22, height 0.21, breadth 0.2.
_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.
Subfamily 2. CONCHOPSIDA, Haeckel.
_Definition._--#Concharida# with the lateral margins of the two valves
dentate, the teeth of both catch one into another.
{1720}Genus 722. _Conchellium_,[338] n. gen.
_Definition._--#Concharida# with the lateral margins of the valves dentate,
without sagittal keel and without horns on the hinge.
The genus _Conchellium_ and the four following genera represent together
the subfamily Conchopsida, differing from the Conchasmida in the dentate
lateral margins of the two valves. These are armed with a series of strong,
conical teeth, and catch one into another just as the two valves of many
Lamellibranchiata and Brachiopoda do (Pl. 124, figs. 1-16). _Conchellium_
is the simplest form among the Conchopsida, since the valves are
hemispherical, and possess neither a sagittal keel nor projecting horns.
1. _Conchellium tridacna_, n. sp. (Pl. 123, figs. 7, 7_a_).
Shell nearly spherical, finely tuberculated, the sagittal diameter somewhat
longer than the two others. Borders of the two hemispherical valves smooth
in 0.2 of the oral, and 0.1 at the aboral part, dentated in the remaining
0.7 part; on one side of each valve fourteen to sixteen very strong and
long teeth, all nearly of the same size, about one-fourth as long as the
shell-radius. In the half frontal perimeter of the shell (on one border of
each valve) twenty-five to thirty pores, in the half sagittal perimeter
thirty-five to forty, in the equator twenty-five to thirty. Pores circular,
hexagonally framed, of equal size (except some smaller rows along the
fissure), twice as broad as the bars. On the conical inside of each
funnel-like pore six small spinules, between every three neighbouring pores
a triangular facette (fig. 7_a_).
_Dimensions._--Length of the shell 0.34 to 0.38, height 0.38 to 0.42,
breadth 0.32 to 0.36.
_Habitat._--North Pacific, Stations 250 to 253, depth 2740 to 3125 fathoms.
2. _Conchellium hippopus_, n. sp.
Shell nearly spherical, in the lateral perimeter (along the girdle-fissure)
somewhat constricted. Borders of the two hemispherical valves semicircular,
smooth in 0.3 of the oral, and 0.2 of the aboral part, dentated only in the
remaining 0.5 middle part; on one side of each valve seven to eight very
strong and long teeth, increasing in size towards the mouth, the longest
(foremost) teeth nearly one-third as long as the shell-radius. In the half
frontal perimeter of the shell (along one border of each valve) twenty-four
to twenty-eight pores, in the half sagittal perimeter thirty-two to
thirty-six, in the half equator twelve to fourteen. Pores circular, twice
to three times as broad as the bars, smaller along the fissure.
_Dimensions._--Length of the shell 0.06, height 0.065, breadth 0.055.
_Habitat._--Central area of the Tropical Pacific, Station 274, depth 2750
fathoms.
{1721}Genus 723. _Conchidium_,[339] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 6.
_Definition._--#Concharida# with the lateral margins of the valves dentate,
without sagittal keel and apical horns, but with two caudal horns on the
hinge (a dorsal and a ventral).
The genus _Conchidium_ is the most common form of all Concharida, and some
of its species occur in great numbers in the tropical zone of the Pacific
and the Atlantic, on the surface as well as at various depths. It differs
from the preceding _Conchellium_, its ancestral form, in the development of
two caudal horns, or two strong pyramidal spines which arise from the
posterior end of the valves; the dorsal horn usually is smaller than the
ventral.
1. _Conchidium terebratula_, n. sp. (Pl. 124, figs. 1, 2).
Shell subspherical, smooth; both valves of nearly equal size and form,
hemispherical. The three dimensive axes of the body are almost equal.
Margins of the valves dentate in nearly the whole periphery; on each side
of one valve eleven or twelve strong conical teeth, all of the same size.
Aboral hinge with two short and stout four-sided pyramidal horns of equal
length. Mouth with two equal short lips. Pores of the shell subregular,
circular, three to four times as broad as the bars, in the dorsal valve
twice as large as in the ventral valve.
_Dimensions._--Diameter of the shell 0.24 to 0.28.
_Habitat._--Central Pacific, Stations 270 to 274, surface, and at various
depths.
2. _Conchidium thecidium_, n. sp. (Pl. 124, fig. 6).
Shell subspherical, slightly compressed on both sides. Dorsal valve
somewhat smaller than the ventral, of similar form. Principal axis of the
shell somewhat longer than the sagittal, and this longer than the frontal
axis. Margins of the valves smooth in the oral quarter, strongly dentate in
the remainder; on each side of one valve eight or nine very large
triangular teeth, half as long as the height of the valve. Aboral hinge
with two unequal, stout, four-sided pyramidal horns; the dorsal horn half
as long at the ventral. Mouth with two unequal lips, the upper shorter than
the lower. Pores of the shell subregular, hexagonal, three to four times as
broad as the bars. The figured specimen, well preserved, contained in the
central capsule two nuclei, one in the dorsal, the other in the ventral
half.
_Dimensions._--Length of the shell 0.28 to 0.33, height 0.27 to 0.3,
breadth 0.22 to 0.24.
_Habitat._--South Pacific, Station 292, depth 1600 fathoms.
{1722}3. _Conchidium rhynchonella_, n. sp. (Pl. 124, fig. 3).
Shell with three different dimensive axes in the proportion = 6 : 5 : 4.
Ventral valve semi-ovate, larger than the humpbacked dorsal valve. Margins
of the valves dentate almost in the whole periphery; on each side of one
valve twelve or thirteen strong conical teeth. Aboral hinge with two very
unequal horns, the dorsal much smaller than the pyramidal ventral. Under
lip of the mouth emarginate, much larger than the acute upper lip. Pores
subregular, circular, twice as broad as the bars.
_Dimensions._--Length of the shell 0.3, height 0.25, breadth 0.2.
_Habitat._--North Pacific, Stations 244 to 253, surface, and at various
depths.
4. _Conchidium dimerella_, n. sp.
Shell laterally compressed, very similar to the preceding, but differing in
the following characters:--Proportion of the three axes = 7 : 5 : 4.
Ventral valve hemispherical, larger than the humpbacked dorsal. Margins of
the valves dentate in the middle half only, whilst the anterior and
posterior quarters are smooth; on each side of one valve six or seven
strong conical teeth. Ventral horn of the aboral hinge very large,
pyramidal, one-third as long as the shell and three times as long as the
dorsal.
_Dimensions._--Length of the shell 0.35, height 0.25, breadth 0.2.
_Habitat._--North Pacific, Station 236, surface.
5. _Conchidium leptæna_, n. sp. (Pl. 124, figs. 4, 5).
Shell laterally compressed, with three different dimensive axes of the
proportions = 4 : 3 : 2. Ventral valve larger than the dorsal, both
semi-ovate. Margins of the valves dentate along the lateral sides; on each
side of one valve nine or ten conical teeth, the middle of which are
smaller. Aboral hinge with two unequal short horns; the dorsal rudimentary.
Under lip of the mouth pointed, much larger than the truncate upper lip.
Pores circular, about twice as broad as the bars.
_Dimensions._--Length of the shell 0.2, height 0.15, breadth 0.1.
_Habitat._--Central Pacific, Stations 271 and 272, surface, and at various
depths.
6. _Conchidium argiope_, n. sp. (Pl. 124, figs. 7-9).
Shell laterally compressed, with three different dimensive axes of the
proportion = 6 : 5 : 3. Both valves nearly equal. Margins of the shell
dentate along the lateral fissure, on each side of one valve thirteen or
fourteen thin conical teeth. Aboral hinge with two equal, short, pyramidal
horns. Mouth with two equal short lips. Pores subregular, circular, twice
as broad as the bars.
_Dimensions._--Length of the shell 0.2, height 0.17, breadth 0.1.
_Habitat._--Tropical Atlantic, Stations 341 to 349, surface, and at various
depths.
