prominent nodal points of which fall into a spherical face. Its diameter is
usually from 2 to 3 mm., rarely more than 3 or less than 1 mm. Its
structure is the same as described for the Aulosphærida, being composed of
hollow cylindrical tubes, which form a loose network and are separated at
its nodal points by astral septa. The meshes of the network are {1639}very
large, usually twice to three times as broad as the inner shell, and
irregularly polygonal; the usual and prevailing form is pentagonal, but
hexagonal meshes are also often intermingled, more rarely meshes with five,
seven, or eight sides.
The cylindrical tangential tubes possess in general the same shape as in
the similar Aulosphærida, have a thin wall, are filled with jelly, and
contain a delicate axial filament in their axis; they differ, however, in a
peculiar constant character; in the middle of each tube is inserted an
inner radial beam coming from the inner shell, so that both together have
the form of a T. The central point of insertion has a somewhat shorter
radial distance from the centre of the body than the two nodal points on
both ends of the tangential tube, so that the latter is somewhat geniculate
(figs. 1-5). The two halves of each tangential tube are usually somewhat
thinner on the central end (where the inner radial beam is inserted),
thicker on the distal end (where the outer radial tube arises); at both
ends they are closed by a thin transverse septum. Often also some other
septa are developed, so that each tangential tube seems to be composed of
four to six joints or segments. Usually the tangential tubes are armed with
spines or anchor threads, similar to those of the inner radial beams. The
length of the single tangential tubes is usually between 0.1 and 0.3, their
diameter from 0.01 to 0.02.
The nodal points of the outer lattice-sphere, in which the outer radial
spines arise, seem to possess the same structure as in the similar
Aulosphærida. Since three tangential tubes are connected to each nodal
point, in its centre is the union of three small astral septa or sutural
partitions. The small nodal cavity on the inside of the nodal point has
probably three small pores, which lead into the three tangential tubes
between the three astral septa. A fourth pore probably leads from the nodal
cavity into the cavity of the hollow radial tube. This structure is
difficult to observe, but seems to be demonstrated by the fact, that in the
complete and carefully purified skeletons which are treated with hot
mineral acids and afterwards dried, all cylinders, the tangential as well
as the radial tubes, become easily filled by air (compare the description
of the similar structure in the Aulosphærida).
The external radial tubes which arise in the nodal points of the outer
shell are either cylindrical or cylindro-conical, straight, and usually
about as long as the diameter of the inner shell. Their structure and
armature is the same as in the similar Aulosphærida. In the axis of each
radial tube runs a delicate axial filament, which is connected with its
thin and fragile wall either by filiform transverse branches or by delicate
transverse septa. The outside of the radial tubes is either smooth (figs.
3-5) or armed with scattered spines (fig. 4) or with verticils of lateral
branches; each verticil is usually composed of three or four branches. The
distal end of the radial tubes is rarely simple, pointed; it is usually
armed with a spathilla of three or four curved terminal branches (figs. 3,
5) sometimes with an elegant corona composed of twenty to thirty thin
radially divergent branches (fig. 4).
{1640}The _central capsule_ of the Cannosphærida is small (of 0.1 to 0.15
in diameter) and hidden in the aboral half of the enclosing inner shell,
whilst the oral half of the latter is filled up by the phæodium (figs. 2,
4). The structure of the capsule and of its three openings seems to be the
same as in the closely allied Aulosphærida. I have, however, not been able
to recognise the two parapylæ or secondary openings, and have only observed
the astropyle or the main-opening with its radiate operculum surrounded by
the phæodium, and directed with its tubular proboscis towards the mouth of
the inner shell. As R. Hertwig also could not recognise the two parapylæ,
it is not impossible that they are wanting, and that the Cannosphærida
possess only one opening, the astropyle, like the Medusettida and
Challengerida. The nucleus, enclosed in the central capsule, is spherical,
half or one-third as broad as the latter, and contains numerous nucleoli.
_Synopsis of the Genera of Cannosphærida._
Internal shell solid, without open pores, 691. _Cannosphæra_.
Internal shell latticed, with open pores, 692. _Coelacantha_.
Genus 691. _Cannosphæra_,[310] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 6.
_Definition._--#Cannosphærida# with a solid, not latticed internal shell.
The genus _Cannosphæra_ comprises those Cannosphærida in which the inner
shell is formed by a thin solid siliceous-plate and exhibits no pores
between the prominent bases of the radial beams.
1. _Cannosphæra atlantica_, n. sp. (Pl. 112, figs. 5, 6).
Internal shell not mammillate, with fifteen to twenty radial rods, which
are loosely studded with single, scattered, simple, lateral spines.
External shell with irregular, mostly hexagonal meshes, armed with numerous
scattered forks of paired divergent spines, and with twenty to thirty
larger simple radial spines, which are about half as long as the internal
rods, and bear at the distal end a verticil of three to five curved,
simple, terminal branches.
_Dimensions._--Diameter of the inner shell 0.1, of the outer 0.5.
_Habitat._--Tropical Atlantic, Stations 347 to 349, depth 2250 to 2450
fathoms.
2. _Cannosphæra antarctica_, n. sp. (Pl. 112, figs. 1-3).
Internal shell mammillate, with sixty to ninety radial rods, which are
studded with cruciate verticils of tridentate anchor-threads. External
shell with irregular, mostly pentagonal meshes, {1641}the bars of which
bear on the outside bunches of similar tridentate anchor-threads. At each
nodal point arises a simple, smooth, radial spine, which bears at the
distal end a verticil of three or four small, curved, terminal branches.
_Dimensions._--Diameter of the inner shell 0.2 to 0.3, of the outer 1.5 to
2.0.
_Habitat._--Antarctic Ocean, Stations 154 to 157, depth 1300 to 1975
fathoms.
3. _Cannosphæra pacifica_, n. sp. (Pl. 112, fig. 4).
Internal shell mammillate, with one hundred to one hundred and twenty
radial rods, which are studded with cruciate verticils of tridentate
anchor-threads. External shell with irregular, mostly hexagonal meshes, the
bars of which bear on the outside and on the inside bunches of similar
tridentate anchor-threads. At each nodal point arises a simple, thorny,
radial spine, which bears at the distal end an elegant verticil of fifteen
to twenty flatly expanded, thin, terminal branches.
_Dimensions._--Diameter of the inner shell 0.25 to 0.35, of the outer 2.0
to 2.5.
_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.
Genus 692. _Coelacantha_,[311] R. Hertwig, 1879, Organism. d. Radiol., p.
91.
_Definition._--#Cannosphærida# with a latticed internal shell.
The genus _Coelacantha_ comprises those Cannosphærida in which the inner
shell is formed by a fenestrated flint-plate, and exhibits numerous pores
between the prominent bases of the radial beams.
1. _Coelacantha anchorata_, R. Hertwig.
_Coelacantha anchorata_, R. Hertwig, 1879, Organism. d. Radiol., p. 92,
Taf. ix. fig. 2.
Internal shell slightly mammillate, with thirty to forty radial rods, which
are densely studded with verticils of tridentate anchor-threads. External
shell with irregular, mostly pentagonal meshes, the bars of which bear the
same verticils, each composed of three thin, tridentate anchor-threads. At
each nodal point arises a slender radial spine, which bears six verticils,
each composed of three to five lateral branches.
_Dimensions._--Diameter of the inner shell 0.5, of the outer 3.0.
_Habitat._--Mediterranean, Messina (R. Hertwig), surface.
2. _Coelacantha mammillata_, n. sp.
Internal shell strongly mammillate, with sixty to eighty radial rods, which
are densely studded with cruciate verticils of quadridentate
anchor-threads. External shell with irregular, mostly {1642}hexagonal
meshes, the bars of which bear the same verticils, each composed of four
thin quadridentate anchor-threads. At each nodal point arises a slender,
smooth, radial spine, which bears at its distal end a verticil of four
large, curved, terminal branches.
_Dimensions._--Diameter of the inner shell 0.4, of the outer 3.2.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
----
Order III. PHÆOGROMIA, Haeckel, 1879.
_Definition._--PHÆODARIA with a simple, not bivalved lattice-shell, which
assumes very different forms, but is always provided with a peculiar mouth
and peristome on the oral pole of the main axis. Central capsule always
excentric, placed in the aboral half of the shell-cavity.
Family LXXVIII. #CHALLENGERIDA#, John Murray (Pl. 99).
_Challengerida_, John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv. p.
471, pl. xxiv. figs. 1, 2.
_Definition._--PHÆODARIA with a monaxonial, usually ovate or lenticular
shell, which exhibits a peculiar, fine, regularly hexagonal, diatomaceous
structure, and is usually provided with teeth on the mouth, but without
articulated feet. Central capsule excentric, placed in the aboral half of
the shell-cavity.
The family #Challengerida# represent a large, peculiar, and interesting
group of PHÆODARIA, which are, for the most part, inhabitants of great
depths, and were perfectly unknown before the discoveries of the
Challenger. The first note on these remarkable Radiolaria was given in 1876
by John Murray, in his Preliminary Reports on Work done on board the
Challenger (Proc. Roy. Soc. Lond., vol. xxiv. pp. 471, 536, pl. xxiv. figs.
1, 2). He described the peculiar exceedingly beautiful tracery of their
shell, similar to that of the Diatomaceæ, the enclosed central capsule
coloured by carmine, and the surrounding mass of black-brown pigment lumps
(the phæodium). "At times these Challengerida come up with a good deal of
sarcode outside of the shell, and two specimens have been seen to throw out
elongated pseudopodia" (_loc. cit._, p. 536). He found also the shells in
the Radiolarian ooze of the deep sea. The number of different forms found
in the collection of the Challenger is so great, that I can describe in the
following pages not less than six genera and fifty-eight species. A part of
these have already been figured by Dr. John Murray in the Narrative of the
Challenger Expedition, vol. i. p. 226, Pl. A, 1885.
In my first preliminary note on the PHÆODARIA, in 1879, I gave a stricter
definition {1643}of the Challengerida (Sitzungsb. med.-nat. Gesellsch.
Jena, Dec. 12, 1879, p. 5). But I united at that time the true
Challengerida with the Tuscarorida, which, however, are sharply separated
by the entirely different structure of their shell. In Plate A given by Dr.
John Murray, and mentioned above, figs. 1-14 represent genuine
Challengerida, with diatomaceous shell-structure, whilst figs. 15-20 are
Tuscarorida, with porcellanous shell-structure. These latter, therefore,
are more closely allied to the Circoporida, whilst the Challengerida
exhibit a closer affinity to the Medusettida and Castanellida. But the two
latter families never possess that peculiar extremely regular and delicate
diatomaceous structure which is exhibited only by the Challengerida.
The general form of the Challengerida is rather simple, usually more or
less ovate, sometimes nearly triangular, at other times subspherical. In
nearly all species, with a few exceptions, the shell is more or less
compressed from the two sides, so that its horizontal transverse section is
not circular, but elliptical or lanceolate. In many species the shell is
more or less lenticular, with a sharp or sometimes keeled margin. This
margin lies in the sagittal plane of the body, whilst the two flat sides
are right and left. The main axis is always perpendicular, and its oral or
anterior pole is marked by the open mouth of the shell; the latter is in
the living organism probably the upper pole, whilst the opposite aboral or
posterior pole (often marked by large spines) is the lower pole. The dorsal
margin of the mouth is usually different from the ventral, and in the
majority of species this difference is so striking, that right and left
sides of the body may be recognised immediately, the fundamental form being
dipleuric or bilaterally-symmetrical. In a few species, however, and mainly
in those simplest forms in which the ovate shell has a circular mouth
without teeth, and a circular transverse section, that difference is not
recognisable, and the ovate shell is monaxonial, as it is in _Gromia_ and
_Lagena_ among the Foraminifera (Pl. 99, figs. 19, 20, 22). The size of the
shell is in the majority of species between 0.2 and 0.5 mm.; there are,
however, some very small species, in which the diameter of the shell is
only 0.05 to 0.08, or even less; and some large species, the diameter of
which attains 0.8 to 0.9 mm.
The peculiar structure of the siliceous shell-wall, which we call shortly
"diatomaceous," and by which the Challengerida differ from all the other
PHÆODARIA, has been already represented very well by Dr. John Murray, in
Pl. A. of the Narrative (vol. i. p. 266, figs. 1_c_-1_e_, 2_a_, 4_a_, 7_a_,
7_b_). This elegant diatomaceous structure is extremely similar or nearly
identical with that well-known regular structure which we find in the
common Diatomaceæ or Bacillariæ. The entire surface of the shell is covered
with a very great number of very small pit-like depressions, perfectly
regular, circular in form, equal in size, and quincuncial in arrangement.
The neighbouring equidistant pits are always surrounded by regular
hexagonal frames of equal size, and the prominent fine crests of these
frames produce the regular hexagonal tracery, which gives to the shell such
a striking similarity to that of the Diatomaceæ. According to {1644}the
different positions to which the focus of the microscope is brought, the
hexagonal tracery exhibits a different appearance; either a regular network
of equal hexagonal frames, or a lattice with equal and equidistant circular
openings, or a combination of three crossed and equidistant systems of
parallel lines (crossed at angles of 120°). All the well-known and often
discussed optical phenomena which are observed in the valves of the
Diatomaceæ, reappear also on the shell of the Challengerida.
To recognise the true nature of this diatomaceous structure, sections and
slides of the shell are required, and also fragments of broken shells, the
broken margins of which are of special value for obtaining further
explanation. The figures given by Dr. J. Murray (_loc. cit._, Pl. A) have
already demonstrated that the pit-like depressions are regular small
cavities in the flinty shell-wall, which possess an inner and an outer
opening. These intraparietal cavities are either spherical (fig. 7_b_) or
cylindrical (fig. 1_d_, 4_a_) or spindle-shaped, with a constriction (fig.
2_a_). Further accurate examinations probably will show a greater variety
in their shape. But each cavity constantly possesses two small openings,
one on the outer, and the other on the inner surface of the shell-wall.
Closer examination (especially of broken shells and slides) proves the
presence of these two openings, which in the smaller species seem to be
absent on the first view. I may, therefore, suppose that also in the
similar valves of the Diatomaceæ, which exhibit exactly the same structure,
an inner and an outer opening are always present in each hexagonal pit, and
that the very small size alone prevents them from being recognised. The
regular hexagonally-framed cavities in the shell-wall of the Challengerida
(probably also of the Diatomaceæ) are therefore genuine pores, differing
from the pores of other Radiolaria only in their smaller size and the
dilatation of the middle part, which is much wider than the two openings.
The mouth of the shell, its single larger opening, exhibits in the various
Challengerida a great variety in form and structure, and offers the best
means for separating genera and species. According to its essential shape
two different subfamilies and six genera may be distinguished in this
family. In the first subfamily, Lithogromida, the mouth is a simple large
opening in the wall of the shell on the oral pole of its main axis (Pl. 99,
figs. 1-15). In the second subfamily, Pharyngellida, the mouth is prolonged
into a cylindrical hollow tube, which is prominent into the shell-cavity,
and comparable to the pharynx of the Metazoa in general form and function
(Pl. 99, figs. 16-20). In this case we may distinguish an inner and an
outer mouth of the tubular pharynx.
