Cortical shell very spiny, on the whole _Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, First Part: Porulosa (Spumellaria and Acantharia) Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII

numerous (thirty to fifty or more) large branched spines, about the length

of the shell; each spine with three to nine lateral branches, simple or

forked (very similar to _Cromyodrymus abietinus_, Pl. 30, fig. 6). Pores

very irregular, roundish. Proportion of the three axes = 2 : 2.5 : 3.

Medullary shell half as long as the cortical shell.

_Dimensions._--Length of the cortical shell 0.16, breadth 0.13, height 0.1;

pores 0.005 to 0.015, bars 0.03; length of the medullary shell 0.08.

_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.

{625}Genus 276. _Larnacoma_,[315] n. gen.

_Definition._--#Larnacida# with double lentelliptical cortical shell,

without radial spines. Medullary shell double, _Larnacilla_-shaped.

The genus _Larnacoma_ has originated from the nearly allied _Larnacalpis_

by duplication of the cortical shell. Whilst in both genera the connection

between the _Larnacilla_-shaped medullary shell and the primary cortical

shell is the same, many short radial beams arise from the surface of the

latter in _Larnacoma_, which at constant equal distances from it unite by a

network forming the secondary or outer cortical shell. It differs from the

similar Druppulida (_Cromyodruppa_) by the sagittal flattening of the

lentelliptical shell and the _Larnacilla_-form of the double medullary

shell.

1. _Larnacoma lentellipticum_, n. sp.

Shell with smooth surface and elliptical perimeter, one and a third times

as long as broad. All four shells lentelliptical. Distance between the two

cortical shells about twice as great as the distance of the inner cortical

and outer medullary shell. Network of both outer shells irregular, with

large roundish pores, twice to six times as broad as the bars.

_Dimensions._--Length (or principal axis) of the first (innermost) shell

0.03, second 0.08, third 0.16, fourth (outermost) 0.27, breadth (or

transverse axis) corresponding--(A) 0.02, (B) 0.05, (C) 0.11, (D) 0.2.

_Habitat._--South Atlantic, Station 323, depth 1900 fathoms.

2. _Larnacoma quadruplex_, n. sp.

Shell with thorny surface and elliptical perimeter, one and a fifth times

as long as broad. All four shells lentelliptical. Distance between the two

cortical shells somewhat smaller than the distance between the inner

cortical and outer medullary shell. Network of both outer shells irregular,

with large roundish pores, twice to ten times as broad as the bars.

_Dimensions._--Length of the first shell 0.02, second 0.06, third 0.15,

fourth 0.24; breadth corresponding--(A) 0.016, (B) 0.04, (C) 0.11, (D) 0.2.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.

3. _Larnacoma hexagonium_, n. sp.

Shell with thorny surface and hexagonal perimeter, as long as broad. All

four shells hexagonal, connected by six piercing radial beams (two in the

principal axis, four others in two crossed diagonals). Distance between the

two cortical shells somewhat greater than the distance between the inner

cortical and outer medullary shell. Network of both outer shells

subregular, with small circular pores, twice as broad as the bars.

{626}_Dimensions._--Length of the first shell 0.02, second 0.05, third

0.09, fourth 0.16; breadth corresponding--(A) 0.015, (B) 0.035, (C) 0.065,

(D) 0.12.

_Habitat._--South Atlantic, west of Tristan da Cunha, Station 332, depth

2200 fathoms.

Genus 277. _Larnacospongus_,[316] n. gen.

_Definition._--#Larnacida# with spongy lentelliptical cortical shell,

without radial spines. Medullary shell double, _Larnacilla_-shaped.

The genus _Larnacospongus_ differs from the nearly allied genera

_Larnacalpis_ and _Larnacoma_ by the spongy texture of the lentelliptical

cortical shell whilst the enclosed medullary shell in both genera is the

same trizonal _Larnacilla_-shell. Therefore _Larnacospongus_ (and the

following nearly related _Larnacostupa_) can be derived directly by

development of a spongy envelop either from _Larnacilla_ and _Larnacalpis_,

or from _Trizonium_ and _Amphipyle_. But some species of these spongy

genera appear to be derived rather from _Tetrapyle_ or _Pylonium_, perhaps

also from _Cubotholus_. Their phylogenetic origin may be explained in

different ways.

1. _Larnacospongus larnacillifer_, n. sp.

Cortical shell lentelliptical, one and a half times as long as broad, with

rough surface and rather loose spongy framework, directly enclosing a

trizonal _Larnacilla_-shell of the same form, but of only one-third its

size.

_Dimensions._--Length of the whole shell 0.17, breadth 0.12; length of the

medullary shell 0.06, breadth 0.04.

_Habitat._--South Atlantic, east coast of Patagonia, Station 319, surface.

2. _Larnacospongus tetrapylifer_, n. sp.

Cortical shell lentelliptical, one and a third times as long as broad, with

thorny surface; composed of an outer envelop of loose spongy framework and

an inner lattice-shell with four kidney-shaped gates, like _Tetrapyle;_ the

latter encloses a trizonal medullary shell of one-fourth its size.

_Dimensions._--Length of the whole shell 0.22, breadth 0.16; length of the

medullary shell 0.045, breadth 0.035.

_Habitat._--South Atlantic, west of Tristan da Cunha, Station 332, surface.

{627}Genus 278. _Larnacostupa_,[317] n. gen.

_Definition._--#Larnacida# with spongy lentelliptical cortical shell, with

radial spines on the surface. Medullary shell double, _Larnacilla_-shaped.

The genus _Larnacostupa_ differs from the preceding Larnacospongus only in

the possession of radial spines, covering either the whole surface

irregularly or disposed in a certain symmetrical order.

1. _Larnacostupa octacantha_, n. sp.

Cortical shell lentelliptical, with thorny surface, and rather dense,

irregular, spongy framework, which arises from an inner latticed cortical

shell, like that of _Tetrapyle_ or _Pylonium_. This latter is twice as

large as the enclosed _Larnacilla_-shell. Eight long and thin, cylindrical,

radial spines, opposite in pairs in two diagonal planes. (Seems to be the

common _Tetrapyle octacantha_, enveloped by an outer spongy framework

mantle.)

_Dimensions._--Length of the whole shell (without spines) 0.22, breadth

0.16; length of the medullary shell 0.06, breadth 0.04.

_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.

2. _Larnacostupa spinosa_, n. sp.

Cortical shell lentelliptical, about one and a half times as long as broad,

with very lax and irregular spongy framework, arising from a nearly

quadrangular lattice-shell like that of _Tetrapyle_; this latter encloses a

_Larnacilla_-shell of half its size. Whole surface covered with thin

bristle-like radial spines, of about the length of the shell.

_Dimensions._--Length of the whole shell (without spines) 0.18, breadth

0.12; length of the medullary shell 0.05, breadth 0.035.

_Habitat._--Antarctic Ocean, off Kerguelen, Station 150, surface.

3. _Larnacostupa dendrophora_, n. sp.

Cortical shell nearly spherical, scarcely longer than broad, with lax,

irregular spongy framework, arising from a lentelliptical trizonal

medullary shell (like _Larnacilla_). Whole surface covered with thin

arborescent radial spines, about half as long as the shell, each spine with

three to six irregular branches.

_Dimensions._--Length of the whole shell (without spines) 0.15, breadth

0.13; length of the medullary shell 0.07, breadth 0.04.

_Habitat._--Antarctic Ocean, Station 154, surface.

{628}Family XXVI. #PYLONIDA#, Haeckel, 1881 (Pl. 9).

_Pylonida_, Haeckel, 1881, Prodromus, p. 463.

_Definition._--#Larcoidea# with regular, incompletely latticed cortical

shell, distinguished by two to four or more symmetrically disposed gates or

large fissures remaining between one to three latticed dimensive girdles

(perpendicular one to another). One, two, or three concentric systems of

such girdles (each system with three girdles) may be developed.

The family #Pylonida# is the most important and interesting among all the

#Larcoidea#, not only because it is much richer in different and peculiar

forms than the other families of this section, but also because it has

direct and very complex relations to all the other families of #Larcoidea#.

It is even possible that the Pylonida represent the original ancestral

group of the whole section, and that the apparently simpler group of the

Larcarida must be derived from the former by retrogressive metamorphosis.

Till the year 1881 the family Pylonida, which here now exhibits ten genera

with eighty-six species, was only represented by one single species,

accurately described and extensively illustrated by Johannes Müller in

1858, the well known and widely distributed cosmopolitan _Tetrapyle

octacantha_ (Abhandl. d. k. Akad. d. Wiss. Berlin, p. 33, Taf. iii.). A

slight modification of it was afterwards described by Ehrenberg as

_Schizomma quadrilobum_ (Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, Taf.

ii. fig. 12). A more accurate description of it, with a good explanation of

its characteristic growth, was given in 1879 by Richard Hertwig in his

Organismus der Radiolarien (pp. 52-54, Taf. iv. figs. 7, 8; Taf. vi. figs.

2, 5). In my Prodromus (1881, p. 463) I constituted for a large number of

allied species, detected in the Challenger collection, the special family

Pylonida, and distinguished among it twelve different genera. However, I

think it now better to restrict the definition of the family as given in

the above definition, and to remove from it a number of genera formerly

with it united, as the genera _Triopyle_ and _Hexapyle_, appertaining to

the #Discoidea#.

The characteristic type of all true Pylonida is clearly demonstrated by

their peculiar mode of growth, the consequence of which is the imperfect

lattice-work of the fenestrated larcoid shell. This remarkable growth is

effected by the development of elliptical latticed girdles (or rings),

which enclose a quite simple, spherical, subspherical, or lentelliptical

primordial shell. The girdles lie in three different planes, perpendicular

to one another, and are of different sizes; each girdle being somewhat

larger than the foregoing and somewhat smaller than the following girdle.

Between these latticed girdles remain on the surface of the shell large

openings or "gates," which are not closed by network, and it is just the

symmetrical disposition and form of these open "gates," separated and

enclosed by the fenestrated girdles, which give to the Pylonida their

characteristic appearance.

{629}To understand clearly this peculiar constitution of the Pylonida-shell

by a system of alternating girdles, developing one after the other it is

indispensable to pay careful attention to the three different elliptical

dimensive planes, which characterise all #Larcoidea#, and to the three

different dimensive axes, which bisect those planes. The girdle which first

develops around simple primordial shell or central chamber is the

transverse girdle, lying in the equatorial plane; then comes, secondly, the

lateral girdle, lying in the lateral plane; and thirdly follows the

sagittal girdle, lying in the sagittal or median plane. The three simplest

genera of the Pylonida--_Monozonium_, _Dizonium_, _Trizonium_--represent

these three different stages, with one, two, or three girdles. These three

genera constitute the first subfamily, Haplozonaria (with one single system

of girdles); all three girdles lie in the surface of a simple

lentelliptical cortical shell.

From this first subfamily the other two subfamilies of Pylonida must be

derived, by repetition of the same characteristic process of growth. In the

Diplozonaria a second system of girdles has been developed, constituting a

second (outer) cortical shell of lentelliptical form, concentric with the

first. Also in this second system the transverse girdle is first developed,

secondly the lateral girdle, thirdly the sagittal girdle. The three genera

_Amphipyle_, _Tetrapyle_ (with _Octopyle_), and _Pylonium_ represent these

three different stages of growth.

Commonly the growth of the Pylonida stops with the completion of the second

system but sometimes the same process is once repeated and a third system

of girdles is formed, constituting a third lentelliptical shell; in this

case also the succession of the three latticed girdles is the same; firstly

the (third) transverse girdle is formed, secondly the (third) lateral

girdle, and thirdly the (third) sagittal girdle. Each of these three

girdles of the third system encloses concentrically the corresponding

girdles of the second and first system. The three corresponding genera of

this third subfamily (Triplozonaria) are _Amphipylonium_, _Tetrapylonium_,

and _Pylozonium_. But in general this highest number of girdles (nine) is

very seldom reached; commonly the growth of the Pylonida stops with five

girdles (_Tetrapyle_ and _Octopyle_). More than nine girdles I have never

observed, though there remains the possibility of the apposition of a

fourth system owing to the peculiar imperfect character of the growth

itself.

The central or primordial chamber of the shell, with which in all Pylonida

the shell-building commences, is a quite simple, very small fenestrated

shell. Commonly one sees on the surface only five to ten small pores (three

to four on the diameter). Its form seems to be sometimes spherical,

sometimes elongated, ellipsoidal or probably lentelliptical. It may be

originally a small _Cenolarcus_. This simple central chamber, the true

"medullary shell" of the small Haplozonaria, is quite different from the

medullary shell of the larger Diplozonaria, and particularly of the

well-known _Tetrapyle_. The former observers, J. Müller as well as R.

Hertwig, have described in these forms also the medullary shell as a simple

spherical or oblong body. But a careful {630}comparison of many hundred

specimens of them and of their dimensions, has convinced me that this was

an error, and that the small spherical or elliptical medullary shell of

_Tetrapyle_ and the other Diplozonaria possesses already the same complex

structure, composed of a system of three girdles, as _Trizonium_ and

_Larnacilla_. Whilst in the Haplozonaria probably the simple central

chamber only represents the medullary shell (enclosed in the central

capsule), and the first system of girdles (complete in _Trizonium_) the

external cortical shell, with the progressive growth this latter becomes

enclosed in the central capsule and so constitutes the "trizonal medullary

shell" of the Diplozonaria and Triplozonaria.

A very difficult matter is the mode of connection between the cortical and

medullary shell. In most of the Pylonida it seems that the first or

transverse girdle (in each system) is produced by the formation of two

lateral wings or chambers (one on each side of the medullary shell), so

that each wing (or half girdle) represents a short and wide, nearly

cylindrical tube, the axis of which (with free openings on both poles) is

parallel to the principal axis of the medullary shell. In this case

(probably the ordinary one) both principal faces of the medullary shell

itself (dorsal and ventral face) constitute the middle part of the first

girdle whilst its lateral parts are formed by the wings (comparable to the

lateral chambers of _Amphitholus_).