{1723}7. _Conchidium magasella_, n. sp.
Shell laterally compressed, with two equal valves, very similar to the
preceding species, but differing in the following characters:--Proportion
of the three axes = 6 : 4 : 3. Margins of the valves with smaller and more
numerous teeth; on each side of one valve sixteen to eighteen short conical
teeth. Pores smaller and more numerous, about as broad as the bars.
_Dimensions._--Length of the shell 0.24, height 0.16, breadth 0.12.
_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.
8. _Conchidium productum_, n. sp.
Shell laterally compressed, prolonged, with two equal valves,
similar to the two preceding species, differing in the following
characters:--Proportion of the three axes = 3 : 2 : 1. Margins of the
valves smooth in the anterior and posterior quarter, dentate in the middle
lateral half; on each side of one valve ten to twelve strong conical teeth.
Horns of the aboral hinge prolonged, conical, half as long as the shell,
the ventral somewhat larger than the dorsal. Pores regular, circular, twice
as broad as the bars.
_Dimensions._--Length of the shell 0.25, height 0.15, breadth 0.08.
_Habitat._--North Atlantic, Station 354, surface.
Genus 724. _Conchonia_,[340] n. gen.
_Definition._--#Concharida# with the lateral margins of the valves dentate,
without sagittal keel, but with an apical horn on the poles of the sagittal
axis, and with two caudal horns on the hinge (a dorsal and a ventral).
The genus _Conchonia_ is closely allied to the preceding _Conchidium_, its
ancestral form, but differs from this and from all other Concharida in the
development of horns on the poles of the sagittal axis. These are probably
of great morphological importance, since they represent the beginnings of
the hollow tubes arising from the poles of the sagittal axis in all
Coelodendrida and Coelographida. In one of the three observed species each
valve possessed an apical or sagittal horn, whilst in the two other species
one valve only was provided with a horn. Since I observed one specimen only
of each species, I cannot say whether this difference is important and of
constant generic value.
1. _Conchonia diodon_, n. sp. (Pl. 124, figs. 10-12).
Shell laterally compressed, with two very unequal valves. Dorsal valve
smaller, hat-shaped, on the apex with a fenestrated protuberance which is
similar to the galea of the Coelodendrida, and bears a short, conical,
backwardly-directed horn. Ventral valve larger, boat-shaped, without apical
{1724}horn. Aboral hinge with two pyramidal, horizontal, caudal horns of
different sizes, the dorsal smaller than the ventral. Lateral margin of
each valve on one side with twelve to fourteen strong conical teeth (fig.
12). Lips of the narrow mouth thickened (fig. 11).
_Dimensions._--Length of the shell 0.3, height 0.27, breadth 0.21.
_Habitat._--Tropical Atlantic, Station 342, depth 1445 fathoms.
2. _Conchonia triodon_, n. sp. (Pl. 124, figs. 13, 14).
Shell laterally compressed, with two very unequal valves. Dorsal valve
(fig. 14) larger, hat-shaped, on the apex with a large pyramidal horn which
is half as long as the shell, curved and directed backwards. Ventral valve
(fig. 13) smaller, boat-shaped, without apical horn. Aboral hinge with two
pyramidal caudal horns of different sizes, the dorsal horn twice as long as
the ventral. Lateral margin of each valve on one side with twelve to
fifteen conical teeth. Perhaps the larger horned valve (fig. 14) may be the
ventral, and the opposite smaller hornless (seen from above in fig. 13) the
dorsal valve.
_Dimensions._--Length of the shell 0.21, height 0.17, breadth 0.12.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
3. _Conchonia tetrodon_, n. sp.
_Conchura tetrodon_, Haeckel, 1882, Manuscript.
Shell subspherical, with two nearly equal hemispherical valves, which are
very thin-walled and similar in structure to those of the Coelodendrida,
with very irregular roundish pores of different shapes and sizes (compare
Pl. 121, fig. 3). Lateral margins of the valves with very numerous and
irregular, thin, bristle-shaped teeth, similar to those of some
Coelographida (compare Pl. 127, fig. 8). Aboral hinge with two equal,
conical, caudal horns, which are straight, parallel, and half as long as
the shell. Two similar straight conical horns are opposed on the poles of
the sagittal axis, and arise from the apex of the two valves. This
remarkable species may perhaps better represent a separate genus,
_Conchura_, forming a direct transition to the ancestral form of the
Coelodendrida, _Coelodoras_; it differs from the latter in the absence of a
galea or hollow conical cupola on the apex of each valve, and in the solid,
not hollow structure of the horns.
_Dimensions._--Diameter of the shell 0.24, length of the two sagittal horns
0.1, of the two caudal horns 0.12.
_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.
Genus 725. _Conchopsis_,[341] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 6.
_Definition._--#Concharida# with dentate lateral margins and a sharp
sagittal keel of the compressed valves, without horns on the hinge.
{1725}The genus _Conchopsis_ and the following _Conchoceras_ differ from
the other Concharida in the strong lateral compression of the shell, so
that each valve is provided in the sagittal plane with a sharp prominent
keel, comparable to the dorsal and the anal fin of fishes. These compressed
shells are in general twice to three times as large as the more roundish
and keelless shells of the five preceding genera. The sculpture of the
fenestrated valves is extremely elegant. _Conchopsis_ possesses at the
aboral hinge not the two prominent caudal horns, which mark the following
genus _Conchoceras_, but in some species a peculiar ligament connects the
aboral ends of both valves.
1. _Conchopsis orbicularis_, n. sp. (Pl. 125, fig. 3).
Shell subcircular, lenticular, strongly compressed on both sides, nearly as
high as long, its sagittal perimeter nearly circular; frontal and cinctural
perimeter spindle-shaped. Borders of the two boat-shaped valves smooth in
0.4 of the oral part, and in 0.1 of the aboral part of their length,
strongly dentated in the remaining 0.5 middle part; about twenty-five
slender, straight teeth on each side of one valve, size of the teeth
increasing from the aboral towards the oral pole. In the half lateral
perimeter of the shell (along the right and the left borders of each valve)
sixty to sixty-five pores, in the half sagittal perimeter (along the keel
of each valve) eighty to eighty-five pores, in the half equator sixty to
sixty-five pores.
_Dimensions._--Length of the shell 0.53, height 0.55, breadth about 0.2.
_Habitat._--South Atlantic, west of Tristan da Cunha, Station 333, depth
2025 fathoms.
2. _Conchopsis compressa_, n. sp. (Pl. 125, figs. 7, 8).
Shell lenticular, strongly compressed on both sides; proportion of its
longitudinal diameter to the sagittal and lateral = 10 : 9 : 3, its
sagittal perimeter elliptical (fig. 7), cinctural and frontal perimeter
spindle-shaped (fig. 8). Borders of the two boat-shaped valves smooth in
0.3 of the oral, and 0.3 in the aboral part, dentated in the remaining 0.4
middle part; about forty to forty-four very slender teeth of equal size on
one lateral edge of each valve. In the half frontal perimeter of the shell
(along the border of the valve) sixty-four to sixty-eight pores, in the
half sagittal perimeter (along one valve-keel) seventy to eighty pores, in
the half equator forty-four to forty-eight pores. Ventral and dorsal pores
linear, three to four times as long as the circular, lateral pores.
_Dimensions._--Length of the shell 0.6 to 0.8, height 0.55 to 0.72, breadth
0.2 to 0.3.
_Habitat._--North Pacific, between 30° and 40° north latitude (between
Japan and San Francisco), in depths from 2000 to 3000 fathoms frequent,
Stations 241 to 252.
3. _Conchopsis carinata_, n. sp. (Pl. 123, fig. 8).
