_Spongocyclia triangularis_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 119,
Taf. vii. fig. 5.
Spongy disk lenticular, in the thicker central part with eleven to twelve
circular, concentric rings, in the thinner, peripheral zone irregularly
spongy. Meshes twice to four times as broad as the bars. (The triangular
form in the specimen figured by Stöhr is accidental, produced by the broken
margin.)
_Dimensions._--Diameter of the disk 0.2 to 0.3, of the meshes 0.006 to
0.008.
_Habitat._--Fossil in Tertiary rocks of Barbados (Haeckel) and Sicily
(Stöhr).
Subgenus 3. _Spongospira_, Stöhr, 1880, Palæontogr., vol xxvi. p. 120.
_Definition._--Spongy framework of the disk in the inner part with spiral
convolutions, in the outer part irregular.
8. _Spongodiscus florealis_, Haeckel.
_Spongospira florealis_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 120,
Taf. vii. fig. 6.
Spongy disk lenticular, in the thicker central part with five to six spiral
convolutions, in the outer peripheral zone irregularly spongy. No radial
beams piercing the framework. Meshes three to four times as broad as the
bars.
_Dimensions._--Diameter of the disk 0.26, of the meshes 0.006 to 0.008.
_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte), Stöhr.
9. _Spongodiscus spiralis_, n. sp.
_Spongospira spiralis_, Haeckel, 1881, Prodromus.
Spongy disk on both sides plain, with twelve to sixteen spiral convolutions
in the central part, with irregular, spongy framework in the outer part,
pierced by numerous interrupted radial beams. Meshes five to six times as
broad as the bars.
_Dimensions._--Diameter of the disk 0.2 to 0.3, of the meshes 0.01 to
0.012.
_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.
{579}Genus 254. _Spongophacus_,[293] Haeckel, 1881, Prodromus, p. 461.
_Definition._--#Spongodiscida# with a simple circular disk, without radial
appendages, on the margin surrounded by a thin porous or solid equatorial
girdle.
The genus _Spongophacus_, represented hitherto only by a single but
interesting species, differs from _Spongodiscus_ by the peculiar girdle
which surrounds the margin of the disk in the equatorial plane. It
simulates the same formation as _Perichlamydium_ in the Porodiscida, and
resembles also _Periphæna_, &c., in the Phacodiscida.
1. _Spongophacus periphæna_, n. sp.
Spongy disk lenticular, with an irregular, dense framework, in the centre
darker than in the peripheral part. Margin of the disk very thin,
surrounded by a broad, circular girdle, lying in the equatorial plane,
about as broad as the half radius of the spongy disk. The inner part of the
girdle is perforated by numerous irregular, small pores, which pass over
gradually into the spongy meshes; the outer part is quite homogeneous,
solid, transparent, with an extremely thin margin.
_Dimensions._--Diameter of the disk 0.2; breadth of the girdle 0.05.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
Subfamily 2. SPONGOTROCHIDA, Haeckel, 1881, Prodromus, p. 461.
_Definition._--#Spongodiscida# with a circular disk, the margin of which is
armed with solid radial spines, situated in the equatorial plane (rarely
also on both sides of the disk with radial spines).
Genus 255. _Spongolonche_,[294] Haeckel, 1881, Prodromus, p. 461.
_Definition._--#Spongodiscida# with two solid marginal spines, opposite in
one equatorial diameter of the disk.
The genus _Spongolonche_ opens the series of the Spongotrochida, or of
those Spongodiscida in which the margin of the disk is armed with solid
radial spines, situated in the equatorial plane. _Spongolonche_ possesses
only two such spines, opposite in one equatorial diameter of the disk; it
corresponds therefore to _Stylocyclia_ among the Coccodiscida, to
_Xiphodictya_ among the Porodiscida.
{580}1. _Spongolonche conostyla_, n. sp..
Spongy disk circular, with irregular framework, without concentric rings.
Both opposite radial spines conical, about as long as the radius of the
disk, and four times as long as broad at the base. Margin of the disk
nearly smooth.
_Dimensions._--Diameter of the disk 0.16; length of the radial spines 0.18,
basal thickness 0.045.
_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.
2. _Spongolonche amphistyla_, n. sp.
Spongy disk circular, with four to six concentric rings in the inner part,
with quite an irregular framework in the outer part. Both opposite radial
spines cylindrical, twice to three times as long as the diameter of the
disk, at the base about as broad as two meshes of the framework. Margin of
the disk ciliated.
_Dimensions._--Diameter of the disk 0.2; length of the radial spines 0.4 to
0.6, basal thickness 0.01.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
Genus 256. _Spongotripus_,[295] Haeckel, 1881, Prodromus, p. 461.
_Definition._--#Spongodiscida# with three solid radial spines on the margin
of the circular or triangular disk.
The genus _Spongotripus_ is characterised by three marginal spines, which
are commonly regularly disposed, more rarely in a bilateral or an irregular
manner. It corresponds to _Trigonocyclia_ among the Coccodiscida, to
_Tripodictya_ among the Porodiscida.
Subgenus 1. _Spongotripodiscus_, Haeckel.
_Definition._--Radial spines of equal size and distance; triangle regular.
1. _Spongotripus regularis_, n. sp.
Spongy disk circular; three radial spines on its margin of equal size and
equidistant, strong, conical, about as long as the diameter of the disk,
and five times as long as broad at the base.
_Dimensions._--Diameter of the disk 0.15; length of the spines 0.16, basal
breadth 0.03.
_Habitat._--Pacific, central area, Station 272, surface.
{581}2. _Spongotripus neumayri_, Haeckel.
_Spongechinus neumayri_, Dunikowski, 1882, Denskchr. d. k. Akad. d. Wiss.
Wien, xlv. p. 28, Taf. v. fig. 59.
Spongy disk circular, nearly spherical; three radial spines on its margin
of equal size and equidistant, pyramidal, nearly as long as the diameter of
the disk, and three times as long as broad at the base.
_Dimensions._--Diameter of the disk 0.15 to 0.2; length of the spines 0.11,
basal breadth 0.04.
_Habitat._--Fossil in the Jura of the Alps and in Tertiary rocks of
Barbados.
3. _Spongotripus strepsiceros_, n. sp.
Spongy disk circular; three radial spines on its margin of equal size and
equidistant, angular, twice as long as the diameter of the disk, spirally
twisted like the horns of Antilope strepsiceros.
_Dimensions._--Diameter of the disk 0.15; length of the spines 0.3, basal
breadth 0.02.
_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.
Subgenus 2. _Spongotripodium_, Haeckel.
_Definition._--Radial spines of different size or at different distances;
triangle either isosceles or irregular.
4. _Spongotripus ypsilon_, n. sp.
Spongy disk triangular, isosceles, with convex sides; three spines angular,
of different size and at different distances; the odd spine straight and
twice as long as the two paired spines, which are more approximated and
curved concavely one to the other, like y.
_Dimensions._--Diameter of the disk 0.12; length of the odd spine 0.2, of
the paired spines 0.1, basal breadth 0.04.
_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.
5. _Spongotripus irregularis_, n. sp.
Spongy disk circular; three spines conical, irregularly curved, all three
of different size, and at irregular distances; once to three times as long
as the diameter of the disk; margin of the disk thorny.
_Dimensions._--Diameter of the disk 0.1; length of the spines 0.1 to 0.3,
basal breadth 0.05.
_Habitat._--South Pacific, Station 300, depth 1375 fathoms.
{582}Genus 257. _Spongostaurus_,[296] Haeckel, 1881, Prodromus, p. 461.
_Definition._--#Spongodiscida# with four solid radial spines on the margin
of the circular or square disk, commonly crossed in two equatorial
diameters perpendicular one to another.
The genus _Staurodictya_ exhibits four marginal spines in cross form.
Commonly the cross is regular and rectangular, the four spines being
opposite in pairs in two perpendicular diameters; sometimes more or less
irregular. The genus repeats _Staurodictya_ among the Porodiscida,
_Staurocyclia_ among the Coccodiscida.
1. _Spongostaurus cruciatus_, n. sp.
Spongy disk circular; four radial spines on its margin opposite in two
crossed equatorial diameters, perpendicular one to another, conical, about
as long as the diameter of the disk.
_Dimensions._--Diameter of the disk 0.16; length of the spines 0.18, basal
breadth 0.04.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
2. _Spongostaurus serratus_, n. sp.
Spongy disk circular; four crossed radial spines very large, twice to three
times as long as the diameter of the central disk, serrated on both edges,
with two rows of strong conical perpendicular teeth (similar to the saw of
_Pristis antiquorum_).
_Dimensions._--Diameter of the disk 0.1; length of the spines 0.2 to 0.3,
breadth 0.02.
_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.
3. _Spongostaurus hastatus_, n. sp.
Spongy disk square, with concave sides; four crossed radial spines
cylindrical, on the broader distal end spear-shaped or nearly lanceolate,
one and a half times as long as the diameter of the disk.
_Dimensions._--Diameter of the disk 0.13; length of the spines 0.2, basal
breadth 0.01, distal breadth 0.03.
_Habitat._--Tropical Atlantic, Station 347, surface.
4. _Spongostaurus quadratus_, n. sp.
Spongy disk square, with rectilinear sides; four crossed radial spines
pyramidal, arising from the corners of the square, about as long as its
half diagonal.
_Dimensions._--Diameter of the disk 0.16; length of the spines 0.08, basal
breadth 0.02.
_Habitat._--Pacific, central area, Station 271, surface.
{583}Genus 258. _Stylotrochus_,[297] Haeckel, 1862, Monogr. d. Radiol., p.
463.
_Definition._--#Spongodiscida# with numerous solid radial spines on the
margin of the disk (five to ten or more), all situated in the equatorial
plane.
The genus _Stylotrochus_ comprises those Spongodiscida in which the margin
of the circular disk bears numerous radial spines. All these spines lie in
the same equatorial plane, whilst in the following genus they are disposed
over the whole surface of the disk. _Stylotrochus_ corresponds to
_Astrocyclia_ among the Coccodiscida, to _Stylodictya_ among the
Porodiscida. The spongy framework of the disk is either quite irregular
(_Stylotrochiscus_), or includes in the middle part some concentric
circular rings (_Stylospongia_).
Subgenus 1. _Stylotrochiscus_, Haeckel.
_Definition._--Spongy framework of the whole disk irregular, without
concentric circular rings or spiral convolutions.
1. _Stylotrochus arachnius_, Haeckel.
_Spongotrochus arachnius_, Haeckel, 1862, Monogr. d. Radiol., p. 464.
Spongy framework of the whole disk irregular. Eight to twelve marginal
spines very long and thin, bristle-shaped, twice to four times as long as
the diameter of the disk. (Very similar to the common _Stylodictya
arachnia_, but without concentric circular rings and sieve-plates, with
quite irregular network of fine bars.)
_Dimensions._--Diameter of the disk 0.12 to 0.15; length of the radial
spines 0.2 to 0.6, basal breadth 0.001.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific,
surface; also fossil in Tertiary rocks of Barbados and the Mediterranean.
2. _Stylotrochus craticulatus_, Haeckel.
_Spongotrochus craticulatus_, Stöhr, 1880, Palæontogr., vol. xxvi. p.
118, Taf. vi. fig. 12.
? _Spongodiscus aculeatus_, Ehrenberg, 1854, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 246.
Spongy framework of the whole disk irregular. Sixteen to twenty short
marginal spines (twice to four times as long as the diameter of one mesh of
the framework), free prolongations of internal radial beams which arise
from the darker centre of the disk. (The interruption of the disk-margin on
one point of its circumference, figured by Stöhr as osculum or
"Mündungs-Oeffnung," is probably an accidental abnormality; I did not find
it in other specimens.)
{584}_Dimensions._--Diameter of the disk 0.2 to 0.25; length of the radial
spines 0.005 to 0.018, basal breadth 0.001 to 0.003.
_Habitat._--Pacific, central area, Stations 266 to 268, surface; fossil in
Barbados and Sicily.
3. _Stylotrochus helianthus_, n. sp.
Spongy framework of the whole disk irregular. Thirty to fifty very large,
conical radial spines, about as long as the diameter of the disk, and at
the base two to four times as broad as one mesh of the framework (without
internal prolongations).
_Dimensions._--Diameter of the disk 0.15 to 0.2; length of the radial
spines 0.16 to 0.24, basal breadth 0.008 to 0.016.
_Habitat._--Pacific, central area, Station 272, surface.
4. _Stylotrochus rhabdostylus_, Haeckel.
_Spongosphæra rhabdostyla_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
Wiss. Berlin, p. 256, Taf. xxvi. figs. 1, 2.
Spongy framework of the whole disk irregular. Four very large marginal
primary spines crossed in two equatorial diameters, perpendicular one to
another, and between them numerous (twelve to twenty or more) smaller
secondary spines. The latter arise from the margin, whilst the former
pierce the disk and are nearly united in its centre. All the spines are
cylindrical, the smaller as broad as one mesh, the larger three to six
times as broad.
_Dimensions._--Diameter of the disk 0.2; length of the four main spines
0.15 to 0.3, breadth 0.01 to 0.02; length of the accessory spines 0.05 to
0.1, breadth 0.005.
_Habitat._--Fossil in the rocks of Barbados.
5. _Stylotrochus heteracanthus_, Haeckel.
_Spongotrochus heteracanthus_, Haeckel, 1862, Monogr. d. Radiol., p. 464.
Spongy framework of the whole disk irregular. Ten very long needle-shaped
marginal spines (symmetrically distributed), and between them numerous very
fine, shorter, accessory, bristle-shaped spines.
_Dimensions._--Diameter of the disk 0.16; length of the main spines 0.16,
basal breadth 0.002; length of the secondary spines 0.03.
_Habitat._--Mediterranean (Messina), surface.
Subgenus 2. _Stylospongia_, Haeckel, 1862, Monogr. d. Radiol., p. 473.
_Definition._--Spongy framework of the disk in the inner part with
concentric rings or spiral convolutions, in the outer part quite irregular.