In the second case (probably a much rarer one) there is a free ring-shaped

space between the medullary shell and the first (transverse) girdle, and

both are connected by a small number of very short and small radial beams

(R. Hertwig, _loc. cit._, p. 52, line 19 to 21 from above). This mode of

connection would be the same as is common between the concentric shells of

the #Sphæroidea# and #Prunoidea#. The distinction between these two

different modes of connection is often very difficult.

The second or lateral girdle is commonly not in direct connection with the

medullary shell, or only by some scattered radial beams (mainly in the

principal axis). This lateral guide arises by prolongation of both wings of

the transverse girdle in the lateral plane, so that from both sides (right

and left) they become united on the poles of the principal axis. The minor

axis of the elliptical lateral ring (thus formed) is therefore the major

axis of the foregoing (transverse) elliptical ring; the major axes of both

are perpendicular one to another. The major axis of the lateral ring is the

principal (or longitudinal) axis of the whole body.

The third or sagittal girdle becomes developed from the second almost in

the same manner as the second from the first. On both poles of the

principal axis two latticed wings arise from the lateral girdle, growing

further in the direction of an elliptical ring, which represents the

perimeter of the sagittal plane or median plane. These wings are already

mentioned by J. Müller as "prominent roofs, protecting the gates of the

_Tetrapyle_-shell." If these roofs grow towards the equatorial plane of the

shell and become united in pairs on the poles of the sagittal axis, the

third girdle becomes {631}complete. R. Hertwig supposes that the minor axis

of this sagittal girdle is constantly at the same time the major axis of

the lateral girdle, but this is not always the case. Very often the size of

both these girdles is nearly the same, or one is not much larger than the

other. In this case the principal axis of the body is the major axis of the

second as well as of the third girdle.

The characteristic "gates" of the Pylonida, or the large wide openings in

their cortical shell, remaining between the crossed latticed girdles, are

in general roundish, sometimes nearly circular, commonly more elliptical,

kidney-shaped or semilunar, their special form varying much according to

the different form of the girdles. The narrowest part of each girdle, or

its "isthmus," in the case of the halves of the transverse girdle is

commonly at their origin from the medullary shell, in the case of the

halves of the lateral girdle at the poles of the principal axis, and in the

case of the halves of the sagittal girdle at the poles of the sagittal

axis. The number of the gates is quite constant in the different genera. If

only one girdle (the transverse) be developed, we find only two large

gates, between the two wings on the poles of the principal axis (in

_Monozonium_, _Amphipyle_, _Amphipylonium_). In all other cases there are

four gates (determining the original name "_Tetrapyle_"), as well if only

two or if all three girdles be completed. If two girdles be complete (in

_Dizonium_, _Tetrapyle_, _Tetrapylonium_) the four gates lie opposite in

pairs on the sagittal faces (two anterior and two posterior gates), and are

limited by the transverse and lateral girdles. If all three girdles be

complete (in _Trizonium_, _Pylonium_, _Pylozonium_) the four gates lie

opposite in pairs on the lateral faces (two dorsal and two ventral gates),

and are limited by the sagittal and the transverse girdles. If we turn the

shell through an angle of 90°, we have the same aspect as in the former

group. A sagittal septum sometimes becomes developed, beginning with two

polar beams, rising from the poles of the principal axis. If these polar

beams become branched and connected with the middle part of the lateral

girdle, we get a latticed vertical septum, which divides the four gates of

_Tetrapyle_ into eight gates, _Octopyle_.

The lattice-work of the Pylonida is commonly very variable and irregular,

with roundish meshes of very unequal size, therefore without value in the

determination of the species. Commonly the outside of the shell is thorny,

and often distinguished by larger radial spines, symmetrically disposed. We

can separate these into two groups; "dimensive" spines, lying in one of the

three dimensive axes (principal, transverse, or sagittal), and "diagonal"

spines, lying crossed in pairs in diagonal axes. Among these latter eight

diagonal wing-spines, which arise from the lateral edges of the four gates,

are particularly remarkable; they are not only characteristic of _Tetrapyle

octacantha_, but also of a large number of other Pylonida, and form the

starting-point for many specific forms.

The shell of the Pylonida is characterised by extraordinary variability and

great {632}inclination to individual abnormalities, formation of varieties

and transitions into other families, hence derived, as Larnacida,

Tholonida, Lithelida, &c.

The central capsule in all Pylonida, in which I could observe it, was a

true lentellipsis (or a "triaxial ellipsoid" in the geometrical sense, with

the three unequal isopolar axes of the "rhombic octahedron"). In the living

Pylonida it is commonly coloured pink or scarlet. During growth its

dimensions are probably more or less changed, and perhaps the axes

alternate. Regarding the relation of the central capsule to the skeleton,

we can distinguish two different groups, quite as in the nearly allied

Larnacida. In the Haplozonaria (as also in the Larnacillida) the central

capsule encloses only the central chamber and is enveloped by the first

system of girdles, whereas in the Diplozonaria and Triplozonaria (as in the

Larnacalpida) that "trizonal shell" becomes enclosed (as the "medullary

shell") in the central capsule, which is now enveloped by the second system

of girdles as the "cortical shell."

_Synopsis of the Genera of Pylonida._

-------------------------------------------------------------------------

I. Subfamily Haplozonaria.

One system of girdles. Medullary shell simple, spherical or

lentelliptical; cortical shell simple, with one, two, or three

girdles.

-------------------------------------------------------------------------

Cortical shell only with one latticed (transverse)

girdle, 279. _Monozonium_.

Cortical shell with two perfect girdles (transverse

and lateral), 280. _Dizonium_.

Cortical shell with three perfect girdles

(transverse, lateral, and sagittal), 281. _Trizonium_.

-------------------------------------------------------------------------

II. Subfamily Diplozonaria.

Two systems of concentric girdles. Medullary shell trizonal, with

three perfect girdles; cortical shell simple, with one, two or three

girdles.

-------------------------------------------------------------------------

Cortical shell only with one perfect (transverse)

girdle, 282. _Amphipyle_.

Cortical shell with two { Four gates simple, 283. _Tetrapyle_.

perfect girdles (the {

transverse and lateral).{ Four gates bisected by

{ a sagittal septum, 284. _Octopyle_.

Cortical shell with three perfect girdles

(transverse, lateral, and sagittal), 285. _Pylonium_.

-------------------------------------------------------------------------

III. Subfamily Triplozonaria.

Three systems of concentric girdles. Medullary shell trizonal, with

three perfect girdles, quite as the inner cortical shell; outer

cortical shell with one, two, or three girdles.

-------------------------------------------------------------------------

Outer cortical shell (third system) only with one

perfect (transverse) girdle, 286. _Amphipylonium_.

Outer cortical shell with two perfect girdles

(transverse and lateral), 287. _Tetrapylonium_.

Outer cortical shell with three perfect girdles

(transverse, lateral, and sagittal), 288. _Pylozonium_.

Subfamily 1. HAPLOZONARIA, Haeckel.

_Definition._--#Pylonida# with one single system of fenestrated girdles

(with one, two, or three girdles, lying in one lentelliptical face).

{633}Genus 279. _Monozonium_,[318] n. gen.

_Definition._--#Pylonida# with simple, spherical or subspherical, central

chamber, surrounded by one single (transverse) latticed girdle.

The genus _Monozonium_ is the most simple and primitive of all Pylonida,

and may be regarded as their common ancestral form; it may probably be

derived phylogenetically either directly from _Cenosphæra_ or from

_Lentellipsis_, either by apposition of two imperfect lateral chambers, or

by surrounding it with an equatorial latticed girdle. This transverse

girdle is composed of three parts, the central chamber and two lateral

wings, which represent two short hollow latticed tubes, the axes of which

are parallel to the principal axis. On both principal sides (on the

anterior and posterior faces) there are two large open gates as in

_Amphipyle_. If we imagine the openings of the tube-shaped lateral wings

closed by lattice-work, _Monozonium_ becomes transformed into _Tholartus_,

the most simple form of Tholonida. Probably in all Pylonida the ontogeny of

the shell begins with the formation of a _Monozonium_.

Subgenus 1. _Monozonaris_, Haeckel.

_Definition._--Shell smooth or rough, without radial spines or thorns.

1. _Monozonium primordiale_, n. sp.

Central chamber of the shell spherical, smooth, with three to four pores on

the half equator. Both wings of the girdle of the same breadth, but of

twice the length of the central chamber, with three to four longitudinal

rows of pores. No radial spines.

_Dimensions._--Diameter of the central chamber 0.02; breadth of the wings

0.02, length 0.04; pores and bars 0.003.

_Habitat._--Pacific, central area, Station 271, surface.

2. _Monozonium alatum_, n. sp. (Pl. 9, fig. 1).

Central chamber of the shell lentelliptical, smooth, one and a half times

as long as broad, with three to four pores on the half equator. Both wings

of the girdle twice as broad, and somewhat longer than the central chamber,

with five to six longitudinal rows of pores. No radial spines.

_Dimensions._--Length of the central chamber 0.03, breadth 0.02; breadth of

the wings 0.04, length 0.05; pores and bars 0.004.

_Habitat._--North Pacific, Station 241, surface.

_Monozonium hartingii_ = _Haliomma amphiaspis_, Harting, 1863 (L. N. 18, p.

15, pl. 2, fig. 43).

{634}Subgenus 2. _Monozonitis_, Haeckel.

_Definition._--Shell with radial spines or thorns, symmetrically disposed.

3. _Monozonium pleurostylum_, n. sp.

Central chamber spherical, smooth, with four to five pores on the half

equator. Both wings of the girdle of the same breadth, but somewhat longer

than the central chamber, with four to five longitudinal rows of pores. On

the poles of the lateral axis two opposite strong conical spines (one in

the middle of each wing).

_Dimensions._--Diameter of the central chamber 0.025; breadth of the wings

0.025, length 0.03; pores and bars 0.005.

_Habitat._--Pacific, central area, Station 265, surface.

4. _Monozonium amphistylum_, n. sp.

Central chamber lentelliptical, one and a half times as long as broad, with

three to four pores on the half equator. Breadth and length of each wing

somewhat greater than that of the central chamber. On the latter two strong

conical spines, opposite on the poles of the principal or longitudinal

axis.

_Dimensions._--Length of the central chamber 0.03, breadth 0.02; breadth of

the wings 0.025, length 0.04; pores and bars 0.004.

_Habitat._--South Atlantic, Station 332, surface.

5. _Monozonium staurostylum_, n. sp.

Central chamber lentelliptical, one and a third times as long as broad,

with four to five pores on the half equator. Both wings of the girdle have

the same breadth, but one and a half times the length of the central

chamber. Four conical radial spines, two opposite on the poles of the

lateral, two on the poles of the principal axis.

_Dimensions._--Length of the central chamber 0.028, breadth 0.021; breadth

of the wings 0.02, length 0.04.

_Habitat._--South Pacific, Station 295, surface.

Genus 280. _Dizonium_,[319] n. gen.

_Definition._--#Pylonida# with simple, spherical or subspherical, central

chamber, surrounded by two crossed latticed girdles, one smaller (primary)

transverse and one larger (secondary) lateral girdle.

The genus _Dizonium_ differs from the preceding _Monozonium_ in the

possession of two crossed elliptical lattice-girdles. The smaller girdle,

immediately surrounding the {635}central chamber, is the transverse girdle

(the single girdle of _Monozonium_). On the poles of its major axis (the

transverse axis) it is connected with the larger girdle, the elliptical

perimeter of which circumscribes the lateral plane. The minor axis of this

latter is the major axis of the former. Between the two crossed girdles

remain four larger openings or gates, quite as in _Tetrapyle_. But whilst

in _Tetrapyle_ the enclosed medullary shell is a trizonal

_Larnacilla_-shell, here in _Dizonium_ it is a simple spherical or

lentelliptical chamber.

Subgenus 1. _Dizonaris_, Haeckel.

_Definition._--Shell smooth or rough, without radial spines or thorns.

1. _Dizonium circulare_, n. sp.

Central chamber of the shell spherical, smooth, with four to five pores on

the half equator. Lateral girdle circular, three times as broad as the

former. Four gates semilunar, twice as broad as high. No radial spines.

_Dimensions._--Diameter of the central chamber 0.02, of the lateral girdle

0.06; height of the gates 0.02, breadth 0.04.

_Habitat._--Pacific, central area, Station 274, surface.

2. _Dizonium ellipticum_, n. sp.

Central chamber of the shell elliptical, smooth, with three to four pores

on the half equator. Lateral girdle elliptical, three times as long and

broad as the central chamber. Four gates kidney-shaped, twice as broad as

high. No radial spines.

_Dimensions._--Length of the central chamber 0.03, breadth 0.02; length of

the lateral girdle 0.09, breadth 0.06; height of the gates 0.02, breadth

0.038.

_Habitat._--South Pacific, Station 288, surface.

3. _Dizonium transversum_, n. sp.

Central chamber of the shell spherical, rough, with five to six pores on

the half equator. Lateral girdle transverse-elliptical, so that its longer

axis corresponds to the lateral axis of the transverse girdle, and equals

four times the diameter of the central chamber. Four gates kidney-shaped,

four times as broad as high. No radial spines.

_Dimensions._--Diameter of the central chamber 0.02; length of the lateral

girdle 0.05, breadth 0.08; height of the gates 0.01, breadth 0.04.

_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.

{636}Subgenus 2. _Dizonitis_, Haeckel.

_Definition._--Shell with radial spines or thorns, symmetrically disposed.

4. _Dizonium pleuracanthum_, n. sp. (Pl. 9, fig. 2).

Central chamber of the shell nearly spherical, smooth. Lateral girdle

elliptical, one and a third times as long as broad, three times as long as

the central chamber. Four gates transverse-elliptical, one and a half times

as broad as high. Two conical spines, opposite on the poles of the lateral

axis.

_Dimensions._--Diameter of the central chamber 0.03; length of the lateral

girdle 0.1, breadth 0.075; height of the gates 0.026, breadth 0.04.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.

5. _Dizonium amphacanthum_, n. sp.