Shell subcircular, lenticular, in the central half slightly compressed,
nearly spherical, in the peripheral half strongly compressed, with a broad,
hyaline, smooth keel on the sagittal plane. Borders of the two valves
smooth in the 0.2 of the oral, and 0.1 of the aboral part, strongly
{1726}dentated in the remaining 0.7 middle part; about fifty slender teeth
of equal size on one lateral edge of each valve. In the half lateral
perimeter of the shell about forty-five to fifty pores, in the half
sagittal perimeter sixty-five to seventy, in the half equator thirty-two to
forty pores. The pores are arranged in parallel curved rows, which are
separated by high denticulate crests. Aboral hinge with a strong ligament.
_Dimensions._--Length of the shell 0.6 to 0.7, height 0.55 to 0.65, breadth
0.35 to 0.45.
_Habitat._--South Atlantic (east of Patagonia), Station 318, depth 2040
fathoms.
4. _Conchopsis lenticula_, n. sp. (Pl. 123, fig. 9).
Shell subcircular, lenticular, strongly compressed on both sides, with a
sharp and broad hyaline keel in the sagittal perimeter. Borders of the two
valves smooth in 0.3 of the oral, and 0.2 of the aboral part, strongly
dentated in the remaining 0.5 middle part; about thirty strong, conical
teeth on the lateral edge of each valve. In the half lateral perimeter of
the shell fifty to fifty-five pores, in the half sagittal seventy to
seventy-five, in the half frontal forty to forty-five pores. The large
central capsule of this species fills up the posterior half of the
shell-cavity, the dark green phæodium the anterior half; the latter
contains numerous peculiar, longish, nucleated cells (fig. 9_a_), parasites
or symbiontes (?). Aboral hinge of the shell with a strong ligament.
_Dimensions._--Length of the shell 0.7, height 0.6, breadth 0.3.
_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750
fathoms.
5. _Conchopsis pilidium_, n. sp. (Pl. 125, fig. 9).
Shell ovate, lenticular, compressed on both sides, with a broad, wing-like
sagittal keel. Proportion of its longitudinal diameter to the sagittal and
lateral = 6 : 5 : 3. Sagittal perimeter elliptical. Borders of the two
hat-like valves smooth in 0.15 of the oral, and 0.2 of the aboral part,
strongly dentated in the remaining 0.65 middle part; about twenty-five to
thirty teeth of nearly equal size on one side of each valve. In the half
lateral perimeter of the shell (along one border of each valve) forty-five
to fifty pores, in the half sagittal perimeter (on the keel of one valve)
seventy to seventy-five pores, in the half equator thirty-six to forty
pores. Each pore is surrounded by a hexagonal frame. The opening of each
valve in this species is bordered and partly closed by a broad, horizontal
diaphragm or velum, like the deck of a boat; it is broadest on the oral
side.
_Dimensions._--Length of the shell 0.78 to 0.8, height 0.66 to 0.7, breadth
0.3 to 0.4.
_Habitat._--South Atlantic, between Buenos Ayres and Tristan da Cunha,
Stations 324 to 334, at depths between 1715 and 2900 fathoms.
6. _Conchopsis aspidium_, n. sp. (Pl. 125, figs. 1, 2).
Shell scutiform, strongly compressed on both sides, in the centre only
lenticular, in the periphery wing-like, keeled. Proportion of the
longitudinal diameter to the sagittal and frontal = 6 : 5 : 2. Sagittal
circumference in the oral half semicircular, in the aboral half pentagonal,
two {1727}acute corners jutting out near the aboral hinge, one corner in
the keel of the dorsal, the outer in the keel of the ventral valve. Borders
of the two boat-shaped valves smooth in 0.3 of the oral part, and in 0.1 of
the aboral part, strongly dentated in the remaining 0.6 middle part; about
thirty-five teeth in one side of each valve, larger on both ends than in
the middle. In the half frontal perimeter of the shell sixty to sixty-five
pores, in the half sagittal perimeter eighty to eighty-five, in the half
equator of the shell forty to fifty pores.
_Dimensions._--Length of the shell 0.55 to 0.65, height 0.5 to 0.55,
breadth 0.2 to 0.22.
_Habitat._--North Pacific, Stations 243 and 244, depth 2800 to 2900
fathoms.
7. _Conchopsis navicula_, n. sp. (Pl. 125, figs. 4-6).
Shell pear-shaped, compressed on both sides, in the sagittal periphery
keeled. Proportion of the longitudinal diameter to the sagittal and lateral
= 4 : 3 : 2. Its sagittal perimeter nearly ovate. Borders of the two
boat-shaped valves smooth in 0.3 of the oral, and 0.15 of the aboral part,
strongly dentated in the remaining 0.55 middle part; teeth conical, of
nearly equal size. In the half frontal perimeter of the shell (along one
border of each valve) forty to forty-five pores, in the half sagittal
fifty-four to fifty-six pores, in the half equator thirty-two to thirty-six
pores. Each pore is surrounded by a hexagonal frame, and pierces the shell
in an oblique direction, dilated in the middle part (figs. 5, 6). Shell
very thick-walled, several longitudinal crests on both sides of the keel of
each valve. Hinge very strong, usually with a broad ligament between the
two unequal aboral lips of the hinge.
_Dimensions._--Length of the shell 0.8, height 0.6, breadth 0.4.
_Habitat._--South Pacific, Station 293, depth 2025 fathoms.
Genus 726. _Conchoceras_,[342] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 6.
_Definition._--#Concharida# with dentate lateral margins and a sharp
sagittal keel of the compressed valves, and with two caudal horns on the
hinge (a dorsal and a ventral).
The genus _Conchoceras_ has the same lenticular keeled and laterally
compressed shell as the preceding ancestral genus _Conchopsis_, but is
distinguished from it by the development of two large caudal horns on the
aboral hinge. It bears therefore the same relation to the latter as
_Conchidium_ does to _Conchellium_.
1. _Conchoceras caudatum_, n. sp. (Pl. 124, fig. 15).
Shell lenticular, slightly compressed; proportion of the longitudinal
diameter to the sagittal and lateral = 6 : 5 : 4; sagittal and cinctural
perimeter ovate, frontal perimeter elliptical. Free {1728}margins of the
two boat-shaped valves dentate nearly in the whole perimeter; in one
lateral border of each valve eleven or twelve very large conical teeth, the
largest of which are nearly half as high as the valve. On the aboral hinge
of the shell two divergent, very large horns, four-sided pyramidal, acute,
straight, at the base perforated by a few large pores. The dorsal horn (of
the smaller valve) is somewhat shorter than the ventral horn (of the larger
valve). The apical distance of both horns is somewhat greater than their
length, and about half the length of the shell. In the half frontal
perimeter (along one border of each valve) thirty-two to thirty-four pores,
in the half sagittal perimeter thirty-four to thirty-eight, in the half
equator thirty to thirty-three. The pores are smaller near the
girdle-fissure, irregularly quadrangular, and arranged in longitudinal
rows, which are separated by meridional crests, and converge towards both
poles of the main axis.
_Dimensions._--Length of the shell (without the horns) 0.24 to 0.26, height
0.20 to 0.22, breadth 0.16 to 0.18; length of the horns 0.1 to 0.13.
_Habitat._--Eastern part of the Tropical Atlantic, near the Equator,
Station 348, depth 2450 fathoms.
2. _Conchoceras cornutum_, n. sp. (Pl. 124, fig. 16).
Shell lenticular, strongly compressed on both sides; proportion of the
longitudinal axis to the sagittal and lateral = 4 : 3 : 2. Sagittal
perimeter ovate, frontal perimeter elliptical, cinctural perimeter
spindle-shaped. Free margins of the two keeled valves in the oral third
smooth, in the remaining part strongly dentate; ten or eleven large teeth
on one lateral border of each valve, the largest about half as high as the
valve. On the aboral hinge of the shell two fenestrated apophyses which
bear two stout, strongly curved horns, like pincers; the dorsal horn (of
the smaller upper valve) is shorter and less curved than the ventral horn
(of the larger lower valve). The lips of the mouth (at left on fig. 16) are
also unequal, the upper lip emarginate. In the half frontal perimeter of
the valve twenty-two to twenty-four pores, in the half sagittal perimeter
twenty-eight to thirty, in the half equator twenty to twenty-two. The pores
are separated by high parallel crests and arranged in longitudinal rows,
which converge towards the aboral hinge.
