The physiological signification of the p_Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, Second Part: Subclass Osculosa; Index Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII

not yet known; but the general facts quoted above, their constant presence,

position, volume, and composition, make it probable that their

physiological value in the PHÆODARIAN organism is very great. The following

hypotheses may be taken provisionally into consideration:--A. The phæodella

are peculiar symbiontes, or unicellular algæ, comparable to the xanthellæ

or zooxanthellæ of the other Radiolaria. This hypothesis is probably

correct for those phæodella which are true nucleated cells; and the more

so, as the majority of PHÆODARIA do not exhibit those common yellow

xanthellæ, which are usually found in the SPUMELLARIA and NASSELLARIA. It

is even possible that the latter are absent in all PHÆODARIA. B. The

phæodella are dark pigment-bodies, which absorb light and heat in a manner

similar to the simple "pigment-eyes" of many lower animals, and may

therefore be optical sense-organs of the PHÆODARIA. This hypothesis may be

supported by a comparison with the large-eyed unicellular Protist,

_Erythropsis agilis_, described by R. Hertwig. C. The phæodella are organs

of nutrition of the PHÆODARIA and active in their metastasis

("Stoffwechsel"). Regarding them from this point of view, we may suppose

that the phæodella are secreted products which serve for digestion, acting

like the bile or the saliva of higher animals. Perhaps they too act like

the venomous matter produced in the thread-capsules of the Acalephæ. The

suggestion that they are mere excretions, or half-digested matters, as

Hertwig supposes ("halb assimilirte Nahrungs-bestandtheile," 1879, _loc.

cit._, p. 99) seems less probable. The most important fact illustrating

their high signification for the processes of nutrition, digestion and for

effecting changes on matter, seems to be the close relation of the phæodium

to the astropyle; the radiate operculum of the latter, and the proboscis

arising from it, being constantly covered and completely hidden by the

central main mass of the phæodium.

{1537}The skeleton of the PHÆODARIA is always extracapsular, and exhibits

in the majority of this legion such a characteristic shape, form, and

structure, that these organisms may be easily recognised by it, even apart

from the central capsule and the phæodium. In a few cases, however, the

skeleton is so similar to that of some NASSELLARIA and SPUMELLARIA, that it

may be accidentally confounded with it. In general the skeleton of the

PHÆODARIA is much larger, and much more highly developed, than that of most

other Radiolaria, and exhibits the most wonderful appearances, and the most

marvellous complications, which are found in the whole world of Protists,

or of unicellular organisms. The varied composition and differentiation of

the skeleton alone distinguishes the numerous families, genera, and species

of PHÆODARIA described in the sequel; all the fifteen families, however,

agree so completely in the structure of the central capsule and the

phæodium described, that we may derive them all phylogenetically from a

small skeletonless family, the Phæodinida.

The chemical composition of the skeleton seems to be, in the majority of

PHÆODARIA, somewhat different from that of the other Radiolaria. In a few

groups only, especially in the Cannobelida (_Dictyocha_, _Mesocena_, &c.),

and in a part of the Castanellida and Concharida, the substance of the

skeleton seems to be of pure silica, as in the NASSELLARIA and SPUMELLARIA;

these flinty skeletons, therefore, may be also found fossil. In the

majority of PHÆODARIA, however, the skeleton does not consist of pure

silica, but of an organic silicate; it becomes more or less intensely

stained by carmine, and browned or blacked by fire; in many cases it even

becomes completely burned and destroyed by the prolonged action of heat.

This circumstance explains why PHÆODARIA in general are rare in deep-sea

deposits, as in the common Radiolarian ooze of the Pacific, and why they

are generally absent in fossil deposits. Even the pure Radiolarian rocks of

the Barbados, &c., contain only a few PHÆODARIA, mainly Dictyochida.