Central chamber elliptical. Lateral girdle elliptical, twice as long as

broad. Four gates heart-shaped, about as high as broad. Two conical

spines, opposite on the poles of the principal axis.

_Dimensions._--Length of the central chamber 0.03, breadth 0.02; length of

the lateral girdle 0.1, breadth 0.05; height and breadth of the gates 0.03.

_Habitat._--Pacific, central area, Station 270, depth 2925 fathoms.

6. _Dizonium stauracanthum_, n. sp. (Pl. 9, fig. 3).

Central chamber spherical. Lateral girdle elliptical, one and a third times

as long as broad. Four gates elliptical, one and a half times as broad as

high, halved by an axial beam (as in _Octopyle_). Four conical radial

spines opposite in pairs, two on the poles of the principal, two on the

poles of the transverse axis.

_Dimensions._--Diameter of the central chamber 0.025; length of the lateral

girdle 0.09, breadth 0.06; height of the gates 0.024, breadth 0.036.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

7. _Dizonium octacanthum_, n. sp.

Central chamber spherical. Lateral girdle elliptical, one and a half times

as long as broad. Four gates kidney-shaped, twice as broad as high. Eight

radial spines, opposite in pairs in two crossed diagonal planes.

_Dimensions._--Diameter of the central chamber 0.02; length of the lateral

girdle 0.075, breadth 0.05; height of the gates 0.02, breadth 0.04.

_Habitat._--Pacific, central area, Station 272, surface.

{637}Genus 281. _Trizonium_,[320] n. gen.

_Definition._--#Pylonida# with simple, spherical or subspherical, central

chamber, surrounded by three latticed girdles, one smaller (primary)

transverse, one larger (secondary) lateral, and one (tertiary) sagittal

girdle.

The genus _Trizonium_ represents the most highly developed form of the

Haplozonaria, with three complete elliptical latticed girdles, crossed at

right angles and lying in the perimeter of the three dimensive planes.

Commonly the first (transverse) girdle is the smallest, immediately

connected with the spherical or lentelliptical central chamber. The minor

axis of the second (lateral) girdle is identical with the major axis of the

first girdle. The third (sagittal) girdle is either larger than both

others, or intermediate between them. If the four gates between the girdles

become afterwards closed by lattice-work, the "trizonal shell" of

_Trizonium_ passes over into the typical _Larnacilla_, the ancestral form

of a great many #Larcoidea#.

Subgenus 1. _Trizonaris_, Haeckel.

_Definition._--Shell smooth or rough, without radial spines or thorns.

1. _Trizonium tricinctum_, n. sp. (Pl. 9, fig. 4).

Central chamber of the shell elliptical. Lateral girdle elliptical, one and

a half times as long as broad. Four gates kidney-shaped, one and a half

times as broad as high. Ten to eleven pores on the half equator, fourteen

to sixteen on the half meridian of the lentelliptical shell. No radial

spines on the surface.

_Dimensions._--Length of the central chamber 0.024, breadth 0.016; length

of the lateral girdle 0.075, breadth 0.05; height of the four gates 0.026,

breadth 0.04.

_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.

2. _Trizonium constrictum_, n. sp.

Central chamber elliptical. Lateral girdle violin-shaped, on both sides in

the middle constricted, twice as long as broad. Four gates

transverse-elliptical, twice as broad as high. Eight to nine pores on the

half equator, twelve to thirteen on the half meridian. No radial spines.

_Dimensions._--Length of the central chamber 0.03, breadth 0.02; length of

the lateral girdle 0.09, breadth (in the middle) 0.045; height of the gates

0.022, breadth 0.044.

_Habitat._--Pacific, central area, Station 263, surface.

{638}3. _Trizonium hexagonium_, n. sp.

Central chamber spherical. Lateral girdle hexagonal, with parallel sides,

twice as long as broad. Four gates triangular, twice as broad as high.

Eleven to twelve pores on the half equator, sixteen to eighteen on the half

meridian. No radial spines.

_Dimensions._--Diameter of the central chamber 0.025; length of the lateral

girdle 0.08, breadth 0.04; height of the gates 0.018, breadth 0.036.

_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.

4. _Trizonium octogonium_, n. sp.

Central chamber spherical. Lateral girdle octagonal; two lateral sides of

the octagon twice as long as the two polar sides and the four diagonal

sides. Four gates hexagonal, one and a half times as broad as high. Nine to

ten pores on the half equator, twelve to fourteen on the half meridian. No

radial spines.

_Dimensions._--Diameter of the central chamber 0.02; length of the lateral

girdle 0.01, breadth 0.07; height of the gates 0.04, breadth 0.06.

_Habitat._--Indian Ocean, surface; Ceylon, Haeckel.

Subgenus 2. _Trizonitis_, Haeckel.

_Definition._--Shell with radial spines or thorns, symmetrically disposed.

5. _Trizonium pleurobelonium_, n. sp.

Central chamber spherical. Lateral girdle elliptical, one and a third times

as long as broad. Four gates nearly circular. Ten to eleven pores on the

half equator, fifteen to sixteen on the half meridian. Two opposite conical

spines on the poles of the lateral axis.

_Dimensions._--Diameter of the central chamber 0.02; length of the lateral

girdle 0.08, breadth 0.06; height and breadth of the gates 0.025.

_Habitat._--South Atlantic, off Buenos Ayres, Station 323, depth 1900

fathoms.

6. _Trizonium amphibelonium_, n. sp.

? _Echinosphæra datura_, R. Hertwig (partim), 1879, Organismus d.

Radiol., p. 54, Taf. iv. figs. 8, 8_a_.

Central chamber lentelliptical. Lateral girdle lanceolate, nearly one and a

half times as long as broad. Four gates subtriangular. Eight to nine pores

on the half equator, ten to twelve on the half meridian. Two opposite thin

and long spines on the poles of the principal axis, numerous shorter radial

spines on the whole surface. Possibly this species is identical with one of

the three different #Larcoidea# which R. Hertwig has described as

_Echinosphæra datura_. His fig. 8, Taf. iv., would be the aspect from the

sagittal girdle.

{639}_Dimensions._--Length of the central chamber 0.04, breadth 0.025;

length of the lateral girdle 0.11, breadth 0.08; height of the gates 0.03,

breadth 0.04.

_Habitat._--Mediterranean (Genoa), Haeckel, (Messina), R. Hertwig, surface;

Tropical Atlantic, Station 348, surface.

7. _Trizonium staurobelonium_, n. sp.

Central chamber spherical, with two opposite polar beams. Lateral girdle

elliptical, one and a half times as long as broad. Four gates

transverse-elliptical, half as high as broad. Ten to eleven pores on the

half equator, fourteen to fifteen on the half meridian. Four conical radial

spines, two on the poles of the lateral, two on the poles of the principal

axis.

_Dimensions._--Diameter of the central chamber 0.02; length of the lateral

girdle 0.075, breadth 0.05; height of the gates 0.014, breadth 0.028.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.

8. _Trizonium hexabelonium_, n. sp.

Central chamber elliptical. Lateral girdle hexagonal, one and a half times

as long as broad. Four gates rhombic, two-thirds as high as broad. Eight to

nine pores on the half equator, twelve to thirteen on the half meridian.

Six radial spines in the lateral plane, opposite in pairs on the six

corners of the lateral girdle (two principal and four diagonal).

_Dimensions._--Length of the central chamber 0.024, breadth 0.018; length

of the lateral girdle 0.06, breadth 0.04; height of the gates 0.02, breadth

0.03.

_Habitat._--Pacific, central area, Station 263, depth 2650 fathoms.

9. _Trizonium octobelonium_, n. sp.

Central chamber elliptical. Lateral girdle hexagonal, one and one-third

times as long as broad. Four gates kidney-shaped or nearly rhombic, twice

as broad as high. Eleven to twelve pores on the half equator, sixteen to

seventeen on the half meridian. Eight radial spines, opposite in pairs in

two crossed diagonal planes. (An intermediate stage between _Dizonium

octacanthum_ and _Amphipyle octostyle_.)

_Dimensions._--Length of the central chamber 0.03, breadth 0.024; length of

the lateral girdle 0.09, breadth 0.07; height of the gates 0.025, breadth

0.05.

_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.

10. _Trizonium decabelonium_, n. sp.

Central chamber elliptical. Lateral girdle hexagonal, one and a half times

as long as broad. Four gates rhombic, twice as broad as high. Twelve to

thirteen pores on the half equator, seventeen to eighteen on the half

meridian. Ten radial spines, two opposite on the two poles of the principal

axis, eight others opposite in pairs in two crossed diagonal planes.

{640}_Dimensions._--Length of the central chamber 0.04, breadth 0.03;

length of the lateral girdle 0.12, breadth 0.08; height of the gates 0.03,

breadth 0.06.

_Habitat._--North Atlantic, Station 353, surface.

11. _Trizonium dodecabelos_, n. sp.

Central chamber spherical. Lateral girdle octagonal, nearly twice an long

as broad. Four gates hexagonal, one and a half times as broad as high. Nine

to ten pores on the half equator, fifteen to sixteen on the half meridian.

Twelve radial spines, four in the lateral plane, in pairs on both sides of

the poles of the principal axis, eight others opposite in pairs in two

crossed diagonal axes.

_Dimensions._--Diameter of the central chamber 0.025; length of the lateral

girdle 0.1, breadth 0.06; height of the gates 0.033, breadth 0.05.

_Habitat._--Pacific, central area, Station 272, surface.

Subfamily 2. DIPLOZONARIA, Haeckel.

_Definition._--#Pylonida# with two concentric systems of fenestrated

girdles, lying in two concentric lentelliptical faces (every one system

with one to three girdles, lying in one lentelliptical face).

Genus 282. _Amphipyle_,[321] Haeckel, 1881, Prodromus, p. 463.

_Definition._--#Pylonida# with trizonal lentelliptical medullary shell,

surrounded by one single (transverse) latticed cortical girdle.

The genus _Amphipyle_ opens the large series of Diplozonaria, comprising

all Pylonida, the shell of which is composed of two concentric systems of

latticed girdles; the first system constituting the characteristic

"trizonal medullary shell" or "_Larnacilla_-shell;" the second system

composed of one to three girdles of the second order. The first system lies

inside, the second outside the central capsule. In _Amphipyle_ only the

first (transverse) girdle of the second system becomes developed, and

therefore on both poles of the principal axis are two large open gates.

_Amphipyle_ repeats the two-winged form of _Monozonium_; but whilst the

medullary shell in this latter is a simple central chamber, it is here a

trizonal _Larnacilla_-shell.

Subgenus 1. _Amphipylissa_, Haeckel.

_Definition._--Cortical shell smooth or thorny, but without large,

symmetrically disposed spines.

{641}1. _Amphipyle aceros_, n. sp.

Cortical shell quite smooth, without any spines or thorns. Both lateral

wings (or opposite half girdles) semilunar, with convex lateral crest,

three times as long as broad; twice as broad as the trizonal lentelliptical

medullary shell.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.03; length of

each lateral wing (or principal dimension of the latticed girdle) 0.18,

breadth of it (or transverse dimension of each girdle-tube) 0.06.

_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.

2. _Amphipyle stenoptera_, n. sp.

Cortical shell smooth, without spines. Both lateral wings of the same

breadth as the lentelliptical medullary shell, but five times as long as

broad, prolonged on both ends into cylindrical latticed tubes, with

rectilinear lateral crest.

_Dimensions._--Length of the medullary shell 0.06, breadth 0.04; length of

each cylindrical lateral wing 0.2, breadth 0.04.

_Habitat._--South Atlantic, off Ascension Island, Station 343, surface.

3. _Amphipyle platyptera_, n. sp.

Cortical shell thorny, but without larger spines. Both lateral wings nearly

triangular, very broad and short, four times as broad as the medullary

shell between them, and only twice as long as broad, with rectilinear

lateral crest.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.25; length of

each lateral wing 0.18, breadth 0.09.

_Habitat._--Indian Ocean, Ceylon, Haeckel, surface.

Subgenus 2. _Amphipylura_, Haeckel.

_Definition._--Cortical shell armed with large, symmetrically disposed

spines.

4. _Amphipyle amphiceros_, n. sp.

Cortical shell with two conical spines on the poles of the longitudinal

axis (of the lentelliptical medullary shell), without other large spines,

but with small thorns on the surface; two to three longitudinal rows of

irregular, roundish pores on each half wing of the cortical girdle.

_Dimensions._--Length of the medullary shell (or principal axis) 0.06,

breadth (or transverse axis) 0.04; length of each lateral wing 0.2, breadth

of it 0.05.

_Habitat._--Western Tropical Pacific, Station 222, surface.

{642}5. _Amphipyle tetraceros_, n. sp. (Pl. 9, fig. 5).

Cortical shell with smooth surface, and with four strong conical spines in

the lateral plane, opposite in pairs on the ends of the concave lateral

crests (one pair on the end-points of the lateral line of each wing); four

to five longitudinal rows of irregular, roundish pores on each half wing of

the cortical girdle. Surface of the medullary shell spiny.

_Dimensions._--Length of the medullary shell 0.08, breadth of the same

0.05; length of each lateral wing 0.16, breadth 0.04.

_Habitat._--Pacific, central area, Station 271, surface.

6. _Amphipyle stauroceros_, n. sp.

Cortical shell with four strong conical spines, two on the poles of the

longitudinal axis, two opposite on the poles of the transverse axis

(perpendicular to the former). Three to four longitudinal rows of

irregular, roundish pores on each half wing of the cortical girdle, about

six pores in the longest row. Lateral crest convex.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.03; length of

each lateral wing 0.15, breadth 0.08.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

7. _Amphipyle amphiptera_, n. sp. (Pl. 9, fig. 7).

Cortical shell with six strong conical spines, lying in the lateral plane

in three parallel longitudinal lines; two on the poles of the longitudinal

axis, two others on the poles of the wing axes, which are parallel to the

former. Two to three longitudinal rows of irregular, roundish pores on each

half wing of the cortical girdle, about eight pores in the longest row.

Lateral crest convex, thorny.