_Dimensions._--Length of the shell (without the horns) 0.36 to 0.4, height
0.27 to 0.3, breadth 0.2 to 0.22; length of the horns 0.16 to 0.22.
_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.
Family LXXXIV. #COELODENDRIDA#, Haeckel (Pl. 121).
_Coelodendrida_, Haeckel, 1862, Monogr. d. Radiol., p. 360.
_Definition._--PHÆODARIA with a bivalved lattice-shell, composed of two
hemispherical valves, a dorsal and a ventral. A conical cupola or a
pyramidal galea arises from the apical pole of both valves, therefore at
the opposite poles of the sagittal axis. Rhinocanna and frenula wanting.
Three or more hollow radial tubes arise from each valve and are
symmetrically disposed. Sometimes their branches form an outer
{1729}bivalved mantle. The central capsule is so enclosed between the two
inner valves, that its three openings lie in the open frontal fissure
between them.
The family #Coelodendrida# differs from the preceding Concharida (its
probable ancestral group) in the development of a conical galea or
pyramidal cupola on the apical pole of each valve, and of three or more
hollow radial tubes arising from each galea. They do not possess, however,
the peculiar sagittal nasal tube or rhinocanna, which is constantly
developed from the base of each cupola (and connected with its apex by a
frenulum) in the following family, the Coelographida. These latter differ
also from the former in the constant possession of prominent verticillate
styles.
The family Coelodendrida was founded in 1862 in my Monograph (p. 360) and
represented hitherto only by two species of the genus _Coelodendrum_, there
described (p. 361, Taf. xiii. figs. 1-3, and Taf. xxxii. fig. 1). This
first description, however, contained some errors, which were afterwards
(in 1879) corrected by Richard Hertwig; this author also gave the first
accurate description of the central capsule and its three openings. In the
rich collection of the Challenger, the Coelodendrida are represented by
four genera, but only seventeen species, some of which, however, are
cosmopolitan and very common, particularly _Coelodendrum_.
The two valves of the lattice-shell, dorsal and ventral, are either
hemispherical, or somewhat more flatly vaulted or cap-shaped. They are
never connected in the equatorial zone of the body, as I supposed in my
Monograph (1862, _loc. cit._); but they are separated by the
girdle-fissure, a free circular equatorial interval, in which lie the three
openings of the enclosed central capsule. Though the two valves, therefore,
have no direct connection, they are, however, always opposed so accurately,
that their equal free circular edges correspond exactly one to the other,
so that the apex of each valve lies in one pole of the sagittal axis. From
this apex there arises on each valve an irregular conical or three-sided
pyramidal cupola, the galea (Pl. 121, figs. 3, 4, 8). The Coelodendrida
differ in the possession of this galea from the Concharida, and agree with
the Coelographida; but they never exhibit the peculiar rhinocanna or nasal
tube, which arises from each galea in the latter family.
The siliceous lattice-plate of the two valves, and of the galea arising
from them, is very thin and fragile, and its irregular roundish pores are
extremely variable in size, number, and disposition. Sometimes the pores
are so small and so scarce, that the plate appears nearly solid. At other
times the siliceous plate seems to be really solid, and covered by a
network of thin crests, the small dimples between which give to it the
appearance of being fenestrated. Often the pores or the dimples are wanting
in the central part of each valve, while they are very numerous and dense
in the peripheral part. The same may be said of the lattice-plate of the
galea, which is sometimes nearly solid, at other times richly fenestrated.
The Coelodendrida agree in this structure with the following {1730}family,
the Coelographida, and differ from the preceding family, the Concharida, in
which the siliceous wall of the two valves is much thicker, and perforated
by regular circular or roundish pores.
The galea or conical cupola in the apex of the two valves ("der
kegelförmige Aufsatz" of the German authors) has in all Coelodendrida a
triangular base and an irregularly conical or nearly three-sided pyramidal
form. Its cavity is about one-third or one-fourth as large in diameter as
the cavity of the hemispherical valve upon which it rests. The galea is
relatively smaller and more irregularly formed than in the Coelographida,
and differs essentially from that of the latter in the constant absence of
a rhinocanna; there are also wanting, therefore, the characteristic
frenula, which connect the nasal tube with the apex of the galea. The
cavity of the galea probably always communicates with that of the valves by
pores in the separating siliceous plate, and is besides pierced by
irregular pores in its outer wall, very variable in form, size, and number,
but it does not communicate with the cavity of the hollow radial tubes,
from which it is separated by a thin, solid, siliceous plate.
The hollow radial tubes which arise from the galea in the Coelodendrida do
not seem to possess that constant regularity in number, origin, and
disposition, which is found in the following family, and there serves for
distinction of genera. In my first description of the Coelodendrida (1862,
_loc. cit._, p. 362), I pointed out this irregularity, and mentioned that
the number of radial tubes arising from each galea varies from three to
eight; the total number therefore amounts to from six to sixteen, the same
minimum and maximum numbers which we shall encounter also in the radial
styles of the following family. But whilst it is easy to determine the
position and relation of these hollow tubes in the Coelographida, owing to
the constant sagittal position of their rhinocanna, this task is very
difficult in the Coelodendrida, where the rhinocanna is wanting. In the
most frequent cases there arise from each galea three or four tubes, more
rarely five or six, and very rarely seven or eight. The simplest and
probably the original case is the development of three tubes, two of which
are paired (divergent on the right and left), while the third is odd, lying
in the sagittal plane. Perhaps these three primary tubes may be compared to
the three cortinar feet of the NASSELLARIA, so that we may regard the two
paired anterior as pectoral, and the odd posterior as a caudal tube.
Usually the two paired or pectoral tubes arise from two corners of the
triangular base of the galea, whilst the third odd or caudal tube does not
arise from the third corner of the base, but more or less above it, and
often even from the highest point or the apex of the galea. In the majority
of species observed, this odd sagittal tube is forked even at its origin,
so that two divergent tubes (an anterior and a posterior) arise from the
apex of the galea (Pl. 121, figs. 3, 8). More rarely the two paired or
pectoral tubes are also forked at the base, so that three pairs of tubes
arise from each galea, and the total number of tubes amounts to twelve.
Very rarely {1731}four separate tubes or four pairs of tubes arise from
each galea, viz., two from the two anterior corners of the basal triangle,
one from the posterior corner, and one from the apex of the galea. It is
possible that this difference in the origin, furcation, and number of the
hollow radial tubes may be employed for the distinction of genera of
Coelodendrida, in the same manner as it is employed in the next following
family, the Coelographida. But I have not been able, in spite of numerous
and accurate examinations, to demonstrate in the former the same regularity
in number and arrangement of the tubes as in the latter. It seems that
these relations here are very variable, even in one and the same Species,
and not yet fixed.
It is, however, probable, on the other hand, that the primary tubes (all or
partly) are identical to the Coelodendrida and Coelographida. This is most
probably the case with the posterior odd or caudal tube, which seems to be
never wanting, and in both families is developed in the form of a
dichotomous brush (never in the form of a verticillate style). Possibly
also the two paired pectoral tubes are homologous in both families.
The hollow tubes are perfectly simple and unbranched only in one genus,
_Coelodoras_, which is probably the common ancestral form of both families,
and which may have been derived from _Concharium_ by development of a galea
and tubes on the sagittal apex of the valves. All the other Coelodendrida
have branched spines, and the ramification is constantly dichotomous, or
repeatedly forked. There never occur in this family those characteristic
"styles," or verticillate prolonged tubes, which we find in all
Coelographida. Usually the cylindrical tubes are slightly curved and forked
even near their base. The furcation is repeated a variable number of times
in the different species. In the largest species each tube becomes a brush
with more than one hundred terminal bristles.