According to the different forms of the skeleton, we may divide the legion

or subclass of PHÆODARIA into two sublegions, four orders, and fifteen

families. Firstly, we may distinguish as two groups the #Phæocystina#,

without a lattice-shell, and the #Phæocoscina#, with a lattice-shell

(compare above, p. 5). The #Phæocystina# comprise three different families,

viz., (1) Phæodinida, without any skeleton (Pl. 101, figs. 1, 2); (2)

Cannorrhaphida, with an incomplete skeleton, composed of numerous separate,

not radial pieces, which are scattered around the capsule in the calymma

(Pl. 101, figs. 3-14; Pl. 114, figs. 7-13), and (3) Aulacanthida (Pl.

102-105), with an incomplete skeleton, composed of numerous hollow radial

tubes, which pierce the calymma and come in contact by their proximal ends

with the surface of the central capsule.

The #Phæocoscina#, or the PHÆODARIA with a lattice-shell (embracing the

great majority of the whole legion) exhibit three principal differences in

the shape of their shell, and from these we distinguish the three following

orders; (A) #Phæosphæria#, with a spherical, not bivalved shell (rarely of

an ellipsoidal or lenticular, or another {1538}modified form), without a

shell-mouth or a peculiar constant large opening on the lattice-shell; (B)

#Phæogromia#, with an ovate or polyhedral, not bivalved shell (often also

of a subspherical, ellipsoidal, or another modified form), constantly

provided with a shell-mouth or a peculiar large opening on one pole of the

main axis of the lattice-shell; (C) #Phæoconchia#, with a bivalved shell,

composed of two completely separated, hemispherical, cap-shaped or

boat-shaped valves (a dorsal and a ventral), comparable to that of the

Brachiopoda.

The #Phæosphæria#, or those PHÆODARIA the big shell of which is usually

spherical, never bivalved and never provided with a peculiar shell-mouth,

comprise a great number of common and large-sized PHÆODARIA, which may be

arranged into four different families, according to the different structure

of the shell--(1) Orosphærida (Pl. 106, 107), spherical shell extremely big

and robust, composed of single piece of coarse lattice-work, the thick bars

of which are stratified and contain partly a fine axial-canal, meshes of

the network usually irregularly polygonal, no astral septa in the nodal

points; (2) Sagosphærida (Pl. 108), spherical shell large-sized, but

extremely delicate and fragile, composed of a single piece of arachnoidal

lattice-work, the thin bars of which are simple solid threads, without

axial-canal, meshes of the network always large and triangular, no astral

septa in the nodal points; (3) Aulosphærida (Pl. 109-111), spherical shell

large-sized, but very fragile, composed of numerous hollow cylindrical

tubes, which are connected (and at the same time separated) by peculiar

astral septa in the nodal points, meshes either triangular or polygonal;

(4) Cannosphærida (Pl. 112), spherical shell double, composed of two

concentric shells which are connected by thin hollow radial tubes, the

inner shell simple, solid or fenestrated, with a shell-mouth on the basal

pole, the outer shell composed of hollow cylindrical tubes which are

connected by astral septa in the nodal points. The structure of this outer

shell is the same as in the Aulosphærida, while the basal mouth of the

inner shell brings this family in closer relationship to the #Phæogromia#.

The #Phæogromia#, or those PHÆODARIA the shell of which is not bivalved,

but provided with a peculiar constant mouth on the oral pole of the main

axis, are in general similar to the NASSELLARIA (Monocyrtida), and may be

divided into five different families, viz., (1) Challengerida (Pl. 99),

shell ovate or subspherical, also often triangular or lenticular,

distinguished by a peculiar diatomaceous structure, an exceedingly fine

tracery of regular hexagonal, very delicate network; (2) Medusettida (Pl.

118-120), shell ovate, campanulate or cap-shaped, distinguished by a

peculiar alveolar structure, with a corona of peculiar hollow, large,

articulated feet around the mouth; (3) Castanellida (Pl. 113), shell

spherical or subspherical, of ordinary simple lattice-work, usually with a

corona of simple solid teeth around the mouth; (4) Circoporida (Pl.