{585}6. _Stylotrochus huxleyi_, Haeckel.
_Stylospongia huxleyi_, Haeckel, 1862, Monogr. d. Radiol., p. 473, Taf.
xxviii. fig. 7.
Spongy framework of the disk in the inner part with five concentric rings,
in the outer part quite irregular. Ten marginal spines, conical at the
base, about as long as the radius of the disk, without inner piercing
prolongations.
_Dimensions._--Diameter of the disk 0.12; length of the radial spines 0.06,
basal breadth 0.003.
_Habitat._--Mediterranean (Messina), Haeckel.
7. _Stylotrochus geddesii_, n. sp. (Pl. 41, fig. 11).
_Stylospongidium geddesii_, Haeckel, 1881, Atlas (pl. xli. fig. 11).
Spongy framework of the disk in the inner part with four to eight
concentric rings (or partially spiral convolutions), in the outer part
quite irregular. Thirty to fifty pyramidal marginal spines of variable
size, one-fourth to one-half as long as the radius of the disk, outer
prolongations of inner piercing radial beams, which arise from various
concentric rings. I call this interesting species, which is intermediate
between _Stylodictya_ and _Stylotrochus_, in honour of the morphologist Mr.
Patrick Geddes of Edinburgh.
_Dimensions._--Diameter of the disk 0.15 to 0.25; length of the radial
spines 0.03 to 0.06, basal breadth 0.004 to 0.01.
_Habitat._--Pacific, central area, Stations 270 to 274, in 2350 to 2925
fathoms.
Genus 259. _Spongotrochus_,[298] Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 844.
_Definition._--#Spongodiscida# with numerous solid radial spines (five to
ten or more), which are scattered over the whole surface and the margin of
the disk, or regularly disposed on both sides of it.
The genus _Spongotrochus_ differs from the foregoing and nearly allied
genus by the distribution of the numerous radial spines. These are not
confined to the margin of the disk, but also scattered on its whole
surface, and sometimes symmetrically disposed on both its sides in a
regular manner. Also in this genus the spongy framework is sometimes quite
irregular (_Spongotrochiscus_), at other times in the middle part with
enclosed concentric rings (_Stylospongidium_).
Subgenus 1. _Spongotrochiscus_, Haeckel, 1862, Monogr. d. Radiol., p. 463.
_Definition._--Spongy framework of the whole disk irregular, without
concentric rings or spiral convolutions.
{586}1. _Spongotrochus brevispinus_, Haeckel.
_Spongotrochus brevispinus_, Haeckel, 1862, Monogr. d. Radiol., p. 462,
Taf. xxvii. figs. 4, 5.
Spongy framework of the whole disk irregular, everywhere equal. The whole
surface of the disk covered with numerous short, needle-shaped, radial
spines, about as long as the thickness of the disk, which is one-fifth of
its diameter.
_Dimensions._--Diameter of the disk 0.18; length of the radial spines 0.03
to 0.04, basal breadth 0.002.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
2. _Spongotrochus multispinus_, n. sp.
Spongy framework of the whole disk irregular, in the centre darker. The
whole surface of the disk covered with numerous conical radial spines,
about as long as the radius of the disk.
_Dimensions._--Diameter of the disk 0.22; length of the radial spines 0.1,
basal breadth 0.008.
_Habitat._--Pacific, central area, Stations 271 to 274, surface.
3. _Spongotrochus longispinus_, Haeckel.
_Spongotrochus longispinus_, Haeckel, 1862, Monogr. d. Radiol., p. 463,
Taf xxvii. figs. 2, 3.
Spongy framework of the whole disk irregular, everywhere equal. Surface
thorny. Twenty long, needle-shaped, radial spines, about as long as the
diameter of the disk, symmetrically distributed in pairs on both flat sides
of the disk, so that the opposite pairs lie in five equidistant, meridian
planes (compare the figures).
_Dimensions._--Diameter of the disk 0.2; length of the twenty radial spines
0.2, basal breadth 0.001.
_Habitat._--Mediterranean (Messina), surface.
Subgenus 2. _Stylospongidium_, Haeckel, 1881, Prodromus, p. 460.
_Definition._--Spongy framework of the disk in the inner part with
concentric rings or spiral convolutions, in the outer part quite irregular.
4. _Spongotrochus scutella_, n. sp.
_Spongotrochus ehrenbergii_, Bütschli, 1882, L. N. 41, Taf. xxvi. figs.
1_a_, 1_b_.
Spongy framework of the disk in the inner part with four to six concentric
rings, in the outer part quite irregular. The whole surface of the disk
covered with bristle-shaped radial spines, about half as long as the radius
of the disk.
_Dimensions._--Diameter of the disk 0.24; length of the radial spines 0.06,
basal breadth 0.02.
_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.
{587}5. _Spongotrochus parma_, n. sp.
Spongy framework of the disk in the inner part with five to eight spiral
convolutions (or partly concentric rings), in the outer part quite
irregular. Thirty to forty long, bristle-shaped, radial spines, about as
long as the diameter of the disk, disposed on both flat sides of the disk,
but not on the margin.
_Dimensions._--Diameter of the disk 0.16; length of the radial spines 0.18,
basal breadth 0.003.
_Habitat._--South Atlantic, Station 325, surface.
Subfamily 3. SPONGOBRACHIDA, Haeckel, 1881, Prodromus, p. 461.
_Definition._--#Spongodiscida# with two or more (commonly three or four)
spongy radial arms on the margin of the disk, situated in its equatorial
plane (with or without a connecting patagium between the arms).
Genus 260. _Spongolena_,[299] n. gen.
_Definition._--#Spongodiscida# with two opposite spongy arms on the margin
of the disk, without a connecting patagium.
The genus _Spongolena_ opens the series of the Spongobrachida, or of the
Spongodiscida provided with radial spongy arms on the margin of the disk.
_Spongolena_ is the most simple form of this subfamily, and bears only two
simple opposite arms, without a connecting patagium. It corresponds to
_Amphibrachium_ (Porodiscida) and to _Diplactura_ (Coccodiscida). Also
there is no patagium. _Spongolena_ may easily be confounded with
_Spongurus_ (compare my Prodromus, 1881, p. 461); but in the true
_Spongurus_ (an ellipsoid) the transverse section is circular, in
_Spongolena_ elliptical.
1. _Spongolena rhopalura_, n. sp.
Arms club-shaped, three times as long as broad, at the rounded distal end
twice as broad as at the base, and twice as long as the diameter of the
circular central disk. Surface nearly smooth.
_Dimensions._--Radius of the arms (or the distance from the centre to the
distal arm-end) 0.16, distal breadth 0.05, basal breadth 0.03.
_Habitat._--Pacific, central area, Station 273, depth 2350 fathoms.
2. _Spongolena spongura_, n. sp.
Arms nearly cylindrical, twice as long as broad, and a little longer than
the diameter of the elliptical central disk. Surface thorny, some longer
bristle-shaped spines on the distal end of the {588}arms. (Very similar to
the ellipsoid _Spongurus cylindricus_, Monogr. d. Radiol., p. 465, Taf.
xxvii. fig. 1, but differs in the compressed lenticular (not ellipsoidal)
form of the central disk; the transverse section of the arm is elliptical,
not circular.)
_Dimensions._--Radius of the arms 0.1, breadth 0.04.
_Habitat._--Pacific, central area, Station 270, depth 2925 fathoms.
3. _Spongolena cypselura_, n. sp.
Arms nearly triangular, not longer than broad, about half as large as the
elliptical central disk, at the broader distal end with two very large,
widely divergent lateral spines, and between them several smaller, like the
tail of a swallow. Surface thorny.
_Dimensions._--Radius of the arms 0.2, distal breadth (without spines)
0.15, basal breadth 0.07.
_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.
Genus 261. _Spongobrachium_,[300] Haeckel, 1881, Prodromus, p. 461.
_Definition._--#Spongodiscida# with two opposite spongy arms on the margin
of the disk, connected by a spongy patagium of different texture.
The genus _Spongobrachium_ differs from the foregoing only in the loose
spongy patagium, which envelops both opposite spongy arms. It corresponds
to _Amphymenium_ among the Porodiscida and to _Amphiactura_ among the
Coccodiscida.
1. _Spongobrachium ellipticum_, Haeckel.
_Spongocyclia elliptica_, Haeckel, 1862, Monogr. d. Radiol., p. 470, Taf.
xxviii. fig. 2.
_Spongodiscus ellipticus_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 844.
Arms nearly square, scarcely as long and broad as the radius of the
circular central disk, at the broader distal end truncated. Patagium
complete, enveloping the whole disk with the arms, and forming a larger
elliptical disk of looser framework. (In my Monograph, 1862, _loc. cit._, I
had not distinguished the opposite darker arms, opposite in the longer axis
of the elliptical disk, from the enveloping looser framework of the
patagium. In larger specimens of the Challenger collection this distinction
is very evident.)
_Dimensions._--Radius of the arms 0.12, breadth 0.05; major axis of the
elliptical patagium 0.24, minor 0.16.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
2. _Spongobrachium lanceolatum_, n. sp.
Arms club-shaped, twice as long as broad, at the distal end pointed, five
times as long as the radius of the circular central disk. Patagium
complete, enveloping the whole disk with the arms, {589}and forming a
larger lanceolate disk of looser framework. (Similar in form to
_Amphymenium pupula_, Pl. 44, fig. 8, but with an irregular spongy
framework and pointed ends.)
_Dimensions._--Radius of the arms 0.16, breadth 0.05; major axis of the
lanceolate patagium 0.32, minor axis 0.12.
_Habitat._--Pacific, central area, Station 270, surface.
Genus 262. _Rhopalodictyum_,[301] Ehrenberg, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 830.
_Definition._--#Spongodiscida# with three spongy arms on the margin of the
circular or triangular disk, without a connecting patagium.
The genus _Rhopalodictyum_ comprises those very common forms of
Spongodiscida in which the margin of the disk is provided with three
simple, free, spongy arms. It corresponds to _Dictyastrum_ and
_Rhopalastrum_ among the Porodiscida, to _Trigonactura_ among the
Coccodiscida. The typical species of this genus is _Rhopalodictyum
abyssorum_ of Ehrenberg, the only species figured by him. His diagnosis of
the genus was very insufficient, and agreed with that of his _Dictyastrum_
(compare above the improved diagnosis of this genus, p. 526, and my
Monograph, p. 466).
Subgenus 1. _Rhopalodictya_, Haeckel.
_Definition._--Triangular shell regular, with three arms of equal size and
equidistant.
1. _Rhopalodictyum abyssorum_, Ehrenberg.
_Rhopalodictyum abyssorum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d.
Wiss. Berlin, p. 299, Taf. viii. fig. 17.
Arms of equal size and equidistant, club-shaped, about as long as the
diameter of the triangular central disk, and a little longer than the
breadth of the pear-shaped rounded distal end. Surface rough.
_Dimensions._--Radius of the arms 0.11, basal breadth 0.03, distal breadth
0.06.
_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific; tropical zone,
surface.
2. _Rhopalodictyum truncatum_, Ehrenberg.
_Rhopalodictyum truncatum_, Ehrenberg, 1861, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 301.
? _Dictyastrum angulatum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 289, Taf. viii. fig. 18.
Arms of equal size and equidistant, nearly square, with straight edges,
towards the truncated end a little broader, about of the same diameter as
the central triangular disk. This species is indicated {590}by Ehrenberg
only by the short diagnosis, "Radiis stellæ tribus apice truncatis." It is
probably identical with his figure of _Dictyastrum angulatum_ (_loc.
cit._). This latter name I have retained for the similar Porodiscid (above,
p. 526), mainly because the genera _Dictyastrum_ and _Rhopalodictyum_,
according to the insufficient diagnosis of Ehrenberg, seem to be identical.
(Compare my Monograph, 1862, p. 466.)
_Dimensions._--Radius of each arm 0.13, basal breadth 0.09, distal breadth
0.1.
_Habitat._--Tropical Pacific, Philippine Sea, Station 200, depth 250
fathoms; Atlantic (Mexican Gulf Stream).
3. _Rhopalodictyum subacutum_, Ehrenberg.
_Rhopalodictyum subacutum_, Ehrenberg, 1861, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 301.
Arms of equal size and equidistant, club-shaped, three times as long as the
diameter of the central disk, which equals the breadth of the thickened
distal end; the latter is armed with a strong pyramidal terminal spine.
(The diagnosis of Ehrenberg is "Radiis stellæ tribus, apice cuneatis
subacutis.")
_Dimensions._--Radius of the arms 0.2, basal breadth 0.04, distal breadth
0.07.
_Habitat._--North Atlantic, surface and various depths; Greenland; Mexican
Gulf Stream; Færöe Channel (John Murray).
4. _Rhopalodictyum bifidum_, n. sp.
Arms of equal size and equidistant, in the distal half forked, twice as
long as the diameter of the central disk; both fork branches half as broad
as the simple basal part, truncated at the distal end.
_Dimensions._--Radius of the arms 0.16, basal breadth 0.08, distal breadth
0.04.
_Habitat._--North Pacific, Station 237, surface.
Subgenus 2. _Triactinosphæra_, Dunikowski, 1882, Denkschr. d. k. Akad. d.
Wiss. Wien, vol. 45, ii. p. 192.
_Definition._--Triangular shell bilateral or irregular, with three arms of
different size or distance.
5. _Rhopalodictyum zittelii_, Haeckel.
_Triactinosphæra zittelii_, Dunikowski, 1882, Denkschr. d. k. Akad. d.
Wiss, Wien, vol. 45, ii. p. 192.
Arms of different size and at unequal distances, one odd arm being a little
shorter than the two paired arms; the odd angle between the latter is
larger than the paired angles between them and the {591}former. Arms
club-shaped, their basal semi-cylindrical, half as broad as the spherical
distal half, which bears a strong, conical, terminal spine. The discoverer
of this remarkable, very old, Liassic species, Dunikowski, supposes that it
is not a true Discoid, from the absence of a central disk; in my opinion
the central disk (nearly spherical) has the same relation to the arms as in
many other #Discoidea#, their equatorial plane is the same.