We divide the Coelodendrida into two subfamilies, according to the
different development of the distal branches of the hollow tubes. In the
Coelodorida all the branches of the tubes remain free and are never
connected by anastomoses, so that the surface of the bivalved skeleton is
protected by the free radial distal branches of the tubes. In the larger
species of _Coelodendrum_ (_e.g._, _Coelodendrum furcatissimum_, Pl. 121,
fig. 1), the numerous branches of the dichotomous tubes form a dense
thicket, similar to that in the Coelotholida.
In the second subfamily, Coelodrymida, the distal branches of the tubes are
connected by numerous anastomoses, and compose either a simple
lattice-plate on the surface of the skeleton (_Coelodrymus_), or a thicker
envelope of spongy framework (_Coelodasea_). The lattice-mantle so produced
is always bivalved, and its two outer hemispherical valves (dorsal and
ventral) correspond exactly to the two inner valves, from which arise the
hollow tubes. The free margins of the two external mantle-valves come
externally into contact in the equatorial plane of the body, in which the
girdle-fissure lies internally between the two central shell-valves. The
free edges {1732}of the two external mantle-valves, opposed to one another
in the circle of the equator, seem usually to catch one into another in the
same way as the corresponding mantle-valves of the Coeloplegmida are
loosely connected (Pl. 128, figs. 1, 7). A true concrescence between the
two valves seems never to take place.
The two subfamilies of Coelodendrida therefore exactly correspond to the
two subfamilies of the following family, the Coelographida. The Coelodorida
and Coelotholida form in a similar way a thicket, by dichotomous
ramification of the hollow tubes, all the branches of which remain free.
The Coelodrymida and Coeloplegmida, on the other hand, form an outer
lattice-mantle by anastomosing branches. The latter two subfamilies, of
course, have been derived correspondingly from the two former, and the
common ancestral form of all four is probably _Coelodoras_, derived from
the Concharida.
Though the two corresponding subfamilies in both groups are very similar,
they are, however, separated by important hereditary characters. All
Coelodendrida (the Coelodorida without a mantle as well as the Coelodrymida
with a mantle) possess no rhinocanna and no frenula on the galea, and they
never develop prominent verticillate styles; the surface of their calymma
is probably always spherical or subspherical. All Coelographida, however
(the Coelotholida without a mantle as well as the Coeloplegmida with a
mantle), possess a rhinocanna and frenula on the galea, and always develop
prominent verticillate styles; the surface of their calymma is probably
always symmetrically polyhedral.
The superficial armature of the skeleton in the Coelodendrida is rather
simple, and by no means so manifold and differentiated as in the more
highly developed Coelographida. The thin terminal branches of the hollow
tubes are in the Coelodorida closed at the distal end, and armed with a
variable number of short teeth (Pl. 121, fig. 2), or with a spinulate
terminal knob, or a corona of recurved hooks (_ibid._, figs. 5-7). In the
Coelodrymida, however, where the distal ends of the branches by
anastomosing form the lattice-mantle, the spherical surface of this latter
is armed with numerous thin spathillæ or radial bristles (often zig-zag or
spinulate), and each bristle usually bears at the distal end a small anchor
with two, three, or four recurved teeth; the outer convex edge of these
teeth is usually smooth, the inner concave edge denticulate. All these
ramules and branches of the tubes (also the thinnest terminal threads) are
hollow, and filled up by jelly.
The _central capsule_ of the Coelodendrida does not lie outside the two
central valves (as I supposed in my first description, in 1862, being
deceived by the dark enveloping phæodium, Monogr. d. Radiol., Taf. xxxii.
fig. 1), but it is enclosed between the two valves, as in the preceding and
the following family. The first accurate description of it was given by
Richard Hertwig in 1879 (_loc. cit._, p. 95, Taf. x. fig. 3). Its constant
position between the two lattice-valves (dorsal and ventral) is such, that
its three openings lie in the frontal plane, in the open fissure between
the valves. The astropyle or the main-opening, with the radiate operculum
and the tubular proboscis arising from it, lies on the anterior (or oral)
{1733}pole of the main axis, whilst the two lateral accessory openings, or
parapylæ, lie on both sides of the posterior (or aboral) pole, to the right
and left. The position of the capsule is therefore the same as in the
preceding Concharida (Pls. 123-125), and the following Coelographida (Pls.
126-128). The large nucleus, enclosed in the central capsule, is usually
half as broad, and contains numerous nucleoli.
The calymma, or the extracapsular jelly-veil, is in the Coelodendrida
usually spherical, very voluminous, and includes the entire skeleton, the
thicket of the Coelodorida as well as the lattice-mantle of the
Coelodrymida. Only the outermost terminal branches of the tubes in the
former, and the radial bristles and spathillæ on the surface of the latter,
remain free and project beyond the surface of the calymma. The phæodium is
usually very large, three to four times as broad as the central capsule,
and envelops it often completely. Usually it envelops only the anterior
half of it, and the proboscis (Pl. 121, figs. 1, 9). Often numerous green,
brown, or blackish phæodellæ are scattered through the whole calymma, and
sometimes accumulate in a superficial layer on its surface. The galea of
both valves is usually also filled up by the phæodium.
_Synopsis of the Genera of Coelodendrida._
-------------------------------------------------------------------------
I. Subfamily Coelodorida.
Hollow tubes, arising from the galea of both valves, simple or
dichotomously branched; the branches always free, not anastomosing.
No outer lattice-mantle.
-------------------------------------------------------------------------
Tubes simple, not branched, 727. _Coelodoras_.
Tubes forked or dichotomously branched, 728. _Coelodendrum_.
-------------------------------------------------------------------------
II. Subfamily Coelodrymida.
Hollow tubes, arising from the galea of both valves, dichotomously
branched; the branches anastomose and form an outer bivalved
lattice-mantle.
-------------------------------------------------------------------------
Lattice-mantle simple; its meshes lying
in a spherical surface, 729. _Coelodrymus_.
Lattice-mantle spongy; its meshes lying
in different planes, 730. _Coelodasea_.
Subfamily I. COELODORIDA, Haeckel.
_Definition._--#Coelodendrida# without an external bivalved lattice-mantle,
with simple or branched hollow tubes, the terminal branches of which are
free, not anastomosing.
Genus 727. _Coelodoras_,[343] n. gen.
_Definition._--#Coelodendrida# without external lattice-mantle, with
simple, not branched, radial tubes, which arise separately from the galea.
{1734}The genus _Coelodoras_ is the simplest form of the Coelodendrida, and
may be regarded as the common ancestral form of this and of the following
family. It differs from all other members of these two families in the
simple shape of the hollow radial tubes which arise from the galea, and are
neither branched nor forked; the galea is very small, a flat triangular
cap. _Coelodoras_ may be derived immediately from _Concharium_ or
_Conchonia_ (p. 1723), by development of the galea and the radial tubes.
1. _Coelodoras hexagraphis_, n. sp.
Three straight, cylindrical, equidistant hollow tubes arise divergent from
the three corners of each galea, and are about as long as the diameter of
the valves, at the distal end armed with a spinulate knob. The odd sagittal
(or caudal tube) is directed backwards, the two paired (or pectoral) tubes,
forwards.
_Dimensions._--Diameter of the valves 0.16, length of the tubes 0.2.
_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.
2. _Coelodoras octographis_, n. sp.
Four hollow cylindrical tubes, slightly curved, arise divergent from each
galea, and are about one and a half times as long as the diameter of the
valves, at the distal end knob-shaped, and armed with four crossed,
recurved teeth. Two anterior (or pectoral) tubes arise from the two frontal
corners of the galea basis, and diverge forwards to right and left. Two
posterior tubes (a sagittal and a caudal) arise from the posterior corner
of each galea, and diverge in the sagittal plane backwards.
_Dimensions._--Diameter of the valves 0.2, length of the tubes 0.3.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
Genus 728. _Coelodendrum_,[344] Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 801.
_Definition._--#Coelodendrida# without external lattice-mantle, with
branched radial tubes, the hollow branches of which are free and never
connected by anastomoses.