In a few forms of both subfamilies the mouth is toothless, smooth, and not
armed with prominent external spines or teeth, as in _Lithogromia_, the
simplest form of all (Pl. 99, fig. 22) and in _Entocannula_ (figs. 19, 20).
In the great majority of Challengerida, however, the outer opening of the
mouth is armed with one or more teeth, usually strong prominent spines
(figs. 1-18). Usually the base of these teeth is {1645}semitubular or a
half cylinder, forming a more or less prominent peristome or a proboscis;
and always in this case the open concave side of the canal-shaped groove is
directed towards the ventral side of the shell, the closed convex side
towards the dorsal side. When several teeth arise from the two lateral free
margins of the groove, they are also directed towards the ventral side
(figs. 2, 12, 17, &c.). Often a deep ventral incision or a guttural
constriction separates the base of the proboscis from the genuine shell.
The structure of this proboscis or peristome is usually the same as in the
diatomaceous shell-wall; but sometimes its lattice-work assumes a different
shape.
The opening of the mouth itself is rarely circular, usually it is
elliptical or even lanceolate, often triangular. Sometimes two prominent
opposite lips may be distinguished as right and left, when the fissure of
the mouth is prolonged in a sagittal or longitudinal direction; as upper
and lower, when it is prolonged in a frontal or transverse direction. The
upper or dorsal lip is always more developed than the lower or ventral; and
the entire semitubular proboscis may be regarded as a production of the
upper lip. Sometimes the latter attains an extraordinary size and
development, the greatest in _Challengeria murrayi_ (Pl. 99, fig. 1).
The teeth of the mouth, which arise from the upper lip, are usually hollow,
at least on the base; a prolongation of the shell-cavity arising into the
base of the teeth. Their form is very variable, conical, lanceolate,
triangular, sabre-shaped, &c. Usually they are more or less curved, and
shorter than the radius of the shell; rarely they are straight, and longer
than the radius (Pl. 99, figs. 5, 6). More important is their different
number, which we have employed for the distinction of subgenera; future
observations may prove that they are different genera. The most important
are the following cases:--(A.) a single odd dorsal tooth (figs. 5, 16);
(B.) two paired lateral teeth (figs. 4, 6, 17); (C.) three teeth, an odd
dorsal and two paired lateral (figs. 7, 9, 10); (D.) four paired teeth, two
dorsal and two ventral (figs. 3, 13); (E.) five teeth, an odd dorsal and
two pairs of lateral (figs. 2, 12); (F.) six teeth in three lateral pairs
(fig. 1).
The teeth of the peristome are not the only apophyses which arise from the
shell of the Challengerida. In the majority other spines appear on the
sagittal margin, which separates the right and left halves of the shell.
These marginal spines are characteristic of the genera _Challengeron_ and
_Porcupinia_; they are usually radially directed, straight, conical,
sometimes solid, at other times hollow. Their number and arrangement is
very variable and serves for the distinction of species; the following
differences are the most important:--(A.) a single odd spine on the apical
pole of the shell, in the principal axis, opposite to the centre of the
mouth (Pl. 99, figs. 6, 7); (B.) two aboral spines, a dorsal and a ventral
(figs. 8-10); (C.) a bunch or a crowded group of radial spines on the
aboral margin of the shell, usually one larger apical spine surrounded by
several smaller dorsal and ventral (figs. 11, 12, 16); (D.) numerous radial
spines along the whole sagittal margin of the shell (figs. 13-15).
{1646}The _central capsule_ of the Challengerida is constantly placed in
the aboral half of the shell-cavity, whilst its oral half is occupied by
the phæodium; the intervals between them and the inner surface of the shell
are filled up by the calymma. Frequently from the outer surface of the
capsule arise numerous branched streams of sarcode, which pierce the
calymma and are directed towards the inside of the shell-wall, where they
are united by a thin continuous layer of protoplasm (Pl. 99, fig. 1). The
phæodium is usually more voluminous than the capsule and envelops the
latter on its anterior or oral face; more rarely the entire capsule is
hidden in the phæodium. The phæodella, constituting the latter, are of very
different sizes, of variable colour, olive and greenish-brown, red-brown,
black-brown or nearly black. In some preparations, stained with carmine,
numerous red coloured granula, similar to nuclei, were scattered in the
phæodium (compare Murray, _loc. cit._, Pl. A, figs. 1-14).
The diameter of the central capsule is usually about one-half or one-third
as great as that of the enclosing shell (Pl. 99, figs. 1-20). Its form is
either spherical or slightly compressed, spheroidal, or sometimes
lenticular. The large nucleus has the same form, is about half as broad as
the capsule and contains numerous nucleoli. Sometimes the capsule contained
two nuclei of equal size, and in a few specimens the shell contained two
central capsules, each with a nucleus, so that the Challengerida seem to
propagate also by self-division (Pl. 99, fig. 6).
The astropyle, or the large opening of the central capsule, exhibits the
usual radiate operculum of the PHÆODARIA, and the tubular proboscis arising
from it. This is constantly placed on the oral or anterior pole of the
capsule and directed towards the mouth of the shell. I was never able to
discover any parapyle or secondary opening in the central capsule, though
numerous and well-preserved specimens of the Challenger collection were
accurately examined. It seems therefore that the Challengerida are not
TRIPYLEA (as the majority of PHÆODARIA), but MONOPYLEA with a single
opening (like the closely allied Medusettida and Castanellida).
_Synopsis of the Genera of Challengerida._
{ Shell smooth, without
{ adoral teeth and
{ marginal spines, 693. _Lithogromia_.
I. Subfamily Lithogromida. {
Shell without pharynx { Shell with adoral
or inner prominent tube { teeth, but without
of the mouth. { marginal spines, 694. _Challengeria_.
{
{ Shell with adoral
{ teeth and with
{ marginal spines, 695. _Challengeron_.
{ Shell smooth, without
{ adoral teeth and
II. Subfamily Pharyngellida.{ marginal spines, 696. _Entocannula_.
Shell with a pharynx, {
or an inner cylindrical { Shell with adoral
tube, arising from the { teeth, but without
mouth and prominent { marginal spines, 697. _Pharyngella_.
inside. {
{ Shell with adoral
{ teeth and with
{ marginal spines, 698. _Porcupinia_.
{1647}Subfamily 1. LITHOGROMIDA, Haeckel.
_Definition._--#Challengerida# without pharynx, with a simple mouth, not
prolonged into an inner prominent tube.
Genus 693. _Lithogromia_,[312] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Challengerida# without pharynx, without adoral teeth and
marginal spines.
The genus _Lithogromia_ and the two following genera represent together the
subfamily Lithogromida, comprising those Challengerida in which the mouth
of the shell is a simple opening, and not prolonged into a pharynx or an
internal prominent tube. _Lithogromia_ may be regarded as the common
ancestral form of this family, since it is the simplest of all, and
possesses no external apophyses, neither teeth on the mouth, nor spines on
the margin of the smooth shell.
1. _Lithogromia silicea_, n. sp. (Pl. 99, fig. 22).
Shell ovate, one and a half times as long as broad, not compressed.
Transverse section circular. Mouth a simple circular opening with smooth
edges about one-third as broad as the shell.
_Dimensions._--Length of the shell 0.2, breadth 0.15; mouth 0.05.
_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth
600 fathoms.
2. _Lithogromia diatomacea_, n. sp. (Pl. 99, fig. 21).
Shell ovate, lenticular, one and one-third times as long as broad, strongly
compressed. Transverse section elliptical. Mouth a broad fissure, half as
broad as the shell.
_Dimensions._--Length of the shell 0.27, breadth 0.2; mouth 0.1.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
3. _Lithogromia lenticula_, n. sp.
Shell subcircular, lenticular, about as long as broad, strongly compressed.
Transverse section lanceolate. Mouth a narrow fissure, one-third as broad
as the shell.
_Dimensions._--Diameter of the shell 0.15, mouth 0.05.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
{1648}Genus 694. _Challengeria_, John Murray, 1876, Proc. Roy. Soc. Lond.,
vol. xxiv. p. 536.
_Definition._--#Challengerida# without pharynx, with one or more adoral
teeth, but without spines on the sagittal margin.
The genus _Challengeria_, and the following closely allied _Challengeron_,
differ from the preceding _Lithogromia_, their ancestral form, in the
development of teeth on the mouth of the shell. _Challengeron_ has also
radial spines on the sagittal margin, while these are wanting in
_Challengeria_. The latter genus exhibits not less than twenty-one, the
former twenty-five species, so that both together make by far the greatest
part of the family (containing fifty-eight species). They are also more
common and more widely distributed than the four other genera of
Challengerida, and many species appear in great numbers in certain
localities. With a few exceptions living on the surface, they are all
inhabitants of great depths.
Subgenus 1. _Challengerantha_, Haeckel.
_Definition._--Peristome with a single simple tooth, which is neither
forked nor branched (_Challengeriæ monodontes_).
1. _Challengeria naresii_, John Murray.
_Challengeria naresii_, John Murray, 1876, Proc. Roy. Soc. Lond., vol.
xxiv. pl. xxiv. fig. 1.
_Challengeria naresii_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 236, pl. A, figs. 1, 1_a_-1_e_.
Shell circular or nearly circular, strongly compressed, lenticular.
Peristome on the dorsal corner with a single simple vertical tooth, which
is nearly straight, conical, with two sharp lateral edges on the base,
about half as long as the shell.
_Dimensions._--Diameter of the shell 0.5 to 0.6, length of the tooth 0.2 to
0.3.
_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, at depths between 1000
and 3000 fathoms.
2. _Challengeria xiphodon_, n. sp.
Shell circular, nearly spherical, slightly compressed. Peristome on the
dorsal corner with a single simple vertical tooth, which is straight,
three-sided prismatic, and as long as the shell.
_Dimensions._--Diameter of the shell 0.1 to 0.13, length of the tooth 0.1
to 0.12.
_Habitat._--Tropical Atlantic, Stations 349 to 352, surface.
{1649}3. _Challengeria sigmodon_, n. sp.
Shell circular, nearly spherical, slightly compressed. Peristome with a
single simple tooth, which is S-shaped, more or less curved, and about
one-third as long as the shell.
_Dimensions._--Diameter of the shell 0.3 to 0.4, length of the tooth 0.1 to
0.14.
_Habitat._--North Pacific, Station 231, depth 2250 fathoms.
4. _Challengeria tritonis_, n. sp. (Pl. 99, fig. 5).
Shell ovate, slightly compressed. Peristome with a single simple tooth,
which is vertical, straight, slenderly conical, and about half as long as
the shell.
_Dimensions._--Diameter of the shell 0.15 to 0.2, length of the tooth 0.1
to 0.12.
_Habitat._--North Atlantic, Færöe Channel, Gulf Stream, in great numbers,
in depths from 100 to 600 fathoms. (Expedition of H.M.S. "Triton," 1882),
John Murray.
5. _Challengeria pyramidalis_, n. sp.
Shell slenderly ovate, one and a half times as long as broad, slightly
compressed. Peristome with a single, simple, large tooth, which is
three-sided pyramidal, vertical, straight, and longer than half the shell.
_Dimensions._--Length of the shell 0.6 to 0.8, breadth 0.4 to 0.5; length
of the tooth 0.4 to 0.5.
_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.
6. _Challengeria cyrtodon_, n. sp.
Shell ovate, lenticular, strongly compressed. Peristome with a single
simple tooth, which is crescent-shaped, curved over the mouth, and about
half as long as the shell.
_Dimensions._--Length of the shell 0.4 to 0.5, breadth 0.3 to 0.4; length
of the tooth 0.2 to 0.25.
_Habitat._--South Pacific, Station 289, depth 2550 fathoms.
Subgenus 2. _Challengeretta_, Haeckel.
_Definition._--Peristome with a forked or bifid tooth, or with two parallel
lateral teeth (_Challengeria diodontes_).
7. _Challengeria sloggettii_, John Murray (Pl. 99, fig. 4).
_Challengeria harstoni_, John Murray, 1879 (_partim_), _in litteris_,
Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 14.
Shell triangular, strongly compressed, with three rounded corners, or
nearly semicircular; its aboral margin straight, horizontal, longer than
the convex, dorsal, and ventral margins. Peristome {1650}with two parallel,
triangular pointed teeth, which are obliquely ascending, lamellar, with
inflated ovate base, and about as long as the shell-radius.
_Dimensions._--Diameter of the shell 0.2 to 0.3, length of the teeth 0.1 to
0.15.
_Habitat._--Tropical Atlantic, Stations 347, 348, depth 2250 to 2450
fathoms.
8. _Challengeria harstoni_, John Murray.
_Challengeria harstoni_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 14_a_.
Shell subcircular or somewhat triangular, with convex margins. Peristome
with two parallel, slender, lanceolate teeth, which are obliquely
ascending, and about half as long as the shell-radius.
_Dimensions._--Diameter of the shell 0.15 to 0.18, length of the teeth 0.04
to 0.05.
_Habitat._--North Pacific, Station 231, depth 2250 fathoms.
9. _Challengeria campbelli_, John Murray.
_Challengeria campbelli_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 9.
Shell cordate, nearly triangular, compressed, with blunt apex. Peristome in
the excavated middle of the broad base, with two short, parallel,
triangular teeth. This species is very similar to _Porcupinia cordiformis_
(Pl. 99, fig. 16), but differs from it in the absence of an internal
pharynx and of external apical spines.
_Dimensions._--Diameter of the shell 0.2 to 0.24; length of the teeth 0.03
to 0.05.
_Habitat._--South Atlantic, Stations 332 to 335, depth 1425 to 2200
fathoms.
10. _Challengeria thomsoni_, John Murray.
_Challengeria thomsoni_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 2.
Shell ovate, slightly compressed, with rounded apical pole. Peristome
semitubular, obliquely ascending, nearly straight, in the lower half an
open half-cylinder, in the upper half forked, with two parallel, thin,
oblique teeth. Sometimes a third small (dorsal) tooth is developed.
_Dimensions._--Length of the shell 0.3 to 0.35, breadth 0.2 to 0.25; length
of the peristome 0.08 to 0.12.
_Habitat._--South Atlantic, Stations 318 to 330, surface, and in depths
from 1900 to 2900 fathoms.
11. _Challengeria bidens_, n. sp.
Shell ovate, strongly compressed, lenticular. Peristome with two curved,
long and thin bristle-shaped teeth, which are obliquely inclined over the
mouth, and longer than the radius of the shell.
_Dimensions._--Length of the shell 0.12 to 0.18, breadth 0.1 to 0.14;
length of the teeth 0.08 to 0.1.
_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750
fathoms.
{1651}12. _Challengeria havergalli_, John Murray.
_Challengeria havergalli_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, figs. 13, 13_a_.
Shell subspherical, slightly compressed. Peristome semitubular, slender,
somewhat curved, in the lower half a simple half-cylinder, in the upper
half forked, with two divergent teeth, nearly as long as the shell.
_Dimensions._--Diameter of the shell 0.1 to 0.15, length of the peristome
0.08 to 0.12.