114-117), shell spherical or polyhedral, with panelled or dimpled surface,

distinguished by a peculiar porcellanous structure (numerous thin needles

being {1539}embedded in a punctulate cement-substance), with hollow radial

spines and with a corona of simple solid teeth around the mouth; (5)

Tuscarorida (Pl. 100), shell ovate or subspherical, with smooth surface, of

the same peculiar porcellanous structure as the Circoporida, but with

hollow, very long tubular teeth around the mouth.

The #Phæoconchia# are the peculiar and most interesting "PHÆODARIA

bivalva," differing from all other PHÆODARIA, and from all known Radiolaria

in general, in the possession of a bivalved lattice-shell, composed of a

dorsal and a ventral valve. They may be divided into three families: (1)

Concharida (Pl. 123-125), shell with two thick and firm, regularly latticed

valves, which bear no hollow tubes and no cupola or galea on their apex or

sagittal pole; (2) Coelodendrida (Pl. 121), shell with two thin and

fragile, scarcely latticed valves, which bear a conical cupola or a

helmet-shaped galea on their apex, and hollow branched tubes arising from

it (without rhinocanna and frenula); (3) Coelographida (Pl. 122, 126-128),

shell with two thin and fragile, scarcely latticed valves, similar to those

of the Coelodendrida, but differing from them in the development of a

peculiar rhinocanna or nasal tube upon each valve; this tube is connected

by an odd or paired frenulum with the apex of the galea, and both together

contain the phæodium.

The phylogenetic affinity of the fifteen families enumerated, and the

morphological relationship based upon it, form a very difficult problem.

The whole legion of PHÆODARIA is probably monophyletic, in as much as all

the families may be derived from a single ancestral group, the skeletonless

Phæodinida (_Phæodina_ and _Phæocolla_); but at the same time polyphyletic,

in as much as probably many families have been derived, independently one

from another, from different branches of Phæodinida; or in other words, the

characteristic malacoma of the PHÆODARIA (the cannopylean central capsule

and the calymma with the phæodium) may be a monophyletic product, inherited

from a single ancestral form; the manifold skeleton, however, is certainly

a polyphyletic product, originating from different skeletonless Phæodinida.

Among the independent families of PHÆODARIA, derived directly from

skeletonless Phæodinida by production of a peculiar skeleton, may be the

following: Cannorrhaphida (Pl. 101, probably polyphyletic), Aulacanthida

(Pl. 102-105), Castanellida (Pl. 113), Challengerida (Pl. 99), Concharida

(Pl. 123-125), Circoporida (Pl. 114-117) and Tuscarorida (Pl. 100). The

four families of #Phæosphæria# (the Orosphærida, Sagosphærida, Aulosphærida

and Cannosphærida (Pl. 106-112), may be derived perhaps from the

Castanellida; and the Medusettida (Pl. 118-120), have been perhaps derived

from the Challengerida. The complicated affinities of these groups are

however difficult to explain. The Coelodendrida (Pl. 121) are probably

derived from the Concharida, and the Coelographida (Pl. 126-128) from the

Coelodendrida.

The geometrical fundamental form of the shell is in the majority of

PHÆODARIA monaxonial, corresponding to the main axis of the enclosed

central capsule; the {1540}astropyle of the latter, placed on the oral pole

of the main axis, corresponds to the mouth of the shell in all

#Phæogromia#. In the #Phæosphæria#, where no peculiar shell mouth is

developed, the general fundamental form of the shell is usually homaxonial

or spherical, often an endospherical polyhedron, rarely ellipsoidal or

spindle-shaped (with prolonged main axis), or lenticular (with shortened

main axis). The bivalved #Phæoconchia# have usually either an amphithect

shell (with the same fundamental form as the Ctenophora), or a dipleuric,

bilaterally symmetrical shell (with a dorsal and a ventral valve, a right

and a left parapyle). A small number of PHÆODARIA (mainly Circoporida) are

remarkable on account of the regular polyhedral form of their shell, the

geometrical axes of which resemble crystalline axes and are defined by

regular radial tubes; as the octahedral _Circoporus_ (Pl. 117, fig. 6), the

dodecahedral _Circorrhegma_ (fig. 2), and the icosahedral _Circogonia_

(fig. 1).