The genus _Coelodendrum_ is the first described form not only of the family
Coelodendrida, but of all #Phæoconchia# or bivalved PHÆODARIA; it is also
the most common form of this group, and represented by ten different
species, some of which are cosmopolitan, very common, and widely
distributed. In my first description of _Coelodendrum_ I confounded it
erroneously with some forms of _Coelodasea_ and _Coelographis_, the
separated fragments of which I had found entangled between the branches of
the former. The first figures of _Coelodendrum_ are given in my Monograph,
in 1862, {1735}Taf. xiii. figs. 1-3 (not 4) and Taf. xxxii. fig. 1 (not 2
and 3). _Coelodendrum_ has been derived from _Coelodoras_ by furcation and
repeated dichotomous ramification of the hollow radial tubes which arise
from the galea.
Subgenus 1. _Coelodendridium_, Haeckel.
_Definition._--Ramification of the hollow tubes regularly dichotomous, each
branch being forked again; therefore the two terminal ramules of the last
branches equal.
1. _Coelodendrum ramosissimum_, Haeckel.
_Coelodendrum ramosissimum_, Haeckel, 1862, Monogr. d. Radiol., p. 363,
Taf. xiii. figs. 1-3.
_Coelodendrum ramosissimum_, R. Hertwig, 1879, Organism. d. Radiol., p.
93, Taf. x. figs. 3, 12.
Terminal branches regularly forked, with two equal, smooth, nearly straight
or slightly curved fork-branches, diverging at right angles; their
end-knobs with four crossed (or sometimes five or six) short recurved
teeth.
_Dimensions._--Diameter of the spherical skeleton 1.2 to 1.8, of the two
central valves 0.2 to 0.25.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; many
Stations, surface and at various depths.
2. _Coelodendrum spinosissimum_, n. sp. (Pl. 121, fig. 7).
Terminal branches regularly forked, with two equal, smooth, straight,
fork-branches, diverging at right angles, their end-knobs echinoidal,
subspherical or club-shaped, with numerous short radial thorns.
_Dimensions._--Diameter of the skeleton 2 to 2.2, of the two central valves
0.25 to 0.03.
_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.
3. _Coelodendrum furcatissimum_, n. sp. (Pl. 121, fig. 1-4).
Terminal branches regularly forked, with two equal, smooth, straight, or
slightly curved fork-branches, diverging at acute angles; their end-knobs
very small, with three short, diverging, conical teeth.
_Dimensions._--Diameter of the skeleton 2 to 2.5, of the two central valves
0.3 to 0.4.
_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific; many Stations,
surface, and at various depths.
4. _Coelodendrum bifurcum_, n. sp.
Terminal branches regularly forked, with two equal, smooth, more or less
curved fork-branches, diverging at acute angles; their end-knobs thin, with
two slender, parallel, bristle-shaped teeth.
_Dimensions._--Diameter of the skeleton 0.6 to 0.8, of the two central
valves 0.1 to 0.15.
_Habitat._--North Pacific, Stations 252 to 256, surface.
{1736}5. _Coelodendrum gracillimum_, Haeckel.
_Coelodendrum gracillimum_, Haeckel, 1862, Monogr. d. Radiol., p. 364,
pl. xxxii. fig. 1.
Terminal branches regularly forked, with two equal, spinulate, curved
fork-branches, diverging at obtuse angles and covered with numerous small
thorns; their end-knobs cap-shaped, with a corona of six to eight small
recurved teeth. In one specimen of this species (in 1859) I found entangled
the fragments of _Coelographis gracillima_, figured in Taf. xxxii. figs. 2,
3, _loc. cit._ I supposed at that time, erroneously, that the latter
belonged to full-grown specimens of the former.
_Dimensions._--Diameter of the skeleton 1 to 1.2, of the valves 0.15 to
0.2.
_Habitat._--Mediterranean (Messina), surface.
6. _Coelodendrum lappaceum_, n. sp.
Terminal branches regularly forked, with two equal, spinulate, straight or
slightly curved fork-branches, diverging at acute angles and covered with
small recurved hooks; their end-knobs large, conical, with a prominent apex
and a basal corona of six to eight recurved teeth.
_Dimensions._--Diameter of the skeleton 1.5 to 1.8, of the valves 0.22.
_Habitat._--South Pacific, Stations 285 to 295, depth 1500 to 2600 fathoms.
Subgenus 2. _Coelodendronium_, Haeckel.
_Definition._--Ramification of the hollow tubes more or less irregular,
mainly in the periphery; the terminal ramules of the last branches unequal.
7. _Coelodendrum cervicorne_, n. sp. (Pl. 121, fig. 8).
Terminal branches irregularly ramified, with unequal, smooth, curved
ramules, diverging at obtuse angles, their end-knobs echinoidal, small,
with short, diverging, conical thorns.
_Dimensions._--Diameter of the skeleton 1 to 1.2, of the valves 0.2.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
8. _Coelodendrum digitatum_, n. sp.
Terminal branches irregularly ramified, with unequal, spinulate, straight
ramules, diverging at acute angles; the two last fork-branches digitate,
each with five diverging finger-shaped ramules, lying in a meridian plane;
their end-knobs conical, pointed, with a corona of recurved hooks.
_Dimensions._--Diameter of the skeleton 1.6, of the valves 0.24.
_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.
{1737}9. _Coelodendrum flabellatum_, n. sp. (Pl. 121, fig. 6).
Terminal branches flabellate, irregularly ramified, each of the last two
fork-branches being divided into four or five diverging straight branches
of different lengths; usually the last eight or ten ramules lie in a
meridional plane; their end-knobs cap-shaped, with a corona of recurved
teeth.
_Dimensions._--Diameter of the skeleton 2.0 to 2.5, of the valves 0.25 to
0.3.
_Habitat._--North Pacific, Station 235 to 240, surface.
10. _Coelodendrum serratum_, n. sp. (Pl. 121, fig. 5).
Terminal branches flabellate, irregularly ramified like the preceding
species; it differs from this in the strong compression of the broad,
saw-shaped, terminal branches; the two opposite edges (placed in the
meridional plane of the flabellum) are finely serrated; their end-knobs
with a corona of diverging teeth.
_Dimensions._--Diameter of the skeleton 3.0 to 3.2, of the valves 0.3 to
0.36.
_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.
Subfamily 2. COELODRYMIDA, Haeckel.
_Definition._--#Coelodendrida# with an external bivalved lattice-mantle,
produced by the anastomosing branches of the hollow radial tubes.
Genus 729. _Coelodrymus_,[345] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 6.
_Definition._--#Coelodendrida# with an external bivalved lattice-mantle,
produced by the anastomosing terminal branches of the hollow tubes, which
are connected in a spherical face.
The genus _Coelodrymus_, and the following closely allied genus
_Coelodasea_, represent together the small subfamily Coelodrymida,
differing from the Coelodorida in the possession of an outer bivalved
lattice-mantle. They exhibit therefore the same relation to the latter,
that in the following family the Coeloplegmida bear to the Coelotholida.
The bivalved spherical mantle is composed of a simple lattice-plate in
_Coelodrymus_, of a spongy framework in _Coelodasea_; the anastomosing
branches of the hollow radial tubes become connected in the former in a
spherical face, in the latter in the form of a spongy framework.
{1738}1. _Coelodrymus ancoratus_, n. sp. (Pl. 121, figs. 9, 10).
Network of the mantle loose, with large, irregular, polygonal meshes; the
terminal branches of the forked trees, which communicate at the spherical
surface of the calymma, and compose the mantle, are smooth. Spherical
surface covered with very numerous and thin zigzag radial filaments, which
are about as long as the galea, and bear at the distal end an anchor with
two recurved teeth, denticulate at the concave proximal edge (fig. 10).
_Dimensions._--Diameter of the spherical lattice-mantle 2 to 2.5, of the
valves 0.3 to 0.4.
_Habitat._--South-Eastern Pacific (off Juan Fernandez), Station 300, depth
1375 fathoms.