_Habitat._--South Pacific, Station 300, depth 1375 fathoms.
13. _Challengeria elephas_, n. sp.
Shell ellipsoidal, not compressed. Peristome very similar to that of
_Challengeron diodon_ (Pl. 99, fig. 6), from which this species differs
mainly in the absence of an apical spine, and in a more constricted mouth.
The two conical teeth of the mouth are very large, nearly as long as the
shell, straight, and almost parallel, each tooth has a large hole on the
thickened base.
_Dimensions._--Diameter of the shell 0.22, length of the teeth 0.2.
_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.
Subgenus 3. _Challengerilla_, Haeckel.
_Definition._--Peristome with three teeth or trifid, with an odd dorsal and
two paired lateral teeth (_Challengeriæ triodontes_).
14. _Challengeria macleari_, John Murray.
_Challengeria macleari_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 3.
Shell subcircular, lenticular, with a sharp marginal edge. Peristome
semitubular, an oblique half-cylinder, with three divergent, short,
triangular teeth; the dorsal odd tooth nearly vertical, the paired lateral
teeth subhorizontal. Length of the peristome about one-third or one-fourth
of the diameter of the shell.
_Dimensions._--Diameter of the shell 0.25 to 0.35, length of the peristome
0.1 to 0.12.
_Habitat._--South Atlantic, Stations 325 to 332, depth 1715 to 2900
fathoms.
15. _Challengeria tridens_, n. sp.
Shell subspherical, slightly compressed. Peristome about as long as the
radius of the shell, with three diverging and obliquely descending teeth;
the dorsal odd tooth twice as long as the paired lateral teeth.
_Dimensions._--Diameter of the shell 0.08 to 0.12, length of the peristome
0.05 to 0.07.
_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray.
{1652}16. _Challengeria trigona_, Haeckel.
_Challengeria macleari_, var., John Murray, 1879, _in litteris_, Narr.
Chall. Exp., vol. i. p. 226, pl. A, fig. 3_b_.
Shell triangular, with three rounded corners; the two lateral sides nearly
straight, equal, the aboral side more or less convex and somewhat shorter.
Peristome a curved half-tube (often longer than in Murray's figure),
one-third to one-half as long as the shell, with three short triangular
diverging and ascending teeth of equal length.
_Dimensions._--Length of the shell 0.25 to 0.3, breadth 0.2 to 0.25; length
of the peristome 0.08 to 0.12.
_Habitat._--South Atlantic, Stations 332 to 335, depth 1425 to 2200
fathoms.
17. _Challengeria trifida_, n. sp.
Shell ovate, more or less compressed, about two-thirds as long as broad.
Peristome semitubular, obliquely ascending, about one-third as long as the
shell, in the lower half simple, in the upper trifid, with three curved
divergent teeth; the dorsal odd tooth shorter than the paired lateral
teeth.
_Dimensions._--Length of the shell 0.3 to 0.36, breadth 0.24 to 0.28.
_Habitat._--South Pacific, Station 289, depth 2550 fathoms.
Subgenus 4. _Challengeromma_, Haeckel.
_Definition._--Peristome with four to six or more teeth.
18. _Challengeria quadridens_, n. sp.
Shell subglobose, with nearly circular perimeter. Peristome an oblique
short and broad tube, the breadth of which is twice as great as its length
and equal to the radius of the shell. Margin of the peristome with four
divergent, short, triangular teeth, the two dorsal teeth half as long as
the two ventral.
_Dimensions._--Diameter of the shell 0.22 to 0.24, breadth of the peristome
0.1.
_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.
19. _Challengeria bromleyi_, n. sp. (Pl. 99, fig. 3).
Shell ovate, lenticular, strongly compressed. Peristome a broad,
trapezoidal, horizontal lamella, the breadth of which is twice as great as
its length and nearly equal to the diameter of the shell; its margin with
four divergent triangular lamellar teeth, the two dorsal teeth three times
as long as the two ventral.
_Dimensions._--Length of the shell 0.08 to 0.1, breadth 0.05 to 0.07;
breadth of the peristome 0.08.
_Habitat._--North Pacific, Stations 244 to 253, surface, and in various
depths.
{1653}20. _Challengeria wildi_, n. sp. (Pl. 99, fig. 2).
Shell subspherical, slightly compressed. Peristome semitubular, curved, as
long as the shell-radius; with five curved lamellar teeth, an odd longer
dorsal tooth and two pairs of lateral teeth.
_Dimensions._--Diameter of the shell 0.12 to 0.18, length of the peristome
0.08 to 0.12.
_Habitat._--Tropical Atlantic, Stations 347 to 348, depth 2250 to 2450
fathoms.
21. _Challengeria aldrichi_, John Murray, _Challengeria aldrichi_1876, L.
N. 27, pl. 24, fig. 2.
_Challengeria aldrichi_, John Murray, 1879, in litteris, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 4.
Shell subspherical, slightly compressed. Peristome a collar-like curved
lamella, the breadth of which is twice as great as its length, and equals
the radius of the shell; its margin with six short triangular teeth, two
convergent ventral, two external horizontal lateral, and two ascending
dorsal.
_Dimensions._--Diameter of the shell 0.2, breadth of the peristome 0.1.
_Habitat._--North Pacific, Station 244 to 248, depth 2050 to 2900 fathoms.
22. _Challengeria murrayi_, n. sp. (Pl. 99, fig. 1).
Shell subcircular, lenticular, strongly compressed. Peristome a
trapezoidal, curved, collar-like lamella, the breadth of which is three
times as great as its length and equal to the diameter of the shell; its
margin with six triangular teeth, disposed like the preceding species, but
larger.
_Dimensions._--Diameter of the shell 0.15, breadth of the peristome 0.15.
_Habitat._--North-Western Pacific (south of Japan), Station 231, depth 2250
fathoms.
Genus 695. _Challengeron_, John Murray, 1879, _in litteris et schedulis_.
_Definition._--#Challengerida# without pharynx, with one or more teeth on
the mouth, and with marginal spines.
The genus _Challengeron_ has in general the same shape as the preceding
closely allied _Challengeria_, but differs from it in the development of
radial spines on the sagittal margin of the shell, which in the latter
genus is smooth. According to the different number and arrangement of these
marginal spines, which give a very singular appearance to them, we divide
the twenty-five species of this cosmopolitan genus into four
subgenera:--(1) with a single, odd apical spine; (2) with two opposed
aboral spines (a dorsal and a ventral); (3) with a bunch of aboral spines;
(4) with numerous radial spines along the whole sagittal margin of the
shell.
Subgenus 1. _Challengeranium_, Haeckel.
_Definition._--Margin of the shell with a single spine on the apical pole,
opposite to the peristome (_Challengeriæ caudatæ_).
{1654}1. _Challengeron monodon_, n. sp.
Shell subspherical, slightly compressed, with a single straight conical
spine on the apical pole, about as long as the radius. Peristome with a
single vertical, straight, conical tooth, diametrically opposite to the
apical spine and of the same length. (Similar to _Challengeria naresii_.)
_Dimensions._--Diameter of the shell 0.2 to 0.3, length of the two opposite
spines 0.1 to 0.15.
_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.
2. _Challengeron cochlear_, n. sp.
Shell nearly circular, lenticular, strongly compressed, with a single
straight conical spine on the apical pole, about half as long as the
radius. Peristome spoon-shaped, obliquely curved and inclined over the
mouth, with a single terminal tooth, somewhat longer than the radius.
_Dimensions._--Diameter of the shell 0.1, length of the peristome 0.06.
_Habitat._--Indian Ocean, Cocos Islands, Rabbe, surface.
3. _Challengeron diodon_, n. sp. (Pl. 99, fig. 6).
Shell ovate, slightly compressed, with a single straight conical spine on
the aboral pole, half as long as the radius. Peristome short and broad,
collar-shaped, about twice as broad as long, and half as long as the
radius, obliquely inclined over the mouth, with two divergent straight
teeth, which are conical and longer than the shell-radius; beyond each
tooth a large ovate hole in the wall of the peristome.
_Dimensions._--Diameter of the shell 0.08 to 0.1, length of the teeth 0.06
to 0.08.
_Habitat._--South-Eastern Pacific, Station 298, depth 2225 fathoms.
4. _Challengeron pearceyi_, n. sp. (Pl. 99, fig. 7).
Shell ellipsoidal or subspherical, scarcely compressed, with a single
straight conical spine on the apical pole, about as long as the diameter.
Peristome slender, semitubular, nearly as long as the diameter, somewhat
obliquely inclined over the mouth, with three divergent triangular or
lanceolate teeth; the dorsal odd tooth about twice as large as the paired
lateral teeth.
_Dimensions._--Diameter of the shell 0.08 to 0.12, length of the peristome
0.08 to 0.1.
_Habitat._--Antarctic Ocean, between Kerguelen and Heard Island, Station
157.
5. _Challengeron swirei_, John Murray.
_Challengeria swirei_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 11.
Shell subspherical or somewhat ovate, with a single straight conical spine
on the apical pole, about as long as the radius. Peristome slender,
semitubular, straight and vertical, nearly as long as the shell, with three
pointed teeth, an odd longer terminal and two paired shorter lateral.
_Dimensions._--Diameter of the shell 0.06 to 0.08, length of the peristome
0.05 to 0.06.
_Habitat._--Antarctic Ocean, Station 157, surface, common.
{1655}6. _Challengeron triodon_, n. sp.
Shell ovate, one and a half times as long as broad, not compressed, with a
single short and stout conical spine on the apical pole, shorter than half
the radius. Peristome short and broad, collar-shaped, nearly half as broad
and one-third as long as the shell, with three divergent terminal teeth, an
odd dorsal and two paired lateral.
_Dimensions._--Length of the shell 0.25 to 0.3, breadth 0.15 to 0.2; length
and breadth of the peristome 0.1.
_Habitat._--North Pacific, Station 245, surface.
Subgenus 2. _Challengerebium_, Haeckel.
_Definition._--Margin of the shell with two widely distant aboral spines,
opposite in the sagittal plane, a dorsal and a ventral.
7. _Challengeron balfouri_, John Murray.
_Challengeria balfouri_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 10.
Shell subcircular, lenticular, strongly compressed, with two short
divergent spines on the apical margin (a dorsal and a ventral). Peristome
slender, semitubular, as long as the radius, vertical, in the distal half
forked, with two parallel teeth.
_Dimensions._--Diameter of the shell 0.08 to 0.16, length of the peristome
0.04 to 0.08.
_Habitat._--North Atlantic, Stations 353 to 354, Hebrides, surface.
8. _Challengeron golfense_, n. sp.
Shell ovate, lenticular, compressed, with two short divergent spines on the
apical margin (a dorsal and a ventral). Peristome slender, semitubular,
half as long as the radius, with three terminal teeth, two short,
vertically ascending, paired teeth and a larger odd tooth, which is
inclined obliquely over the mouth.
_Dimensions._--Diameter of the shell 0.15 to 0.2, peristome 0.05 to 0.07.
_Habitat._--North Atlantic, Færöe Channel, Gulf Stream, surface and at
various depths, John Murray.
9. _Challengeron richardsii_, n. sp. (Pl. 99, fig. 8).
Shell subcircular, lenticular, strongly compressed, with two stout,
divergent, straight spines on the aboral margin (a dorsal and a ventral)
which reach the length of the radius. Peristome slender, semitubular,
slightly curved, about as long as the radius, with three short, divergent,
{1656}terminal teeth. Mouth obliquely truncate. The dorsal odd tooth is
nearly vertical, the two lateral paired teeth almost horizontal.
_Dimensions._--Diameter of the shell 0.2 to 0.25, length of the spines and
the peristome 0.08 to 0.12.
_Habitat._--Antarctic Ocean, Station 157, surface, common.
10. _Challengeron fergusoni_, n. sp. (Pl. 99, fig. 9).
Shell isosceles triangular, with three slightly convex edges and two short,
nearly vertically descending spines on the two corners of the aboral
margin. Peristome inversely funnel-shaped, with a deep ventral incision on
the base, and three broad, ovate, triangular teeth. The dorsal odd tooth is
nearly vertical, whilst the two lateral paired teeth are almost horizontal;
therefore the angle between the former and the latter is about a right
angle.
_Dimensions._--Diameter of the shell 0.2 to 0.3, length of the peristome
0.1.
_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.
11. _Challengeron tizardi_, John Murray.
_Challengeria tizardi_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol i. p. 226, pl. A, figs. 7-7_b_.
Shell nearly equilateral triangular, with concave ventral, convex dorsal
and aboral edges, on the two corners of the latter two opposite horizontal
spines (a dorsal and a ventral). Peristome auriculate and bilobate, with a
deep ventral incision on the base, and three pointed triangular teeth, the
upper margins of which are nearly horizontal.
_Dimensions._--Diameter of the shell 0.22 to 0.3, length and breadth of the
peristome 0.01 to 0.12.
_Habitat._--South Atlantic, Stations 332 to 335, depth 1425 to 2200
fathoms.
12. _Challengeron triangulum_, n. sp. (Pl. 99, fig. 10).
Shell nearly equilateral triangular, with three slightly convex or nearly
straight sides, and two opposite obliquely descending and diverging spines
on the two corners of the aboral margin. Peristome auriculate and bilobate,
with a very thin basal neck and a deep incision on its ventral side; its
distal margin is obliquely truncate, and exhibits an odd ascending dorsal
tooth and two parallel, paired, descending, lateral teeth.
_Dimensions._--Diameter of the shell 0.2 to 0.3; length and breadth of the
peristome 0.1 to 0.12.
_Habitat._--North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.
Subgenus 3. _Challengeridium_, Haeckel.
_Definition._--Margin of the shell smooth on the dorsal and the ventral
side, but with three to five or more large spines (or a bunch of spines) on
the aboral side; the middle spine is placed in the main axis, and larger
than the others.
{1657}13. _Challengeron bisternum_, n. sp.
Shell subcircular, lenticular, strongly compressed, with three stout
conical spines on the aboral pole; the middle spine is placed in the main
axis, as long as the radius and three times as long as the two others.
Peristome semitubular, straight, vertical, about as long as the radius,
with three divergent teeth, the middle of which is odd and twice as large
as the two paired lateral teeth.
_Dimensions._--Diameter of the shell 0.22; length of the peristome 0.1.
_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.
14. _Challengeron heptacanthum_, n. sp.
Shell ovate, slightly compressed, with a series of five stout, conical,
radial spines on the aboral margin; the middle spine is placed in the main
axis and longer than the radius, twice as long as the two next, and three
times as long as the more distant spines. Peristome short and broad,
collar-shaped, with two large, divergent, straight teeth, each of which is
longer than the shell-radius and bears at its base a large hole.
_Dimensions._--Length of the shell 0.09 to 0.11, breadth 0.07 to 0.08;
length of the teeth 0.07.
_Habitat._--Tropical Atlantic, Stations 347, 348, depth 2250 and 2450
fathoms.
15. _Challengeron crosbiei_, n. sp. (Pl. 99, fig. 11).