The siliceous or silicate bars, which compose the skeleton of the

PHÆODARIA, are in the majority hollow tubes, filled up by jelly; in some

other families, however, they are solid rods, as in the NASSELLARIA and

SPUMELLARIA. Such usual lattice-work, composed of solid rods, occurs only

in the families Sagosphærida (Pl. 108), Castanellida (Pl. 113), and

Concharida (Pls. 123-125). A quite peculiar structure, a diatomaceous

tracery of extremely fine and regular hexagonal frames, distinguishes the

Challengerida (Pl. 99). The hollow cylindrical tubes, which are found in

the other families, appear in three different forms, simple, articulate,

and provided with an axial thread. Simple hollow tubes, which are neither

articulate nor provided with an axial thread, occur in the Cannorrhaphida

(Pl. 101), Aulacanthida (Pl. 102-105), Coelodendrida (Pl. 121, 122), and

Coelographida (Pl. 126-128). In all these families the hollow cylindrical

tubes have a very thin wall and contain a wide cavity, filled only by

jelly. The Orosphærida (Pl. 106, 107), differ in the reduction of the

cavity, which becomes very narrow (often rudimentary or lost), whilst the

walls of the tubes become extremely thickened and stratified, numerous

concentric layers of silica being disposed one over the other. The hollow

cylindrical tubes contain an axial filament, or a thin thread of silica,

placed in its axis, in the families Aulosphærida (Pl. 109-111),

Cannosphærida (Pl. 112), Circoporida (Pl. 114-117), and Tuscarorida (Pl.

100). Usually the axial filament is connected with the thin wall of the

tube by numerous horizontal branches. A quite peculiar structure

distinguishes the Medusettida (Pl. 118-120); their hollow tubes, extremely

prolonged, are articulate owing to the presence of numerous, regular,

equidistant transverse septa; these are pierced by a short tubule, similar

to the siphon of the shells of _Nautilus_; this remarkable alveolar

structure also occurs in the peripheral part of their shell-wall (and

sometimes in the whole shell), numerous small polyhedral chambers or

alveoles which communicate by small openings, being developed; they become

easily filled with air in the dry shell (Pl. 120, figs. 11-16).

{1541}The substance of the siliceous or silicated shell-wall is, in the

majority of PHÆODARIA, homogeneous and structureless, as in the SPUMELLARIA

and NASSELLARIA; but sometimes it acquires a peculiar structure. The

thickened wall of the hollow tubes in the Orosphærida and in several

Aulacanthida (Pl. 105, figs. 6-10) becomes distinctly stratified,

concentric strata being disposed one over the other. A very remarkable

structure, differing from that in all other Radiolaria, is found in the

porcellanous shell of the Circoporida (Pl. 114-117), and Tuscarorida (Pl.

100). The thickened wall of the opaque shell is here composed of a peculiar

silicated cement, which encloses numerous very thin and irregularly

scattered needles (Pl. 115, figs. 6-9; Pl. 116, fig. 3). Dry fragments of

these shells, observed by a strong lens, appear finely punctulate, and

probably air, entering into these fine porules of the cement, causes the

white colour and the calcareous or porcellanous appearance of the opaque

dry shell. Its surface is smooth in the Tuscarorida (Pl. 100), panelled in

the Circoporida (Pl. 114-117).

The hollow or solid spines, which arise from the shell of the PHÆODARIA,

exhibit an extraordinary variety and elegance in the production of

different branches, bristles, hairs, secondary spine, and thorns, hooks,

anchor-threads, pencils, spathillæ, &c. These appendages are developed

similarly to those of many SPUMELLARIA, but exhibit a far greater variety

and richness in form. They are organs partly for protection, partly for

retention of food. They are much more interesting than in other Radiolaria.

_Synopsis of the Orders and Families of_ PHÆODARIA.

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

I. Order PHÆOCYSTINA.

Skeleton absent or incomplete, composed of numerous single scattered

pieces, without connection. Central capsule placed in the centre of

the calymma.