_Dimensions._--Radius of the odd arm 0.18, of the paired arms 0.24; basal
breadth 0.08, distal breadth 0.16.
_Habitat._--Fossil in the Alpine Lias, Schafberg, near Salzburg,
Dunikowski.
6. _Rhopalodictyum elongatum_, n. sp.
Arms of different size and at unequal distances, one odd arm being twice as
long as both paired arms; the odd angle between the latter much larger than
both equal paired angles. Arms nearly cylindrical, little flattened, three
to six times as long as broad, with rounded blunt distal end.
_Dimensions._--Radius of the arms 0.15 to 0.3, breadth 0.05.
_Habitat._--Pacific, central area, Station 274, surface.
7. _Rhopalodictyum curvatum_, n. sp.
Arms of different size and at unequal distances, irregular, more or less
curved, nearly cylindrical, five to ten times as long as broad, with
rounded blunt distal end. (There were observed only two specimens of this
remarkable irregular species; in one specimen all three arms were simple,
in the other one odd arm forked. The length of the arms and the size of the
angles between them seems to be very different and variable.)
_Dimensions._--Radius of the arms 0.3 to 0.6 to 1.15, breadth 0.06 to 0.12.
_Habitat._--Pacific, central area, Station 271, surface.
Genus 263. _Dictyocoryne_,[302] Ehrenberg, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 830.
_Definition._--#Spongodiscida# with three spongy arms on the margin of the
circular or triangular disk, connected by a spongy patagium of different
texture.
The genus _Dictyocoryne_ differs from the foregoing _Rhopalodictyum_ only
in the patagium, connecting the three spongy arms, and bears to it the same
relation as in the Porodiscida _Euchitonia_ does to _Rhopalastrum_. The
typical species of this genus is _Dictyocoryne profunda_, the only species
figured by Ehrenberg. After his {592}insufficient diagnosis _Dictyocoryne_
was identical with his _Spongaster_ (compare my Monograph, p. 467); but as
the type of this latter genus (_Spongaster tetras_) figured by him, 1872,
had four crossed arms, we retain this genus here separate.
Subgenus 1. _Dictyocorynula_, Haeckel.
_Definition._--Triangular shell regular, with three arms of equal size and
equal distance.
1. _Dictyocoryne profunda_, Ehrenberg.
_Dictyocoryne profunda_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 307, Taf. vii. fig. 23.
Arms of equal size and equidistant, club-shaped, in the outer circular half
three times as broad as in the inner cylindrical half, and much larger than
the small triangular central disk. Patagium complete, forming an
equilateral triangle with rounded corners.
_Dimensions._--Radius of the arms 0.14, basal breadth 0.025, distal breadth
0.07.
_Habitat._--Pacific, Philippine Sea, depth 3300 fathoms, Ehrenberg; Station
198, depth 2150 fathoms; Station 274, depth 2750 fathoms.
2. _Dictyocoryne tetradiscus_, n. sp.
Arms of equal size and equidistant, club-shaped, their outer circular half
is quite as large as the circular central disk, and is connected with it by
the thin cylindrical inner half, which is scarcely one-fourth as broad.
Patagium complete, forming an equilateral triangle with rounded corners and
convex sides.
_Dimensions._--Radius of the arms 0.16, basal breadth 0.02, distal breadth
0.08.
_Habitat._--Pacific, central area, Stations 271 to 274, in 2350 to 2750
fathoms.
3. _Dictyocoryne euchitonia_, Haeckel.
_Dictyocoryne euchitonia_, Haeckel, 1862, Monogr. d. Radiol., p. 468.
Arms of equal size and equidistant, lanceolate, twice as long as broad in
the distal part, and three times as long as the small circular central
disk. Patagium complete, forming an equilateral triangle with pointed
corners. (Very similar to _Euchitonia köllikeri_, Monograph, 1862, p. 511,
Taf. xxxi. fig. 6, but quite spongy, not concentric.)
_Dimensions._--Radius of the arms 0.15, basal breadth 0.03, distal breadth
0.06.
_Habitat._--Mediterranean (Messina), Haeckel.
{593}4. _Dictyocoryne trigona_, n. sp.
Arms of equal size and equidistant, lanceolate, three times as long as
broad in the middle part, and as the diameter of the triangular central
disk; their distal end armed with a strong conical radial spine. Patagium
complete, forming an equilateral triangle with pointed corners.
_Dimensions._--Radius of the arms 0.2, basal breadth 0.02, distal breadth
0.06.
_Habitat._--North Atlantic, Canary Islands, surface.
Subgenus 2. _Dictyocorynium_, Haeckel.
_Definition._--Triangular shell bilateral or irregular, with three arms of
different sizes or at different distances.
5. _Dictyocoryne charybdaea_, Haeckel.
_Spongocyclia charybdaea_, Haeckel, 1862, Monogr. d. Radiol., p. 472,
Taf. xxviii. figs. 5, 6.
_Spongodiscus charybdaeus_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 844.
Arms at different distances, nearly equilateral triangular, scarcely half
as long as the radius of the large circular central disk. Both paired arms
touching at their bases, separated by a great distance from the opposite
odd arm. Patagium complete, nearly pentagonal. (The illustration in my
Monograph, in the coloured plate xxviii., is better than my description, as
I had not exactly separated the arms from the patagium.)
_Dimensions._--Radius of the arms 0.18, basal breadth 0.08.
_Habitat._--Mediterranean (Messina), surface.
6. _Dictyocoryne pentagona_, Stöhr.
_Dictyocoryne pentagona_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 118,
Taf. vii. fig. 2.
Arms at different distances, club-shaped, little longer than broad at their
rounded distal end. Both paired arms smaller and more approximate than the
opposite odd arm. Patagium complete, very large, enveloping the whole
shell, and forming a pentagon with rectilinear base and transverse
constriction, and with five rounded corners.
_Dimensions._--Radius of the arms 0.1 to 0.15, middle breadth 0.04.
_Habitat._--Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.
7. _Dictyocoryne agrigentina_, Stöhr.
_Dictyocoryne agrigentina_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 118,
Taf. vii. fig. 1.
Arms at different distances, club-shaped, about twice as long as broad, and
smaller than the large triangular central disk. Both paired arms smaller
and more approximate than the opposite odd {594}arm. Patagium incomplete,
enveloping only the basal half of the arms as a circular spongy disk of
loose framework.
_Dimensions._--Radius of the arms 0.18, basal breadth 0.05, distal breadth
0.08.
_Habitat._--Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.
8. _Dictyocoryne echinata_, n. sp.
Arms unequal and at different distances, club-shaped, in the distal half
twice as broad as in the basal half, three times as long as the small
triangular central disk, at their distal end armed with one larger and
several smaller conical spines. Both paired arms with touching bases, and
only half as large as the doubly remote odd arm. Patagium incomplete,
enveloping only the basal half of the arms, and forming a circular disk of
looser framework. Surface thorny.
_Dimensions._--Radius of the arms 0.15 to 0.2, basal breadth 0.03, distal
breadth 0.06.
_Habitat._--South Atlantic, Station 325, surface.
Genus 264. _Spongasteriscus_,[303] Haeckel, 1862, Monogr. d. Radiol., p.
474 (_sensu restricto_).
_Definition._--SPONGODISCIDA with four spongy arms on the margin of the
circular or quadrangular disk, crossed in two equatorial diameters, without
a connecting patagium.
The genus _Spongasteriscus_ (in the restricted definition here stated)
exhibits on the margin of the disk four spongy arms, which form either a
regular or a bilateral cross. It corresponds to _Stauralastrum_ and
_Myelastrum_ among the Porodiscida, to _Astractura_ among the Coccodiscida.
Subgenus 1. _Spongasteriscinus_, Haeckel.
_Definition._--Cross formed by the four arms regular, rectangular, with
equal-sized and equidistant arms.
1. _Spongasteriscus ovatus_, n. sp.
Arms at equal distances, forming a regular, rectangular cross, egg-shaped,
with a broader rounded distal end, one and a third times as long as broad,
and three times as long as the radius of the central disk; in the latter
three to four concentric rings.
_Dimensions._--Radius of the arms 0.1, greatest breadth 0.06.
_Habitat._--Western Tropical Pacific, Station 225.
{595}2. _Spongasteriscus clavatus_, n. sp.
Arms at equal distances, forming a regular, rectangular cross, club-shaped,
about as long as the diameter of the central disk, and at their rounded
distal end one and a third times as long as broad, at their narrow base
only one third as broad. In the centre five to six concentric rings.
_Dimensions._--Radius of the arms 0.13, distal breadth 0.06, basal breadth
0.02.
_Habitat._--Pacific, central area. Station 271, surface.
3. _Spongasteriscus mucronatus_, n. sp.
Arms at equal distances, forming a regular, rectangular cross, club-shaped,
three times as long as the radius of the central disk, in the distal half
nearly circular, three to four times as broad as at the narrow base. The
rounded distal end armed with a strong pyramidal spine. In the centre no
concentric rings. (Similar to _Stauralastrum rhopalophorum_, Pl. 45, fig.
1, but quite spongy.)
_Dimensions._--Radius of the arms 0.12, basal breadth 0.03, distal breadth
0.02.
_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.
4. _Spongasteriscus furcatus_, n. sp.
Arms at equal distances, forming a regular, rectangular cross, in the
distal third forked; both fork branches half as long as the basal undivided
part of the arm, which is twice as long as broad. Distal ends of the eight
branches blunt, rounded. In the central disk no concentric rings.
_Dimensions._--Radius of the arms 0.12, basal breadth 0.03; distal breadth
of the branches 0.02.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
5. _Spongasteriscus armatus_, n. sp.
Arms at equal distances, forming a rectangular, regular cross, in the
distal half forked; both fork branches of the same length as the basal
undivided part of the arm, which is nearly square. Distal ends of the eight
branches armed with a strong pyramidal spine. In the central disk no
concentric rings. (Similar to _Dicranastrum cornutum_, Pl. 45, fig. 2, but
quite spongy.)
_Dimensions._--Radius of the arms 0.18, basal breadth 0.03, distal breadth
0.015.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
Subgenus 2. _Spongasterisculus_, Haeckel.
_Definition._--Cross formed by the four arms, bilateral or irregular, with
the arms at different distances.
{596}6. _Spongasteriscus quadricornis_, Haeckel.
_Spongasteriscus quadricornis_, Haeckel, 1862, Monogr. d. Radiol., p.
474, Taf. xxviii. figs. 8-10.
_Spongodiscus quadricornis_, Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 844.
Arms at different distances, forming a bilateral or irregular cross,
grouped in two opposite pairs; their form equilateral triangular; their
length smaller than the radius of the large circular central disk, which
exhibits in the interior eight to sixteen concentric rings.
_Dimensions._--Radius of the arms 0.2, of the central disk 0.13; basal
breadth of the arms 0.08.
_Habitat._--Mediterranean (Messina), Haeckel, surface.
7. _Spongasteriscus tetraceros_, Haeckel.
_Spongasteriscus tetraceros_, Haeckel, 1862, Monogr. d. Radiol., p. 475.
Arms at different distances, forming a bilateral or irregular cross,
grouped in two opposite pairs; their form isosceles triangular; their
length larger than the radius of the large elliptical central disk, which
exhibits in the interior six to twelve concentric rings.
_Dimensions._--Radius of the arms 0.16, of the central disk 0.1; basal
breadth of the arms 0.06.
_Habitat._--Mediterranean (Messina), North Atlantic (Canary Islands),
surface.
8. _Spongasteriscus myelastrum_, n. sp.
Arms at different distances, forming a bilateral or irregular cross,
grouped in two opposite pairs; the arms of one pair broader and shorter
than the arms of the other pair. Each arm in its basal half simple, in the
distal half forked; ends of the fork branches blunt. In the central disk no
concentric rings. (Similar to _Myelastrum octocorne_, Pl. 47, fig. 12, but
quite spongy.)
_Dimensions._--Radius of the arms 0.2, basal breadth 0.05, distal breadth
0.02.
_Habitat._--North Pacific, Station 236, surface.
Genus 265. _Spongaster_,[304] Ehrenberg, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 833.
_Definition._--#Spongodiscida# with four spongy arms on the margin of the
circular or quadrangular disk, connected by a spongy patagium of different
texture.
The genus _Spongaster_ differs from the foregoing _Spongasteriscus_ in the
patagium connecting the spongy arms, and bears therefore to it the same
relation as, in the Porodiscida, _Histiastrum_ does to _Stauralastrum_, or,
in the Coccodiscida, _Stauractura_ does to _Astractura_. The typical
specimen, figured by Ehrenberg (_Spongaster tetras_), exhibits a regular,
square disk, as also some other species. In a certain number of other
species (formerly united by me with _Spongocyclia_) the quadrangular disk
is bilateral.
{597}Subgenus 1. _Spongastrella_, Haeckel.
_Definition._--Cross formed by the four arms regular, rectangular, with the
arms of equal size and equidistant.
1. _Spongaster tetras_, Ehrenberg.
_Spongaster tetras_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 299, Taf. vi. (iii.) fig. 8.
_Dictyocoryne tetras_, Haeckel, 1862, Monogr. d. Radiol., p. 469.
Arms at equal distances, forming a rectangular, regular Myelastrum,
papiliocross, club-shaped, about twice as long as the diameter of the
square central disk and eight times as long as broad at their base. Distal
ends rounded, perfectly enclosed by the complete patagium, which forms a
regular square, with slightly concave sides.
_Dimensions._--Radius of the arms 0.12, distal breadth 0.03, basal breadth
0.015; length of the square side 0.2.
_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface and in various
depths.
2. _Spongaster quadratus_, n. sp.