_Dimensions._--Length of the medullary shell 0.06, breadth 0.045; length of

each lateral wing 0.09, breadth 0.035.

_Habitat._--Western Tropical Pacific, Station 224, surface.

8. _Amphipyle hexaceros_, n. sp.

Cortical shell thorny, with six strong conical spines lying in the lateral

plane; two on the poles of the lateral axis (in the central point of each

wing), two on the end-points of the triangular crest of each wing (on both

poles of the longitudinal wing-axis).

_Dimensions._--Length of the medullary shell 0.06, breadth 0.04; length of

each lateral wing 0.13, breadth 0.07.

_Habitat._--South Pacific, Station 291, surface.

{643}9. _Amphipyle octoceros_, n. sp.

Cortical shell thorny, with eight long radial spines, lying in two crossed

diagonal planes, opposite in pairs. These eight horns are the

prolongations of the anterior and posterior edges of each wing, on both

sides of its lateral plane; they are of great importance, as appearing (by

heredity) in many other Pylonida (_e.g._, in _Tetrapyle octacantha_).

Lateral crest of each wing without spines, slightly convex.

_Dimensions._--Length of the medullary shell 0.07, breadth 0.05; length of

each lateral wing 0.15, breadth 0.06.

_Habitat._--Pacific, central area, Stations 270 to 274, surface.

10. _Amphipyle cladoceros_, n. sp.

Cortical shell spiny, with eight strong ramified radial spines, lying in

the same two crossed diagonal planes as in the preceding species. It

differs from this in the ramification of the eight horns, which bear six to

nine irregular lateral branches, partly simple, partly bifurcate. Lateral

crest of each wing spiny, convex.

_Dimensions._--Length of the medullary shell 0.06, breadth 0.045; length of

each lateral wing (without spines) 0.2, breadth 0.09.

_Habitat._--Indian Ocean, surface, Madagascar, Rabbe.

11. _Amphipyle decaceros_, n. sp.

Cortical shell spiny, with ten strong conical spines; eight lying in two

crossed diagonal planes, in the same disposition (opposite in pairs) as in

both preceding species; two others opposite on the poles of the principal

axis, arising from both poles of the medullary shell (columella-beams).

Spiny crest of the wings convex, semilunar.

_Dimensions._--Length of the medullary shell 0.04, breadth 0.03; length of

each lateral wing 0.12, breadth 0.04.

_Habitat._--North Atlantic, Station 354, surface.

12. _Amphipyle dodecaceros_, n. sp.

Cortical shell thorny, with twelve large cylindrical spines; eight lying in

two crossed diagonal planes, in the same disposition (opposite in pairs) as

in the three preceding species; four others crossed at right angles in the

lateral plane, two opposite on the poles of the principal, two on the poles

of the lateral axis (the latter shorter). Both lateral wings nearly

rhombic.

_Dimensions._--Length of the medullary shell 0.06, breadth 0.04; length of

the lateral wings 0.15, breadth 0.05.

_Habitat._--South Atlantic, coast of Brazil, Rabbe, surface.

{644}13. _Amphipyle callizona_, n. sp. (Pl. 9, fig. 6).

Cortical shell smooth, with sixteen strong and short conical spines, lying

opposite in pairs in two crossed diagonal planes; each lateral wing

four-sided prismatic, its lateral face concave, both ends truncated, and

each end provided with four divergent spines. Length of the wings somewhat

greater, but breadth smaller, than that of the medullary shell.

_Dimensions._--Length of the medullary shell 0.07, breadth 0.05; length of

the lateral wings 0.09, breadth 0.03.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 283. _Tetrapyle_,[322] J. Müller, 1858, Monatsber. d. k. preuss.

Akad. d. Wiss. Berlin, p. 154.

_Definition._--#Pylonida# with trizonal lentelliptical medullary shell,

surrounded by two crossed latticed cortical girdles, one smaller (primary)

transverse, and one larger (secondary) lateral girdle. Four gates between

the two cortical girdles simple, without a sagittal septum.

The genus _Tetrapyle_, till 1881 the only known genus of the whole family,

was founded by Johannes Müller in 1858, and clearly illustrated by the

Mediterranean (and common cosmopolitan) _Tetrapyle octacantha_, hitherto

the best known type of this family. Afterwards (1860, Monatsber. d. k.

preuss. Akad. d. Wiss. Berlin, p. 832) Ehrenberg founded the genus

_Schizomma_ for a nearly allied form, which exhibits only slight specific

differences (compare my Monograph, 1862, p. 434). Some good remarks on the

structure of this typical genus and its relations to other Pylonida are to

be found in Richard Hertwig's Organismus, &c., 1879, p. 52, but the true

trizonal structure of the medullary shell in this genus was not recognised

by him, so that his description agrees more with _Dizonium_. We confine

here the genus _Tetrapyle_ to those Pylonida for which _Tetrapyle

octacantha_ of J. Müller remains the determining type; the cortical shell

is composed only of two perfect lattice-girdles (the transverse and

lateral), between which four wide gates remain open. This structure is

similar to that of _Dizonium_; but whilst here the medullary shell is a

simple central chamber, in _Tetrapyle_ it is a complete trizonal or

_Larnacilla_-shell.

Subgenus 1. _Tetrapylissa_, Haeckel.

_Definition._--Cortical shell smooth or thorny, but without large,

symmetrically disposed spines.

{645}1. _Tetrapyle circularis_, n. sp. (Pl. 9, fig. 8).

Cortical shell rough, without radial spines. Lateral girdle circular,

therefore the longitudinal axis is equal to the transverse. Four gates

kidney-shaped, twice as broad as high. In each half wing of the transverse

girdle six to seven longitudinal rows of irregular, roundish pores.

_Dimensions._--Medullary shell 0.05 long, 0.04 broad; cortical shell 0.15

long and broad; gates 0.04 high, 0.08 broad.

_Habitat._--Pacific, central area, Station 263, surface.

2. _Tetrapyle circopyle_, n. sp.

Cortical shell smooth, without radial spines. Lateral girdle elliptical,

one and a half times as long as broad. Four gates nearly circular. On each

half wing of the transverse girdle four to five rows of subregular,

circular pores. (Similar to _Tetrapyle pleuracantha_, Pl. 9, fig. 9, but

without lateral spines.)

_Dimensions._--Medullary shell 0.04 long, 0.03 broad; cortical shell 0.16

long, 0.11 broad; gates 0.05 high and broad.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

3. _Tetrapyle quadriloba_, Haeckel.

_Tetrapyle quadriloba_, Haeckel, 1862, Monogr. d. Radiol., p. 436.

_Schizomma quadrilobum_, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 815; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, Taf.

x. figs. 12-14.

Cortical shell thorny, without regular, radial spines. Lateral girdle

elliptical, one and a half times as long as broad. Four gates nearly

circular. On each half wing of the transverse girdle three to four rows of

irregular, roundish pores.

_Dimensions._--Medullary shell 0.06 long, 0.04 broad; cortical shell 0.16

long, 0.1 broad; diameter of the gates 0.05.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian Ocean, Pacific,

surface.

4. _Tetrapyle nephropyle_, n. sp.

Cortical shell thorny, without radial spines. Lateral girdle elliptical,

one and a third times as long as broad. Four gates kidney-shaped, nearly

twice as broad as high, with two prominent polar spines on the poles of the

longitudinal axis of the medullary shell. On each half wing of the

transverse girdle three to four longitudinal rows of large roundish pores.

_Dimensions._--Medullary shell 0.06 long, 0.04 broad; cortical shell 0.24

long, 0.18 broad; gates 0.05 high, 0.08 broad.

_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.

{646}5. _Tetrapyle cardiopyle_, n. sp.

Cortical shell rough, without radial spines. Lateral girdle with hexagonal

contour, nearly cylindrical in the middle part, conical at both ends, twice

as long as broad. Four gates heart-shaped, about as high as broad. On each

half wing of the transverse girdle three to four longitudinal rows of

subregular, polygonal pores.

_Dimensions._--Medullary shell 0.04 long, 0.02 broad; cortical shell 0.14

long, 0.07 broad; gates 0.05 high and broad.

_Habitat._--Eastern Tropical Atlantic, Station 348, depth (2450) fathoms.

Subgenus 2. _Tetrapylura_, Haeckel.

_Definition._--Cortical shell armed with large, symmetrically disposed

spines.

6. _Tetrapyle fusiformis_, n. sp.

Cortical shell rough, with two strong conical spines on the poles of the

longitudinal axis. Lateral girdle spindle-shaped, one and a half times as

long as broad. Four gates kidney-shaped, twice as broad as high. On each

half wing of the transverse girdle four to five longitudinal rows of

irregular, roundish pores.

_Dimensions._--Medullary shell 0.07 long, 0.05 broad; cortical shell 0.18

long, 0.12 broad; gates 0.04 high, 0.08 broad.

_Habitat._--Western Tropical Atlantic, Mexican Gulf Stream, depth 1500

fathoms, Schaffner.

7. _Tetrapyle pleuracantha_, n. sp. (Pl. 9, fig. 9).

Cortical shell rough, with two strong conical spines on the poles of the

transverse axis. Lateral girdle elliptical, one and half times as long as

broad. Four gates subcircular or nearly hexagonal, about as high as broad.

On each half wing of the transverse girdle three to four longitudinal rows

of very irregular pores.

_Dimensions._--Medullary shell 0.045 long, 0.035 broad; cortical shell 0.16

long, 0.11 broad; gates 0.045 high and broad.

_Habitat._--Western Tropical Pacific, off New Guinea, Stations 222 to 224,

depths 1850 to 2450 fathoms.

8. _Tetrapyle transversa_, n. sp.

Cortical shell thorny, with two strong conical lateral spines on the poles

of the transverse axis. Lateral girdle elliptical, only four-fifths as long

as broad. Four gates elliptical, twice as broad as high, with two prominent

spines on the poles of the longitudinal axis of the medullary shell. On

each half wing of the transverse girdle five to six longitudinal rows of

subregular, roundish pores. (Similar to _Octopyle transversa_, but without

sagittal septum and with stronger lateral spines.)

{647}_Dimensions._--Medullary shell 0.05 long, 0.035 broad; cortical shell

0.12 long, 0.15 broad; gates 0.03 high, 0.06 broad.

_Habitat._--Southern Pacific, Station 290, surface.

9. _Tetrapyle cruciata_, n. sp.

Cortical shell smooth, with four strong radial spines, two on the poles of

the longitudinal axis, two on the poles of the transverse axis. Lateral

girdle nearly circular, quite as long as broad. Four gates kidney-shaped,

twice as broad as high. On each half wing of the transverse girdle five to

six rows of subregular, circular pores.

_Dimensions._--Medullary shell 0.06 long, 0.05 broad; cortical shell 0.16

long and broad; gates 0.05 high, 0.09 broad.

_Habitat._--South Atlantic, Station 330, surface.

10. _Tetrapyle staurophora_, n. sp.

Cortical shell thorny, with four strong radial spines, two on the poles of

the longitudinal axis, two on the poles of the transverse axis. Lateral

girdle elliptical, one and a half times as long as broad. Four gates nearly

hexagonal, quite as high as broad. On each half wing of the transverse

girdle three to four longitudinal rows of irregular, roundish pores.

_Dimensions._--Medullary shell 0.06 long, 0.04 broad; cortical shell 0.18

long, 0.12 broad; gates 0.08 high and broad.

_Habitat._--Western Tropical Atlantic, coast of Brazil, Rabbe, surface.

11. _Tetrapyle quadricornis_, n. sp.

Cortical shell thorny, with four strong horn-like curved spines, lying in

the lateral plane and converging in pairs towards the poles of the

transverse axis. Lateral girdle elliptical, one and a third times as long

as broad. Four gates kidney-shaped, twice as broad as high. On each half

wing of the transverse girdle four to five rows of irregular, roundish

pores. (May be only the young form of _Pylonium quadricorne_, Pl. 9, fig.

14.)

_Dimensions._--Medullary shell 0.05 long, 0.04 broad; cortical shell 0.16

long, 0.12 broad; gates 0.03 high, 0.07 broad.

_Habitat._--Pacific, central area, Stations 270 to 274, surface.

12. _Tetrapyle tetracantha_, n. sp.

Cortical shell thorny, with four strong radial spines lying in the lateral

plane and in pairs in its two crossed diagonal axes. Lateral girdle

elliptical, constricted in the middle, nearly twice as long as broad. Four

gates kidney-shaped, one and a half times as broad as high. On each half

wing of the transverse girdle three to four longitudinal rows of large,

irregular, roundish pores. {648}(Similar to _Tetrapylonium quadrangulare_,

Pl. 49, fig. 15, but without a sagittal girdle and with stronger lateral

spines.)

_Dimensions._--Medullary shell 0.06 long, 0.04 broad; cortical shell 0.18

long, 0.1 broad; gates 0.007 high, 0.01 broad.

_Habitat._--North Atlantic, Canary Islands, Station 353, surface.

13. _Tetrapyle quadrigata_, n. sp.

Cortical shell thorny, with four brush-like groups of radial spines on the

four diagonal corners of the lateral plane, opposite in pairs in diagonal

axes. Lateral girdle nearly square, somewhat broader than long. Four gates

kidney-shaped, twice as broad as high. On each half wing of the transverse

girdle five to six longitudinal rows of irregular, roundish pores.

_Dimensions._--Medullary shell 0.06 long, 0.04 broad; cortical shell 0.14

long, 0.15 broad; gates 0.03 high, 0.07 broad.

_Habitat._--Pacific, central area, Station 270, surface.

14. _Tetrapyle octacantha_, J. Müller.

_Tetrapyle octacantha_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 33, Taf. ii. figs. 1-6.

_Tetrapyle octacantha_, Haeckel, 1862, Monogr. d. Radiol., p. 435.