2. _Coelodrymus lappulatus_, n. sp.
Network of the mantle rather dense, with numerous and small irregular
polygonal meshes; the terminal branches of the forked trees, which compose
the mantle, are spinulate. Spherical surface densely studded with very
numerous spinulate, radial filaments, which are about half as long as the
galea, and bear at the distal end an anchor with four crossed recurved
teeth, denticulate at the concave proximal edge.
_Dimensions._--Diameter of the spherical lattice-mantle 2.5 to 3, of the
valves 0.4 to 0.5.
_Habitat._--South-Western Pacific (east of New Zealand), Station 169, depth
700 fathoms.
3. _Coelodrymus echinatus_, n. sp.
Network of the mantle very dense, with very numerous and small irregular
roundish meshes; the terminal branches of the forked trees, which compose
the mantle, are spiny. Spherical surface studded with very numerous, thin,
radial bristles, which bear no anchor at the distal end.
_Dimensions._--Diameter of the spherical lattice-mantle 1.8, of the valves
0.22.
_Habitat._--South Pacific, Station 289, depth 2550 fathoms.
Genus 730. _Coelodasea_,[346] n. gen.
_Definition._--#Coelodendrida# with an external spongy lattice-mantle,
produced by the anastomosing branches of the hollow tubes, which are
connected in different heights.
The genus _Coelodasea_ differs from the preceding _Coelodrymus_ in the
spongy structure of the outer bivalved mantle. The hollow branches of the
radial tubes of _Coelodendrum_, which anastomose in _Coelodrymus_ only on
the spherical surface of the calymma, and form a simple lattice-sphere,
become connected in _Coelodasea_ in different planes (laterally and
terminally), and therefore form an irregular spongy framework. The latter
exhibits therefore to the former a relation similar to that which
_Spongoplegma_ bears to _Carposphæra_ among the #Sphæroidea#.
{1739}1. _Coelodasea ramosissima_, Haeckel.
_Coelodendrum ramosissimum_ (_partim_), Haeckel, 1862, Monogr. d.
Radiol., p. 363, Taf. xiii. fig. 4.
Spongy framework of the spherical bivalved mantle very dense and thick,
produced by very numerous, irregular anastomoses of the lateral and
terminal branches, which arise from the hollow tubes. The last and thinnest
terminal branches are forked, as seen in the radial section of fig. 4
(_loc. cit._), their ends are closed and armed with some very small
denticles (not open, as figured in fig. 4). In my Monograph I had
confounded this species with _Coelodendrum ramosissimum_, which however,
may possibly be its ancestral form.
_Dimensions._--Diameter of the spongy spherical mantle 2 to 2.5, of the
central valves 0.15.
_Habitat._--Mediterranean (Messina), surface.
2. _Coelodasea spongiosa_, n. sp.
Spongy framework of the bivalved mantle rather loose, not nearly so thick
and dense as in the preceding species. The last and thinnest terminal
branches are prolonged into denticulate, zigzagged, radial filaments, which
bear at their distal end an anchor with two recurved teeth (similar to
_Coelodrymus ancoratus_, Pl. 121, figs. 9, 10).
_Dimensions._--Diameter of the spongy spherical mantle 3 to 3.2, of the
central valves 0.24.
_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.
Family LXXXV. #COELOGRAPHIDA#, n. fam. (Pls. 122, 126-128).
_Definition._--PHÆODARIA with a bivalved lattice-shell, composed of two
hemispherical valves, a dorsal and a ventral. A conical cupola or a
helmet-shaped galea arises on the apical pole of each valve, therefore on
the opposite poles of the sagittal axis. The cavity of the galea
communicates with the sagittal rhinocanna, a peculiar nasal tube, which
rests upon the valve, and is connected with the galea by a simple or double
frenulum; its opening being directed towards the proboscis. Three or more
branched hollow radial tubes arise from each valve, and are symmetrically
disposed. Sometimes their branches form an outer bivalved mantle. The
central capsule is so enclosed between the two inner valves, that its three
openings lie in the open frontal fissure between them.
The family #Coelographida#, the last family of the PHÆODARIA, exhibits the
highest degree of morphological development, not only in this group, but
among all Radiolaria. They attain also the greatest size of all members of
the class, since the diameter of their body is sometimes more than 20 mm.,
and in a few species even more than 30 mm. The complexity of their
structure attains at the same time such a high degree, that they may be
regarded as the most complicated, and (in a morphological sense) as the
most highly developed of all Protozoa. Nevertheless their body always
remains a single cell, {1740}and is closely allied to the preceding
Coelodendrida; they differ from the latter mainly in the development of a
peculiar new organ, the "rhinocanna," or "nasal tube." This is a hollow
tube placed in the sagittal plane, arising from the base of each galea, and
is connected with its apex by a simple or double frenulum. Between the oral
openings of the two opposed rhinocannæ (one dorsal and one ventral) lies
the proboscis of the central capsule.
The first observed species of Coelographida was _Coelographis gracillima_,
some parts of which (but not the entire skeleton) were figured in my
Monograph (1862, Taf. xxxii. figs. 2, 3). But I confounded these with
_Coelodendrum gracillimum_, in the branched hollow trees of which the
fragments of the former were entangled. I detected this error afterwards,
when I had the opportunity of the observing some complete specimens. The
first description of a complete skeleton was given in 1882 by O. Bütschli,
who examined a large specimen of _Coelothamnus davidoffii_, captured by
Davidoff in the Mediterranean (Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 486,
Taf. xxxi.). In the rich collection of the Challenger I was able to
distinguish not less than nine genera and twenty-six species of
Coelographida, but the majority of their large and most fragile skeletons
were more or less injured, or quite broken. It was, therefore, of the
highest importance for the minute study of this difficult group, that Dr.
John Murray, during his expedition to the Færöe Channel (in 1882, in H.M.S.
"Triton"), discovered in the Gulf Stream the beautiful _Coeloplegma
murrayanum_, and brought up home hundreds of well-preserved specimens (Pl.
127). Only by the complete examination of this excellent material it was
possible to answer many difficult questions as to their morphology, and to
correct the errors in my description and in that of Bütschli.
We divide the family Coelographida into two rather different subfamilies,
which may afterwards be separated as two divergent families, the
Coelotholida (Pl. 122) and Coeloplegmida (Pls. 126-128). Both groups may be
easily distinguished at a glance, since the numerous branches, arising from
the hollow radial tubes, remain constantly free and independent in the
former, and represent a spiny thicket, whilst in the latter they constantly
become united, and by anastomosing form a peculiar "mantle," or outer
envelope of delicate network. But besides, there are other and more
important differences between the two groups. The peculiar hollow tube,
arising from the base of the galea on each valve, which is filled with
phæodella, and which we call the rhinocanna, develops in the Coelotholida
on its open mouth two paired lateral frenula (right and left), which
connect it (like two lateral bridges) with the base of two paired hollow
main tubes (the "frontal tubes"). In the Coelospathida, however, the mouth
of the rhinocanna develops a single odd frenulum only (in the sagittal
plane), and is connected by it with the base of an odd, single, hollow main
tube, directed forwards, the "nasal style."
The central bivalve lattice-shell, from which the galea and the tubes
arise, exhibits in {1741}the Coelographida essentially the same form and
structure as in the preceding Coelodendrida. The only (but important)
difference between them is indicated by the constant presence of the
peculiar rhinocanna in the former, whilst this is always absent in the
latter. The two valves of the shell, dorsal and ventral, are either
hemispherical or somewhat flatter, sometimes nearly cap-shaped, and formed
of an extremely delicate and irregularly fenestrated plate of silica, as in
the Coelodendrida. As in the latter, so also in the Coelographida both
valves are of similar form and usually of equal size, but sometimes the
dorsal is a little smaller than the ventral valve. The remarkable
difference which Bütschli describes in his _Coelothamnus davidoffii_, and
the inverse origin of the three tubes in both valves (_loc. cit._, Taf.
xxxi; figs. 2, 4), depends upon an error of observation, produced by the
artificial inversion of one valve, and the dislocation of their natural
arrangement. The valves are never in direct contact, but separated by the
equatorial fissure or girdle-cleft, in which the girdle zone of the
enclosed central capsule and its three openings lie freely (Pl. 127, figs.