Arms at equal distances, forming a regular, rectangular cross, club-shaped,
about four times as long as the diameter of the central circular disk, and
five times as long as broad at the base. Basal third of the arms square;
distal two thirds triangular, three times as broad, with a truncated distal
end. Patagium complete, perfectly enveloping the arms, and bordered by an
elegant, radially striated, broad edge, forming a regular square. (Similar
to _Histiastrum quadratum_, Pl. 46, fig. 4, but quite spongy.)
_Dimensions._--Radius of the arms 0.15, distal breadth 0.06, basal breadth
0.02; length of the square side 0.25.
_Habitat._--Pacific, central area, Stations 270 to 274, depths 2350 to 2925
fathoms.
3. _Spongaster cruciatus_, n. sp.
Arms at equal distances, forming a rectangular, regular cross, lanceolate,
three times as long as broad and as the diameter of the central circular
disk. Ends of the arms provided with a short conical spine. Patagium
incomplete, enveloping only the basal half of the arms, forming a regular
square with concave sides.
_Dimensions._--Radius of the arms 0.18, greatest breadth 0.05; length of
the square side 0.2.
_Habitat._--South Pacific, Station 288, surface.
{598}4. _Spongaster pentacyclus_, n. sp.
Arms at equal distances, forming a rectangular, regular cross, of the same
size and form as the circular central disk, so that the dark interior part
of the shell is composed of five equal circular disks, situated in a
quincuncial manner. The clearer complete patagium, enveloping the whole
cross perfectly, forms a regular square with rounded edges.
_Dimensions._--Radius of the arms 0.2; diameter of each of the five
circular disks 0.01; length of the square side 0.35.
_Habitat._--West Indies, Cuba, surface (Thomson).
Subgenus 2. _Spongastromma_, Haeckel.
_Definition._--Cross formed by the four arms bilateral or irregular, with
the arms at different distances.
5. _Spongaster orthogonus_, Haeckel.
_Spongocyclia orthogona_, Haeckel, 1862, Monogr. d. Radiol., p. 471, Taf.
xxviii. fig. 3.
_Spongodiscus orthogonus_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 844.
Arms at different distances, forming a bilateral cross, grouped in two
opposite pairs of equal size and similar form. Arms club-shaped, about as
long as the diameter of the central circular disk, enveloped perfectly by
the complete patagium, which forms a regular rectangle, the longer side of
which is one and a half times as long as the shorter side. (The arms in my
figure are not distinctly enough marked.)
_Dimensions._--Radius of the arms 0.08, breadth 0.02; length of the larger
side of the rectangle 0.15, of the smaller 0.1.
_Habitat._--Mediterranean (Messina), surface.
6. _Spongaster scyllaeus_, Haeckel.
_Spongocyclia scyllaea_, Haeckel, 1862, Monogr. d. Radiol., p. 471, Taf.
xxviii. fig. 4.
_Spongodiscus scyllaeus_, Haeckel, 1860, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 844.
Arms at different distances, forming a bilateral cross, grouped in two
opposite pairs of different size and form, one pair smaller and less
divergent than the other. Arms club-shaped, little longer than the radius
of the central circular disk, enveloped perfectly by the complete patagium,
which forms a trapezium; the convergent longer sides of the latter are one
and a half times as long as the larger, and twice as long as the smaller
parallel side. (The arms are in my figure, _loc. cit._, not distinctly
enough marked.)
_Dimensions._--Radius of the arms 0.12 to 0.14, breadth 0.02; length of
both convergent sides 0.24, of the larger parallel side 0.18, of the
smaller 0.12.
_Habitat._--Pacific, central area, Station 272, surface; Mediterranean
(Messina).
{599}----
Suborder VI. LARCOIDEA, Haeckel, 1883 (Pls. 9, 10, 49, 50).
_Definition_.--SPUMELLARIA with lentelliptical central capsule (rarely
somewhat modified or allomorphic), with a lentelliptical fenestrated
siliceous shell (often modified or allomorphic, and sometimes quite
irregular). Growth different in the three unequal dimensive axes,
perpendicular one to another. The typical Lentellipsis is characterised by
three elliptical dimensive planes of different sizes, perpendicular one to
another.
The section #Larcoidea#, the fourth and last of the #Sphærellaria#,
comprises all those forms of this group in which the fenestrated shell
originally is lentelliptical, characterised by different growth in three
different axes, perpendicular one to another, all three equal on both
poles. The geometrical fundamental form of the shell is therefore a
lentellipsis or a triaxial ellipsoid; and this typical form is preserved
completely in the majority of #Larcoidea# in the pure geometrical form of
the central capsule.
The three dimensive axes, which determine the typical form of #Larcoidea#,
are commonly differentiated in such a way, that the first, the longitudinal
or principal axis, is the longest; both its poles, oral and aboral (or
anterior and posterior) are equal. The second, the lateral or transverse
axis, is commonly less than the first, greater than the third axis; both
its poles are the equal lateral poles (right and left not differentiated).
The third dimensive axis, the equatorial or sagittal axis, is commonly the
shortest; both its equal poles are the sagittal poles (dorsal and ventral
poles not different). The relative size of the three dimensive axes in the
human body exhibits similar relations.
The three dimensive planes of the #Larcoidea#, the sagittal, lateral, and
transverse planes, are elliptical, all three of different sizes. The first
plane, the median or sagittal plane, is commonly as regards size between
the two others; its major axis is the principal, its minor the sagittal
axis; it separates the right half of the body from the left. The second
plane or lateral plane, is commonly larger than the two others; its major
axis the principal, its minor the transverse axis; it separates the dorsal
half of the body from the ventral. The third plane, the equatorial or zonal
plane, is commonly less than the two others; its major axis the lateral,
its minor the sagittal axis; it separates the two principal halves of the
body, the oral and aboral halves.
In my Monograph (1862) only very few forms of #Larcoidea# are described,
_Tetrapyle_ and _Lithelius_ (the latter representing a peculiar family,
Lithelida). In my Prodromus (1881, pp. 463, 464) I disposed all observed
forms of #Larcoidea# in two different families, the Pylonida and Lithelida.
The rich materials of the Challenger collection have since offered an
astonishing number of new and interesting forms of this section, so that I
can enumerate here fifty-one genera and two hundred and sixty-five species.
I dispose them here in four subsections and nine families. Three of these
have regular lentelliptical shells, which are not articulate, and
{600}without annular constrictions (Larcarida, Larnacida, Pylonida); these
form the subsection Pylolarcida. Two other families (Tholonida and
Zonarida) are distinguished by annular constrictions, which divide the
regular lentelliptical shell into a number of dome-shaped chambers or
cupolas; we call these Thololarcida. A third group, Spirolarcida, comprises
the #Larcoidea# with spiral growth; the two families of Lithelida and
Streblemida. Finally a fourth group the Sorolarcida is formed by the
#Larcoidea# with irregular shells, also two families, the Phorticida and
Soreumida.
The first family of #Larcoidea#, the Larcarida, contains the most simple
forms, beginning with _Cenolarcus_, a quite simple lentelliptical latticed
shell. In _Coccolarcus_ we find already two concentric shells, connected by
radial beams, an inner medullary and an outer cortical shell. In
_Spongolarcus_ the lentelliptical shell becomes spongy.
The second family, Larnacida, is very similar to the Larcarida, and seems
to diverge only by the different mode of connection between the two
concentric lentelliptical shells. But in truth this slight difference is of
great morphological importance, as it depends on a quite different and
peculiar mode of growth. In the foregoing Larcarida (_Coccolarcus_, &c.),
the concentric shells originate in the same manner as in the concentric
#Prunoidea# and #Sphæroidea#, by radial beams, which arise from the surface
of the inner (medullary) shell and become connected by a network to form
the outer (cortical) shell. Here, in the Larnacida, a quite similar shell
originates in a quite different way, first arrived at in the Pylonida
(_Trizonium_). Both concentric shells become here connected by peculiar
lattice girdles, which are developed in the perimeter of the three
elliptical dimensive planes. Firstly, on both sides of a simple, spherical,
or lentelliptical central chamber, arise two lateral wings (on the poles of
the transverse axis), and build around the former a transverse girdle. This
is crossed by a larger lateral girdle, the minor axis of which is the major
of the former, and perpendicular to both girdles is yet developed a third,
the sagittal girdle. If the open fissures or "gates" between these three
girdles become closed by network, we obtain _Larnacilla_, the probable
ancestral form of all Larnacida.
Whilst in _Larnacilla_ and _Larnacidium_ this typical trizonal
lentelliptical shell constitutes by itself alone the whole skeleton, in the
other Larnacida it becomes overgrown by outer envelops, and so becomes
enclosed in the interior of the central capsule as a "_Larnacilla_-shaped
medullary shell." If the enclosing external envelops be simply latticed, we
get the subfamily Larnacalpida; if they be spongy, we get the
Larnacospongida.
The third family, Pylonida, is the most important of all #Larcoidea#, as
not only the largest and most interesting number of species belong to it,
but also many other genera (far the greater part of all #Larcoidea#) may be
derived from it. The peculiar character of the Pylonida is determined by
the imperfect fenestration of the lentelliptical shell growing in the three
dimensive axes in a quite different manner. Each elliptical dimensive plane
becomes circumscribed by an elliptical latticed girdle (or fenestrated
{601}ring), and between these three girdles (perpendicular one to another)
remain wide open fissures of the shell or "gates" (_Pylæ_). The beginning
of the shell-building is the same as in _Larnacilla_, the most simple form
of Larnacida. From a quite simple medullary shell, a spherical,
subspherical, ellipsoidal, or lentelliptical central chamber, arise two
latticed wings, opposite on the poles of the transverse axis
(_Monozonium_). Both wings are short and wide hollow fenestrated tubes, the
axes of which are parallel to the principal axis. Therefore they form
together with the central chamber an elliptical transverse girdle. This
first girdle becomes crossed by a second lateral girdle; from both poles of
the transverse axis arise latticed wings, which unite on the poles of the
principal axis, therefore the minor axis of this second larger ring is the
major axis of the first smaller ring (_Dizonium_). Between the two crossed
rings remain four wide open gates. Now follows the development of a third
sagittal girdle, arising from both poles of the principal axis and
overgrowing the four gates. But as this third girdle is larger than the
second, four other larger gates arise between the two (in planes
perpendicular to the former four gates). Now we have the characteristic and
most important trizonal shell (_Trizonium_), composed of three elliptical
lattice-girdles of different size, perpendicular one to another, and
enclosing a simple central chamber. If the four gates of this _Trizonium_
become closed by lattice-work, it passes over into _Larnacilla_, the most
important ancestral form of the Larnacida.
This most significant "trizonal shell," either incompletely latticed in
_Trizonium_ (with four open gates), or completely latticed by fenestration
of the four gates, in _Larnacilla_, is to be found in far the greater part
of all #Larcoidea#, representing the medullary shell, which is overgrown by
an outer cortical shell. In many #Larcoidea#, in which this
"_Larnacilla_-shell" is absent, it is perhaps lost by phylogenetic
reduction, or retrograde metamorphosis.
The same process of triple girdle-building, by which the typical
_Trizonium_-shell or _Larnacilla_-shell is produced (Haplozonaria), is
repeated once or twice in the larger forms of Pylonida. The first system of
three girdles (perpendicular one to another) becomes overgrown by a second
system of the same formulation in the Diplozonaria, and this becomes
overgrown by a third system in the Triplozonaria; in the highest genus of
this group, _Pylozonium_, we find not less than nine girdles (three
systems, each of three girdles). Till now only one genus of the whole
polymorphous family was well known, _Tetrapyle_ (with five girdles, three
of the medullary, two of the cortical shell). If the gates between the
girdles remain open, all these forms must be regarded as Pylonida; if the
gates afterwards become closed by a network, they pass over into other
families.
The fourth family of the _Larcoidea_ is the Tholonida, distinguished by the
polythalamous shell being composed of a certain number of roundish or
hemispherical chambers (domes or cupolas), which surround a primordial
central chamber in quite regular disposition, lying opposite in pairs on
the poles of the three dimensive axes. {602}If we imagine that each "wing"
(or open half-girdle) of the Pylonida becomes closed by a lattice-work, and
so transformed into a hemispherical or roundish cupola, we obtain the
characteristic shell of the Tholonida. Indeed every girdle of the former
corresponds to a pair of opposite domes of the latter. The axis of each
pair of domes is one of the three dimensive axes.
The primordial chamber of the Tholonida (or the central chamber, around
which all cupolas are regularly disposed) is either a simple lentelliptical
lattice-shell, like _Cenolarcus_, or it is a trizonal shell (with an
enclosed concentric medullary shell), like _Larnacilla_. As in both cases
the building and the disposition of the cupolas around it are quite the
same, we can suppose that the whole family of Tholonida may have been
derived originally from _Larnacilla_ (or _Trizonium_), and that the
Cenotholida (with a simple central chamber) are sprung from the
Coccotholida (with a _Larnacilla_-shaped central chamber) by reduction and
loss of the original medullary shell.
The family Tholonida can be divided into three subfamilies according to the
disposition of the cupola-pairs in one, two, or three dimensive axes. In
the Cubotholida lie two cupolas on the poles of the transverse axis of the
central chamber (corresponding to _Amphipyle_); in the Staurotholida we
find four cupolas crosswise disposed, on the poles of the transverse and
principal axes (corresponding to _Tetrapyle_); in the Cubotholida are at
least six cupolas, on the poles of all three dimensive axes (corresponding
to _Tholonium_). In all three cases the number of cupolas may be augmented
by the secondary apposition of other chambers or domes in the same
disposition. Sometimes also the whole cortical shell becomes enclosed by an
external veil or mantle of delicate network. The lentelliptical (or often
nearly cubical) central chamber becomes often reduced, so that its sides
are incompletely latticed or widely opened; in some Cubotholida only the
twelve edges of the eight cornered cubical central chamber remain; its six
sides are quite open and only over-vaulted by the six hemispherical
cupolas. From the opposite points of the latter (in the deep annular
constrictions between them) often arise radial spines, and these lie
commonly in diagonal planes, separating the dome-pairs.