_Tetrapyle octacantha_, R. Hertwig, 1879, Organismus d. Radiol., p. 52,

Taf. iv. fig. 7, Taf. vi. figs. 2, 5, 5_a._

Cortical shell thorny, with eight long and thin, cylindrical radial spines,

lying in two crossed diagonal planes, opposite in pairs. These eight

characteristic diagonal spines (or "angular spines") are the same as in

_Amphipyle octoceros_ and many other Pylonida, and arise as prolongations

of the proximal edges of the four gates (or of the lateral wings on the

eight points, where they are intersected by the edges of the lateral ring).

This cosmopolitan, widely distributed and very variable species was a long

time the only known species of all the Pylonida, and very accurately first

described (1858) by Johannes Müller, afterwards (1879) by R. Hertwig. But

in the descriptions of these authors also some different species (such as

the following) may be confounded with the true typical _Tetrapyle

octacantha_. The four gates of this species are transverse-elliptical or

almost triangular, nearly twice as broad as high.

_Dimensions._--Length of the medullary shell 0.04, breadth 0.03; length of

the cortical shell 0.18, breadth 0.13; height of the gates 0.05, breadth

0.08.

_Habitat._--Cosmopolitan; very common in all warmer seas, Mediterranean,

Atlantic, Indian, Pacific, surface.

15. _Tetrapyle cladacantha_, n. sp.

Cortical shell thorny, with eight strong ramified radial spines, lying

opposite in pairs in two crossed diagonal planes, as in the preceding

species. It differs from this by the peculiar ramification of the eight

spines, which bear two to eight simple or furcate lateral branches arising

under {649}right angles (already commencing in a transitional variety of

_Tetrapyle octacantha_, J. Müller, _loc. cit._, Taf. ii. figs. 5, 6). Four

gates transverse-elliptical, one and a half times as broad as high.

_Dimensions._--Medullary shell 0.05 long, 0.04 broad; cortical shell 0.16

long, 0.13 broad; gates 0.05 high, 0.08 broad.

_Habitat._--Mediterranean (Corfu), Haeckel, surface.

16. _Tetrapyle pluteus_, Haeckel.

_Tetrapyle octacantha_, var., J. Müller, 1858, Abhandl. d. k. Akad. d.

Wiss. Berlin, Taf. iii. figs. 7-12.

Cortical shell thorny, with eight strong radial spines, lying opposite in

pairs, as in the two foregoing species. On the distal edge each of the four

triangular gates is protected by a prominent roof of lattice-work (or

"pluteus"), which arises from the distal part of the lateral girdle and

connects the two angular diagonal spines of each gate. Therefore the shell

assumes the characteristic form very well represented by J. Müller in his

fig. 11 (seen from the lateral side) and fig. 7 (seen from the pole of the

principal axis).

_Dimensions._--Medullary shell 0.04 long, 0.03 broad; cortical shell 0.15

long, 0.11 broad; gates 0.045 high, 0.07 broad.

_Habitat._--Mediterranean, Atlantic, Stations 348 to 353, &c., surface.

17. _Tetrapyle turrita_, n. sp. (Pl. 9, fig. 10).

Cortical shell smooth, but with ten strong conical spines, two on the poles

of the principal axis, eight others symmetrically distributed on both sides

of the distal edge of the four roundish gates, and directed towards the

transverse axis. Lateral girdle lanceolate, twice as long as broad.

_Dimensions._--Medullary shell 0.05 long, 0.04 broad; cortical shell 0.2

long, 0.1 broad; gates 0.05 high, 0.07 broad.

_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.

18. _Tetrapyle dodecaceros_, n. sp.

Cortical shell thorny, with twelve stronger conical spines, eight diagonal

spines in two crossed planes (as in _Tetrapyle octacantha_), and four

others in the lateral plane, in pairs on both sides of a deep sagittal

constriction of the quadrangular lateral girdle. Four gates kidney-shaped,

twice as broad as high. On each half wing of the transverse girdle five to

six longitudinal rows of irregular, roundish pores.

_Dimensions._--Medullary shell 0.06 long, 0.04 broad; cortical shell 0.18

long, 0.14 broad; gates 0.04 high, 0.08 broad.

_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.

{650}Genus 284. _Octopyle_,[323] Haeckel, 1881, Prodromus, p. 464.

_Definition._--#Pylonida# with trizonal lentelliptical medullary shell,

surrounded by two crossed, latticed, cortical girdles; one smaller

(primary) transverse, and one larger (secondary) lateral girdle. Four gates

between the two cortical girdles divided by a sagittal septum into eight

gates.

The genus _Octopyle_ comprises those Pylonida which are distinguished from

the nearly allied _Tetrapyle_ by the development of a sagittal septum,

dividing the four gates of the latter into eight separate gates. The septum

begins with the formation of two axial rods or columellæ, which afterwards

become branched; the branches communicating one with another and with the

middle parts of the lateral girdle (on the poles of the principal axis),

there is formed a latticed septum in the sagittal plane, which separates

more or less incompletely the right and left halves of the shell. The four

gates of _Tetrapyle_ become halved by this septum, and their number

doubled.

Subgenus 1. _Octopylissa_, Haeckel.

_Definition._--Cortical shell smooth or thorny, but without larger

symmetrically disposed spines.

1. _Octopyle ovulina_, n. sp.

Cortical shell lentelliptical, smooth, without thorns. Lateral girdle

elliptical, one and a third times as long as broad. Transverse girdle

narrow, with two pores on the isthmus (or on the narrowest part of each

quadrant). Sagittal septum as long as the elliptical medullary shell. Eight

gates egg-shaped.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.035; length of

the cortical shell 0.16, breadth 0.12.

_Habitat._--Pacific, central area, Station 274, surface.

2. _Octopyle quadrata_, n. sp.

Cortical shell thorny, nearly square, of equal length and breadth. Lateral

girdle quadrangular, with rounded edges, of equal length and breadth.

Transverse girdle narrow, with three pores on the isthmus. Sagittal septum

of the same length as the subspherical medullary shell. Eight gates nearly

circular.

_Dimensions._--Diameter of the medullary shell 0.04, of the cortical shell

0.14.

_Habitat._--Northern Pacific, Station 244, depth 2900 fathoms.

{651}3. _Octopyle subglobosa_, n. sp.

Cortical shell nearly spherical, thorny, of equal length and breadth.

Lateral girdle broad, nearly circular. Transverse girdle broad, with four

pores on the isthmus. Sagittal septum shorter than the subspherical

medullary shell. Eight gates egg-shaped.

_Dimensions._--Diameter of the medullary shell 0.05, of the cortical shell

0.13.

_Habitat._--Southern Pacific, Station 300, depth 1375 fathoms.

4. _Octopyle transversaria_, n. sp.

Cortical shell thorny, transverse-elliptical. Lateral girdle very broad,

one and a third times as broad as long. Transverse girdle also very broad,

with five pores on the isthmus. Sagittal septum shorter than the elliptical

medullary shell. Eight gates small, roundish.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.04; length of

the cortical shell 0.11, breadth 0.15.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.

Subgenus 2. _Octopylura_, Haeckel.

_Definition._--Cortical shell armed with large, symmetrically disposed

spines.

5. _Octopyle amphistyle_, n. sp.

Cortical shell smooth, nearly spindle-shaped, about twice as long as broad.

Transverse girdle broad, with four large pores on the isthmus. Lateral

girdle lanceolate. Sagittal septa about as long as the medullary shell,

prolonged at both poles of the principal axis into two opposite, strong,

angular spines. Eight gates obliquely quadrangular.

_Dimensions._--Length of the medullary shell 0.07, breadth 0.05; length of

the cortical shell 0.2, breadth 0.12.

_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.

6. _Octopyle staurostyle_, n. sp.

Cortical shell nearly rhombic, smooth, one and a half times as long as

broad, with four strong, conical, radial spines, two on the poles of the

principal axis (as prolongations of the sagittal septa), two others on the

poles of the transverse axis. Transverse girdle narrow, with two pores on

the isthmus. Sagittal septa longer than the medullary shell. Eight gates

triangular.

_Dimensions._--Length of the medullary shell 0.04, breadth 0.03; length of

the cortical shell 0.18, breadth 0.12.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

{652}7. _Octopyle tetrastyle_, n. sp.

Cortical shell lentelliptical, with rough surface and four angular radial

spines in the lateral plane, opposite in pairs in two crossed diagonals.

Lateral girdle nearly rectangular (each angle with one spine), one and a

third times as long as broad. Sagittal septum longer than the hexagonal

medullary shell. Eight gates egg-shaped.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.03; length of

the cortical shell 0.16, breadth 0.12.

_Habitat._--North Atlantic, Station 354, surface.

8. _Octopyle tetraptera_, n. sp.

Cortical shell quadrangular, with thorny surface and four latticed

wing-like prolongations on the corners of the quadrangle, opposite in pairs

in two crossed diagonals, each wing supported by a strong radial spine.

Lateral girdle quadrangular, one and a half times as long as broad. On the

isthmus of the transverse girdle four pores. Sagittal septum longer than

the hexagonal medullary shell. Eight gates triangular.

_Dimensions._--Length of the medullary shell 0.07, breadth 0.04; length of

the cortical shell 0.24, breadth 0.16.

_Habitat._--Pacific, central area, Station 271, surface.

9. _Octopyle stenozona_, n. sp. (Pl. 9, fig. 11).

Cortical shell quadrangular, with thorny surface, and four conical spines

in the lateral plane, on the points, where both cortical girdles are

crossed. Lateral girdle very narrow, nearly square, with rounded corners,

of equal length and breadth. On the isthmus of the narrow transverse girdle

only one pore. Sagittal septum of the same length as the subspherical

medullary shell. Eight gates irregular roundish or nearly circular.

_Dimensions._--Diameter of the medullary shell 0.04, of the cortical shell

0.14.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.

10. _Octopyle euryzona_, n. sp.

Cortical shell nearly quadrangular, very thorny, with four bunches of

stronger radial spines on the four corners. Lateral girdle broad, with

rounded edges of the quadrangle, little longer than broad. On the isthmus

of the broad transverse girdle four pores. Sagittal septum of the same

length as the elliptical medullary shell, with many radial beams. Eight

gates nearly square.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.035; length of

the cortical shell 0.16, breadth 0.14.

_Habitat._--Southern Atlantic, Station 332, depth 2200 fathoms.

{653}11. _Octopyle hexastyle_, n. sp.

Cortical shell nearly rectangular, thorny, with six strong radial spines in

the lateral plane, two opposite on the poles of the principal axis

(prolongations of the principal beam at the sagittal septum), four others

on the truncate corners of the quadrangular lateral girdle, which is one

and a half times as long as broad. On the isthmus of the broad transverse

girdle three pores. Sagittal septum longer than the hexagonal medullary

shell. Eight egg-shaped gates.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.04; length of

the cortical shell 0.18, breadth 0.12.

_Habitat._--Northern Atlantic, surface; Canary Islands, Station 9, depth

3150 fathoms.

12. _Octopyle sexangulata_, n. sp. (Pl. 9, fig. 12).

Cortical shell thorny, hexagonal, with six strong conical radial spines on

the six corners of the lateral girdle, lying in the lateral plane, two

opposite on the poles of the transverse axis, four others in pairs on both

sides of the annular sagittal constriction, which is only twice as long as

the elliptical medullary shell. Transverse girdle broad, with five pores on

the isthmus. Eight gates roundish, smaller than the medullary shell.

_Dimensions._--Length of the medullary shell 0.045, breadth 0.035; length

of the cortical shell 0.11, breadth 0.13.

_Habitat._--Pacific, central area, Station 270, surface.

13. _Octopyle octostyle_, n. sp.

Cortical shell elliptical, thorny, with eight long cylindrical radial

spines, lying in two crossed diagonal planes, opposite in pairs, quite as

in the nearly related _Tetrapyle octacantha_. It differs from this species

by the perfect, latticed, vertical sagittal septum, which divides every

gate into two triangular halves. Lateral girdle elliptical, one and a third

times as long as broad. Transverse girdle on the isthmus with three pores.

Septum longer than the elliptical medullary shell.

_Dimensions._--Length of the medullary shell 0.06, breadth 0.045; length of

the cortical shell 0.16, breadth 0.12.

_Habitat._--South Pacific, Station 288, surface.

14. _Octopyle obtecta_, n. sp.

Cortical shell quadrangular, thorny, with eight strong diagonal spines,

lying in two crossed planes, and arising from the proximal edges of the

gates in the same way as in the foregoing species. It differs from this by

four prominent latticed roofs, which arise from the distal edge of the

gates and connect the diagonal spines of one gate. _Octopyle obtecta_ bears

therefore the same relation to _Octopyle octostyle_ that _Tetrapyle

pluteus_ does to _Tetrapyle octacantha_.

_Dimensions._--Length of the medullary shell 0.055, breadth 0.04; length of

the cortical shell 0.16, breadth 0.12.

_Habitat._--Indian Ocean, surface, Madagascar, Rabbe.

{654}15. _Octopyle decastyle_, n. sp. (Pl. 9, fig. 13).

Cortical shell thorny, nearly quadrangular, with ten stronger radial

spines, two opposite on the poles of the principal axis (as prolongations

of the axial beams), eight others opposite in pairs in two diagonal planes

(as in the foregoing species). Lateral girdle nearly square, with slightly

convex lateral faces, slightly concave principal faces. Transverse girdle

broad, with four pores on the isthmus. Sagittal septum of the same length

as the hexagonal medullary shell. Eight gates elliptical or irregular

roundish.

_Dimensions._--Length of the medullary shell 0.05, breadth 0.032; diameter

of the cortical shell 0.15.

_Habitat._--Western Tropical Pacific, Station 224, depth 1850 fathoms.

Genus 285. _Pylonium_,[324] Haeckel, 1881, Prodromus, p. 464.

_Definition._--#Pylonida# with trizonal lentelliptical medullary shell

surrounded by three crossed latticed cortical girdles, one smaller

(primary) transverse, one larger (secondary) lateral, and one (tertiary)

sagittal girdle.