Shell ovate, strongly compressed, with a series of seven to nine conical
spines on the aboral margin; the middle spine is placed in the main axis,
as long as the radius, and much larger than the six or eight other spines.
Peristome short and broad, collar-like, with several small spines and two
slender, widely distant, conical teeth, which are half as long as the
shell, and curved towards one another like a pincer, each with a large hole
at its base.
_Dimensions._--Length of the shell 0.08 to 0.09, breadth 0.06 to 0.07;
length of the two larger teeth 0.04 to 0.05.
_Habitat._--Central Pacific, Station 270 to 274, depth 2350 to 2925
fathoms.
16. _Challengeron buchanani_, n. sp. (Pl. 99, fig. 12).
Shell ovate, slightly compressed, with a terminal comb of nine to twelve
conical radial spines, densely crowded on the aboral pole; the middle spine
is placed in the main axis, about half as long as the shell and much larger
than the others. Peristome subconical, semitubular, recurved, half as long
as the shell, with five triangular teeth; the dorsal odd tooth is inclined
backwards, the two parallel pairs of lateral teeth directed ventrally.
_Dimensions._--Length of the shell 0.15 to 0.18, breadth 0.1 to 0.12;
length of the peristome 0.06 to 0.08.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
{1658}Subgenus 4. _Challengerosium_, Haeckel.
_Definition._--Margin of the shell dentated or serrated, with a continuous
series of numerous short radial spines.
17. _Challengeron channeri_, John Murray.
_Challengeron channeri_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 12.
Shell subcircular, lenticular, strongly compressed, with fourteen to
eighteen slender, straight, radial spines on the margin; the spines are
straight, equidistant, cylindrical, and about as long as the radius of the
shell. Peristome short, with two parallel, vertical, lateral, straight
teeth, which are less than half the length of a spine.
_Dimensions._--Diameter of the shell 0.14 to 0.17; length of the spines
0.06 to 0.08.
_Habitat._--North Pacific, Station 231, depth 2250 fathoms.
18. _Challengeron moseleyi_, n. sp. (Pl. 99, fig. 14).
Shell circular, lenticular, strongly compressed, with thirty to forty
slender, straight, equidistant, radial spines on the margin, larger and
smaller spines alternating; the larger spines are about as long as the
radius, the smaller only half as long. Peristome short, tubular, with two
divergent ovate or nearly triangular teeth, a dorsal and a ventral, about
as long as the shorter marginal spines.
_Dimensions._--Diameter of the shell 0.13 to 0.15; length of the larger
spines 0.06 to 0.07, of the smaller 0.03 to 0.04.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
19. _Challengeron bethelli_, John Murray.
_Challengeron bethelli_, John Murray, 1879, _in litteris_, Narr. Chall.
Exp., vol. i. p. 226, pl. A, fig. 6.
Shell subcircular, lenticular, strongly compressed, with numerous (twenty
to thirty) short conical spines on the margin (often wanting in the upper
part of the dorsal margin). Peristome with a deep labial incision and two
parallel triangular lateral teeth, the upper margin of which is horizontal.
_Dimensions._--Diameter of the shell 0.2 to 0.25; length of the spines 0.02
to 0.03.
_Habitat._--North Pacific, Stations 238, 241 (off Japan), depth between
2300 and 3950 fathoms.
20. _Challengeron bathybium_, n. sp.
Shell subcircular, lenticular, slightly compressed, with a corona of
numerous (thirty to forty or more) short, conical, radial spines on the
margin. Peristome helmet-shaped, nearly as long as the {1659}radius, with
two widely divergent, conical, curved teeth, a vertical dorsal and a nearly
horizontal ventral tooth.
_Dimensions._--Diameter of the shell 0.22; length of the peristome 0.1.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
21. _Challengeron johannis_, n. sp.
Shell ovate, slightly compressed, with a corona of numerous (forty to sixty
or more) short radial spines on the margin, ten to fifteen of them (in the
aboral half) are pyramidal, and much larger than the others. Peristome
helmet-shaped, about one-third as long as the shell, with a deep bosom and
two widely divergent teeth on the concave upper margin, a forked dorsal and
a conical ventral.
_Dimensions._--Length of the shell 0.13, breadth 0.1; length of the
peristome 0.04.
_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray.
22. _Challengeron carpenterii_, John Murray.
_Challengeron carpenterii_, John Murray, 1877, _in litteris_, Narr.
Chall. Exp., vol. i. p. 226, pl. A, fig. 8.
Shell ovate, with a series of twelve to fifteen short, conical, radial
spines on the aboral half of the margin. Peristome slender, semitubular,
nearly as long as the shell, in the upper half forked, with two short
parallel teeth.
_Dimensions._--Length of the shell 0.13 to 0.18, breadth 0.1 to 0.14;
length of the peristome 0.1 to 0.12.
_Habitat._--Tropical Atlantic, Stations 347 to 348, depth 2250 to 2450
fathoms.
23. _Challengeron ciliatum_, n. sp.
Shell ovate, slightly compressed, with numerous (forty to fifty or more)
short and thin, bristle-shaped, radial spines on the margin. Peristome
obliquely truncate, with three curved spines; the dorsal odd spine
subvertical, nearly as long as the radius, and much stronger than the two
parallel, nearly horizontal, lateral spines.
_Dimensions._--Length of the shell 0.15, breadth 0.11; length of the
peristome 0.1.
_Habitat._--North Pacific, Station 231, depth 2250 fathoms.
24. _Challengeron willemoesii_, n. sp. (Pl. 99, fig. 13).
Shell broadly-ovate or nearly circular, lenticular, with numerous (fifty to
sixty) short and stout, conical, radial spines on the margin, increasing in
size towards the aboral pole; the spines are alternately larger and
smaller, the largest about half as long as the radius. Peristome
helmet-shaped or half conical, longer than the radius of the shell, with
two pairs of conical, curved, {1660}divergent teeth; the terminal teeth are
the halves of a forked dorsal tooth and diverge laterally; the lower teeth
are nearly horizontal and directed ventrally.
_Dimensions._--Diameter of the shell 0.13 to 0.15; length of the peristome
0.07 to 0.1.
_Habitat._--Tropical Pacific, Stations 274 to 276, depth 2350 to 2750
fathoms.
25. _Challengeron wyvillei_, n. sp. (Pl. 99, fig. 15).
Shell ovate, lenticular, strongly compressed, with numerous (forty to
fifty) short, conical, radial spines on the margin; the spines are larger
on the aboral side and spinulate. Peristome narrow, with two parallel,
lateral, lamellar, forked teeth, about as long as the radius; the upper
branch of the forks is sabre-shaped, obliquely truncate, subvertical,
ciliate, and much broader than the lower nearly horizontal branch, which is
directed towards the ventral side and curved upwards.
_Dimensions._--Length of the shell 0.12 to 0.16, breadth 0.1 to 0.14;
length of the peristome 0.08 to 0.11.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
Subfamily 2. PHARYNGELLIDA, Haeckel.
_Definition._--#Challengerida# with a pharynx, or an internal prominent
mouth tube.
Genus 696. _Entocannula_,[313] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Challengerida# with a pharynx, without teeth on the mouth,
and without marginal spines.
The genus _Entocannula_ and the two following genera represent together the
subfamily Pharyngellida, differing from the preceding Lithogromida in the
development of a peculiar pharynx, an internal, cylindrical, or
funnel-shaped tube, which is conspicuous, leads from the mouth into the
shell-cavity, and is provided with an inner and an outer opening. The
Pharyngellida are much rarer than the Lithogromida; only ten species have
been observed of the former, fifty of the latter. _Entocannula_ is the
simplest form of the Pharyngellida, having a smooth shell, without aboral
teeth and marginal spines; it differs from _Lithogromia_ only in the
possession of the pharynx. One remarkable species is covered entirely with
extremely thin, flinty hairs, and may represent therefore a peculiar genus,
_Trichogromia_.
{1661}1. _Entocannula circularis_, n. sp.
Shell circular or nearly circular, lenticular, strongly compressed. Pharynx
cylindrical, one-third or one-fourth as broad as the shell, twice as broad
as long, its outer and inner apertures of equal breadth. Surface smooth.
_Dimensions._--Diameter of the shell 0.20 to 0.32, of the pharynx 0.07 to
0.09.
_Habitat._--North Pacific, Station 250, depth 3050 fathoms.
2. _Entocannula subglobosa_, n. sp.
_Challengeria bromleyi_, (_partim_), John Murray, 1879, _in schedulis_
Chall. Coll.
Shell circular, nearly spherical, slightly compressed. Pharynx
funnel-shaped, truncate, conical, its outer opening twice as broad as the
inner. Surface smooth.
_Dimensions._--Diameter of the shell 0.25 to 0.28, of the inner mouth 0.05.
_Habitat._--South Pacific, Station 289, depth 2550 fathoms.
3. _Entocannula infundibulum_, n. sp. (Pl. 99, fig. 19).
_Challengeria bromleyi_ (_partim_), John Murray, 1879, _in litteris_,
Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 5.
Shell ovate, truncate at the mouth, slightly compressed. Pharynx
funnel-shaped, its outer aperture two to three times as broad as the inner.
Surface smooth.
_Dimensions._--Length of the shell 0.22 to 0.28, breadth 0.2 to 0.25; inner
mouth 0.04 to 0.08.
_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.
4. _Entocannula hirsuta_, n. sp. (Pl. 99, fig. 20).
_Trichogromia hirsuta_, Haeckel, 1881, Manuscript.
Shell ovate. Pharynx cylindrical, one-fourth as broad as the shell, its
inner and outer apertures of equal breadth. The whole surface of the shell,
and mainly the outer mouth, is densely covered with thin, curved, siliceous
bristles.
_Dimensions._--Length of the shell 0.27 to 0.36, breadth 0.2 to 0.3; mouth
0.05 to 0.08.
_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth
600 fathoms.
Genus 697. _Pharyngella_,[314] n. gen.
_Definition._--#Challengerida# with a pharynx, and with one or more teeth
on the mouth, but without marginal spines.
The genus _Pharyngella_ differs from the preceding _Entocannula_, its
ancestral form, in the development of one or more teeth on the peristome,
and exhibits therefore the same relation to it that _Challengeria_ bears to
_Lithogromia_. Only a few species of this genus have been observed, all in
the Atlantic.
{1662}1. _Pharyngella monoceros_, n. sp.
Shell ovate, slightly compressed, with a single large tooth on the dorsal
corner of the peristome. The tooth is cylindro-conical, half as long as the
shell, straight or slightly curved, and lies in the main axis of the shell.
Pharynx cylindrical, straight, half as long as the shell-radius. This
species is very similar to _Challengeria tritonis_ (Pl. 99, fig. 5), and to
the common cosmopolitan _Challengeria naresii_, but differs generically
from them in the possession of the pharynx.
_Dimensions._--Diameter of the shell 0.25 to 0.28; length of the tooth
0.14.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
2. _Pharyngella gastrula_, n. sp. (Pl. 99, fig. 18).
Shell ovate. Peristome with two parallel, vertical, straight, pointed
teeth, which are half as long as the shell-radius. Pharynx of the same
length, cylindrical or funnel-shaped, its outer aperture scarcely broader
than the inner.
_Dimensions._--Length of the shell 0.3 to 36, breadth 0.24 to 0.3; teeth
and pharynx 0.07 to 0.09.
_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth
600 fathoms.
3. _Pharyngella invaginata_, n. sp.
Shell circular, slightly compressed or nearly spherical. Peristome with two
parallel, vertical, straight, pointed teeth, which are about as long as the
shell-radius. Pharynx of the same length, funnel-shaped; its outer aperture
twice as broad as the inner.
_Dimensions._--Diameter of the shell 0.2 to 0.22, teeth and pharynx 0.05.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
4. _Pharyngella gastræa_, n. sp. (Pl. 99, fig. 17).
Shell broad, ovate or nearly circular, lenticular, strongly compressed.
Peristome with two parallel, pointed teeth, which are nearly as long as the
shell-radius, slightly curved, and obliquely inclined over the mouth.
Pharynx half as long, cylindrical, obliquely descending; its outer and
inner apertures of equal breadth.
_Dimensions._--Diameter of the shell 0.3 to 0.33, teeth 0.12, pharynx 0.06.
_Habitat._--South Atlantic, Stations 328 to 334, surface.
Genus 698. _Porcupinia_,[315] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Challengerida# with a pharynx, with teeth on the mouth and
marginal spines.
The genus _Porcupinia_ differs from the preceding _Pharyngella_ in the
development {1663}of marginal spines, and exhibits therefore the same
relation to it that _Challengeron_ bears to _Challengeria_. Only two
species have been observed; the first of these bears, besides the large
marginal spines, numerous flinty bristles on the surface of the shell.
1. _Porcupinia aculeata_, n. sp.
Shell ovate, one and one-third times as long as broad, slightly compressed,
covered with short, bristle-shaped spines over the whole surface, similar
to _Entocannula hirsuta_ (Pl. 99, fig. 20). The keeled margin is armed with
numerous long and stout radial spines, which are alternately larger and
smaller, as in _Challengeron moseleyi_ (Pl. 99, fig. 14); the larger about
as long as the radius, the smaller half as long. Peristome with two
straight, parallel teeth. Pharynx funnel-shaped, half as long as the
radius, its outer aperture twice as broad as the inner.
_Dimensions._--Length of the shell 0.24, breadth 0.18; peristome 0.05.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
2. _Porcupinia cordiformis_, n. sp. (Pl. 99, fig. 16).
Shell heart-shaped, nearly triangular, with a deep, concave bosom at the
broad oral base, and a bunch of five to nine divergent spines at the blunt
aboral apex, the middle spine (in the main axis) larger than the others.
Peristome with two parallel, short, triangular teeth, which are obliquely
inclined over the mouth (their upper convex edge nearly horizontal).
Pharynx cylindrical, short, curved, and obliquely descending.
_Dimensions._--Diameter of the shell 0.2 to 0.25, of the pharynx 0.05 to
0.08.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
Family LXXIX. #MEDUSETTIDA#, n. fam. (Pls. 118-120).
_Definition._--PHÆODARIA with a simple, ovate, hemispherical or cap-shaped
lattice-shell of peculiar alveolate structure, and with hollow articulate
feet surrounding the widely open mouth. Central capsule excentric, placed
in the aboral half of the shell-cavity.
The family #Medusettida# represents a peculiar group of remarkable
PHÆODARIA, which are similar to the Challengerida and Tuscarorida in the
general form of the monaxonian shell and its apophyses, but differ from
both families in the strange alveolate structure of the shell and of the
hollow articulate feet surrounding its mouth. All the forms of this family
here described are new, and not a single species was known before the
discoveries of the Challenger. The majority seem to be inhabitants of the
deep-sea, and occur mainly in those places where other families of
PHÆODARIA (Aulacanthida, Aulosphærida, Coelodendrida) are also well
represented; they are, however, nowhere so common as these latter families.
Their long feet and the small delicate {1664}shell are extremely fragile,
so that complete and well-preserved specimens are rare. Some species are
among the most admirable forms of Radiolaria, and are similar to small
elegant Medusæ, _e.g._, _Medusetta_ (Pl. 120, figs. 1-4), _Gazelletta_ (Pl.