4, 5; Pl. 128, fig. 2). The free margins of both valves, which are opposite
to one another, and bound the girdle-cleft, are always equidistant, so that
the cleft in the whole equatorial circumference is of equal breadth. The
margins are usually irregularly denticulate, sometimes armed with longer
bristles (Pl. 127, fig. 8), more rarely smooth (fig. 5). The delicate
lattice-work of the valves is always irregular and very variable, usually
with numerous small and unequal pores, sometimes rudimentary, so that the
valves appear partly solid and hyaline. The size of the valves is usually
between 0.2 and 0.5 (in diameter).
The galea (_g_) or the apical cupola, which arises from the vaulted apex of
each valve (or its sagittal pole) is more developed in the Coelographida
than in the preceding Coelodendrida, and differs from the latter in the
peculiar rhinocanna arising from its base, and in the single or double
frenulum, connecting the open mouth of the rhinocanna with the odd or
paired main tube arising from the galea. The two opposite galeæ lie
therefore on the poles of the sagittal axis of the bivalve shell, and are
so symmetrically disposed in the sagittal plane, that the open mouths of
their rhinocannæ are directed towards the oral pole of the main axis, and
nearly come in contact with the proboscis arising from the radiate
operculum of the central capsule (Pl. 127, figs. 4, 5).
The size and form of the galea are very variable, even in one and the same
species. The volume of its cavity is generally about as great as that of
the hemispherical valve from which it arises, sometimes larger, at other
times smaller. Its fundamental form is constantly dipleuric or bilateral,
since the radial hollow tubes arise symmetrically on both its sides, and
the rhinocanna proceeding from its base determines the sagittal plane.
Usually the galea has the form of a vaulted helmet, the convex crest of
which is inclined towards the mouth (Pl. 127, figs. 4, 5, 8, 9). Its
anterior or apical part is broad and truncated in the Coelotholida, more or
less conical in the Coelospathida; sometimes it assumes nearly the form of
a bilateral three-sided pyramid, at other times it is more
{1742}pear-shaped (Pls. 126-128). The thin siliceous wall of the galea has
the same irregular and delicate network as the valve from which it arises,
and sometimes the small irregular pores are also here reduced, so that the
wall becomes partly solid. In some cases the thin, solid, siliceous plate
of the galea and of the valve is covered by an irregular delicate network
of crests; the dimples between these crests may be easily confounded with
true pores.
The cavity of the galea is filled with phæodella and does not communicate
with the cavity of the shell-valves, nor with the cavity of the radial
tubes filled by jelly; it is closed towards the latter and the former by a
thin solid plate of silex. Bütschli (1882, _loc. cit._, p. 488) describes
in _Coelothamnus_ a large circular opening (Taf. xxxi. figs. 2_a_, 4_a_),
and states that this is a direct communication between the cavities of the
valves and of their galeas which are called by him "der dreiseitige
kastenförmige Aufsatz" ([epsilon]). This error was caused by the fact that
he observed the valves from the apical face only. The apparent opening of
communication does not exist, and is the optical section of the rhinocanna,
the shortened walls of which he describes as "trapezförmige Kiesellamelle"
([gamma]); the two lateral edges of the latter ("die seitlichen Zipfel,"
[delta]) are the paired frenula, which connect the open mouth of the
rhinocanna with the base of the two frontal tubes.
The "rhinocanna or nasal tube" (Pl. 126, figs. 1, 4; Pl. 127, figs. 4-9_t_)
is a very remarkable organ which is common to all Coelographida (without
any exception), and distinguishes them markedly from all the other
Radiolaria, and particularly from the closely allied Coelodendrida in which
we find no trace of it. The rhinocanna is a cylindrical or three-sided
prismatic hollow tube, which lies in the sagittal plane, on the outer
surface of each valve, arises from the base of the galea, and is directed
towards the proboscis of the central capsule. The two opposite rhinocannæ
open on each side of the latter (Pl. 127, figs. 4-9_m_), and usually this
"nasal mouth" or the anterior opening of the nose is somewhat dilated or
even funnel-shaped. The posterior opening of the nose passes directly over
into the base of the cavity of the galea.
Usually the rhinocanna is densely filled up by dark phæodella, which enter
by this channel into the cavity of the galea (Pl. 127, figs. 4, 5, 9).
Sometimes the entire phæodium is enclosed in the two galeæ and their
rhinocannæ (figs. 5, 9), whilst at other times a great part of the phæodium
lies outside of their cavities, and surrounds the proboscis of the mouth,
or even the anterior half of the central capsule (fig. 4). The length of
the cylindrical rhinocanna is usually about equal to that of the galea,
whilst the diameter of the latter is from three to five times as great as
that of the former. The structure of the thin wall is the same in both. The
fine reticulation (fig. 8) is produced either by true, very small and
irregular pores, or by a fine network placed on the solid thin wall. We may
distinguish on each rhinocanna an outer or distal convex face, which is
opposite to the proximal concave face of the galea, and an inner concave or
proximal face, which rests immediately upon the convex outer face of the
shell-valve; a thin solid lamella of {1743}silica here completely separates
the cavities of the valve and of the rhinocanna resting upon it.
The "frenula or nasal suspensoria" (Pl. 127, figs. 4-9_b_) are thin
ligaments of silica, which connect the nasal mouth (_m_) with the base of
the main tubes arising from the galea; they are, therefore, also common to
all Coelographida, and an exclusive and marked attribute of this family.
They are, however, different in the two subfamilies of this group,
corresponding to the different origin of the odd or paired main tubes. In
the Coeloplegmida (Pls. 126-128) from the apex of each galea arises an odd
main style, the nasal style (_g_ 1), and its base is connected with the
nasal mouth by an odd frenulum (_b_). In the Coelotholida however (Pl. 122)
the large nasal odd style is always wanting, and there arise two paired
frontal tubes from the two corners of the truncate frontal face of the
galea; therefore two paired frenula are developed (a right and a left), and
these, converging towards the nasal mouth, connect its distal corner with
the base of the two frontal tubes.
The odd frenulum of each valve of the Coeloplegmida lies therefore in the
sagittal plane, whilst the two paired frenula of the Coelotholida lie on
both sides of it, to the right and left. The frenula seem to be supporting
columellæ or pillars, which support the fragile skeleton, and mainly effect
a fixed prop for the fragile galea. In the Coelotholida the frenula are
often rather broad and irregularly fenestrated lamellæ of silica (Pl. 122,
fig. 2), whilst in the Coeloplegmida they are usually thin ligaments,
fenestrated only at the broadened ends, which are inserted inside on the
distal apex of the nasal mouth, and outside on the base of the nasal main
styles.
The large hollow tubes which arise from the galea of all Coelographida, are
very variable in number, size and shape, but are always richly branched and
symmetrically arranged in the dorsal and the ventral valve of the shell.
They exhibit an important difference in the two subfamilies of the group;
in the Coelotholida all the branches, and also the thin terminal ramules,
are free, without any junction; in the Coeloplegmida, however, they
communicate by frequent anastomoses, and the connected terminal ramules
form on the surface of the calymma an outer lattice-mantle of very delicate
network. Another marked difference between the two families is indicated by
the origin and site of those main tubes which are connected with the
rhinocanna by a frenulum. In the Coeloplegmida an odd, very large main tube
(the nasal style) arises from the anterior apex of each galea and bears on
its base an odd frenulum. This nasal style and its frenulum is altogether
wanting in the Coelotholida, where two paired main tubes (the frontal
tubes) arise from the lateral corners of the truncate anterior side of the
galea, and are connected with the mouth of the rhinocanna by two paired
convergent lateral frenula.