The genus _Pylonium_ is the most highly developed among the Diplozonaria,

with six complete latticed girdles, three on the medullary shell, three on

the cortical shell, the latter corresponding to the former. In each of the

two systems the transverse girdle is smaller than the lateral; the sagittal

girdle may be smaller or larger than the lateral girdle. _Pylonium_ repeats

the typical form of _Trizonium_; but whilst in this latter the medullary

centre of the shell is a simple spherical chamber, here in _Pylonium_ it is

a true trizonal or _Larnacilla_-shaped medullary shell.

Subgenus 1. _Pylonissa_, Haeckel.

_Definition._--Cortical shell smooth or thorny, but without large,

symmetrically disposed spines.

1. _Pylonium circozonium_, n. sp.

Cortical shell thorny, without radial spines; all its three girdles nearly

of the same size, subcircular, very narrow, only with one to two rows of

pores. Four gates subcircular.

_Dimensions._--Principal axis 0.12, transverse axis 0.11; diameter of the

subspherical medullary shell 0.05.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

{655}2. _Pylonium hexazonium_, n. sp.

Cortical shell smooth, without symmetrical radial spines. Transverse girdle

elliptical, one and a half times as long as broad. Lateral and sagittal

girdles nearly circular. Four gates egg-shaped.

_Dimensions._--Principal axis 0.16, transverse axis 0.15; diameter of the

subspherical medullary shell 0.04.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.

3. _Pylonium nephropylium_, n. sp.

Cortical shell thorny, without radial spines. All its three girdles

elliptical, one and a third times as long as broad. Four gates

kidney-shaped, nearly twice as broad as high.

_Dimensions._--Principal axis 0.17, transverse axis 0.13; length of the

lentelliptical medullary shell 0.04, breadth 0.03.

_Habitat._--Pacific, central area, Station 273, depth 2350 fathoms.

Subgenus 2. _Pylonura_, Haeckel.

_Definition._--Cortical shell armed with large, symmetrically disposed

spines.

4. _Pylonium quadricorne_, n. sp. (Pl. 9, fig. 14).

Cortical shell thorny, with four strong horn-like curved spines in the

lateral plane. All its three girdles elliptical, one and a third times as

long as broad. Four gates kidney-shaped, twice as broad as high. (This

species is a further developmental stage of _Tetrapyle quadricornis_, with

perfect sagittal girdle.)

_Dimensions._--Principal axis 0.16, transverse axis 0.12; length of the

medullary shell 0.05, breadth 0.04.

_Habitat._--Pacific, central area, Stations 270 to 274, surface; Indian

Ocean, Madagascar, Rabbe, surface.

5. _Pylonium octacanthum_, n. sp.

Cortical shell thorny, with eight long and thin cylindrical radial spines,

lying in two crossed diagonal planes, opposite in pairs, and arising from

the eight points where the transverse girdle is crossed by the lateral

girdle. All three girdles elliptical, one and a half times as long as

broad; four gates triangular. (This species is a further developmental

stage of _Tetrapyle octacantha_, with perfect sagittal girdle.)

_Dimensions._--Principal axis 0.18, transverse axis 0.13; length of the

medullary shell 0.03 to 0.04.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

{656}6. _Pylonium stenozonium_, n. sp.

Cortical shell thorny, with eight short conical radial spines, lying in two

crossed diagonal planes (as in the foregoing species). All three girdles

nearly of the same size, subcircular, very narrow, only with one to two

rows of pores. Four gates kidney-shaped.

_Dimensions._--Principal axis 0.15, transverse axis 0.14; diameter of the

quadrangular medullary shell 0.04.

_Habitat._--Equatorial Atlantic, Station 347, surface.

Subfamily 3. TRIPLOZONARIA, Haeckel.

_Definition._--#Pylonida# with three concentric systems of fenestrated

girdles, lying in three concentric lentelliptical faces (every system with

one to three girdles lying in one lentelliptical face).

Genus 286. _Amphipylonium_,[325] Haeckel, 1881, Prodromus, p. 463.

_Definition._--#Pylonida# with trizonal lentelliptical medullary shell,

surrounded by a double latticed cortical shell; inner cortical shell

_Pylonium_-shaped, with three perfect crossed girdles; outer cortical shell

only represented by a single (transverse) girdle.

The genus _Amphipylonium_ opens the series of Triplozonaria, or of those

Pylonida in which the shell is composed of three concentric systems of

latticed girdles. The first (and innermost) system represents the complete

trizonal medullary shell, which is probably a lentelliptical

_Larnacilla_-shell. The first and intermediate system is formed of a

complete trizonal cortical shell of the same form, but much larger (like

_Pylonium_). The third (and outermost) system is represented by one to

three latticed girdles, corresponding to the former and forming an outer or

second cortical shell. In _Amphipylonium_ (as the most simple form of the

Triplozonaria) there is only developed the first (transverse) girdle of the

third system. It repeats therefore the form of _Amphipyle_, the cortical

shell of which is here double (Prodromus, 1881, p. 463).

1. _Amphipylonium semilunare_, n. sp.

Inner cortical shell lentelliptical, one and a half times as long as broad,

with smooth surface and four semilunar gates. Transverse girdle of the

outer cortical shell with two smooth semilunar wings, with convex, smooth

lateral crests; each wing as broad as the transverse girdle of the inner

cortical shell and twice as long as its lateral girdle.

_Dimensions._--Length of the lentelliptical medullary shell 0.04, breadth

0.03; length of the inner cortical shell 0.15, breadth 0.1; length of each

lateral wing of the outer cortical shell 0.3, breadth 0.1.

_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.

{657}2. _Amphipylonium spinosissimum_, n. sp.

Inner cortical shell lentelliptical, one and a third times as long as

broad, with thorny surface and four kidney-shaped gates. Transverse girdle

of the outer cortical shell very spiny, with two semilunar wings, with

convex thorny lateral crests; each wing one and a half times as broad as

the transverse girdle of the inner cortical shell, and one and a half times

as long as its lateral girdle.

_Dimensions._--Length of the lentelliptical medullary shell 0.05, breadth

0.03; length of the inner cortical shell 0.16, breadth 0.12; length of each

lateral wing of the outer cortical shell 0.24, breadth 0.18.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. _Amphipylonium tetraceros_, n. sp.

Inner cortical shell hexagonal, one and a half times as long as broad, with

smooth surface and four transverse elliptical gates. Transverse girdle of

the outer cortical shell smooth, with rectilinear smooth lateral crests,

which are prolonged at both ends into strong conical spines (therefore four

spines in the lateral plane); each wing of the same breadth as the

transverse girdle of the inner cortical shell, and twice as long as its

lateral girdle.

_Dimensions._--Length of the hexagonal medullary shell 0.03, breadth 0.02;

length of the inner cortical shell 0.12, breadth 0.08; length of each

lateral wing of the outer cortical shell 0.24, breadth 0.08.

_Habitat._--Northern Pacific, Station 253, depth 3125 fathoms.

4. _Amphipylonium octoceros_, n. sp.

Inner cortical shell quadrangular, one and a third times as long as broad,

with thorny surface and four kidney-shaped gates. Transverse girdle of the

outer cortical shell thorny, constricted at the equator, with concave

thorny lateral crests, and with eight strong radial spines, opposite in

pairs and lying in two crossed diagonal planes; each wing narrower than the

transverse girdle of the inner cortical shell and twice as long as its

lateral girdle.

_Dimensions._--Length of the subspherical medullary shell 0.04, breadth

0.035; length of the inner cortical shell 0.14, breadth 0.11; length of

each lateral wing of the outer cortical shell 0.26, breadth 0.09.

_Habitat._--Southern Pacific, Station 295, depth 1500 fathoms.

Genus 267. _Tetrapylonium_,[326] Haeckel, 1881, Prodromus, p. 464.

_Definition._--#Pylonida# with trizonal lentelliptical medullary shell,

surrounded by a double latticed cortical shell; inner cortical shell

_Pylonium_-shaped, with three perfect crossed girdles; outer cortical shell

represented by two crossed girdles, one (smaller) transverse and one

(larger) lateral girdle.

{658}The genus _Tetrapylonium_ represents a further developmental stage of

the foregoing _Amphipylonium_; whilst in this latter the outer cortical

shell (or the third system of girdles) is formed only by a transverse

girdle, here this is crossed by a lateral girdle. _Tetrapylonium_ repeats

therefore the typical form of _Tetrapyle_, but with doubled cortical shell

(Prodromus, 1881, p. 464).

1. _Tetrapylonium pantellipticum_, n. sp.

Outer cortical shell elliptical, one and a third times as long as broad,

with smooth surface and four elliptical gates. Inner cortical shell

elliptical, with smooth surface and four elliptical gates which repeat the

form of the four outer gates, but are of half the size. Transverse girdle

broad, with five pores on the isthmus.

_Dimensions._--Length (or principal axis) of the first shell (medullary

shell) 0.04, breadth (or transverse axis) 0.03; length of the second (or

inner cortical) shell 0.12, breadth 0.09; length of the third (or outer

cortical) shell 0.18, breadth 0.14.

_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.

2. _Tetrapylonium reniforme_, n. sp.

Outer cortical shell elliptical, one and a half times as long as broad,

with thorny surface and four large kidney-shaped gates. Inner cortical

shell of the same form, but one-third smaller, also with four kidney-shaped

gates. Transverse girdle small, but with two pores on the isthmus.

_Dimensions._--Length of the first (innermost) shell 0.03, breadth 0.02;

length of the second (middle) shell 0.14, breadth 0.08; length of the third

(outermost) shell 0.2, breadth 0.11.

_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.

3. _Tetrapylonium quadrangulare_, n. sp. (Pl. 9, fig. 15).

Outer cortical shell nearly quadrangular, one and a third times as long as

broad, with four rounded corners, from which arise in the lateral plane

four three-sided pyramidal radial spines, opposite in pairs in two crossed

diagonal axes. Surface thorny; four gates elliptical or nearly

quadrangular. Inner cortical shell more elliptical, by one half smaller,

with broader transverse girdle and four kidney-shaped gates. Medullary

shell nearly spherical, of half the size.

_Dimensions._--Length of the first shell 0.045, breadth 0.035; length of

the second shell 0.1, breadth 0.07; length of the third shell 0.16, breadth

0.11.

_Habitat._--South Atlantic, off Tristan da Cunha, Station 332, depth 2200

fathoms.

4. _Tetrapylonium octacanthum_, n. sp.

Outer cortical shell elliptical, one and a third times as long as broad,

with thorny surface, and eight long and thin radial spines arising from the

corners of the four triangular gates, and lying {659}opposite in pairs in

two crossed diagonal planes. Inner cortical shell of the same shape, but

two-thirds smaller, also thorny. Transverse girdle broad, with four pores

on the isthmus. (This species appears to be the common _Tetrapyle

octacantha_, with doubled cortical shell.)

_Dimensions._--Length of the first shell 0.04, breadth 0.03; length of the

second shell 0.16, breadth 0.12; length of the third shell 0.24, breadth

0.18.

_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.

5. _Tetrapylonium armatum_, n. sp.

Outer cortical shell nearly quadrangular, one and a fourth times as long as

broad, with very spiny surface. Between numerous smaller (simple or

branched) thorns arise twelve larger radial spines, symmetrically

distributed, eight wing-spines crossed in two diagonal planes (as in

_Tetrapylonium octacanthum_) and four corner spines on the four rounded

corners of the lateral plane (as in _Tetrapylonium quadrangulare_).

Therefore this species combines the armature of both foregoing species.

Four gates kidney-shaped. Inner cortical shell elliptical, smooth,

three-fourths smaller.

_Dimensions._--Length of the first shell 0.045, breadth 0.035; length of

the second shell 0.18, breadth 0.15; length of the third shell 0.25,

breadth 0.2.

_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.

Genus 288. _Pylozonium_,[327] n. gen.

_Definition._--#Pylonida# with trizonal lentelliptical medullary shell,

surrounded by double latticed cortical shell; inner cortical shell as well

as the outer _Pylonium_-shaped, each with three perfect crossed girdles

(transverse, lateral, and sagittal).

The genus _Pylozonium_ is the most highly developed form of the Pylonida,

as all three systems of concentric girdles here become fully developed,

each system with three perfect girdles. In this genus only among all the

Pylonida we find nine complete latticed girdles, and in each of the three

dimensive planes three concentric elliptical girdles. The first system

forms the medullary shell, the second system the inner cortical shell, and

the third system the outer cortical shell.

1. _Pylozonium novemcinctum_, n. sp.

Outer cortical shell lentelliptical, thorny, one and a third times as long

as broad, without radial spines, with four kidney-shaped gates. Inner

cortical shell of the same shape, but one-third smaller, four times as

large as the lentelliptical medullary shell.

_Dimensions._--Length of the medullary shell 0.04, breadth 0.03; length of

the inner cortical shell 0.16, breadth 0.12; length of the outer cortical

shell 0.24, breadth 0.18.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.

{660}2. _Pylozonium octacanthum_, n. sp. (Pl. 9, fig. 16).

Outer cortical shell lentelliptical, one and a third times as long as

broad, with thorny surface and eight long and thin radial spines arising

from the corners of the four elliptical gates, and lying opposite in pairs

in two crossed diagonal planes. Inner cortical shell of the same shape but

one-fourth smaller, about twice as large as the lentelliptical medullary

shell.

_Dimensions._--Length of the medullary shell 0.065, breadth 0.045; length

of the inner cortical shell 0.18, breadth 0.12; length of the outer

cortical shell 0.24, breadth 0.18.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

Family XXVII. #THOLONIDA#, n. fam. (Pl. 10).

_Definition._--#Larcoidea# with regular, completely latticed cortical

shell, which is composed of two to six or more hemispherical or cap-shaped

domes (vaulted chambers or cupolas). The domes lie opposite in pairs on the

poles of the three dimensive axes, are separated by annular constrictions,

and surround a simple or _Larnacilla_-shaped central chamber.

The family #Tholonida# represents a peculiar and very remarkable group of

the #Larcoidea#, distinguished from the other groups of this suborder by

the characteristic form of the shell, composed of a variable number of

hemispherical domes or cupolas. The middle and original part of the shell

is constantly formed of an elliptical or subspherical central chamber,

which often, but not constantly, contains a small medullary shell. An even

number (two, four, six, or more) of domes is attached to the poles of the

three dimensive axes of the central chamber; according as only one, or two,

or all three axes develop cupolas, we distinguish in this family three

different subfamilies (the Amphitholida, Staurotholida, and Cubotholida).