118, fig. 1), and _Gorgonetta_ (Pl. 119).
The shell of the Medusettida is usually very small and delicate, in
comparison to the long, often exceedingly large, feet, which depend from
the margin of its mouth. From the size and the weight of these feet, we
must suppose that the shell floats in the water in the same position as in
the NASSELLARIA, so that the main axis is vertical, and the open mouth with
the feet on its lower pole. The form of the shell exhibits the same
varieties as the similar umbrella of the Medusæ. It is usually more or less
hemispherical, sometimes flatter, cap-shaped, at other times more highly
vaulted, campanulate or ovate. The similarity with the umbrella of a Medusa
is so great, that in many species the large lower opening on the mouth of
the shell is surrounded by a prominent ring or diaphragm, comparable to the
velum of the Craspedotæ or Hydromedusæ (Pl. 120, figs. 3-4).
The structure of the shell, which we term shortly "alveolate," is very
remarkable, and seems to be different from that of the other PHÆODARIA. Its
reticulate appearance seems to indicate at first sight the usual
lattice-shell, pierced by numerous very small pores (Pl. 118, figs. 1-3).
But as soon as we make the shell dry, air always enters into its thin
walls, and each apparent pore is found to be a small alveole or a separate
compartment, which contains a small bubble of air (Pl. 120, figs. 11, 16).
The thin wall of the shell is therefore double, composed of two parallel,
very thin lamellæ of silica, which are little distant from one another, and
are connected by a network of small rods or septa. This network is rarely
regular, with square meshes (Pl. 118, fig. 3), or with hexagonal or
triangular meshes (Pl. 116, fig. 2); it is usually irregular, with
polygonal meshes (Pl. 120, figs. 11-16). The size of the meshes or alveoles
is usually smallest on the aboral apex of the shell, and increases
gradually towards the mouth. The largest alveoles are around the mouth, on
the velum-shaped peristome, and here the marginal alveoles of the shell
pass directly over into the separate alveoles or hollow compartments of the
articulate feet (Pl. 118, fig. 1). Probably each alveole is a separate
compartment, filled up by jelly, and has a small opening or pore on its
inside; this pore is very distinct in the marginal alveoles of some larger
species (Pl. 116, fig. 1_a_; Pl. 120, fig. 14), but I have not been able to
recognise it everywhere. Moreover, it often happens that the alveoles are
apparently completely closed. In some smaller species the alveolate
structure seems to be present only in the peripheral part of the shell,
whilst the central part is solid.
The outer convex surface of the shell is usually smooth, sometimes
papillate (Pl. 116, fig. 1), at other times studded with small, conical,
radial spines (Pl. 118, fig. 1; Pl. 120, figs. 4-11). Prolonged cylindrical
spines or tubes are rarely {1665}scattered over the surface (Pl. 116, figs.
1, 2). In some genera a long vertical or oblique spine is developed from
the apex of the shell, and is comparable to the "apical horn" of the
NASSELLARIA (Pl. 118, figs. 2, 3; Pl. 120, figs. 1-4).
The mouth of the shell, or the large opening on the lower pole of its
vertical main axis, is usually widely open, circular or polygonal, more
rarely constricted. In many species the peristome is broadened and its
margin developed in the form of a horizontal diaphragm, which constricts
the entrance into the shell-cavity, and is comparable to the velum of the
Hydromedusæ (Pl. 120, figs. 1-4). Sometimes the margin of the velum is
fringed and bears numerous small dependent filaments of silica, comparable
to the marginal tentacles of many Medusæ (Pl. 118, figs. 1, 3; Pl. 120,
fig. 16). Rarely the mouth is strongly constricted and prolonged into a
narrow, long, cylindrical tube, comparable to a proboscis; its opening is
usually fringed (Pl. 116, figs. 1, 2).
The hollow articulate feet, or the large radial apophyses of the peristome,
are the most remarkable organs of the Medusettida, and occur in the same
form in no other family of Radiolaria. Their number is variable from three
to twelve or more, and is here employed for the distinction of genera, as
it is rather constant; the most frequent number is four (_Medusetta_) or
six (_Gazelletta_). The feet are usually cylindrical, much longer than the
shell, and more or less curved; more rarely they are straight or slightly
compressed. They are always articulate, and divided by numerous transverse
parallel septa into hollow compartments or alveoles; the transversely
striated appearance of the feet is brought about by these septa. The
alveoles have usually the form of short discoidal cylinders, and are
broader than long (Pl. 120, figs. 5-13); rarely they are longer than broad
(fig. 15). The septa between the alveoles are always perforated by a small
opening and usually this opening is prolonged into a shorter or longer
tubule, comparable to the siphuncle in the septa of the chambered shells of
Cephalopoda; as in these latter, the succeeding siphons are arranged in a
continuous series, which lies either in the axis of the foot or parallel to
it (Pl. 120, figs. 8, 13, 15). The siphons are directed towards the distal
end of the foot, so that, _e.g._, the siphon which arises from the septum
between the ninth and tenth alveole, projects into the cavity of the
latter. The communicating cavities of all the alveoles are filled up by
jelly. In the dry shells, which are cleaned by hot mineral acids or by
fire, and in which, therefore, the jelly is destroyed, the cavities become
easily filled by air-bubbles (Pl. 120, figs. 8, 11, 15). Whilst the
alveoles of each foot always form a long simple series, this series becomes
doubled on the base of the larger feet, where they are broadened, and pass
over into the compartments of the peristome (Pl. 122, figs. 10, 11, 14).
The terminal alveole of each foot is closed.
The feet of the Medusettida are rarely quite simple and smooth (Pl. 120,
figs. 1, 5, 7, 10, &c.). Usually they are armed with numerous spines or
with elegant pencils of spathillæ. These secondary appendages or branches
are also hollow, with a {1666}thin wall of silex; but they seem usually not
to communicate with the alveoles of the foot directly; the cavities of the
foot and its appendages are separated by a thin, solid septum. In
_Medusetta_ the convex outer edge of each curved foot is studded with a
series of simple alveolate branches (Pl. 120, figs. 2-4). In _Gazelletta_,
the feet are usually armed with verticillate or alternate spines, which are
either simple or branched (Pl. 120, figs. 11-15); sometimes each branch is
elegantly arborescent (Pl. 118, fig. 1). Sometimes the distal end of each
branch is armed with a spathilla or a coronet of recurved teeth. The
branches attain their highest development in the admirable _Gorgonetta_
(Pl. 119). The twelve feet of this most interesting genus are
differentiated into two different and alternating groups, six descending
and six ascending. The six upper or ascending feet are arborescent, and
each branch is armed at the distal end with a spathilla (figs. 1, 2). The
six lower or descending feet are covered with most elegant arborescent
pencils or anchor-bearing trees; each terminal branch of a tree is armed
with two spathillæ, a smaller terminal and a larger below it (figs. 3, 4).
The distal ends of the feet are rarely simple, usually they are forked or
branched, or armed with peculiar spathillæ; and sometimes these terminal
branches are very large (Pls. 118, 119).
The _central capsule_ of the Medusettida is usually subspherical or
somewhat lenticular, and hidden in the aboral or upper part of the
shell-cavity, whilst its oral or lower part is filled up by the phæodium
(Pl. 120, figs. 2, 9, 10, 11). Sometimes the phæodium is very large and
prominent at the aperture of the mouth (Pl. 118, figs. 2, 3; Pl. 119, fig.
1). The nucleus is usually ellipsoidal, half as large as the central
capsule, and includes numerous nucleoli. The membrane of the central
capsule seems in all Medusettida to possess only one opening, the astropyle
or main-opening with a radiate operculum and proboscis, placed at the lower
or oral pole (Pl. 120, fig. 2). I have never been able to observe any
secondary opening or parapyle. The free space between the shell wall and
the capsule is filled up by the calymma, which also includes the phæodium.
The jelly of the calymma is probably in direct continuity with the jelly
which fills up the alveoles of the shell-wall and of the articulate feet.
_Synopsis of the Genera of Medusettida._
I. Subfamily Euphysettida. { Three equal feet, 699. _Cortinetta_.
Peristome of the shell with {
a corona of three or four { Four equal feet, 700. _Medusetta_.
feet. Apex of the shell {
(usually) with an apical { One large and three
horn. { small feet, 701. _Euphysetta_.
{ Six descending feet, 702. _Gazelletta_.
{
II. Subfamily Gazellettida. { Six descending and six
Peristome of the shell with { ascending alternating
six to twelve or more feet. { feet, 703. _Gorgonetta_.
Apex of the shell (usually) {
without apical horn. { Numerous (ten to twenty
{ or more) descending
{ feet, 704. _Polypetta_.
{1667}Genus 699. _Cortinetta_,[316] n. gen.
_Definition._--#Medusettida# with three articulate feet on the peristome.
The genus Cortinetta comprises Medusettida which exhibit the minimum number
of feet, three, and which therefore may be compared to the tripodal
NASSELLARIA (_Cortina_, _Cortiniscus_, _Tripodiscus_, &c.). This similarity
is the greater, as in the few observed species an apical horn is developed
(as also in the following genus). The three feet are in the two species
observed of equal size and similar form, and equidistant, so that they
cannot be distinguished as an odd caudal and two paired lateral feet, as in
the similar NASSELLARIA.
1. _Cortinetta tripodiscus_, n. sp. (Pl. 117, fig. 7).
Shell campanulate, covered with numerous curved ascending bristles, with a
prominent annular velum on the peristome, similar to that of _Medusetta
craspedota_. (Pl. 120, fig. 4). Feet equal, widely divergent and
equidistant, somewhat longer than the shell, slightly curved, and covered
on their convex outer edge with a series of short lateral branches, the
three ramules of which bear a spathilla. Apical horn conical, straight,
about as long as the shell, also covered with curved bristles.
_Dimensions._--Length of the shell 0.14, breadth 0.11; length of the feet
0.16, of the apical horn 0.11.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
2. _Cortinetta cortiniscus_, n. sp.
Shell campanulate, subspherical, thorny, with a prominent annular velum on
the peristome. Feet equal, very large, widely divergent, about three times
as long as the shell and studded with arborescent branches, similar to
those of _Gazelletta drymonema_ (Pl. 118, fig. 1). Apical horn slender,
conical, straight, thorny, twice as long as the shell.
_Dimensions._--Length of the shell 0.18, breadth 0.16; length of the feet
0.5 to 0.6, of the apical horn 0.33.
_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.
Genus 700. _Medusetta_,[317] n. gen.
_Definition._--#Medusettida# with four equidistant articulate feet of equal
size on the peristome.
The genus _Medusetta_ comprises those forms of the family which bear on the
peristome four equal radial feet, and therefore exhibit a striking
similarity to many {1668}small Medusæ (_e.g._, _Codonium_, _Tiara_,
_Sarsia_, &c.). This similarity is the greater, as usually the four feet
are elegantly curved and the entrance in the shell-cavity partly closed by
a marginal diaphragm, comparable to the velum of the Craspedotæ or
Hydromedusæ. In all the species observed the apex of the shell bears a
slender vertical or curved spine, comparable to the apical horn of the
NASSELLARIA. In most species the feet bear on their convex outside a series
of teeth or branches, which are also alveolate.
1. _Medusetta codonium_, n. sp. (Pl. 120, fig. 1).
Shell ovate, smooth, twice as broad as the constricted mouth. Apical horn
about as long as the shell, nearly straight, smooth. Feet cylindrical,
smooth, irregularly curved, about as long as the shell.
_Dimensions._--Length of the shell 0.08, breadth 0.05.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
2. _Medusetta tiara_, n. sp.
Shell campanulate, smooth, about as long as broad, and three times as broad
as the constricted mouth, which is surrounded by a horizontal broad ring,
like the velum of a Hydromedusa. Apical horn conical, straight, half as
long as the shell. Feet divergent, irregularly curved, twice as long as the
shell.
_Dimensions._--Length of the shell 0.07, breadth 0.06.
_Habitat._--North Atlantic (Færöe Channel), John Murray, surface.
3. _Medusetta minima_, n. sp.
Shell slenderly ovate, smooth, about twice as long as broad, twice as broad
as the constricted mouth. Apical horn straight, vertical, of the same
length. Feet somewhat longer, very thin, slightly curved at the base, in
the distal half nearly parallel and descending vertically.
_Dimensions._--Length of the shell 0.06, breadth 0.03.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
4. _Medusetta quadrigata_, n. sp. (Pl. 120, fig. 2).
Shell ovate, campanulate, smooth, little broader than the wide open mouth.
Apical horn longer than the shell, more or less curved, smooth. Feet
cylindrical, about as long as the shell, strongly curved and somewhat
spirally revoluted, with a series of short curved teeth on the abaxial
margin.
_Dimensions._--Length of the shell 0.07 to 0.09, breadth 0.04 to 0.06.
_Habitat._--North Pacific (off Japan), Stations 231 to 237, surface.
{1669}5. _Medusetta tetranema_, n. sp. (Pl. 120, fig. 3).
Shell campanulate, conical, smooth, nearly twice as broad as the
constricted mouth, without prominent velum. Apical horn somewhat shorter,
straight, conical, thorny. Feet strongly curved inwards, convergent, twice
as long as the shell, each with four to six strong, ascending, alveolate
branches on the abaxial margin.
_Dimensions._--Length of the shell 0.07 to 0.09, breadth 0.05 to 0.07.
_Habitat._--Tropical Atlantic, Station 352, surface.
6. _Medusetta spiralis_, n. sp.
Shell hemispherical, thorny, with wide open mouth. Apical horn straight,
vertical, thorny, twice as long as the shell; feet cylindrical, three times
as long as the shell, spirally convoluted around the vertical axis of the
shell, with a series of recurved teeth on the abaxial margin.
_Dimensions._--Length of the shell 0.05, breadth 0.08.
_Habitat._--Central Pacific, Stations 271 to 272, surface.
7. _Medusetta craspedota_, n. sp. (Pl. 120, fig. 4).
Shell campanulate or nearly spherical, spiny, twice as broad as the
constricted mouth, which is surrounded by a funnel-shaped truncate velum.
Apical horn conical, straight, spiny, half as long as the shell. Feet
strongly curved, longer than the shell, with a series of short conical
spines on the abaxial side.
_Dimensions._--Length of the shell 0.06, breadth 0.06.
_Habitat._--North Pacific, Station 239, surface.
Genus 701. _Euphysetta_,[318] n. gen.
_Definition._--#Medusettida# with four articulate feet on the peristome,
one odd very large, and three small or rudimentary feet.
The genus _Euphysetta_ agrees with the preceding _Medusetta_ in the
possession of four articulate feet; but whilst these in the latter are of
equal size and similar shape, in the former a single odd foot only is
developed, and very large, whilst the three others are rudimentary and very
small. _Euphysetta_ exhibits therefore the same relation to _Medusetta_
that the Euphysidæ (_Euphysa_, _Steenstrupia_, &c.) bear to the Sarsiadæ
(_Codonium_, _Sarsia_), among the Hydromedusæ (compare my System der
Medusen, 1879, vol. i. p. 12).