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

Skeleton completely absent, 1. PHÆODINIDA.

Skeleton composed of numerous

scattered pieces, not of radial tubes, 2. CANNORRHAPHIDA.

Skeleton composed of numerous hollow

radial tubes, the proximal ends of which

are in contact with the central capsule, 3. AULACANTHIDA.

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

II. Order PHÆOSPHÆRIA.

Skeleton a simple or double lattice-shell, not bivalved, without a

peculiar shell-mouth (shell usually spherical, rarely of a modified

form, always without peristome). Central capsule placed in the centre

of the shell-cavity.

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

{ Network very robust and

Shell composed { coarse, with irregular

of a simple { polygonal meshes; bars

non-articulated { very thick, partly hollow, 4. OROSPHÆRIDA.

lattice-plate, {

without astral { Network very delicate and

septa in the { fragile, with subregular,

nodal points. { triangular meshes; rods

{ very thin, filiform, always

{ solid, 5. SAGOSPHÆRIDA.

Shell composed { Shell articulated, with

of numerous { astral septa, without a

hollow, tangential { simple central shell, 6. AULOSPHÆRIDA.

cylindrical tubes, {

which are { Shell double, composed of

separated by { two concentric shells;

astral septa in { the outer articulated, the

the nodal points. { inner simple, 7. CANNOSPHÆRIDA.

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

III. Order PHÆOGROMIA.

Skeleton a simple lattice-shell, not bivalved, constantly provided

with a peculiar large shell-mouth placed on the oral pole of the

main axis; peristome usually surrounded by peculiar feet or teeth.

(Shell either spherical or ovate, or of another form). Central

capsule excentric, placed in the aboral half of the shell-cavity.

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

{ Structure of the shell

{ diatomaceous, with very

{ delicate and regular

{ hexagonal pores. No

{ articulate feet, 8. CHALLENGERIDA.

Structure of the {

shell not { Structure of the shell

porcellanous { alveolar, with hollow

(without needles { alveoles between a double

imbedded in { plate. A corona of

a punctulate { articulated feet around

cement-substance). { the mouth, 9. MEDUSETTIDA.

{

{ Structure of the shell of

{ simple lattice-work, neither

{ diatomaceous nor alveolar.

{ No articulate feet, 10. CASTANELLIDA.

Structure of the { Surface of the shell

shell porcellanous, { (sphericalpanelled or

with peculiar fine { dimpled or polyhedral).

needles imbedded { Peristome flat, 11. CIRCOPORIDA.

in a punctulate {

cement-substance { Surface of the shell

(a circle of { smooth, even (ovate or

pores around the { subspherical). Peristome

base of each tube). { prominent, 12. TUSCARORIDA.

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

IV. Order PHÆOCONCHIA.

Skeleton a bivalved lattice-shell, composed of a dorsal and a ventral

valve which are completely separated (rarely connected by a ligament

on the aboral pole). Central capsule enclosed between the two valves.

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

The two valves of the bivalved shell thick and firm,

regularly latticed, without a galea or cupola on

their apex, and without hollow tubes, 13. CONCHARIDA.

The two valves { Galea without rhinocanna

of the bivalved { or nasal tube, without

shell very thin { frenula, 14. COELODENDRIDA.

and fragile, {

scarcely latticed, { Galea with a rhinocanna or

each with a conical { nasal tube, both connected

cupola or a { by an odd or

helmet-shaped galea { paired frenulum, 15. COELOGRAPHIDA.

on its sagittal {

pole or apex, and {

with hollow tubes. {

Order I. PHÆOCYSTINA, Haeckel (1879).

_Definition._--PHÆODARIA without lattice-shell, either without any

skeleton, or with an incomplete skeleton, composed of numerous single

pieces, which are scattered in the calymma without connection. Central

capsule placed in the centre of the spherical calymma.

{1543}Family LXXI. #Phæodinida#, Haeckel (Pl. 101, figs. 1, 2).

_Phæodinida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec.

12, p. 4.

_Definition._--PHÆODARIA without skeleton. Central capsule with one to

three (or more) openings, placed in the centre of the spherical naked

calymma.