The Amphitholida (or Tholonida monaxonia) form cupolas only on the two

poles of one single axis, and this axis corresponds to the minor (or

transverse) axis of the central chamber, we find here therefore constantly

at least two lateral cupolas (Pl. 10, figs. 1-7). The Staurotholida (or

Tholonida diaxonia) form cupolas on the poles of two axes perpendicular one

to another; these two axes are the major (principal) and the minor

(transverse) axis of the central chamber, we find here therefore constantly

at least four cupolas crossed in pairs (Pl. 10, figs. 8-11). The

Cubotholida (or Tholonida triaxonia) form cupolas on the poles of all three

dimensive axes (perpendicular one to another); corresponding to the

principal, transverse, and sagittal axes of the lentelliptical central

chamber; therefore we find here constantly at least six cupolas, attached

in pairs on the six sides of the central chamber (Pl. 10, figs. 12-17).

The number of genera and species in the family #Tholonida# is rather large,

but the number of individuals is much smaller than in most of the other

SPUMELLARIA, and {661}particularly than in the nearly allied Pylonida; the

greater number of the species are very rare. Besides this they seem to be

very variable and inclined to produce numerous abnormalities. Very often

intermediate forms of transition are to be found between the Tholonida and

other #Larcoidea#, particularly the Pylonida and Lithelida. In many species

the thick-walled shell is very opaque, and offers great difficulties to the

clear study; in the greater number the structure of the shell cannot be

understood completely without rolling the shell to the different sides; and

the distinction between the Staurotholida and Cubotholida is often very

difficult.

The primordial chamber of the Tholonida, or the central chamber in which

its growth begins, is either a simple lentelliptical shell (without

enclosed medullary shell), like _Cenolarcus_, or it is a trizonal shell,

like _Larnacilla_, and contains a small concentric medullary shell. But

this important inner shell of the central chamber offers peculiar

difficulties for study. In many cases (probably in the greater number)

there is no doubt the same characteristic trizonal medullary shell, which

we found in the Larnacida and Pylonida, and this is our principal argument,

if we regard the Tholonida as #Larcoidea#, which are most nearly allied to

both these families, and in which the fenestrated open cortical girdles of

the Pylonida are replaced by fenestrated closed cupolas or domes; the

characteristic "gates" or large fissures in the cortical shell of the

former are therefore here perfectly closed by network. The Tholonida agree

in this point with the Larnacida, but are distinguished from them by the

prominent vaultings of the hemispherical cupolas or domes, which give them

a peculiar appearance. Each pair of domes (opposite on both poles of one

dimensive axis) corresponds to one single girdle of the Pylonida.

Regarding the absence or presence of a medullary shell in the central

chamber, we may divide the Tholonida into two groups, Cenotholida (without

medullary shell) and Coccotholida (with medullary shell). The absence of

the medullary shell in many Tholonida may be either primary (original) or

secondary (by reduction and loss of it). Probably in the larger proportion

(if not always?) its absence is the consequence of reduction and loss, and

in this case the Cenotholida must be derived phylogenetically from the

Coccotholida, but possibly often (or always?) the contrary may also be the

case. At present we cannot find certain arguments for one opinion or the

other.

The connection between the medullary (internal) and the cortical (external)

shell of the central chamber in the Coccotholida is effected by two lateral

wings of a latticed transverse girdle; on both sides of the latter remain

the four internal open "gates" of the Pylonida and Larnacida. Very often

the limiting edges of these four gates are prolonged into eight external

radial spines which lie opposite in pairs in two crossed diagonal planes,

and correspond to the eight portal-spines of _Tetrapyle octacantha_.

Besides these, we often find four other beams opposite in pairs in the two

crossed axes (principal and lateral). Very often also these radial beams

(between medullary and {662}cortical shells) are prolonged on the outside

into prominent free radial spines. But other spines may also arise from the

surface. Very remarkable is the presence of twenty symmetrically disposed

radial spines in some forms of Amphitholida (_Amphitholus acanthometra_ and

_Amphitholonium acanthonium_, &c.). It recalls the twenty radial spines of

the #Acanthonida#, though the laws of distribution in the two similar cases

are quite different.

The cortical shell of the Tholonida remains either simple, or it becomes

doubled by formation of an outer veil or envelope. This outer cortical

shell or "veil" may either repeat completely the typical form of the inner

with its cupolas, or it may form an ellipsoidal envelope without

dome-shaped partitions. Its network is either like that of the inner, or it

is very delicate and irregular, spider-web like. The connection between the

two cortical shells is effected by a variable number of radial beams, often

prolonged on the outside into radial spines.

The growth of the Tholonida by apposition of new chambers is very

characteristic, constantly pairs of chambers originating at both opposite

poles of the three dimensive axes, firstly on the transverse axis, secondly

on the principal axis, thirdly on the sagittal axis. It is possible that by

repeated apposition of new chambers the Tholonida are transformed into

#Discoidea#, but commonly the number of domes is restricted, two in the

Amphitholida, four in the Staurotholida, six in the Coccotholida. If new

chambers in an irregular manner or in a spiral order be opposed to those

first formed pairs of chambers, the Tholonida may be transformed into

Soreumida, Streblemida, or Lithelida. The phylogenetic connection between

these families is probably very complex and very worthy of further

research.

The network of the shell in the Tholonida is sometimes regular, with

circular (often hexagonally framed) pores of equal size, sometimes

irregular, with roundish pores of unequal size. Commonly the shell is thick

and compact; in those genera in which the cortical shell is doubled, the

inner is commonly compact, the outer a very delicate veil.

The central capsule of the Tholonida is originally always enclosed by the

central chamber, and like this of lentelliptical form, a triaxial

ellipsoid. With the apposition of cupolas the growing central capsule may

form dome-shaped protuberances which enter into the former. So we may find

in the Amphitholida a central capsule with three joints (separated by two

annular parallel constrictions), in the Staurotholida a cross-shaped

capsule (with four caps around the central lentellipsis), in the

Cubotholida a clustered capsule with six caps, surrounding six sides of the

cubical central mass. In the Coccotholida (with medullary shell in the

central chamber) the latter encloses in the centre the nucleus of the cell.

The calymma, or the jelly-veil between the central capsule and the

enveloping shell, probably always exhibits annular constrictions,

corresponding to those which separate the cupolas of the shell. All these

anatomical peculiarities in the Tholonida require a further accurate study.

{663}_Synopsis of the Genera of Tholonida._

-------------------------------------------------------------------------

I. Subfamily Amphitholida.

Cupolas developed only in the direction of one single axis (commonly

two cupolas).

(Tholonida unidimensiva.)

-------------------------------------------------------------------------

{Two simple cupolas

{ (without veil), 289. _Tholartus_.

Central chamber simple, {

without medullary shell. {Two double cupolas

{ (with veil), 290. _Tholodes_.

{Two simple cupolas

Central chamber { (without veil), 291. _Amphitholus_.

_Larnacilla_-shaped, with {

enclosed medullary shell. {Two double cupolas

{ (with veil), 292. _Amphitholonium_.

-------------------------------------------------------------------------

II. Subfamily Staurotholida.

Cupolas developed in the direction of two axes perpendicular one to

another (commonly four cupolas).

(Tholonida bidimensiva.)

-------------------------------------------------------------------------

{Four simple cupolas

{ (without veil), 293. _Tholostaurus_.

Central chamber simple, {

without medullary shell. {Four double cupolas

{ (with veil), 294. _Tholoma_.

{Four simple cupolas

Central chamber { (without veil), 295. _Staurotholus_.

_Larnacilla_-shaped, with {

enclosed medullary shell. {Four double cupolas

{ (with veil), 296. _Staurotholonium_.

-------------------------------------------------------------------------

III. Subfamily Cubotholida.

Cupolas developed in the direction of three axes perpendicular one

to another (commonly six cupolas).

(Tholonida tridimensiva.)

-------------------------------------------------------------------------

{Six simple cupolas

{ (without veil), 297. _Tholocubus_.

Central chamber simple, {

without medullary shell. {Six double cupolas

{ (with veil), 298. _Tholonium_.

{Six simple cupolas

Central chamber { (without veil), 299. _Cubotholus_.

_Larnacilla_-shaped, with {

enclosed medullary shell. {Six double cupolas

{ (with veil), 300. _Cubotholonium_.

Subfamily 1. AMPHITHOLIDA, Haeckel.

_Definition._--#Tholonida# with monaxial growth; cupolas opposite on the

poles of one axis. (Shell commonly three-chambered, with two domes on both

sides of the central chamber.)

Genus 289. _Tholartus_,[328] n. gen.

_Definition._--#Tholonida# with simple cortical shell (without external

veil); with two hemispherical cupolas, opposite on the poles of one axis;

central chamber between them simple (without medullary shell).

{664}The genus _Tholartus_ (Pl. 10, fig. 1) represents the most simple form

of all Tholonida, a three-jointed simple cortical shell without medullary

shell; two hemispherical cupolas or domes are attached on both lateral

sides of a simple triaxial ellipsoidal central chamber, corresponding to

the poles of its lateral or transverse axis. _Tholartus_ may be regarded as

the common ancestral form of all Tholonida, and may be derived either from

the Pylonida _Monozonium_ (by complete lattice-locking of the lateral

wings) or from the Ellipsida _Cenellipsis_ (by development of two lateral

protuberances on the poles of the transverse axis). But it is also possible

that the absence of the medullary shell is produced by reduction, and in

this case _Tholartus_ may be descended from _Amphitholus_.

Subgenus 1. _Tholartella_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial spines.

1. _Tholartus tricolus_, n. sp. (Pl. 10, fig. 1).

Central chamber one and a half times as high and as broad as both cupolas.

Surface of the shell rough. Pores regular, circular, without hexagonal

frames, three times as broad as the bars; about sixteen on the half

meridian of the central chamber (or its vertical diameter).

_Dimensions._--Length of the shell (major axis of the central chamber,

vertical) 0.1, breadth of the shell (major axis of the whole

three-chambered shell, horizontal) 0.13; pores 0.01, bars 0.003.

_Habitat._--Pacific, central area, Station 270, depth 2925 fathoms.

2. _Tholartus paniscus_, n. sp.

Central chamber of the same breadth, but of the double height of both

cupolas. Surface of the shell rough. Pores regular, circular, with

hexagonal frames, of the same breadth as the bars; eight to ten on the half

meridian of the central chamber.

_Dimensions._--Length of the shell (major axis of the central chamber,

vertical) 0.12, breadth of the shell (major axis of the whole

three-chambered shell, horizontal) 0.15; pores and bars 0.008.

_Habitat._--Pacific, central area, Station 271, depth 2425 fathoms.

3. _Tholartus isocolus_, n. sp.

Central chamber of the same breadth and height as both cupolas. Surface of

the shell smooth. Pores irregular, roundish, once to three times as broad

as the bars; ten to fifteen on the half meridian of the central chamber.

_Dimensions._--Length of the shell 0.11, breadth 0.14; pores 0.004 to 0.01,

bars 0.003.

_Habitat._--Pacific, central area, Station 270, depth 2925 fathoms.

{665}Subgenus 2. _Tholartissa_, Haeckel.

_Definition._--Surface of the shell with radial spines.

4. _Tholartus tripanis_, n. sp.

Central chamber of the same size as both cupolas. Surface of the shell

thorny, everywhere covered with short conical radial spines, about as long

as the cupolas. Pores regular or subregular, circular, twice as broad as

the bars; eight to ten on the half meridian.

_Dimensions._--Length of the shell 0.1, breadth 0.12; pores 0.01, bars

0.005.

_Habitat._--South Pacific, Station 295, surface.

5. _Tholartus sagitta_, n. sp.

Central chamber twice as large as both cupolas. Surface of the shell spiny,

with eight to twelve regularly (?) distributed radial spines, radiating

from the two constrictions between the three chambers. Spines

needle-shaped, very thin and long. Pores subregular or irregular, roundish

or circular, about three times as broad as the bars; twelve to sixteen on

the half meridian.

_Dimensions._--Length of the shell 0.11, breadth 0.15; pores 0.01, bars

0.003.

_Habitat._--North Pacific, Station 244, surface.

Genus 290. _Tholodes_,[329] n. gen.

_Definition._--#Tholonida# with double cortical shell (with external veil),

with two hemispherical cupolas, opposite on the poles of one axis; central

chamber between them simple (without medullary shell).

The genus _Tholodes_ (Pl. 10, fig. 2) differs from _Tholartus_, its

probable ancestral form, only in the duplication of the shell; the outer

shell has exactly the same three-jointed form as the inner; both are

connected by eight radial beams, lying in two diagonal planes and

corresponding to the eight frontal spines of _Tetrapyle octacantha_.

Possibly _Tholodes_ may also be descended from _Amphitholonium_ by loss of

the medullary shell. I have observed only one single specimen of this

genus.

1. _Tholodes cupula_, n. sp. (Pl. 10, fig. 2).

Outer shell of the same form and structure as the inner shell. Central

chamber larger than both cupolas. Surface a little rough, without radial

spines. Distance of both shells equals the height of the outer cupolas.

Pores of both shells regular, circular, three times as broad as the

{666}bars; six to seven in the semicircle of one inner cupola, ten to

twelve in the semicircle of one outer cupola. Both shells are connected by

eight radial beams, crossed in two diagonal planes.

_Dimensions._--Major axis of the outer shell 0.1, minor 0.065; major axis

of the inner shell 0.05, minor 0.04; pores 0.006, bars 0.002.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 291. _Amphitholus_,[330] n. gen.

_Definition._--#Tholonida# with simple cortical shell (without external

veil), with two hemispherical cupolas, opposite on the poles of one axis;

central chamber (between them) _Larnacilla_-shaped, with medullary shell.