{1670}1. _Euphysetta staurocodon_, n. sp. (Pl. 118, fig. 2).
Shell ovate, nearly as broad as long, smooth, with an oblique, slender,
conical, apical horn of the same length. The larger odd foot cylindrical,
curved, somewhat longer than the shell, with three diverging branches at
the distal end. The three smaller feet very short, representing the form of
a regular rectangular cross.
_Dimensions._--Length of the shell 0.15, breadth 0.14.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
2. _Euphysetta hybocodon_, n. sp.
Shell ovate, one and one-third times as long as broad, smooth, with an
oblique, stout, conical horn of half the length. The larger odd foot
cylindrical, curved, twice as long as the shell, with a few pairs of short
lateral branches and forked distal end. The three smaller feet half as long
as the shell, thorny.
_Dimensions._--Length of the shell 0.16, breadth 0.12.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
3. _Euphysetta amphicodon_, n. sp. (Pl. 118, fig. 3).
Shell subspherical, smooth, with a short, oblique, conical, apical horn.
The larger odd foot cylindrical, nearly straight, as long as the shell,
with a few short lateral branches, at the distal end forked. The three
smaller feet were in one specimen observed forked, in another (the specimen
figured) replaced by nine small thorns.
_Dimensions._--Length of the shell 0.11, breadth 0.13.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
Genus 702. _Gazelletta_,[319] John Murray, 1876 (_in litteris_).
_Definition._--#Medusettida# with six articulate feet on the peristome.
The genus _Gazelletta_ is by far the most common of all Medusettida, and
some species seem to be widely distributed, or even cosmopolitan. The
number of species, too, is in this genus much larger than in all the other
genera of this family. It differs from the latter in the possession of six
feet, which number is very constant in the majority of species; in some
species, however, single specimens are not rarely found which possess five
or seven feet instead of six. Usually the six feet are rather regularly
formed and disposed, and diverge downwards; but sometimes there is more or
less {1671}irregularity in their shape and arrangement. In the majority of
species the feet are very long, curved, and armed in a very various manner,
so that four subgenera may be distinguished, according to the armatures.
Subgenus 1. _Gazellarium_, Haeckel.
_Definition._--Feet simple, smooth, without spines and without terminal
branches.
1. _Gazelletta hexanema_, n. sp. (Pl. 120, fig. 5).
Shell hemispherical, smooth. Feet very long, cylindrical, straight, smooth,
widely divergent, without terminal branches.
_Dimensions._--Length of the shell 0.03 to 0.04, breadth 0.06 to 0.07;
length of the feet 0.1 to 0.2.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific,
surface.
2. _Gazelletta macronema_, n. sp. (Pl. 120, figs. 7, 8).
Shell hemispherical, smooth. Feet very long, cylindrical, smooth, in the
basal part horizontally expanded, in the distal part strongly curved
downwards, without terminal branches.
_Dimensions._--Diameter of the shell 0.1 to 0.12, length of the feet 1.2 to
1.6.
_Habitat._--Central Pacific, Stations 270 to 274, surface.
3. _Gazelletta orthonema_, n. sp. (Pl. 120, fig. 10).
Shell hat-shaped, thorny. Feet cylindrical, straight, smooth, widely
divergent, without terminal branches.
_Dimensions._--Diameter of the shell 0.12 to 0.16, length of the feet 0.3
to 0.5.
_Habitat._--Central Pacific, Stations 270 to 274, surface.
4. _Gazelletta cyrtonema_, n. sp. (Pl. 120, fig. 9).
Shell hat-shaped, thorny. Feet cylindrical, smooth, widely diverging at the
base, strongly curved and convergent in the distal part, often
semicircular, without terminal branches.
_Dimensions._--Diameter of the shell 0.11 to 0.13, length of the feet 0.4
to 0.6.
_Habitat._--North Atlantic, Station 354, Canary Islands, surface.
Subgenus 2. _Gazellidium_, Haeckel.
_Definition._--Feet smooth, without lateral spines, but branched at the
distal end, or with a bunch of terminal spines.
{1672}5. _Gazelletta furcata_, n. sp.
Shell flat, cap-shaped, smooth. Feet cylindrical, nearly straight, at the
distal end forked, with two divergent, spinulate, terminal branches.
_Dimensions._--Length of the shell 0.12, breadth 0.3; length of the feet
0.6 to 0.8.
_Habitat._--Western Tropical Pacific, Station 224, surface.
6. _Gazelletta bifurca_, n. sp. (Pl. 120, fig. 6).
Shell cap-shaped, thorny. Feet nearly straight, widely divergent,
cylindrical, smooth, at the distal end twice forked, with four divergent,
terminal branches, each of which bears a spathillum with six to eight
recurved teeth (sometimes, as in the specimen figured, five or six terminal
branches instead of four).
_Dimensions._--Diameter of the shell 0.1, length of the feet 0.3 to 0.4.
_Habitat._--South Pacific, Station 288, surface.
7. _Gazelletta penicillata_, n. sp.
Shell campanulate, spiny. Feet cylindrical, strongly curved, smooth, with a
bunch of twelve to twenty or more curved spines at the distal end.
_Dimensions._--Diameter of the shell 0.08, length of the feet 0.6.
_Habitat._--Central Pacific, Station 266, surface.
Subgenus 3. _Gazellonium_, Haeckel.
_Definition._--Feet spiny, armed with simple or branched lateral spines,
and with terminal branches of the same shape.
8. _Gazelletta pectinata_, n. sp.
Shell flat, cap-shaped, thorny, three times as broad as high. Feet straight
or slightly curved, cylindrical, widely divergent, with four longitudinal
rows of short and simple conical spines, which are directed towards the
distal end, and about as long as a single joint of the foot.
_Dimensions._--Length of the shell 0.16, breadth 0.5; length of the feet
1.5 to 2.0, breadth 0.03 to 0.05.
_Habitat._--North Atlantic, Færöe Channel (John Murray), Hebrides
(Moebius).
9. _Gazelletta pinnata_, n. sp.
Shell hat-shaped, thorny. Feet cylindrical, strongly curved, pinnate, with
two opposite longitudinal rows of simple conical spines, which are slightly
curved, directed towards the distal end and opposed in pairs on about each
third or fourth joint.
_Dimensions._--Diameter of the shell 0.3, length of the feet 1.2 to 1.5.
_Habitat._--South Atlantic, Station 325, depth 2650 fathoms.
{1673}10. _Gazelletta studeri_, n. sp. (Pl. 120, fig. 15).
Shell flat, cap-shaped, thorny. Feet widely divergent, nearly straight and
horizontally expanded, with two alternate longitudinal rows of lateral
spines, which arise perpendicularly from the foot, are simple, conical,
slightly curved, and alternate on the succeeding joints. Ends of the feet
constricted, with four to six spines in one row. Dedicated to Professor
Studer.
_Dimensions._--Diameter of the shell 0.15, length of the feet 0.6 to 0.8.
_Habitat._--South Atlantic (east of Patagonia), Station 318, surface.
11. _Gazelletta schleinitzii_, n. sp. (Pl. 120, figs. 11, 12).
Shell hat-shaped, thorny. Feet cylindrical, nearly straight and
horizontally expanded, with four longitudinal rows of equal lateral spines,
which arise perpendicularly from the foot and bear at the end three short
divergent teeth. The end of the arms bears three forked spines. I name this
elegant species in honour of Captain Schleinitz, commander of the German
ship "Gazelle," who conducted the deep-sea soundings during the years 1874
to 1876.
_Dimensions._--Diameter of the shell 0.12, length of the feet 0.6 to 0.8.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
12. _Gazelletta trispathilla_, n. sp. (Pl. 120, fig. 13).
Shell flat, cap-shaped, smooth. Feet cylindrical, nearly straight, widely
divergent, with longitudinal rows of alternate spines, which arise
perpendicularly from the foot and bear at the end three short divergent
branches, each with a spathilla of six short teeth.
_Dimensions._--Diameter of the shell 0.2 to 0.25, length of the feet 1.2 to
1.5.
_Habitat._--North Pacific, Station 235 to 238, surface.
13. _Gazelletta robusta_, n. sp. (Pl. 120, fig. 14).
Shell flat, cap-shaped, thorny. Feet cylindrical, very stout, slightly
curved, covered with short irregularly branched spines; their ends with a
bunch of similar spines.
_Dimensions._--Diameter of the shell 0.6, length of the feet 2.5 to 3.3.
_Habitat._--Central Pacific, Stations 263 to 274, surface.
Subgenus 4. _Gazellusium_, Haeckel.
_Definition._--Feet spiny, armed with simple or branched lateral spines,
and with larger terminal branches of a different shape.
{1674}14. _Gazelletta dendronema_, n. sp. (Pl. 120, fig. 16).
Shell hemispherical, thorny, with a broad, alveolate velum which bears
irregular hollow thorns on the inside and on the free margin (fig. 16).
Feet divergent, irregularly curved, with scattered arborescent lateral
spines, which are irregularly branched, and bear at the distal end of each
branch a small spathilla with four to six teeth. The distal ends of the
feet are dichotomously branched, with stouter simple fork-branches.
_Dimensions._--Length of the shell 0.17, breadth 0.36; length of the feet
0.5 to 0.7.
_Habitat._--North Pacific, Station 252, surface.
15. _Gazelletta melusina_, n. sp. (Pl. 118, fig. 1).
Shell campanulate, spiny. Feet divergent, strongly curved, with scattered
arborescent lateral spines, which are richly and dichotomously branched,
with thin, simple, terminal branches. The distal ends of the feet bear
three or four much larger and stouter branches, which are again
dichotomously branched.
_Dimensions._--Length of the shell 0.2, breadth 0.15; length of the feet
0.5 to 0.8.
_Habitat._--South Pacific, Station 293, depth 2025 fathoms.
Genus 703. _Gorgonetta_,[320] n. gen.
_Definition._--#Medusettida# with twelve articulate feet on the peristome,
six ascending and six alternate descending.
The genus _Gorgonetta_ is the most highly developed of all hitherto
observed Medusettida, and belongs to the most remarkable forms of
Radiolaria. Its general shape is very similar to that of a larva of a
_Geryonia_ or _Carmarina_, in which six interradial larval tentacles are
directed upwards, six alternating perradial permanent tentacles downwards.
The six ascending feet are in all the four species observed smaller, more
or less branched, and armed with spathillæ. The six descending feet are
much larger and covered with very elegant pencils, the single threads of
which bear a double spathilla. The distal ends of the feet are forked or
branched.
1. _Gorgonetta mirabilis_, n. sp. (Pl. 119, figs. 1-4).
Shell cap-shaped, flatly vaulted, or nearly hemispherical, about twice as
broad as long, with smooth surface. Six ascending feet widely divergent,
about twice as long as the breadth of the shell, nearly straight,
arborescent, with numerous curved branches, each of which bears at the
distal end a spathilla with four to six short recurved teeth (fig. 2). Six
descending feet about twice as {1675}long as the six alternate ascending,
nearly straight, covered with numerous elegant pencils. Each pencil is
richly branched, with fifty to one hundred or more thread-like ramules, and
each terminal ramule has two cruciate spathillæ, a larger proximal and a
smaller distal (figs. 3, 4); the four recurved anchor-teeth of the proximal
spathilla are twice as large as those of the distal. The distal end of each
descending foot bears three or four very stout terminal branches, each of
which is about as long as the shell and again trifurcate at the distal end.
_Dimensions._--Length of the shell 0.2 to 0.3, breadth 0.4 to 0.5.
_Habitat._--Tropical Atlantic, Stations 346 to 348, surface.
2. _Gorgonetta geryonia_, n. sp.
Shell hemispherical, twice as broad as long, with short scattered thorns on
the surface. Twelve feet of similar shape to those in the preceding
species, but differing in the following characters:--the six ascending feet
are much smaller, about as long as the breadth of the shell, and each bears
only six to twelve short branches; the six descending feet are about three
times as long as the shell, more or less curved; their pencils much
smaller, and the two spathillæ of each pencil-thread bear five
anchor-teeth. The distal ends are more richly and irregularly branched.
_Dimensions._--Length of the shell 0.4, breadth 0.7.
_Habitat._--Indian Ocean (Cocos Islands), Rabbe, surface.
3. _Gorgonetta carmarina_, n. sp.
Shell flat, cap-shaped, three times as broad as long. Twelve feet similar
in shape to those of the two preceding species, but more irregular in form
and arrangement, and differing in the following characters:--the six
ascending feet are nearly horizontally expanded, one and a half times as
long as the breadth of the shell, with few short branches, each of which
bears a spathilla with six recurved anchor-teeth. The six descending feet
are about five times as long as the shell, irregularly curved, studded with
numerous small pencils, each thread of which bears a double spathilla with
six teeth. The distal ends are irregularly branched.
_Dimensions._--Length of the shell 0.2, breadth 0.7.
_Habitat._--South Pacific, Station 318, depth 2040 fathoms.
4. _Gorgonetta bisenaria_, n. sp.
Shell campanulate, similar to that of _Gazelletta melusina_ (Pl. 118, fig.
1), with smooth surface. Six ascending feet about as long as the shell,
nearly straight, similar to those of _Gorgonetta mirabilis_ (Pl. 119, fig.
1). Six descending feet also similar to those of the latter, but shorter,
about twice as long as the shell, strongly curved, studded with numerous
small pencils, each thread of which has a double spathilla with three
teeth. The distal end of each foot bears a whorl of six to eight irregular
forked branches.
_Dimensions._--Length of the shell 0.5, breadth 0.4.
_Habitat._--Central Pacific, Station 263, surface.
{1676}Genus 704. _Polypetta_,[321] n. gen.
_Definition._--#Medusettida# with numerous (ten to twenty or more)
articulate feet.
The genus _Polypetta_ comprises those Medusettida in which the number of
feet is very large and not limited, usually twenty to thirty or more. The
few specimens of this genus that have been observed are rather different;
and it may be that only the two first species described in the following
lines are true Medusettida; they possess the usual distinctly alveolate
feet, and are derived from the similar _Medusetta_ or _Gazelletta_ simply
by multiplication of the feet. The two other species, however (figured in
Pl. 116, figs. 1, 2, as _Porospathis_), belong perhaps to another family of
PHÆODARIA (Castanellida?); their shell-structure is peculiar and their feet
not distinctly alveolate; they may therefore represent a peculiar genus
_Porospathis_ (Haeckel, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12,
1879, p. 5).
1. _Polypetta polynema_, n. sp.
Shell campanulate, thorny, about as long as broad, with slightly
constricted mouth, similar to that of _Gazelletta orthonema_ (Pl. 120, fig.
10). Shell-wall hollow, with irregular polygonal alveoles. Peristome with a
corona of eighteen divergent, curved, cylindrical feet of unequal size; six
larger primary on the margin of the shell, the other twelve secondary,
between the former, somewhat above the margins at different heights. The
feet are two to three times as long as the shell, irregularly curved and
distinctly alveolate, without appendages.
_Dimensions._--Length of the shell 0.12, breadth 0.11.