The family #Phæodinida# is the simplest and most primitive of the

PHÆODARIA, and differs from all the other families of this legion in the

complete absence of a skeleton. It bears, therefore, the same relation to

the latter as the Thalassicollida do to the other SPUMELLARIA. The soft

body is only composed of the central capsule with the nucleus, and the

calymma with the phæodium.

Of course it is quite possible that the skeletonless PHÆODARIA, which we

regard here as the ancestral family of that legion, may be either members

of other families which have lost their skeleton accidentally, or young

PHÆODARIA which have not yet developed a skeleton. But in some preparations

of the Challenger certain large, well-preserved PHÆODARIA, without any

trace of skeleton, are not rare; and since I myself have observed a

complete living _Phæodina_, I have no doubt that they are independent,

primordial forms (like _Actissa_, _Thalassicolla_, _Cystidium_, _Nassella_,

&c.). Probably also two skeletonless PHÆODARIA belong to this family which

are figured by R. Hertwig, in 1879, in his Organismus d. Radiol. (Taf. x.

fig. 1, 11); this author, however, supposed that they had lost their

original skeleton.

The three species of Phæodinida which are described in the sequel represent

two different genera, _Phæodina_ and _Phæocolla_, already distinguished in

my first note on the PHÆODARIA (Sitzungsb. med.-nat. Gesellsch. Jena, 1879,

Dec. 12, p. 4). _Phæodina_ is a true TRIPYLEA, and has the usual three

openings which occur in the majority of PHÆODARIA, a large astropyle or

main-opening on the oral pole of the main axis, and a pair of lateral

accessory openings, or parapylæ, on the aboral pole. _Phæocolla_, however,

has only a single opening, the astropyle, and agrees therefore with those

PHÆODARIA which possess no parapylæ (Challengerida, Medusettida,

Castanellida, &c.).

The complete body is in all observed Phæodinida a small jelly sphere of 1

to 3 mm. in diameter, with a transparent cortical layer and an opaque dark

central part. This latter is the phæodium, in which the central capsule is

hidden, surrounded on all sides by the gelatinous spherical calymma; the

smooth surface of the latter is spherical.

The _central capsule_ of the Phæodinida (Pl. 101, figs. 1, 2), is either

spherical or spheroidal, somewhat lenticular, slightly depressed in the

direction of the main axis. Its diameter is between 0.15 and 0.25. Its

double membrane exhibits the same structure as in the other PHÆODARIA. The

thick, double-contoured outer membrane is separated from the thin and

delicate inner membrane by a clear space, filled up by jelly or by a fluid;

the two are connected in _Phæocolla_ (fig. 1) only at the astropyle, in

_Phæodina_ (fig. 2), {1544}they are also connected at the two parapylæ. The

radiate operculum of the astropyle opens by a tubular prolongation or

proboscis, which is very long in the former, shorter in the latter. The two

parapylæ of the latter also bear short tubules. The protoplasm, enclosed in

the inner membrane, contains numerous small circular vacuoles. The large

central nucleus is sometimes spherical or ellipsoidal, at other times

spheroidal or lenticular; it always contains numerous nucleoli. One

specimen observed, with two nuclei, was apparently engaged in self-division

(fig. 2).

The spherical gelatinous calymma, in the centre of which the central

capsule is placed, has a diameter of 1 to 2 mm. In the specimen of

_Phæodina tripylea_, which I observed living, it exhibited exactly the same

shape as the figure of _Dictyocha stapedia_ in Pl. 101, fig. 10; the only

distinction in this latter being indicated by the pileated pieces of the

skeleton on the surface. The jelly-sphere contained numerous roundish or

globular alveoles of very different sizes, and between them an areolated

network of protoplasm; the latter has arisen from the outer surface of the

calymma in the form of very numerous, radiating, partly branched and

anastomosing pseudopodia. The dark and opaque centre of the jelly-sphere is

filled up by the granular, blackish-brown phæodium, which envelops the oral

half of the central capsule completely; it exhibits the same characters as

in all the other PHÆODARIA.