A similar dome-building or a composition of the polythalamous shell by
pairs of cupolas we find also in the next (fifth) family, the Zonarida. But
here the true cause of the peculiar dome-structure is quite different, not
an apposition of new chambers, but the constriction of a cortical
shell-like _Larnacalpis_ by two or more constrictions. These constrictions
lie in dimensive planes (or in planes parallel to these), and therefore the
cupolas are (all or partly) in diagonal planes, a condition quite opposite
to that found in the Tholonida. One of the annular constrictions is
constantly in the sagittal plane (separating the right and left halves of
the shell). The number of the constrictions in the few genera is two,
three, and four, and therefore the number of the cupolas four, six, or
eight. As this cortical shell constantly encloses a trizonal medullary
shell (or _Larnacilla_-shell), we cannot doubt that the Zonarida must be
derived from the Larnacida.
{603}Whilst in all the foregoing five families of #Larcoidea# the
shell-form is regular and their geometrical fundamental form is a
lentellipsis (or a triaxial ellipsoid, with three unequal isopolar
dimensive axes), in the four remaining families of this suborder the shell
becomes bilateral or irregular (with the poles of the axes unequal). In two
of these families (Lithelida and Streblemida) the growth of the shell
becomes spiral, in the last two families (Soreumida and Phorticida) quite
irregular. But as in all four families we encounter the typical trizonal
medullary shell (or _Larnacilla_-shell), we are convinced that they must be
derived (wholly or partially) from the Larnacida.
The Lithelida (the sixth family) are #Larcoidea# with spiral growth and
bilateral form (like _Nautilus_); therefore the spiral line lies in one
plane and this spiral plane divides the whole shell into two symmetrical
halves (right and left). The axis of the spiral (around which the shell
winds) is a straight line, one of the three dimensive axes. In the greater
part of Lithelida (in the Larcospirida) the primordial of central chamber
of the polythalamous shell is a trizonal medullary shell or
_Larnacilla_-shell, and the growth of the first spiral turning begins as
the development of the first (transverse) cortical girdle of _Amphipyle_;
but as one wing (or lateral half) of this girdle grows more rapidly than
the other, it overgrows the latter and begins the spiral winding; if the
other wing follow and overgrow the first, the spiral becomes double. Each
of the three dimensive girdles (of the Pylonida) may begin the spiral
winding. There can be no doubt that all these Lithelida (the Larcospirida)
must be derived from the Pylonida, by unequal growth of the two halves of
one girdle. Perhaps from these may also derived the other part of this
family, the Spiremida (_Spirema_ and _Lithelius_); in these the primordial
chamber of the spiral shell is simple, and may be derived by reduction of
the original _Larnacilla_-shell. But it is also possible that the Spiremida
proceed directly from the Larcarida, and that their ancestors did not
possess a _Larnacilla_-shell.
The Streblemida (the seventh family) are #Larcoidea# with spiral growth and
asymmetrical form of the polythalamous shell (like _Helix_ or
_Turrilites_); therefore the spiral line is twisted like a winding stair,
and the spiral face is curved and divides the shell into two unequal
halves. The Streblemida have the same likeness and relation to the
turbinoid Foraminifera (_Rotalia_, _Globigerina_, &c.) as the Lithelida to
the nautiloid Foraminifera (_Polystomella_, _Nummulina_, &c.). As in these
calcareous Rhizopods also the peculiar growth of the siliceous Streblemida
begins from a primordial chamber to which a variable number of roundish
chambers (of increasing size) is apposed. But the building of these
chambers and of their septa is by no means so regular and complete as in
the greater number of turbinoid Foraminifera. As in a part of this family
the primordial chamber is _Larnacilla_-shell, these also may be derived
from the Larnacida, but the other part (with simple central chamber) is
perhaps produced directly from the Larcarida.
The eighth family, Soreumida, is perhaps derived from the Streblemida by
the loss of the spiral growth. The polythalamous shell is similar to the
latter, but the chambers are {604}aggregated without any order, like the
Acervulinida among the Foraminifera. In some cases also here the primordial
chamber is a trizonal _Larnacilla_-shell, in other cases it is a simple,
subspherical or lentelliptical shell.
The last family, the Phorticida, is formed of irregular #Larcoidea#, in
which a lentelliptical trizonal _Larnacilla_-shell (as an inner medullary
shell) is enveloped by an irregular, latticed, or spongy cortical shell.
They can be regarded as abnormalities or irregular deformities of Larnacida
or Pylonida.
The central capsule of the #Larcoidea# is originally lentelliptical and
preserves this form, the "triaxial ellipsoid," in the greater number of
genera. In some groups it follows the prevalent growth of the shell in the
direction of one of the three dimensive axes, and becomes prolonged in this
way. In many chambered forms (particularly Tholonida and Zonarida) the
growing central capsule gets constricted, corresponding to the
constrictions of the shell. In the Soreumida and Phorticida its form often
becomes irregular. But in general for the greater number of #Larcoidea# the
lentelliptical form of their central capsule is quite characteristic.
_Synopsis of the Families of_ #Larcoidea#.
-------------------------------------------------------------------------
#Larcoidea# with a regular or symmetrical shell, the growth of which is
determined by the three dimensive axes. (Both poles of each axis are
equal.)
-------------------------------------------------------------------------
{Medullary shell absent or
Cortical shell completely { simple (spherical or
latticed, without external { lentelliptical), 1. LARCARIDA.
gates (or interzonal {
fissures), without annular {Medullary shell trizonal or
constrictions and domes. { _Larnacilla_-shaped
{ (composed of three
{ dimensive girdles), 2. LARNACIDA.
Cortical shell incompletely latticed, with two to four or
more symmetrically disposed gates or fissures remaining
between latticed dimensive girdles, 3. PYLONIDA.
Cortical shell completely }Constrictions of the
latticed, without external } cortical shell in
gates (or interzonal } diagonal planes; domes
fissures), with two or } in dimensive axes, 4. THOLONIDA.
more annular constrictions,}
which separate three to }Constrictions of the
six or more dome-shaped } cortical shell in
protuberances. } dimensive planes; domes
} in diagonal axes, 5. ZONARIDA.
-------------------------------------------------------------------------
#Larcoidea# with a symmetrical or irregular shell, either with
spiral growth or with quite irregular growth. (Both poles of one axis
are different.)
-------------------------------------------------------------------------
{Spiral cortical shell bilateral
{ (with plane spiral), 6. LITHELIDA.
Cortical shell with {
spiral growth. {Spiral cortical shell
{ asymmetrical (with ascending
{ spiral), 7. STREBLEMIDA.
{Cortical shell simple, with
{ one single chamber, 8. PHORTICIDA.
Cortical shell with quite {
irregular growth. {Cortical shell composed of
{ a number of heaped up
{ or aggregated chambers, 9. SOREUMIDA.
{605}Family XXIV. #LARCARIDA#, Haeckel, 1883 (Pl. 50, figs. 1, 2).
_Definition._--#Larcoidea# with a regular, completely latticed,
lentelliptical cortical shell, without open gates and annular
constrictions; medullary shell absent or simple (not trizonal), connected
with the cortical shell by radial beams.
The family #Larcarida# opens the long series of #Larcoidea# as the most
simple group of this suborder. It commences with _Cenolarcus_, a quite
simple lentelliptical latticed shell, which is characterised by three
unequal isopolar dimensive axes, perpendicular one to another. The major of
these three axes is the longitudinal or principal, the middle is the
lateral or transverse, and the minor is the equatorial or sagittal axis (as
in the human body). Among the three dimensive planes, which are determined
by pairs of these axes, the lateral plane is the largest (halved by the
crossed principal and lateral axes). The intermediate is the sagittal plane
or median plane (halved by the crossed principal and sagittal axes). The
smallest is the equatorial plane or transverse plane (halved by the crossed
lateral and sagittal axes). Therefore the shell has all the characters of
the true _Lentellipsis_ or of the "triaxial ellipsoid," and its axes agree
with the three axes of the "rhombic crystalline system."
In the three subfamilies of Larcarida this lentelliptical shell assumes a
different shape: in the Cenolarcida it remains simple, in the Spongolarcida
it becomes spongy (sometimes quite filled out with a spongy framework), in
the Coccolarcida it is composed of two or more concentric lentelliptical
shells (at least an inner medullary and one outer cortical shell). These
shells are simply connected by radial beams, and not, as in the Larnacida,
by latticed wings (or half girdles).
The network of the Larcarida shell is sometimes regular, commonly irregular
(as in the greater number of #Larcoidea#). The surface of the shell is
sometimes smooth or thorny, at other times covered with radial spines.
These are often symmetrically disposed, either on the poles of the
dimensive axes or in crossed diagonal planes.
The central capsule is a true "lentellipsis" in a geometrical sense; it is
halved by three elliptical dimensive planes of different sizes,
perpendicular one to another. In the Cenolarcida the central capsule lies
freely inside the simple (cortical) shell, only separated from it by the
jelly-mantle. In the Coccolarcida it contains the medullary shell, and is
enclosed by the simple or double cortical shell, perforated by the radial
beams connecting the two shells. The spongy shell of the Spongolarcida
exhibits a different relation to the central capsule: in _Spongolarcus_ the
latter lies freely in the internal cavity of the spongy shell; in
_Stypolarcus_, where this cavity is quite filled with a spongy network, the
central capsule also contains a part of it.
The morphological and phylogenetic relations of the Larcarida to the other
families of SPUMELLARIA admit of a different explanation. As this family
contains the {606}most simple forms of all #Larcoidea#, we can regard the
_Cenolarcus_ as the common ancestral form of this group, having originated
from _Actilarcus_ (or the lentelliptical _Actissa_) by the building of a
simple lentelliptical lattice-shell. But it is also possible that a part of
the Larcarida (or all?) descend from Larnacida by reduction or loss of the
original _Larnacilla_-shell (compare _Cenolarcus triaxonius_, p. 607).
_Synopsis of the Genera of the Larcarida._
-------------------------------------------------------------------------
I. Subfamily Cenolarcida.
Shell simple, latticed (lentelliptical cortical shell).
-------------------------------------------------------------------------
Without radial spines, 266. _Cenolarcus_.
With radial spines, 267. _Larcarium_.
-------------------------------------------------------------------------
II. Subfamily Coccolarcida.
Shell composed of two or more concentric latticed shells (inner
medullary and outer cortical).
-------------------------------------------------------------------------
Without radial spines, 268. _Coccolarcus_.
With radial spines, 269. _Larcidium_.
-------------------------------------------------------------------------
III. Subfamily Spongolarcida.
Shell spongy, partly or whole composed of a spongy framework.
-------------------------------------------------------------------------
With an internal cavity, 270. _Spongolarcus_.
Without an internal cavity, 271. _Stypolarcus_.
Subfamily 1. CENOLARCIDA, Haeckel.
_Definition._--#Larcarida# with a simple, lentelliptical latticed shell
(cortical shell without a medullary shell).
Genus 266. _Cenolarcus_,[305] n. gen.
_Definition._--#Larcarida# with a simple, lentelliptical latticed shell,
without a medullary shell, without radial spines.
The genus _Cenolarcus_ begins the group of #Larcoidea# as the most simple
form of this suborder. It corresponds to _Cenosphæra_ among the
#Sphæroidea#, to _Cenodiscus_ among the #Discoidea#, to _Cenellipsis_ among
the #Prunoidea#. The simple latticed shell is distinguished from that of
the three other genera by its typical lentelliptical form, a triaxial
ellipsoid with three dimensive axes of unequal length. Probably
_Cenolarcus_ is the original ancestral form of the #Larcoidea#, derived
from _Actilarcus_ (the lentelliptical _Actissa_) by the formation of a
simple fenestrated shell around the lentelliptical central capsule. But
possibly also some species of _Cenolarcus_ may be derived from
_Coccolarcus_ or _Larnacilla_ by reduction and loss of the medullary shell
(compare _Cenolarcus triaxonius_, n. sp.).
{607}1. _Cenolarcus primordialis_, n. sp. (Pl. 50, figs. 7, 7_a_, 7_b_).
Network of the shell regular, with circular, hexagonally framed pores,
twice as broad as the elevated bars; about ten pores on the half meridian,
eight on the half equator. Surface a little rough. Proportion of the three
dimensive axes = 2 : 2.5 : 3.
_Dimensions._--Principal axis (or length) 0.12, transverse axis (or
breadth) 0.1, sagittal axis (or thickness) 0.08; pores 0.01, bars 0.005.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
2. _Cenolarcus dimensivus_, n. sp.
Network of the shell regular, with circular pores (without hexagonal
frames), three times as broad as the thin bars; about twelve pores on the
half meridian, nine on the half equator. Surface thorny. Proportion of the
three dimensive axes = 3 : 4 : 5.
_Dimensions._--Principal axis 0.15, transverse axis 0.12, sagittal axis
0.09; pores 0.012, bars 0.004.
_Habitat._--North Pacific, Station 244, surface.
3. _Cenolarcus triaxonius_, n. sp.
Network of the shell regular, with circular, hexagonally framed pores, four
times as broad as the thin bars; about twelve pores on the half meridian,
nine on the equator. Surface smooth. From the inner surface of the shell
arise six very thin radial beams, opposite in pairs in the three dimensive
axes; all six beams end freely in a little knob, at an equal distance from
the centre; therefore this remarkable species seems to have lost a
medullary shell (descending from _Coccolarcus_ or _Larnacilla_?).
Proportion of the three dimensive axes = 2 : 2.5 : 3.
_Dimensions._--Principal axis 0.13, transverse axis 0.11, sagittal axis
0.09; pores 0.012, bars 0.03.
_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.
4. _Cenolarcus lentellipticus_, n. sp.
Network of the shell regular, with circular pores of the same breadth as
the thick bars; about eighteen pores on the half meridian, fourteen on the
half equator. Surface smooth. Proportion of the three dimensive axes =
2 : 3 : 4.
_Dimensions._--Principal axis 0.16, transverse axis 0.12, sagittal axis
0.08; pores and bars 0.004.