_Habitat._--Central Pacific, Station 266, surface.
2. _Polypetta alveolata_, n. sp.
Shell campanulate, thorny, about as long as broad, very similar to that of
_Medusetta craspedota_ (Pl. 120, fig. 4). Shell-wall hollow, with
subregular hexagonal alveoles. Peristome prolonged into a short
funnel-shaped proboscis, twice as long as the similar velum of the latter.
The velum is surrounded by a corona of eight larger and eight to twelve
smaller feet; the larger are about as long as the shell, divergent,
irregularly curved, thorny, and distinctly alveolate; the smaller feet are
scattered above the latter and form an immediate transition to the small
spines of the shell-surface.
_Dimensions._--Length of the shell 0.08, breadth 0.09.
_Habitat._--South Pacific, Station 284, surface.
{1677}3. _Polypetta tabulata_, n. sp. (Pl. 116, figs. 2, 2_a_, 2_b_).
_Porospathis tabulata_, Hæckel, 1879, Sitzungsb. med.-nat. Gesellsch.
Jena, Dec. 12.
Shell subspherical, with elegantly panelled or tabulate surface, composed
of small triangular plates, which are separated by a network of prominent
crests; at each nodal point of the network a small conical thorn arises
(figs. 2_a_, 2_b_). Each triangular plate seems to contain a hollow
alveole, which opens into the shell-cavity (?). On the surface of the shell
are scattered numerous (thirty to forty or more), cylindrical, hollow,
radial spines, which are straight or slightly curved, not distinctly
alveolate, and increase in size towards the mouth. The aboral spines are
scarcely one-third as long as the radius of the shell, whilst the oral
spines are three times as long as its diameter. The proboscis of the
constricted mouth is a hollow cylinder, longer than the shell-radius, and
armed with a corona of fifteen to twenty slender bristle-shaped teeth. The
position of this singular species in this family is doubtful.
_Dimensions._--Diameter of the shell 0.1 to 0.11, length of the peristome
0.07, breadth 0.02.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
4. _Polypetta mammillata_, n. sp. (Pl. 116, figs. 1, 1_a_).
_Porospathis mammillata_, Hæckel, 1879, Sitzungsb. med.-nat., Gesellsch.
Jena, Dec. 12.
Shell subspherical, densely covered with numerous mammiliform hollow
papillæ, between which are scattered single longer, hollow, radial spines;
these are irregularly curved, cylindrical, without distinct alveoles; the
twelve longest are two to three times as long as the shell, divergent in
the oral direction, and surround the base of the peristome in two irregular
alternate circles, each with six spines. The hollow papillæ of the surface,
between which are placed numerous circular pores (or dimples?), open into
the shell-cavity by a small pore (fig. 1_a_); they are perhaps reduced
radial spines. The constricted peristome is conical and prolonged into an
inversely conical proboscis, which is about as long as the radius of the
shell; its dilated mouth is surrounded by a corona of slender, divergent,
bristle-shaped teeth. The position of this species in the family
Medusettida is doubtful; perhaps it is more closely allied to the
Castanellida.
_Dimensions._--Diameter of the shell 0.12; length of the proboscis 0.08,
breadth 0.03; length of the shorter spines 0.1, of the longest spines 0.3.
_Habitat._--North Pacific, Station 252, surface.
Family LXXX. #CASTANELLIDA#, Haeckel, 1879 (Pl. 113).
_Castanellida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec.
12, p. 5.
_Definition._--PHÆODARIA with a spherical or subspherical shell, exhibiting
ordinary lattice-work, with circular or roundish pores. Radial spines
without circles of basal pores. Mouth of the shell large, usually circular
and armed with teeth. Central capsule excentric, placed in the aboral half
of the shell-cavity.
{1678}The family #Castanellida# represents a common and widely distributed
group of PHÆODARIA, which posses a very simple and uniform shell, viz., a
simple lattice-sphere with radial spines and one simple mouth. It may
therefore be easily confounded with the Coscinommida, or those #Sphæroidea#
in which the shell is also a simple lattice-sphere armed with radial spines
(_Astrosphærida simplicia_, p. 209). Indeed the shell of both groups is
very similar, and differs in one important point only; the Castanellida
constantly possess one larger opening in the shell-wall, the shell-mouth,
which is either smooth or armed with a corona of teeth; in the
Coscinommida, however, such a mouth is never present. The living specimens
of both groups, and those shells in which the soft body is preserved, are
very easily distinguished, since the shell encloses in the Coscinommida the
central capsule and the transparent calymma only, whilst the latter,
besides, in the Castanellida contains a voluminous dark brown or green mass
of phæodella, the characteristic phæodium. A closer examination of the
central capsule reveals in all Castanellida the typical operculum, the
astropyle, with the proboscis of the PHÆODARIA, which is never present in
any #Sphæroidea#.
The Castanellida are easily distinguished also from those similar PHÆODARIA
in which the shell is also a lattice-sphere; the lattice-work is constantly
quite simple, as in the similar Coscinommida, never composed of separated
tangential pieces (as in the Aulosphærida), or of porcellanous structure,
with basal circles of pores (as in the Circoporida), or of diatomaceous
structure (as in the Challengerida). The gigantic Orosphærida, which also
in part posses a simple lattice-sphere, differ from the Castanellida in the
absence of the peculiar shell-mouth.
Though the Castanellida belong to the most common PHÆODARIA, and though the
number of individuals, floating on the surface of the tropical seas, is
extraordinarily great, their variety of forms is very small; the six genera
distinguished in the following system differ only in very slight
characters, and the majority of the species are very similar, and often
hardly distinguishable. The seven species figured in Pl. 113 exhibit the
most striking differences which I could distinguish among all the species
observed. The shell usually has the characteristic appearance of a
chestnut, a sphere covered with very numerous short radial spines or
bristles. In the majority of species a certain number of longer thin radial
spines is scattered over the surface; these are usually simple, rarely
branched. The mouth of the shell, corresponding to the proboscis of the
central capsule, and placed in the same radius, is either a quite simple
larger opening with a smooth margin (figs. 3, 5, 7) or is armed with a
corona of teeth (figs. 1, 6).
The size of the shell varies between 0.2 and 0.8 mm., and is usually
between 0.3 and 0.5 mm. Its form is in the majority of species a
geometrical sphere; rarely it is somewhat irregular, slightly ellipsoidal
(prolonged in the axis of the mouth and proboscis), or polyhedral (by
conical protuberances from the bases of the radial spines). {1679}The ideal
fundamental form of the shell, however, is constantly monaxonian, since the
place of the shell-mouth and of the proboscis of the capsule (both lying in
one axis of the sphere), causes a principal axis to be different from all
others. The longer radial spines, quite variable in number and disposition,
are never arranged regularly or symmetrically, and therefore determine no
constant axes.
The lattice-work of the spherical shell offers also but slight differences.
It is usually more or less irregular, with circular or subcircular pores of
unequal sizes. More rarely the network is perfectly regular, with
equidistant circular pores of equal size, and sometimes these are
surrounded by hexagonal frames (fig. 6), as in many #Sphæroidea#. More
rarely the pores are perfectly irregular, roundish or sometimes polygonal,
of unequal sizes and dissimilar forms (fig. 2). The size of the pores is
very variable between 0.01 and 0.05, usually between 0.015 and 0.025. They
are commonly somewhat broader than the bars between them, more rarely
smaller. The substance of the shell-wall is in the the majority of
Castanellida hyaline, transparent (as in the similar #Sphæroidea#); in some
larger forms, however, a network of fine axial filaments is visible in the
lattice (fig. 2), and sometimes this seems to be hollow, with an axial
canal (as in the large Orosphærida). Such an axial filament or fine axial
canal is usually visible in the larger radial spines. The shell-wall of the
Castanellida, however, never exhibits that characteristic structure (with
tangential needles in a cement-like fundamental substance), which we find
in all Circoporida. The latter differ also in the constant presence of
circles of large pores around the bases of the radial spines, which are
never found in the Castanellida. The shell becomes usually stained more or
less purple by carmine, and when burned by fire, becomes of a brown colour.
The inner surface of the shell is always quite smooth, the outer surface
armed with numerous short and thin radial bristles. Sometimes these
bristles or "by-spines" are very short, but never perfectly wanting.
Usually their length is about one-third or one-fourth of the radius of the
shell, often less, rarely more. They arise from the nodal points between
every three or four neighbouring spines, and are commonly very thin and
straight, pointed, with slightly thickened conical basis. Rarely they are
directed not quite radially, but more or less obliquely.
The larger radial spines, which arise between the thin bristles or
"by-spines" and may be opposed to the latter as "main-spines," are wanting
in two genera only, in _Castanarium_ and _Castanella_ (Pl. 113, fig. 6).
They are simple in _Castanidium_ (figs. 2, 5, 7) and _Castanissa_ (fig. 1),
irregularly branched in _Castanopsis_ and _Castanura_ (figs. 3, 4). Their
number and disposition is never regular nor symmetrical (as in the majority
of #Sphæroidea#) and varies even in each single species. In general the
number of main-spines varies between ten and forty (rarely less or more)
usually between twenty and thirty. Their length is commonly about equal to
the diameter of the shell, often somewhat shorter, rarely considerably
longer. Their {1680}thickness is in the majority of species about equal to
the diameter of one or two pores of the lattice. Sometimes they are much
stronger, rarely thinner.
The form of the radial main-spines is not very variable, usually it is
cylindrical or cylindro-conical, rarely angular, prismatic or pyramidal.
Sometimes they are straight (perfectly radial), at other times more or less
irregularly curved. Usually they are simple, rarely branched; the branches
are always very irregular and exhibit a remarkable tendency to unite by
concrescence (figs. 3, 4). Some thicker forms of spines exhibit a
remarkable structure, the surface being covered with small dimples and
spinules between them (fig. 1); sometimes the dimples are hexagonal (fig.
5_a_). In the axis of the thicker spines there is often visible the same
axial filament or funicle which we find in many other PHÆODARIA, more
rarely a hollow axial canal.
The mouth of the shell is usually circular, more rarely polygonal or
irregularly roundish (fig. 2). It is either quite smooth (fig. 3, 5, 7) or
armed with a corona of strong teeth (figs. 1, 4, 6). These teeth are
different from the other spines of the shell; they are much thicker than
the radial bristles, and shorter than the main-spines. Their number varies
between three and twenty, usually between five and seven. They are usually
parallel to the main axis, which is determined by the excentric position of
the mouth and the centre of the sphere (figs. 1, 6). The teeth are usually
conical, more or less irregular in size and form, more rarely of equal
size. The corona of teeth is usually sharply separated from the surrounding
lattice-work of the shell, but has no influence on its regular spherical
form.
The _central capsule_ of the Castanellida immediately determines beyond
doubt their true PHÆODARIAN nature; it lies excentrically in the cavity of
the enclosing shell, and is surrounded at the oral pole by the large and
dark phæodium. The latter covers the radiate operculum of the capsule
membrane and the tubular proboscis, which arises from it and is directed
towards the shell mouth. Usually the diameter of the spherical central
capsule is about one-third of the shell diameter, rarely one-quarter only,
and in a few cases it attains nearly its half. The calymma, therefore, is
larger than the capsule, and fills up the whole cavity of the shell which
is not occupied by the latter. The greater part of the calymma again is
filled up by the dark green or brown, sometimes black phæodella, the
roundish granules which compose the voluminous non-transparent phæodium.
Sometimes the latter proceeds through the mouth and is partially placed
outside the shell (fig. 5).
The astropyle, or the main-opening of the central capsule, is placed on the
oral pole of its main axis, while its radiate operculum and the tubular
proboscis arising from it possess the same structure as in the other
PHÆODARIA. But the two lateral parapylæ or accessory openings which are
present in the majority of the latter seem to be absent in the Castanellida
as well as in the Medusettida and the Challengerida. I could never observe
a trace of them. The proboscis is a small cylindrical tube and is directed
towards the {1681}mouth of the shell, therefore placed in its main axis; it
is usually quite hidden in the dark phæodium, which occupies the oral half
of the shell-cavity, whilst the capsule lies in the aboral half. The large
nucleus of the central capsule and its double membrane present the same
characters as in the other PHÆODARIA.
_Synopsis of the Genera of Castanellida._
-------------------------------------------------------------------------
No long radial main-spines (in addition to the constant short bristles
of the shell-surface).
-------------------------------------------------------------------------
Mouth smooth, 705. _Castanarium_.
Mouth dentate, 706. _Castanella_.
-------------------------------------------------------------------------
Long radial main-spines scattered between the short constant bristles
of the shell-surface.
-------------------------------------------------------------------------
{ Mouth smooth, 707. _Castanidium_.
Main spines simple. {
{ Mouth dentate, 708. _Castanissa_.
{ Mouth smooth, 709. _Castanopsis_.
Main spines branched. {
{ Mouth dentate, 710. _Castanura_.
Genus 705. _Castanarium_,[322] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Castanellida# without radial main-spines, with a smooth
mouth.
The genus _Castanarium_ is the simplest form of all the Castanellida, and
may be regarded as the common ancestral form of this family. The simple
spherical shell has a smooth, toothless mouth and no larger radial spines;
it is densely studded with the simple, radial bristles, which are common to
all Castanellida. The shell therefore is very similar to those species of
the Astrosphæride _Acanthosphæra_, which represent the subgenus
_Rhapidococcus_ (compare above, p. 210, Pl. 26, fig. 3); it differs from
the latter in the possession of the shell-mouth, which is absent in all
#Sphæroidea#.
1. _Castanarium darwini_, n. sp.
Pores regular, circular, hexagonally framed, three times as broad as the
bars. Radial bristles half as long as the radius.
_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.03.
_Habitat._--South Atlantic (east of Patagonia), Station 318, depth 2040
fathoms.
{1682}2. _Castanarium hookeri_, n. sp.
Pores regular, circular, hexagonally framed, twice as broad as the bars.
Radial bristles one-third as long as the radius.
_Dimensions._--Diameter of the shell 0.55, of the pores 0.025.
_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.
3. _Castanarium lyelli_, n. sp.
Pores regular, circular, without hexagonal frames, of the same breadth as
the bars. Radial bristles twice as long as the diameter of one pore.
_Dimensions._--Diameter of the shell 0.24, of the pores 0.015.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
4. _Castanarium lubbocki_, n. sp.
Pores irregularly roundish, about of the same breadth as the roundish,
non-crested bars. Radial bristles one-third as long as the radius.
_Dimensions._--Diameter of the shell 0.36, of the pores 0.01 to 0.02.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
5. _Castanarium huxleyi_, n. sp.
Pores irregularly polygonal, two to three times as broad as the bars,
separated by prominent polygonal crests. Radial bristles half as long as
the radius.
_Dimensions._--Diameter of the shell 0.45, of the pores 0.02 to 0.05.
_Habitat._--South Pacific (off Australia), Station 165, surface.
Genus 706. _Castanella_,[323] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Castanellida# without radial main-spines, with a dentate
mouth.
The genus _Castanella_ comprises the most common and most widely
distributed species of Castanellida. It agrees in general shape with its
ancestral form, the preceding _Castanarium_, differing from it only in the
possession of strong teeth, which form a corona around the mouth.