The genus _Amphitholus_ is the most simple form of all Coccotholida (or all

Tholonida provided with medullary shell). Its simple cortical shell

exhibits, like _Tholartus_, two lateral hemispheric cupolas, attached on

both sides of a lentelliptical central chamber (on the poles of its

transverse axis). The central chamber has the form of a triaxial ellipsoid,

and contains, like _Larnacilla_, a small medullary shell, connected with it

by the wings of a latticed transverse girdle. _Amphitholus_ may be derived

either from _Tholartus_ by secondary production of a cortical shell, or

(more probably) from _Larnacilla_ by apposition of two lateral dome-shaped

protuberances. In the latter case it may be regarded as an _Amphipyle_, the

lateral open wings of which are closed by lattice-work.

Subgenus 1. _Amphitholissa_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial spines.

1. _Amphitholus artiscus_, n. sp. (Pl. 10, fig. 3).

Central chamber of the same height as both cupolas. Surface of the cortical

shell rough. Pores regular, circular, with prominent hexagonal frames,

twice as broad as the bars; eight to ten in the basal semicircle of one

cupola.

_Dimensions._--Major axis of the shell 0.16, minor axis 0.1; pores 0.008,

bars 0.004.

_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.

2. _Amphitholus artidium_, n. sp.

Central chamber one-fourth higher than both cupolas. Surface of the

cortical shell smooth. Pores irregular, roundish, once to three times as

broad as the bars. (Very similar to _Tholartus_ tricolus, Pl. 10, fig. 1,

but different by the medullary shell.)

_Dimensions._--Major axis of the shell 0.15, minor axis 0.12; pores 0.004

to 0.01, bars 0.003.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.

{667}Subgenus 2. _Amphitholura_, Haeckel.

_Definition._--Surface of the shell with radial spines or thorns.

3. _Amphitholus octacanthus_, n. sp.

Central chamber about twice as high and broad as both cupolas. From the

surface arise, symmetrically distributed, eight stout conical radial

spines, lying in two diagonal planes, as prolongations of the eight

wing-beams, which connect the _Tetrapyle_-shaped medullary shell with the

two ring-like constrictions of the cortical shell. Pores of the latter

regular, circular, twice as broad as the bars; ten to twelve in the basal

semicircle of one cupola.

_Dimensions._--Major axis of the shell 0.15, minor 0.12; pores 0.01, bars

0.005.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

4. _Amphitholus dodecanthus_, n. sp.

Central chamber a little larger than both cupolas. From the surface arise

twelve strong conical radial spines, four on the poles of the major and the

minor axis of the shell, lying in the lateral plane; eight others lying in

two diagonal planes, as prolongations of the eight wing-beams, which

connect the _Tetrapyle_-shaped medullary shell with the two ring-like

constrictions of the cortical shell. Pores of the latter irregular,

roundish, twice to four times as broad as the bars; sixteen to eighteen in

the basal semicircle of one cupola.

_Dimensions._--Major axis of the shell 0.15, minor 0.11; pores 0.004 to

0.008, bars 0.002.

_Habitat._--North Pacific, Station 256, surface.

5. _Amphitholus acanthometra_, n. sp. (Pl. 10, figs. 5, 6).

Central chamber about twice as broad and as high as both cupolas. On the

surface quite symmetrically distributed twenty long and strong cylindrical

radial spines; eight in the sagittal plane or in the meridian plane of the

central chamber (four opposite in pairs in the principal and the sagittal

axes, four others in the middle between the principal and the sagittal

spines); four in the horizontal transverse plane, on both sides of the

poles of the major or lateral axis; and eight in diagonal planes

(corresponding to the eight wing-spines of _Tetrapyle octacantha_). In the

centre of the central chamber is a distinct trizonal medullary shell like

that of _Tetrapyle_, with two vertical columella beams. Pores of the

cortical shell subregular, circular, with elevated hexagonal frames, about

four times as broad as the bars; five to seven in the semicircle of one

cupola. (This remarkable species differs from _Tholartus vicenus_ in the

possession of a medullary shell, from _Amphitholonium acanthometra_ by the

simple cortical shell. Compare these species).

_Dimensions._--Major axis of the shell 0.14 to 0.16, minor axis 0.10 to

0.12; pores 0.015, bars 0.004; major axis of the medullary shell 0.04 to

0.05, minor (horizontal) axis 0.02 to 0.03; length of the twenty radial

spines 0.18 to 0.24, basal breadth 0.01.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.

{668}6. _Amphitholus armatus_, n. sp.

Central chamber twice as broad, but of the same height, as the flat vaulted

cupolas. Surface armed with thirty to forty very large three-sided

prismatic spines, longer than the major axis of the shell. Pores irregular,

roundish, twice to five times as broad as the bars; eight to nine on the

basal semicircle of one cupola.

_Dimensions._--Major axis of the shell 0.15, minor axis 0.1; pores 0.006 to

0.015, bars 0.003; length of the spines 0.2 to 0.25, breadth 0.01.

_Habitat._--North Atlantic, Station 353, surface.

7. _Amphitholus polyacanthus_, n. sp.

Central chamber of the same breadth and height as both cupolas. Surface

armed with very numerous (sixty to eighty) strong conical spines, about as

long as the minor axis of the shell. Pores subregular, circular, twice as

broad as the bars; sixteen to eighteen in the basal semicircle of one

cupola.

_Dimensions._--Major axis of the shell 0.13, minor 0.08; pores 0.006, bars

0.003; length of the radial spines 0.09, breadth 0.006.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

8. _Amphitholus panicium_, n. sp. (Pl. 10, fig. 4).

Central chamber ellipsoidal, nearly twice as broad, but of the same height,

as both cupolas. Whole surface thorny; the largest radial thorns about as

long as the medullary shell. Pores irregular, roundish, twice to four times

as broad as the bars. On the base of each cupola a circle of ten to twelve

larger square pores, separated by radial beams, which are prolonged into

stouter free spines. This remarkable formation of the cupolas, very rare in

this family, recalls the characteristic formation of the distal chambers of

the Panartida and Zygartida (_e.g._, Pl. 40, figs. 4, 8, &c.), where it is

very common.

_Dimensions._--Major axis of the shell 0.15, minor 0.1; pores 0.005 to

0.012, bars 0.003; large square pores 0.02; axes of the medullary shell

0.03 and 0.02.

_Habitat._--Indian Ocean, Madagascar, Rabbe, surface.

Genus 292. _Amphitholonium_,[331] n. gen.

_Definition._--#Tholonida# with double cortical shell (with external veil),

with two hemispherical cupolas, opposite on the poles of one axis; central

chamber (between them) _Larnacilla_-shaped, with medullary shell.

The genus _Amphitholonium_ differs from the nearly allied _Amphitholus_

(probably its ancestral form) only in the duplication of the cortical

shell; the outer has the {669}same three-jointed form as the inner, and is

connected with it by a variable number of radial beams. From the similar

_Tholodes_ it differs in the possession of a medullary shell.

1. _Amphitholonium tricolonium_, n. sp. (Pl. 10, fig. 7).

Outer cortical shell smooth, of the same three-jointed form as the inner,

at an equal distance from it throughout the whole circumference; central

chamber higher-vaulted than both cupolas. Network of the outer shell

delicate, with subregular, circular pores. Pores of the thick-walled inner

shell subregular, circular, with hexagonal frames, three times as broad as

the bars; eight to ten in the basal semicircle of one cupola.

_Dimensions._--Major axis of the outer cortical shell 0.2, minor axis 0.15;

major axis of the inner cortical shell 0.16, minor axis 0.11; pores 0.01,

bars 0.0035.

_Habitat._--South Pacific, Station 302, depth 1450 fathoms.

2. _Amphitholonium octostylium_, n. sp.

Outer cortical shell lentelliptical, smooth, not articulated, at a varying

distance from the three-jointed inner shell; central chamber of the latter

twice as high as both hemispherical cupolas. Network of the outer shell

very thin, cob-web like. Pores of the inner shell subregular, roundish,

twice as broad as the bars; six to seven in the semicircle of one cupola.

Eight thin and long, bristle-shaped, radial spines, opposite in pairs in

two crossed diagonal planes.

_Dimensions._--Major axis of the outer cortical shell 0.16, minor 0.12;

major axis of the inner cortical shell 0.12, minor 0.09; pores 0.01, bars

0.005.

_Habitat._--Pacific, central area, Station 273, depth 2350 fathoms.

3. _Amphitholonium acanthonium_, n. sp.

Outer cortical shell of the same three-jointed form as the inner, at a

uniform distance from it; central chamber higher vaulted than both cupolas.

Network of the outer shell irregular, delicate, of the inner regular,

strong, with circular, hexagonally framed pores, three times as broad as

the bars; eight to nine in the semicircle of one cupola. On the surface,

quite symmetrically disposed, twenty long and strong, cylindrical, radial

spines; eight in the sagittal plane, four in the transverse plane; eight in

two diagonal planes between the former and the latter. The remarkable

geometric disposition of the twenty spines is in this species quite the

same as in _Amphitholus acanthometra_. It differs from this nearly allied

species in the double cortical shell.

_Dimensions._--Major axis of the outer cortical shell 0.18, minor 0.14;

major axis of the inner cortical shell 0.14, minor 0.1; pores 0.012, bars

0.004.

_Habitat._--South Pacific, Station 295, surface.

{670}Subfamily 2. STAUROTHOLIDA, Haeckel.

_Definition._--#Tholonida# with diaxial growth; cupolas crossed in pairs,

opposite on the poles of two axes, perpendicular one to another. (Shell

commonly five-chambered, with four domes, cross-wise surrounding the

central chamber.)

Genus 293. _Tholostaurus_,[332] n. gen.

_Definition._--#Tholonida# with simple cortical shell (without external

veil), composed of four hemispherical cupolas in cross-form, opposite in

pairs on the poles of two axes perpendicular one to another; central

chamber simple (without medullary shell).

The genus _Tholostaurus_ is the most simple form of the Staurotholida, or

the Tholonida with four crossed hemispherical cupolas, lying on the poles

of two axes perpendicular one to another. The central chamber communicates

by four wide openings with the four domes, and contains no medullary shell.

_Tholostaurus_ may originate either from _Tholartus_ by apposition of two

opposite cupolas between the first pair, or from _Staurotholus_ by loss of

the medullary shell.

Subgenus 1. _Tholostaurantha_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial spines.

1. _Tholostaurus quadrigatus_, n. sp.

All four cupolas nearly of the same size and form, subregular. Surface

smooth, without radial spines. Pores subregular, circular, four times as

broad as the bars; eight to ten pores in the basal semicircle of one

cupola.

_Dimensions._--Diameter of the shell 0.12; pores 0.008, bars 0.002.

_Habitat._--Pacific, central area, Station 272, surface.

2. _Tholostaurus cruciformis_, n. sp.

Two opposite cupolas larger than the two others. Surface rough, without

radial spines. Pores regular, circular, hexagonally framed, twice as broad

as the bars; twelve to fourteen in the basal semicircle of one cupola.

_Dimensions._--Major axis of the shell 0.16, minor axis 0.12; pores 0.006,

bars 0.003.

_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.

{671}Subgenus 2. _Tholostauroma_, Haeckel.

_Definition._--Surface of the shell with radial spines or thorns.

3. _Tholostaurus tetrabelonis_, n. sp.

All four cupolas nearly of the same size and form, subregular. Pores

regular, circular, hexagonally framed, twice as broad as the bars; twelve

to fourteen in the semicircle of one cupola. Four long and stout conical

radial spines, two vertical on the poles of the principal axis, two

horizontal on the poles of the transverse axis.

_Dimensions._--Major axis of the shell 0.15, minor 0.13; pores 0.006, bars

0.003.

_Habitat._--South Pacific, Station 288, surface.

4. _Tholostaurus octobelonis_, n. sp.

Two opposite cupolas larger than the two others. Pores subregular,

circular, three times as broad as the bars; ten to twelve in the semicircle

of one cupola. Eight long and thin, needle-shaped, radial spines, in pairs

crossed in two diagonal planes.

_Dimensions._--Major axis of the shell 0.16, minor 0.12; pores 0.01, bars

0.003.

_Habitat._--South Pacific, Station 291, surface.

5. _Tholostaurus dodecabelos_, n. sp.

Two opposite cupolas larger than the two others. Pores irregular, roundish,

twice to three times as broad as the bars; six to eight in the semicircle

of one cupola. Twelve thin and long radial spines, four on the poles of the

two crossed axes (principal and lateral), eight crossed in two diagonal

planes.

_Dimensions._--Major axis of the shell 0.14, minor 0.11; pores 0.006 to

0.01, bars 0.003.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

6. _Tholostaurus polybelonis_, n. sp.

Two opposite cupolas larger than the two others. Pores circular,

hexagonally framed, of the same breadth as the bars; ten to twelve in the

semicircle of one cupola. Numerous (twenty to thirty or more) thin,

bristle-like, radial spines, about as long as the radius of the shell.

_Dimensions._--Major axis of the shell 0.15, minor axis 0.12; pores and

bars 0.007.

_Habitat._--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.

Genus 294. _Tholoma_,[333] n. gen.

_Definition._--#Tholonida# with double cortical shell (with external veil),

composed of four hemispherical cupolas in cross-form, opposite in pairs on

the poles of two axes perpendicular one to another; central chamber simple

(without medullary shell).

{672}The genus _Tholoma_ (Pl. 10, figs. 10, 13) differs from the preceding

_Tholostaurus_ (its probable ancestral form) only in the duplication of the

shell. The outer (secondary) shell has the same cross-form as the inner

(primary) shell. In the two observed species the growth seems to be

different, in the first species all four cupolas of each cross being of the

same size, form, and age; in the second two opposite cupolas, larger and

apparently older than the other two. _Tholoma_ is possibly the offspring of

_Staurotholonium_, from which it may have been produced by loss of the

medullary shell.

Subgenus 1. _Tholomantha_, Haeckel.

_Definition._--Surface of the shell smooth, without radial spines.

Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, First Part: Porulosa (Spumellaria and Acantharia) Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII · 第 22 / 27 章

Cortical shell very spiny, on the whole surface covered with a forest of