_Habitat._--Western Tropical Pacific, Station 224, surface.
5. _Cenolarcus minimus_, n. sp.
Network of the shell subregular, with very small circular pores of the same
breadth as the bars; only four pores on the half meridian, three on the
half equator. Surface smooth. Proportion of the three dimensive axes =
3 : 4 : 5.
{608}_Dimensions._--Principal axis 0.05, transverse 0.04, sagittal axis
0.03; pores and bars 0.006.
_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.
Genus 267. _Larcarium_,[306] n. gen.
_Definition._--#Larcarida# with a simple, lentelliptical latticed shell,
without a medullary shell; surface covered with radial spines.
The genus _Larcarium_ differs from _Cenolarcus_ only in the possession of
radial spines on the surface of the simple fenestrated lentelliptical
shell. These spines are commonly disposed symmetrically, opposite in pairs,
either on the poles of the three dimensive axes, or on the poles of certain
diagonal axes. Larcarium differs from the similar genera _Larcidium_,
_Larnacidium_, and _Larnacantha_ by the absence of any medullary shell.
1. _Larcarium amphistylum_, n. sp.
Shell thorny, with two large conical spines, opposite on both poles of the
principal axis, somewhat longer than it. Network of the shell regular, with
circular, hexagonally framed pores, twice as broad as the bars; about
twelve pores on the half meridian, ten on the half equator. Proportion of
the three dimensive axes = 3 : 4 : 5.
_Dimensions._--Principal axis (or length) 0.15, transverse axis (or
breadth) 0.12, sagittal axis (or thickness) 0.09; pores 0.01, bars 0.005.
_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.
2. _Larcarium staurostylum_, n. sp.
Shell smooth, with four short three-sided pyramidal spines of equal length,
opposite in pairs on the poles of the principal and lateral axes. Network
of the shell regular, with circular pores of the same breadth as the bars;
about eight pores on the half meridian, six on the half equator. Proportion
of the three dimensive axes = 2 : 2.5 : 3.
_Dimensions._--Length of the shell 0.12, breadth 0.1, thickness 0.08; pores
and bars 0.006.
_Habitat._--South Pacific, Station 300, depth 1375 fathoms.
3. _Larcarium hexastylum_, n. sp.
Shell smooth, with six short conical spines of equal length (= the shortest
axis of the shell), opposite in pairs on the poles of the three dimensive
axes. Network of the shell subregular, with {609}circular pores three times
as broad as the bars; about eleven pores on the half meridian, nine on the
half equator. Proportion of the three dimensive axes = 3 : 4 : 5.
_Dimensions._--Length of the shell 0.1, breadth 0.08, thickness 0.06, pores
0.006; bars 0.002.
_Habitat._--North Pacific, Station 244, surface.
4. _Larcarium axostylum_, n. sp.
Shell thorny, with six strong conical radial spines, opposite in pairs on
the poles of the three dimensive axes. All three pairs are of different
sizes, the length of each spine corresponding nearly to the size of the
shell-axis, of which it is the prolongation. Network of the shell
subregular, with circular pores twice as broad as the bars; ten on the half
meridian, eight on the half equator. Proportion of the three dimensive axes
= 2 : 3 : 4.
_Dimensions._--Length of the shell 0.12, breadth 0.09, thickness 0.06;
pores 0.01, bars 0.005.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
5. _Larcarium octostylum_, n. sp.
Shell thorny, with eight thin cylindrical radial spines, opposite in pairs
in two crossed diagonal planes. Network of the shell irregular, with
roundish pores, twice to four times as broad as the bars; nine to eleven on
the half meridian, five to seven on the half equator. Proportion of the
three dimensive axes = 3 : 4 : 5.
_Dimensions._--Length of the shell 0.11, breadth 0.09, thickness 0.07;
pores 0.006 to 0.012, bars 0.003.
_Habitat._--Pacific, central area, Station 267, surface.
6. _Larcarium polystylum_, n. sp.
Shell thorny, with numerous (twenty to thirty) stronger conical radial
spines, about as long as the shortest axis of the shell. Network of the
shell irregular, with roundish pores, twice to four times as broad as the
bars; seven to eight on the half meridian, five to six on the half equator.
Proportion of the three dimensive axes = 1 : 2 : 3.
_Dimensions._--Length of the shell 0.09, breadth 0.06, thickness 0.03;
pores 0.006 to 0.012, bars 0.003.
_Habitat._--South Atlantic, Station 323, surface.
7. _Larcarium chætostylum_, n. sp.
Shell bristly, with very numerous (sixty to eighty or more) very thin,
bristle-like, radial spines, somewhat longer than the longest axis of the
shell. Network irregular, with very small roundish pores, about the same
size as the bars; sixteen to eighteen on the half meridian, thirteen to
fifteen on the half equator. Proportion of the three dimensive axes =
1 : 1.5 : 2.
{610}_Dimensions._--Length of the shell (without spines) 0.13, breadth 0.1,
thickness 0.07; pores and bars 0.004 to 0.006.
_Habitat._--Pacific, central area, Station 273, surface.
Subfamily 2. COCCOLARCIDA, Haeckel.
_Definition._--#Larcarida# with encased lentelliptical shell, composed of
two or more concentric lentelliptical latticed shells, which are united by
radial beams (at least one inner medullary shell and one outer cortical
shell).
Genus 268. _Coccolarcus_,[307] n. gen.
_Definition._--#Larcarida# with two concentric latticed shells, an outer
lentelliptical cortical shell, and an inner (spherical or lentelliptical)
medullary shell, both connected by radial beams. Surface without radial
spines.
The genus _Coccolarcus_ differs from _Cenolarcus_ by the possession of an
internal medullary shell. This is quite simple, either spherical or
lentelliptical, and connected with the outer cortical shell by a number of
radial beams. In the similar _Larnacilla_ this connection is effected by
four internal latticed lamellæ (the half lateral wings of the transverse
girdle); therefore we find here four internal gates (on the poles of the
principal axis), absent in _Coccolarcus_.
1. _Coccolarcus lentellipsis_, n. sp.
Cortical shell with smooth surface and regular network; pores circular,
twice as broad as the bars; about thirteen on the half meridian, eleven on
the half equator. Proportion of the three dimensive axes = 3 : 4 : 5.
Medullary shell spherical, half as broad as the transverse radius.
_Dimensions._--Principal axis (or length) of the cortical shell 0.15,
transverse axis (or breadth) 0.12, sagittal axis (or thickness) 0.09; pores
0.01, bars 0.005; diameter of the medullary shell 0.03.
_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.
2. _Coccolarcus platellipsis_, n. sp.
Cortical shell with thorny surface and irregular network; pores roundish,
twice to three times as broad as the bars; sixteen to eighteen on the half
meridian, ten to twelve on the half equator. Proportion of the three
dimensive axes = 1 : 2 : 3. Medullary shell lentelliptical, one-third as
large as the cortical shell.
{611}_Dimensions._--Length of the cortical shell 0.17, breadth 0.11,
thickness 0.06; pores 0.008 to 0.012, bars 0.004; medullary shell 0.03 to
0.06.
_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.
Genus 269. _Larcidium_,[308] n. gen.
_Definition._--#Larcarida# with two concentric latticed shells, an outer
lentelliptical cortical shell, and an inner (spherical or lentelliptical)
medullary shell, both connected by radial beams. Surface covered with
radial spines.
The genus _Larcidium_ differs from the foregoing _Coccolarcus_ only in the
possession of radial spines, and bears to it the same relation that
_Larcarium_ does to _Cenolarcus_. The spines are commonly symmetrically
disposed, opposite in pairs in the dimensive axes, sometimes also in
diagonal axes.
1. _Larcidium dissacanthum_, n. sp.
Cortical shell with thorny surface and regular network; pores circular,
hexagonally framed, three times as broad as the bars; about thirteen on the
half meridian, eleven on the half equator. Proportion of the three
dimensive axes = 2 : 3 : 5. Medullary shell spherical, one-fourth as broad
as the cortical, connected with it by two thin beams, lying in the
principal axis, and prolonged on its poles into two strong conical spines,
somewhat longer than the greatest axis.
_Dimensions._--Length of the cortical shell (or principal axis) 0.15,
breadth 0.09, thickness 0.07; pores 0.015, bars 0.005; medullary shell
0.025.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
2. _Larcidium hexacanthum_, n. sp.
Cortical shell with smooth surface and regular network; pores circular,
twice as broad as the bars; about eleven on the half meridian, nine on the
half equator. Proportion of the three axes = 2 : 2.5 : 3. Medullary shell
spherical, one-third as broad as the cortical. On the surface six strong,
three-sided pyramidal spines, all about as long as the breadth of the
cortical shell.
_Dimensions._--Length of the cortical shell 0.12, breadth 0.1, thickness
0.08; pores 0.01, bars 0.005; medullary shell 0.035.
_Habitat._--Pacific, central area. Station 266, surface.
3. _Larcidium axacanthum_, n. sp.
Cortical shell with rough surface and irregular network; pores roundish,
twice to four times as broad as the bars; about fifteen to nineteen on the
half meridian, twelve to fourteen on the half {612}equator. Proportion of
the three axes = 2 : 3 : 4. Medullary shell lentelliptical, of the same
form and structure as the cortical, but only one-third as large, connected
with it by six thin radial beams, lying in pairs in the three dimensive
axes; on the outside they are prolonged into six strong conical radial
spines, which are in pairs of different size (as in _Larcarium axostylum_);
the length of each spine nearly equals the axis of the cortical shell, of
which it is the prolongation.
_Dimensions._--Length of the cortical shell (and the principal spines)
0.18, breadth of it (and length of the lateral spines) 0.135, thickness of
it (and length of the sagittal spines) 0.09; pores 0.005 to 0.013, bars
0.003.
_Habitat._--Pacific, central area, Station 271, surface.
4. _Larcidium octacanthum_, n. sp.
Cortical shell thorny, with irregular network; pores roundish, once to four
times as broad as the bars; about thirteen to fifteen on the half meridian,
eleven to thirteen on the half equator. Proportion of the three axes =
1 : 2.5 : 4. Medullary shell lentelliptical, one-fifth as large as the
cortical, connected with it by eight radial beams, which are situated in
two crossed diagonal planes (opposite in pairs), and are prolonged on the
surface into eight long and thin cylindrical radial spines similar to
_Tetrapyle octacantha_.
_Dimensions._--Length of the cortical shell 0.16, breadth 0.11, thickness
0.045; pores 0.003 to 0.012, bars 0.003; medullary shell 0.02 to 0.03.
_Habitat._--Pacific, central area, Station 263, depth 2650 fathoms.
5. _Larcidium dodecanthum_, n. sp. (Pl. 50, figs. 8, 8_a_).
Cortical shell rough, with irregular network; pores roundish, twice to four
times as broad as the bars; about twelve to fourteen on the half meridian,
eight to ten on the half equator. Proportion of the three axes = 2 : 3 : 4.
Medullary shell lentelliptical, one-third as large as the cortical,
connected with it by twelve thin radial beams, which are prolonged outside
into twelve strong conical radial spines, about half as long as the breadth
of the shell.
_Dimensions._--Length of the cortical shell 0.14, breadth 0.1, thickness
0.07; pores 0.008 to 0.015, bars 0.004; medullary shell 0.04 to 0.05.
_Habitat._--South Pacific, Station 288, surface.
6. _Larcidium polyacanthum_, n. sp.
Cortical shell spiny, with irregular network; pores roundish, once to twice
as broad as the bars; about ten to twelve on the half meridian, six to
eight on the half equator. Proportion of the three axes = 1 : 2 : 3.
Medullary shell lentelliptical, half as large as the cortical shell,
connected with it by numerous (twenty to twenty-five) radial beams, which
are prolonged outside into three-sided pyramidal spines, about as long as
the breadth of the shell.
_Dimensions._--Length of the cortical shell 0.18, breadth 0.12, thickness
0.06; pores 0.01 to 0.015, bars 0.008; medullary shell 0.03 to 0.09.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
{613}Subfamily 3. SPONGOLARCIDA, Haeckel.
_Definition._--#Larcarida# with spongy lentelliptical shell (with or
without enclosed medullary shell).
Genus 270. _Spongolarcus_,[309] n. gen.
_Definition._--#Larcarida# with lentelliptical spongy shell, containing a
central cavity of the same form, without medullary shell (without radial
spines).
The genus _Spongolarcus_ differs from _Cenolarcus_ (its probable ancestral
form) only in the development of spongy framework forming the wall of the
hollow lentelliptical shell. It corresponds, therefore, to _Plegmosphæra_
among the #Sphæroidea#, and to _Spongellipsis_ among the #Prunoidea#. From
these two similar spongy #Sphærellaria# it differs in its characteristic
lentelliptical form, with three dimensive axes of unequal length.
1. _Spongolarcus lentellipsis_, n. sp.
Spongy network of the shell very loose, its meshes fifteen to twenty times
as broad as the bars. Surface of the shell nearly smooth; diameter of its
internal cavity twice as large as the thickness of its wall. Proportion of
the three dimensive axes = 2 : 3 : 4.
_Dimensions._--Length 0.16, breadth 0.12, height 0.08; thickness of the
spongy wall 0.05.
_Habitat._--Pacific, central area, Station 274, surface.
2. _Spongolarcus triaxonius_, n. sp.
Spongy network of the shell rather loose, its meshes twelve to sixteen
times as broad as the bars. Surface of the shell rough; diameter of its
internal cavity about eight times as large as the thickness of its wall.
Proportion of the three dimensive axes = 2 : 2.5 : 3.
_Dimensions._--Length 0.25, breadth 0.2, height 0.16; thickness of the
spongy wall 0.025.
_Habitat._--North Pacific, Station 253, surface.
3. _Spongolarcus dimensivus_, n. sp.
Spongy network of the shell dense, its meshes four to eight times as broad
as the bars. Surface of the shell thorny; diameter of its internal cavity
about fifteen times as large as the thickness of its wall. Proportion of
the three dimensive axes = 3 : 4 : 5.