{1683}1. _Castanella wyvillei_, n. sp. (Pl. 113, fig. 6).
Pores regular, circular, of equal size, hexagonally framed, of the same
breadth as the bars. Radial bristles twice as long as the diameter of one
pore. Mouth with five to six parallel, conical strong teeth, which are
twice as long as a bristle (fig. 6_a_).
_Dimensions._--Diameter of the shell 0.5 to 0.7, of the pores 0.02 to 0.03.
_Habitat._--North Pacific, Stations 252 to 256, surface.
2. _Castanella thomsoni_, n. sp.
Pores regular, circular, of equal size, hexagonally framed, twice as broad
as the bars. Radial bristles about as long as the diameter of one pore.
Mouth with four strong, conical teeth, forming a regular cross, four times
as long as a bristle.
_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.03.
_Habitat._--South Pacific, Stations 295 to 298, surface.
3. _Castanella campbelli_, n. sp.
Pores regular, circular, hexagonally framed, three times as broad as the
bars. Radial bristles half as long as the radius of the shell. Mouth with a
coronet of eight conical, parallel teeth, of the same length as the
bristles, but four to six times as thick.
_Dimensions._--Diameter of the shell 0.4 to 0.45, of the pores 0.025.
_Habitat._--Central Pacific, Stations 270 to 274, surface.
4. _Castanella sloggetti_, n. sp.
Pores subregular, circular, without frames, of different sizes, about twice
as broad as the bars. Radial bristles three times as long as one pore.
Mouth with five or six strong, conical teeth, twice as long as the
bristles.
_Dimensions._--Diameter of the shell 0.3 to 0.36, of the pores 0.02 to
0.03.
_Habitat._--Tropical Atlantic, Stations 347 to 349, surface.
5. _Castanella balfouri_, n. sp.
Pores irregular, roundish, two to three times as broad as the bars.
Bristles about one-fourth as long as the radius. Mouth with four strong
conical teeth, forming a cross, somewhat longer and much thicker than the
bristles.
_Dimensions._--Diameter of the shell 0.22 to 0.28, of the pores 0.01 to
0.02.
_Habitat._--North Pacific, Stations 240 to 245, surface.
{1684}6. _Castanella channeri_, n. sp.
Pores irregular, roundish, two to four times as broad as the bars. Bristles
nearly half as long as the radius. Mouth with seven to nine short conical
teeth, shorter than the bristles, but much thicker.
_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.02 to
0.025.
_Habitat._--North Atlantic, Stations 352 to 354, surface.
7. _Castanella horstoni_, n. sp.
Pores irregular, polygonal, three to four times as broad as the bars.
Bristles about as long as the radius. Mouth with six stout pyramidal teeth,
which are scarcely one-third as long as the radius.
_Dimensions._--Diameter of the shell 0.55, of the pores 0.02 to 0.025.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
Genus 707. _Castanidium_,[324] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Castanellida#, with simple radial main-spines and a simple
smooth mouth.
The genus _Castanidium_ agrees with its ancestral form _Castanarium_ in the
simple shape of the smooth and toothless mouth, but differs from it in the
possession of long radial main-spines, which are scattered between the
constant radial bristles or by-spines of the surface. The shell agrees
therefore in its general shape with the Astrosphæride _Heliosphæra_, as
defined above (p. 217, Pl. 26, fig. 9), but differs from it in the
possession of the shell-mouth wanting in all #Sphæroidea#.
1. _Castanidium willemoesi_, n. sp.
Pores regular, circular, hexagonally framed, twice as broad as the bars.
Bristles three times as long as the diameter of one pore. Radial
main-spines straight, conical, smooth, as long as the radius.
_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.012 to
0.016.
_Habitat._--Central Pacific, Station 263 to 274, surface.
2. _Castanidium wildi_, n. sp.
Pores regular, circular, hexagonally framed, of the same breadth as the
bars. Bristles twice as long as one pore. Radial main-spines straight and
short, cylindrical, with dimpled surface (as in Pl. 113, fig. 1), as broad
as one pore and as long as the diameter of the shell.
_Dimensions._--Diameter of the shell 0.66, of the pores 0.045.
_Habitat._--South Pacific, Station 297, surface.
{1685}3. _Castanidium buchanani_, n. sp. (Pl. 113, fig. 7).
Pores regular, circular, without frames, twice as broad as the bars, of
variable size. Bristles five to six times as long as one pore. Radial
main-spines numerous, straight, slender, cylindrical, about as long as the
diameter of the shell.
_Dimensions._--Diameter of the shell 0.25 to 0.3, of the pores 0.012 to
0.02.
_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.
4. _Castanidium murrayi_, n. sp. (Pl. 113, figs. 5, 5_a_).
Pores subregular, circular, without frames, three times as broad as the
bars. Bristles three times as long as one pore. Radial main-spines
cylindrical, stout, irregularly curved, longer than the shell-diameter,
covered with longish hexagonal dimples, which are separated by a network of
prominent crests (fig. 5_a_).
_Dimensions._--Diameter of the shell 0.4 to 0.5, of the pores 0.02 to
0.025.
_Habitat._--North Atlantic, Station 352 to 354, surface.
5. _Castanidium aldrichi_, n. sp.
Pores subregular, circular, without frames, of variable size, about as
broad as the bars. Bristles four times as long as one pore. Radial
main-spines conico-cylindrical, irregularly curved, straight, about as long
as the radius. (The conical base of the spines is inflated and fenestrated,
therefore the shell is nearly polyhedral.)
_Dimensions._--Diameter of the shell 0.35 to 0.4, of the pores 0.012 to
0.015.
_Habitat._--Central Pacific, Stations 270 to 274, surface.
6. _Castanidium bromleyi_, n. sp.
Pores irregular, roundish, two to four times as broad as the bars. Bristles
half as long as the radius. Radial main-spines cylindrical, straight,
slender, longer than the shell-diameter.
_Dimensions._--Diameter of the shell 0.22 to 0.26, of the pores 0.006 to
0.02.
_Habitat._--Indian Ocean and Southern Pacific, Stations 162 to 169,
surface.
7. _Castanidium bethelli_, n. sp.
Pores irregular, roundish or polygonal, two to three times as broad as the
bars. Bristles one-third as long as the radius. Radial main-spines
conico-cylindrical, irregularly curved, with dimpled surface, somewhat
longer than the radius.
_Dimensions._--Diameter of the shell 0.5 to 0.6, of the pores 0.015 to
0.03.
_Habitat._--North Pacific, Stations 235 to 245, surface.
{1686}8. _Castanidium moseleyi_, n. sp. (Pl. 113, fig. 2).
Pores irregular, roundish or polygonal, two to four times as broad as the
bars. Bristles about as long as the diameter of one pore, or a little
longer. Radial main-spines cylindrical, irregularly curved, somewhat longer
than the diameter of the shell; their base is more or less inflated and
fenestrated, therefore the shell is nearly polyhedral.
_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.01 to 0.04.
_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.
Genus 708. _Castanissa_,[325] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Castanellida# with simple radial main-spines and a dentate
mouth.
The genus _Castanissa_ agrees with the preceding _Castanidium_ in the
possession of large radial main-spines, scattered between the numerous
bristles or by-spines of the surface; but it differs from it in the
possession of teeth around the mouth, identical with those of _Castanella_;
it may be derived therefore either from the latter by development of
main-spines, or from the former by formation of teeth.
1. _Castanissa challengeri_, n. sp. (Pl. 113, fig. 1).
Pores regular, circular, three times as broad as the bars. Bristles
one-fourth as long as the radius. Radial main-spines (about twelve) very
stout, straight, cylindrical, at the distal end conical, pointed, with
dimpled surface, about half as long as the radius. Mouth very large,
circular, about one-third as broad as the shell, with a corona of twelve to
sixteen very large, triangular, parallel teeth.
_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.03.
_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.
2. _Castanissa pearceyi_, n. sp.
Pores regular, circular, twice as broad as the bars. Bristles half as long
as the radius. Radial main-spines (about twenty) slender, cylindrical,
smooth, irregularly curved, about as long as the radius. Mouth large, half
as broad as the radius, with a corona of ten to twelve irregular, slender
teeth.
_Dimensions._--Diameter of the shell 0.5 to 0.6, of the pores 0.02.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
{1687}3. _Castanissa richardsi_, n. sp.
Pores subregular, circular, about as broad as the bars. Bristles twice as
long as one pore. Radial main-spines (about twenty) slender, cylindrical,
irregularly curved, with dimpled surface (like those in Pl. 113, fig.
5_a_). Mouth with a corona of six stout, parallel, triangular teeth.
_Dimensions._--Diameter of the shell 0.3 to 0.35, of the pores 0.015.
_Habitat._--North Atlantic, Station 354, surface.
4. _Castanissa crosbiei_, n. sp.
Pores irregular, roundish, two to three times as broad as the bars.
Bristles one-third as long as the radius. Radial main-spines very numerous,
straight, cylindrical, smooth, about as long as the diameter of the shell.
Mouth with ten or twelve irregular, conical, parallel teeth.
_Dimensions._--Diameter of the shell 0.28, of the pores 0.01 to 0.015.
_Habitat._--North Pacific, Stations 231 to 235, surface.
5. _Castanissa macleani_, n. sp.
Pores irregular, roundish or polygonal, two to four times as broad as the
bars. Bristles about one-fourth as long as the radius. Radial main-spines
numerous, straight, conical, stout, with dimpled surface, shorter than the
radius. Mouth with six to eight irregular conical teeth.
_Dimensions._--Diameter of the shell 0.32, of the pores 0.012 to 0.024.
_Habitat._--Tropical Pacific, Station 268, depth 2900 fathoms.
6. _Castanissa hoylei_, n. sp.
Pores irregular, polygonal, two to three times as broad as the bars.
Bristles nearly half as long as the radius. Radial main-spines (about
thirty) very long and thin, cylindrical, irregularly curved, at the conical
base inflated and fenestrated; shell therefore slightly polyhedral. Mouth
with five strong conical teeth.
_Dimensions._--Diameter of the shell 0.35 to 0.4, of the pores 0.02 to
0.03.
_Habitat._--North Pacific, Station 245 to 250, surface.
Genus 709. _Castanopsis_,[326] Haeckel, 1879, Sitzungsb. med.-nat.
Gesellsch. Jena, Dec. 12, p. 5.
_Definition._--#Castanellida# with branched radial main-spines and a simple
smooth mouth.
The genus _Castanopsis_ differs from its ancestral form _Castanidium_ in
the ramification of the radial main-spines; the branches are usually very
irregular and often partly {1688}confluent. The shell is very similar to
the Astrosphæride _Cladococcus_ (compare above p. 223, Pl. 27), but differs
from it in the possession of the shell-mouth, absent in all #Sphæroidea#.
1. _Castanopsis naresi_, n. sp. (Pl. 113, fig. 3).
Pores subregular, circular, about twice as broad as the bars. Bristles
twice as long as one pore. Radial main-spines somewhat shorter than the
diameter of the shell, straight, cylindrical, in the proximal half simple,
in the distal half irregularly branched, each with ten to twelve partly
confluent branches.
_Dimensions._--Diameter of the shell 0.6 to 0.7, of the pores 0.02 to 0.03.
_Habitat._--Tropical Atlantic, Station 347 to 349, surface.
2. _Castanopsis macleari_, n. sp.
Pores irregular, roundish, two to four times as broad as bars. Bristles
half as long as the radius. Radial main-spines about as long as the radius,
stout and straight, cylindrical, forked at the distal end, with two or
three unequal fork-branches.
_Dimensions._--Diameter of the shell 0.42, of the pores 0.015 to 0.03.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
3. _Castanopsis fergusoni_, n. sp.
Pores irregular, roundish or polygonal, about as broad as the bars.
Bristles three times as long as one pore. Radial main-spines somewhat
longer than the diameter of the shell, cylindrical, with irregular and
partly confluent lateral branches (similar to Pl. 113, fig. 4_a_).
_Dimensions._--Diameter of the shell 0.55, of the pores 0.012 to 0.016.
_Habitat._--North Atlantic, Station 354, surface.
Genus 710. _Castanura_,[327] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch.
Jena, Dec. 12, p. 5.
_Definition._--#Castanellida# with branched radial main-spines and a
dentate mouth.
The genus _Castanura_ differs from the preceding _Castanopsis_ in the
possession of a corona of teeth surrounding the mouth, similar to that of
_Castanissa_. It differs from the latter in the ramification of the radial
main-spines, wherein it agrees with the former. _Castanura_ may therefore
be derived either from _Castanissa_ by ramification of the main-spines, or
from _Castanopsis_ by development of teeth around the mouth.
{1689}1. _Castanura tizardi_, n. sp. (Pl. 113, fig. 4, 4_a_).
Pores regular, circular, without hexagonal frames, twice as broad as the
bars. Bristles twice as long as one pore. Radial main-spines somewhat
longer than the radius, straight, very stout, with irregular lateral
branches, which are partly confluent. Mouth with six strong conical teeth.
_Dimensions._--Diameter of the shell 0.6, of the pores 0.03.
_Habitat._--Tropical Atlantic, Station 346, surface.
2. _Castanura havergali_, n. sp.
Pores regular, circular, hexagonally framed, as broad as the bars. Bristles
three times as long as one pore. Radial main-spines as long as the
shell-diameter, in the basal half simple, in the distal half with
irregular, not confluent, lateral branches. Mouth with ten to twelve
irregular, parallel, conical teeth of different sizes.
_Dimensions._--Diameter of the shell 0.5, of the pores 0.045.
_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.
3. _Castanura swirei_, n. sp.
Pores regular, circular, hexagonally framed, as broad as the bars. Bristles
half as long as the radius. Radial main-spines straight, longer than the
shell-diameter; on the distal end with a few irregular, confluent, lateral
branches. Mouth with six larger and six alternate smaller, parallel,
conical teeth.
_Dimensions._--Diameter of the shell 0.28, of the pores 0.015.
_Habitat._--North Pacific, Station 253, surface.
4. _Castanura carpenteri_, n. sp.
Pores irregular, roundish, twice to four times as broad as the bars.
Bristles about as long as the largest pores. Radial main-spines irregularly
curved, longer than the shell-diameter, with inflated and fenestrated
conical base; in the distal half irregularly branched, with simple, not
confluent, lateral branches. Mouth with six to nine irregular, strong,
conical teeth.
_Dimensions._--Diameter of the shell 0.3, of the pores 0.012 to 0.025.
_Habitat._--South Atlantic, Station 331, depth 1715 fathoms.
Family LXXXI. #CIRCOPORIDA#, Haeckel, 1879 (Pls. 114-117).
_Circoporida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec.
12, p. 5.
_Definition._--PHÆODARIA with a spherical or polyhedral shell, exhibiting a
peculiar solid porcellanous structure, with a stellate circle of radial
pores around the base of the hollow radial spines. Mouth usually with
teeth. Surface of the shell {1690}tabulate, panelled or dimpled. Central
capsule excentric, placed in the aboral half of the shell-cavity.