_Dimensions._--Length 0.2, breadth 0.16, height 0.12; thickness of the
spongy wall 0.01.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
{614}4. _Spongolarcus amphicentria_, Haeckel.
? _Amphicentria salpa_, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 296; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, Taf.
ii. fig. 18.
? _Spongurus salpa_, Haeckel, 1862, Monogr. d. Radiol., p. 466.
Spongy network of the shell compact, its meshes about the same breadth as
the bars. Surface of the shell spiny, with some larger spines around the
poles of the axis; diameter of the internal cavity about six times as large
as the thickness of its wall. Proportion of the three dimensive axes =
1 : 2 : 3. (Perhaps this _Spongolarcus_ is identical with _Amphicentria
salpa_, very imperfectly described and figured by Ehrenberg, _loc. cit._?)
_Dimensions._--Length 0.14, breadth 0.09, height 0.05; thickness of the
spongy wall 0.015.
_Habitat._--North Atlantic; off Greenland, 1000 fathoms, Ehrenberg; Station
64, depth (2700) fathoms.
Genus 271. _Stypolarcus_,[310] n. gen.
_Definition._--#Larcarida# with lentelliptical spongy shell, composed of
compact spongy framework, without central cavity and medullary shell
(without radial spines).
The genus _Stypolarcus_ differs from _Spongolarcus_ in the absence of any
central cavity. This is quite filled up by spongy framework, which forms
the whole mass of the lentelliptical body. _Stypolarcus_ bears therefore
the same relation to _Spongolarcus_ that _Styptosphæra_ does to
_Plegmosphæra_.
1. _Stypolarcus spongiosus_, n. sp.
Lentelliptical shell composed in the whole mass of loose, spongy framework
of similar texture, with irregular meshes, about ten to twenty times as
broad as the thin bars. Surface rough, without radial spines. Proportion of
the three axes = 3 : 4 : 5.
_Dimensions._--Length 0.2, breadth 0.16, height 0.12.
_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.
Family XXV. #LARNACIDA#, Haeckel, 1883 (Pl. 50, figs. 3-8).
_Definition._--#Larcoidea# with a regular, completely latticed,
lentelliptical cortical shell, without open gates and annular
constrictions; either this cortical shell or the enclosed medullary shell
is trizonal, composed of three elliptical, latticed, dimensive girdles of
different sizes, perpendicular one to another.
{615}The family #Larnacida# immediately follows the Larcarida as the next
simple group of all #Larcoidea#; some genera of both groups (such as
_Larnacalpis_ and _Coccolarcus_, or _Larnacantha_ and _Larcidium_) may
easily be confounded from their being so much alike. In both the
lentelliptical shell is composed of two concentric shells, an inner
(medullary) and an outer (cortical) shell. But the connection between these
shells and the construction of the inner shell is quite different in the
two groups. Whilst in the Larcarida the medullary shell is connected with
the cortical shell simply by radial beams, here in the Larnacida this
connection is effected by two latticed lamellæ, which are the lateral wings
of a transverse girdle. Therefore we encounter here for the first time that
peculiar mode of growth which characterises the greater part of the
#Larcoidea#, but particularly the Pylonida. But whilst in the Pylonida
between the three crossed lattice-girdles, remain four open gates, here in
the Larnacida the gates become closed by lattice-work; the lentelliptical
cortical shell becomes perfect.
The most simple genus of Larnacida, and no doubt the common ancestral form
of this whole family, is _Larnacilla_ (Pl. 50, figs. 1, 1_a_, 1_b_). The
most important shell of this typical genus is composed of a simple
lentelliptical medullary shell and of three elliptical latticed girdles
surrounding it, perpendicular one to another. These three "dimensive
girdles" lie in the perimeter of the three dimensive planes, the minor (and
first) in the equatorial plane, the second (and major) in the lateral
plane, the third (and intermediate) in the sagittal plane. Therefore we
have before us the same "trizonal shell" as in the important genus
_Trizonium_ among the Pylonida. But whilst in _Trizonium_, as in all
Pylonida, the four gates between the girdles remain open, here in
_Larnacilla_ they become perfectly closed by lattice-work.
The formation of the typical "_Larnacilla_-shell" begins with a simple,
spherical or lentelliptical lattice-shell, from both sides of which arise
two latticed "lateral wings" opposite on the poles of the transverse axis.
These two wings are comparable to the lateral chambers of _Tholartus_
(among the Tholonida), but differ by two large openings. Each wing is a
short cylindrical tube with latticed wall, open at both ends; the axis of
the tube (going through the centre of the open ends) is parallel to the
principal axis of the whole shell (and of the central chamber). Therefore
both wings form together a transverse ring, the middle of which encloses
the central chamber. The distal parts of both wings grow towards the poles
of the principal axis; if they became united here, the second (lateral)
girdle would be complete. Between it and the first girdle four open gates
remain ("_Tetrapyle_"); but these become overgrown by the third or sagittal
girdle, and at last the gates between this and the two other girdles become
closed by lattice-work. This perfect fenestration of the trizonal cortical
shell, and the complete closing of the gates between the girdles by
network, is the only difference between _Trizonium_ and _Larnacilla_.
In _Larnacilla_ and in the nearly allied _Larnacidium_ (only differing by
radial spines {616}on the surface) the "trizonal shell" is an external or
"cortical shell," enclosing the central capsule, the interior of which only
contains the simple central chamber and the jointed proximal parts of both
lateral wings. In the other genera of Larnacida (by proceeding growth) this
trizonal _Larnacilla_-shell becomes enclosed by the growing central capsule
and is now only a "medullary shell," whilst on the outside of the central
capsule in the same manner is developed an outer cortical shell
(_Larnacalpis_, _Larnacantha_); and perhaps the same process may be
repeated. But sometimes also this cortical shell becomes doubled by a
simple envelop of network (_Larnacoma_). In the Larnacospongida the
cortical shell is composed of a spongy framework (corresponding to the
Spongolarcida in the foregoing family).
The lattice-work of the Larnacida is commonly irregular (as in most other
#Larcoidea#), and its pores have little signification for the different
species. On the outer surface often arise radial spines, symmetrically
disposed either in dimensive planes or in diagonal planes.
The central capsule is constantly a true lentellipsis or a "triaxial
ellipsoid," characterised by three halving, elliptical dimensive planes,
perpendicular one to another. It bears a different relation to the skeleton
in the two subfamilies of Larnacida. In the first subfamily, the
Larnacillida (_Larnacilla_, _Larnacidium_), the central capsule encloses
only the simple spherical or lentelliptical central chamber ("simple
medullary shell"), and is enveloped by the trizonal cortical shell. In the
other subfamily, the Larnacalpida (_Larnacalpis_, _Larnacospongus_, &c.),
this trizonal "_Larnacilla_-shell" becomes enclosed by the overgrowing
central capsule, which now becomes enveloped by an external, latticed or
spongy, lentelliptical "cortical shell."
_Synopsis of the Genera of Larnacida._
-------------------------------------------------------------------------
I. Subfamily Larnacillida.
Medullary shell simple, spherical or subspherical. Cortical shell
lentelliptical, trizonal; between them four gates.
-------------------------------------------------------------------------
Shell without radial spines, 272. _Larnacilla_.
Shell with radial spines, 273. _Larnacidium_.
-------------------------------------------------------------------------
II. Subfamily Larnacalpida.
Medullary shell _Larnacilla_-shaped, double; the inner spherical or
subspherical, the outer lentelliptical and trizonal.
-------------------------------------------------------------------------
{ { Without radial
{ Cortical { spines, 274. _Larnacalpis_.
{ shell {
Cortical shell simple { simple. { With radial
or double, but not { { spines, 275. _Larnacantha_.
spongy. {
{ Cortical shell double,
{ without radial spines, 276. _Larnacoma_.
{ Shell without radial
Cortical shell simple { spines, 277. _Larnacospongus_.
or double, wholly or {
partly spongy. { Shell with radial spines, 278. _Larnacostupa_.
{617}Subfamily 1. LARNACILLIDA, Haeckel.
_Definition._--#Larnacida# with a simple, spherical or lentelliptical,
medullary shell, connected by the lateral wings of a latticed transverse
girdle with the simple lentelliptical trizonal cortical shell; the central
capsule encloses the former and is enveloped by the latter.
Genus 272. _Larnacilla_,[311] n. gen.
_Definition._--#Larnacida# with a simple lentelliptical cortical shell,
connected by the lateral wings of a latticed transverse girdle with the
simple, spherical or lentelliptical, medullary shell. Surface without
radial spines.
The genus _Larnacilla_ represents the most simple form of Larnacida, and at
the same time the most important common ancestral form, from which the
greater number of #Larcoidea# may be derived, viz., all those genera which
possess the characteristic "_Larnacilla_-shaped medullary shell." This
typical form of medullary shell may be derived from the genus _Trizonium_
among the Pylonida by the closing of the four open gates of this genus. The
free opening of these four gates becomes overgrown and closed by
lattice-work, developed from the free edges of the three crossed girdles,
and thus finally all three girdles are united in the form of a simple
lentelliptical shell (Pl. 50, figs. 1, 1_a_, 1_b_). Seen from the sagittal
poles (or from the poles of the shortest axis, fig. 1), the shell exhibits
on both sides of the small spherical medullary shell the two lateral wings
of the transverse girdle from the face; seen from the lateral poles (or
from the poles of the transverse axis, fig. 1_a_), one of these wings
appears in the optical section as an oblong ring, which seemingly encloses
the concentric medullary shell, and on both sides is grown together with
the sagittal girdle; seen from the principal poles (or from the poles of
the longitudinal axis, fig. 1_b_), both wings exhibit their elliptical
opening (at the right and left from the central medullary shell). The two
concentric shells are only connected by the two lateral tube-like wings of
the transverse girdle; the lateral and the sagittal girdles have no
connection with the medullary shell. The latter is sometimes spherical, at
other times lentelliptical.
1. _Larnacilla typus_, n. sp. (Pl. 50, fig. 1, 1_a_, 1_b_).
Cortical shell with smooth surface and with subregular network; pores twice
as broad as the bars; about twelve pores on the half meridian, ten on the
half equator. Proportion of the three dimensive axes = 2 : 3 : 4. Internal
four gates (between transverse and lateral girdles) roundish-triangular,
little broader than high. Medullary shell spherical, scarcely one-third as
broad as the lentelliptical cortical shell.
{618}_Dimensions._--Length of the cortical shell (or principal axis) 0.13,
breadth of it (or transverse axis) 0.1, height of it (or sagittal axis)
0.07; pores 0.006, bars 0.003; medullary shell (diameter) 0.03.
_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.
2. _Larnacilla prometor_, n. sp.
Cortical shell with rough surface and regular network; pores three times as
broad as the bars; about ten on the half meridian, eight on the half
equator. Proportion of the three axes = 1 : 2 : 3. Internal four gates
(between transverse and lateral girdles) kidney-shaped, twice as broad as
high. Medullary shell lentelliptical, of the same form as the external
cortical shell, but only one third as large.
_Dimensions._--Length of the cortical shell 0.15, breadth 0.1, height 0.05,
pores 0.015, bars 0.005; medullary shell 0.02 to 0.05.
_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.
3. _Larnacilla subglobosa_, n. sp.
Cortical shell nearly spherical, with thorny surface and irregular network;
pores roundish, twice to four times as broad as the bars; twelve to sixteen
in the half circumference. Proportion of the three axes very little
different = 1.3 : 1.4 : 1.5. Internal four gates elliptical, one and a half
times as broad as high. Medullary shell spherical, one-fourth as broad as
the cortical shell.
_Dimensions._--Length of the cortical shell 0.15, breadth 0.14, height
0.13; pores 0.006 to 0.012, bars 0.003; medullary shell 0.035.
_Habitat._--Pacific, central area. Station 266, depth 2750 fathoms.
4. _Larnacilla medullaris_, n. sp.
Cortical shell lentelliptical, with smooth surface and irregular network;
pores roundish, very small, scarcely as broad as the bars; about eight to
nine on the half meridian, six to seven on the half equator. Proportion of
the three axes = 3 : 4 : 6. Internal four gates elliptical. Medullary shell
spherical, scarcely one-third as broad as the cortical shell. (This small
species may be only the medullary shell of some other Larcoid, the cortical
shell of which is not yet formed.)
_Dimensions._--Length of the cortical shell 0.06, breadth 0.04, height
0.03; pores and bars about 0.004; medullary shell 0.013.
_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.
Genus 273. _Larnacidium_,[312] n. gen.
_Definition._--#Larnacida# with a simple lentelliptical cortical shell,
connected by the lateral wings of a latticed transverse girdle with the
simple, spherical or lentelliptical, medullary shell. Surface armed with
radial spines.
{619}The genus _Larnacidium_ has the same shell-formation as the foregoing
_Larnacilla_, and differs from it only in the possession of radial spines
on the surface, which in all known species exhibit a symmetrical
disposition. From the nearly allied genus _Larcidium_ it differs in the
characteristic mode of connection between the two shells, owing to the
different kind of growth. In _Larcidium_ this connection is effected only
by radial beams, whereas in _Larnacidium_ (as in all Larnacida) by two
lateral latticed tubes, the wings of the primary transverse girdle.
1. _Larnacidium staurobelonium_, n. sp.
Cortical shell smooth, with four strong conical, radial spines in the
lateral plane, opposite in pairs, two on the poles of the principal and two
on the poles of the transverse axis. Pores subregular, circular, twice as
broad as the bars; about twelve on the half meridian. Proportion of the
three axes = 2 : 3 : 4. Medullary shell spherical, one-third as broad as
the cortical shell.
_Dimensions._--Length of the cortical shell 0.12, breadth 0.09, height
0.06; pores 0.008, bars 0.04; medullary shell 0.03.
_Habitat._--North Pacific Station 244, depth 2900 fathoms.
2. _Larnacidium hexabelonium_, n. sp.
Cortical shell thorny, with six strong, three-sided pyramidal, radial
spines, lying opposite in pairs on the poles of the three dimensive axes.
Pores subregular, circular, three times as broad as the bars; about
fourteen on the half meridian. Proportion of the three axes = 2 : 2.5 : 3.
Medullary shell spherical, one-third as broad as the cortical shell.
_Dimensions._--Length of the cortical shell 0.14, breadth 0.11, height
0.08; pores 0.01, bars 0.003; medullary shell 0.04.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
3. _Larnacidium polybelonium_, n. sp.
Cortical shell very spiny, with numerous (twenty to thirty or more) larger
thin radial spines, about as long as the shell. Pores irregular, twice to
five times as broad as the bars; about sixteen on the half meridian.
Proportion of the three axes = 2 : 2.5 : 3. Medullary shell
lentelliptical, half as large as the cortical shell.
_Dimensions._--Length of the cortical shell 0.11, breadth 0.09, height
0.07; pores 0.004 to 0.01, bars 0.002; length of the medullary shell 0.06,
breadth 0.05, height 0.04.
_Habitat._--Western Tropical Pacific, Station 225. depth 4475 fathoms.
Subfamily 2. LARNACALPIDA, Haeckel.
_Definition._--#Larnacida# with a double, trizonal, _Larnacilla_-shaped
medullary shell, enclosed in the central capsule, and enveloped by a simple
or double, latticed or spongy, lentelliptical, cortical shell.
{620}Genus 274. _Larnacalpis_,[313] n. gen.
_Definition._--#Larnacida# with a simple lentelliptical cortical shell,
without radial spines. Medullary shell double, _Larnacilla_-shaped.
The genus _Larnacalpis_ represents the most simple form of the sub-family
Larnacalpida, and is very important as the common original form of all
those #Larcoidea# in which a double _Larnacilla_-shaped medullary shell is
surrounded by a simple, perfectly closed, latticed, lentelliptical cortical
shell. Therefore the same typical, trizonal, lentelliptical shell, which in
_Larnacilla_ represents the external envelop (or cortical shell) of the
central capsule, here in _Larnacalpis_ becomes enclosed as an internal
nucleus (or medullary shell) in the interior of the central capsule, and
this latter becomes overgrown by a new lentelliptical cortical shell. The
connection between the two shells of _Larnacalpis_ is either effected by a
number of radial beams (e.g., in _Larnacalpis triaxonia_ by six beams
situated in the three dimensive axes), or by two lateral, latticed,
tube-like wings, which are repetitions of the smaller lateral wings
connecting its external shell with the internal medullary shell (as in
_Larnacalpis lentellipsis_). The latter species may be regarded as a
_Pylonium_ with a completely latticed shell.
1. _Larnacalpis lentellipsis_, n. sp. (Pl. 50, figs. 2, 2_a_, 2_b_).
Cortical shell with thorny surface and irregular network; pores roundish,
twice to four times as broad as the bars; about sixteen on the half
meridian, twelve on the half equator. Proportion of the three dimensive
axes = 2 : 3 : 4. Medullary shell one-third as large as the cortical, with
four elliptical internal gates, connected with it by two opposite beams in
the principal axis and by two latticed wings in the transverse axis;
therefore between the two shells are four large kidney-shaped gates, halved
by the polar beams (as in _Octopyle_).
_Dimensions._--Length of the cortical shell (or principal axis) 0.14,
breadth (or transverse axis) 0.11, height (or sagittal axis) 0.07; pores
0.01 to 0.02, bars 0.005; length of the medullary shell 0.05, breadth 0.04,
height 0.03.
_Habitat._--Pacific, central area, Station 273, depth 2600 fathoms.
2. _Larnacalpis phacodiscus_, n. sp.
Cortical shell with thorny surface and regular network; pores circular,
twice as broad as the bars; about ten on the half meridian, eight on the
half equator. Proportion of the three axes = 2 : 2.5 : 3. Medullary shell
half as large as the cortical, with four kidney-shaped internal gates.
_Dimensions._--Length of the cortical shell 0.13, breadth 0.11, height
0.09; pores 0.012, bars 0.006; length of the medullary shell 0.06, breadth
0.045, height 0.03.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
{621}3. _Larnacalpis macrococcus_, n. sp.
Cortical shell with spiny surface and regular network; pores circular,
small, of the same breadth as the bars; about twenty-two on the half
meridian, nineteen on the half equator. Proportion of the three axes =
2 : 3 : 4. Medullary shell two-thirds as large as the cortical, with four
wide internal semicircular gates.
_Dimensions._--Length of the cortical shell 0.1, breadth 0.075, height
0.05; pores and bars 0.003; length of the medullary shell 0.066, breadth
0.05, height 0.032.
_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.
4. _Larnacalpis subsphærica_, n. sp.
Cortical shell with rough surface and irregular network; roundish pores
twice to five times as broad as the bars; about twenty-four on the half
meridian, twenty-one on the half equator. Proportion of the three axes =
1.2 : 1.3 : 1.4. Medullary shell half as large as the cortical, with four
elliptical internal gates.
_Dimensions._--Length of the cortical shell 0.14, breadth 0.13, height
0.12; pores 0.004 to 0.01, bars 0.002; length of the medullary shell 0.08,
breadth 0.07, height 0.06.
_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.
5. _Larnacalpis triaxonia_, n. sp. (Pl. 50, fig. 3).
Cortical shell with smooth surface and peculiar network, composed of four
meridian rows of larger pores (five large elliptical pores on each half
meridian, the largest in the equator) and numerous small irregular pores
between them. Proportion of the three axes = 2 : 3 : 4. Medullary shell
with four semicircular internal gates, about one-fourth as large as the
cortical, connected with it by six thin radial beams, opposite in pairs in
the three dimensive axes.
_Dimensions._--Length of the cortical shell 0.14, breadth 0.1, height 0.07;
large pores 0.03, small pores 0.002 to 0.01, bars 0.002 to 0.01; length of
the medullary shell 0.04, breadth 0.03, height 0.02.
_Habitat._--Pacific, central area, Station 263, depth 2650 fathoms.
Genus 275. _Larnacantha_,[314] n. gen.
_Definition._--#Larnacida# with a simple lentelliptical cortical shell,
armed with symmetrically disposed radial spines. Medullary shell double,
_Larnacilla_-shaped.
The genus _Larnacantha_ has the same characteristic shell-formation as the
foregoing _Larnacalpis_, and differs from it only in the possession of
radial spines, which are symmetrically distributed on the surface in a
definite order. Commonly these spines are external prolongations of the
internal radial beams, which connect the double _Larnacilla_-shaped
medullary shell with the simple lentelliptical cortical shell.
{622}1. _Larnacantha dissacantha_, n. sp.
Cortical shell smooth, with two large cylindrical spines, opposite on the
poles of the principal axis, and somewhat longer than it. Pores regular,
circular, three times as broad as the bars; about eleven on the half
meridian. Proportion of the three axes = 2 : 3 : 4. Medullary shell
one-third as large as the cortical shell.
_Dimensions._--Length of the cortical shell (principal axis) 0.13, breadth
(transverse axis) 0.1, height (sagittal axis) 0.07; pores 0.009, bars
0.003; length of the _Larnacilla_-shaped medullary shell 0.045.
_Habitat._--North Pacific, Station 256, depth 2950 fathoms.
2. _Larnacantha stauracantha_, n. sp.
Cortical shell smooth, with four large conical spines in the lateral plane,
two larger opposite on the poles of the principal, two smaller on those of
the transverse axis. Pores regular, circular, twice as broad as the bars;
about seventeen on the half meridian. Proportion of the three axes =
3 : 3.5 : 4. Medullary shell one-third as large as the cortical shell.
_Dimensions._--Length of the cortical shell 0.15, breadth 0.13, height
0.11; pores 0.008, bars 0.004; length of the medullary shell 0.05.
_Habitat._--Pacific, central area, Station 274, surface.
3. _Larnacantha quadricornis_, n. sp.
Cortical shell spiny, with four strong, horn-like curved spines in the
lateral plane, opposite in pairs on the poles of the crossed diagonal axes.
Pores irregular, roundish, twice to four times as broad as the bars; about
fourteen on the half meridian. Proportion of the three axes = 2 : 3 : 4.
Medullary shell one-third as large as the cortical shell.
_Dimensions._--Length of the cortical shell 0.14, breadth 0.11, height
0.07; pores 0.006 to 0.012, bars 0.003; length of the medullary shell 0.05.
_Habitat._--Pacific, central area, Station 270, surface.
4. _Larnacantha hexacantha_, n. sp. (Pl. 50, fig. 4).
Cortical shell thorny, with six strong conical radial spines in the lateral
plane, two opposite on the poles of the principal axis, four others
opposite in pairs on the poles of the two crossed diagonal axes. Pores with
peculiar distribution; twelve large elliptical pores (nearly of the size of
the medullary shell) symmetrically disposed in four crossed meridians
(between the sagittal and the lateral meridians), separated by bands of
smaller irregular pores. Proportion of the three axes = 3 : 4 : 5.
Medullary shell hexagonal, one-third as large as the cortical shell.
_Dimensions._--Length of the cortical shell 0.14, breadth 0.11, height
0.08; large pores 0.04, small pores 0.003 to 0.01, bars 0.004; length of
the medullary shell 0.05.
_Habitat._--Pacific, central area, Station 263, depth 2650 fathoms.
{623}5. _Larnacantha bicruciata_, n. sp. (Pl. 50, fig. 5).
Cortical shell thorny, in the lateral plane with eight strong conical
radial spines, alternating with eight smaller spines; four of the eight
stronger spines opposite on the poles of the principal and transverse axes
(in the figure 5, by mistake, not represented large enough), four others
between those, opposite on the poles of the two crossed diagonal axes.
Pores with a peculiar disposition; on both flat sides of the lentellipsis
an elliptical ring of eight large elliptical pores (alternating with the
eight stronger radial spines), separated by bands of smaller irregular
pores. Proportion of the three axes = 2 : 3 : 4. Medullary shell nearly
half as long as the cortical shell.
_Dimensions._--Length of the cortical shell 0.16, breadth 0.13, height
0.08; large pores 0.03, small pores 0.003 to 0.01, bars 0.006; length of
the medullary shell 0.07.
_Habitat._--Indian Ocean, surface, Madagascar (Rabbe).
6. _Larnacantha octacantha_, n. sp.
Cortical shell thorny, with eight long and thin, cylindrical, radial
spines, lying opposite in pairs in two crossed diagonal planes. Pores
irregular, roundish, twice to five times as broad as the bars; about
sixteen on the half meridian. Proportion of the three axes = 1 : 1-1/3 : 2.
Medullary shell scarcely one-fourth as long as the cortical shell. (This
species resembles closely the common _Tetrapyle octacantha_, from which it
seems to be developed by a complete over-growing of the four gates, which
become closed by a network connecting the free edges of the transverse and
lateral girdles.)
_Dimensions._--Length of the cortical shell 0.18, breadth 0.13, height 0.1;
pores 0.005 to 0.015, bars 0.003; length of the medullary shell 0.04.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
7. _Larnacantha cladacantha_, n. sp.
Cortical shell very spiny, with eight longer ramified spines, lying
opposite in pairs in two crossed diagonal planes; each spine with two to
six irregular, lateral branches. Pores irregular, roundish, twice to three
times as broad as the bars; about twelve on the half meridian. Proportion
of the three axes = 5 : 6 : 7. Medullary shell nearly half as long as the
cortical shell. (Differs from the foregoing by the branching spines end the
larger medullary shell.)
_Dimensions._--Length of the cortical shell 0.15, breadth 0.13, height
0.11; pores 0.01 to 0.015, bars 0.005; length of the medullary shell 0.07.
_Habitat._--Indian Ocean, surface, Cocos Islands (Rabbe).
8. _Larnacantha prismatica_, n. sp. (Pl. 50, fig. 6).
Cortical shell smooth, four-sided prismatic, with eight short, parallel,
three-sided pyramidal spines; these lie opposite in pairs in four parallel
longitudinal lines, as prolongations of the four {624}lateral edges of the
prism, and arise from its eight corners. Pores regular, circular, three
times as broad as the bars; about fourteen on the half meridian. Proportion
of the three axes = 2 : 3 : 4. Medullary shell half as long as the cortical
shell.
_Dimensions._--Length of the cortical shell 0.11, breadth 0.07, height
0.05; pores 0.006, bars 0.002; length of the medullary shell 0.06.
_Habitat._--Pacific, central area, Station 263, depth 2650 fathoms.
9. _Larnacantha decacantha_, n. sp.
Cortical shell thorny, with ten short and stout, conical, radial spines,
two opposite on the poles of the principal axis (as prolongations of inner
axial beams), eight others opposite in pairs in two crossed diagonal
planes. Pores irregular, roundish, twice to four times as broad as the
bars; about sixteen on the half meridian. Proportion of the three axes =
3 : 3.75 : 4. Medullary shell about one-third as long as the cortical
shell.
_Dimensions._--Length of the cortical shell 0.16, breadth 0.15, height
0.12; pores 0.008 to 0.016, bars 0.004; length of the medullary shell 0.06.
_Habitat._--North Atlantic, Station 354, surface.
10. _Larnacantha dodecantha_, n. sp.
Cortical shell nearly smooth, but with twelve strong conical radial spines;
four in the lateral plane opposite in pairs (two on the poles of the
principal, and two on the poles of the transverse axis); eight others
opposite in pairs in two crossed diagonal planes. Pores with a peculiar
disposition: twelve large elliptical pores in two crossed meridian planes
(alternating with the twelve spines), separated by bands of irregular small
pores. Proportion of the three axes = 1 : 1.5 : 2. Medullary shell
hexagonal, one-third as long as the cortical shell.
_Dimensions._--Length of the cortical shell 0.15, breadth 0.11, height
0.08; large pores 0.03, small pores 0.005 to 0.01, bars 0.003; length of
the medullary shell 0.05.
_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.
11. _Larnacantha drymacantha_, n. sp.