_Synopsis of the Genera of Phæodinida._

Central capsule with a single opening (an astropyle

on the oral pole), 656. _Phæocolla_.

Central capsule with three openings (an oral

astropyle and two aboral parapylæ), 657. _Phæodina_.

Genus 656. _Phæocolla_,[274] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch.

Jena, Dec. 12, p. 4.

_Definition._--#Phæodinida# with a single aperture to the central capsule

(an astropyle with radiate operculum, placed on the oral pole of the main

axis).

The genus _Phæocolla_ may be regarded as the simplest form of all

PHÆODARIA, and perhaps as the common ancestral form of this legion. It has

no skeleton, and the central capsule exhibits only a single aperture on one

pole of the main axis. In this it agrees with the Challengerida,

Medusettida, and Castanellida, which have also no parapylæ or secondary

openings.

1. _Phæocolla primordialis_, n. sp. (Pl. 101, fig. 1).

Central capsule subspherical, or somewhat depressed in the direction of the

main axis. The oral pole of the latter exhibits a large astropyle, or a

radiate operculum, about as broad as the {1545}nucleus. From its centre

arises a conical mammilla, prolonged into a thin, cylindrical, S-like

tubulus, the proboscis, which is about as long as the diameter of the

capsule. The outer membrane of the capsule is thick and double-contoured;

the inner is very thin, but distinct, and includes finely granulated

protoplasm, and numerous spherical, clear vacuoles, each with some small

granules. Nucleus spheroidal, depressed in the direction of the main axis,

containing numerous dark, irregularly amoebiform nucleoli. The diameter of

the nucleus is about equal to the radius of the central capsule. The

extracapsular calymma is an alveolated sphere, the diameter of which is six

to eight times that of the capsule. The inner part of it contains an

irregular, blackish phæodium, which surrounds and hides the oral half of

the central capsule.

_Dimensions._--Diameter of the central capsule 0.16, of the nucleus 0.08,

of the calymma 1.0 to 1.2.

_Habitat._--Central Pacific, Station 271 to 274, surface.

Genus 657. _Phæodina_,[275] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch.

Jena, Dec. 12, p. 4.

_Definition._--#Phæodinida# with three apertures to the central capsule (an

astropyle on the oral pole of the main axis, and two lateral parapylæ on

both sides of the aboral pole).

The genus _Phæodina_ has the same structure of the central capsule as the

majority of PHÆODARIA; one large main-opening or astropyle on the oral pole

of the main axis, and two smaller lateral accessory openings or parapylæ on

each side of the aboral pole: it is therefore a true Tripylean genus, like

the majority of PHÆODARIA.

1. _Phæodina tripylea_, Haeckel (Pl. 101, fig. 2).

? _Tripylea_ sp., R. Hertwig, 1879, Organismus d. Radiol., Taf. x. figs.

1, 11.

Central capsule spheroidal or lenticular, somewhat depressed in the

direction of the main axis. Astropyle with a strongly ribbed, radiate

operculum, scarcely one-third as broad as the diameter of the capsule, and

prolonged into a short tubular proboscis. Parapylæ also with short tubular

openings. The outer strong (double-contoured) membrane of the central

capsule is separated from the inner thin (simple-contoured) membrane by a

wide interval, filled up by a clear fluid or jelly; only at the three

apertures both membranes are in direct connection. The granulated

protoplasm contains numerous vacuoles, and surrounds a large spheroidal

nucleus, with numerous small nucleoli. The voluminous calymma in a

specimen, observed living, was alveolar, and the ramification of the

pseudopodia, as well as the formation of the dark brown phæodium, very

similar to that of _Dictyocha stapedia_ (Pl. 101, fig. 10). Another

specimen, figured in Pl. 101, fig. 2, exhibited the first stages of

self-division; the reticulated nucleus and the radiate operculum of the

astropyle were already doubled, and the two membranes of the capsule

between them constricted in the median plane. To this species belong

probably the central capsules figured by R. Hertwig, _loc. cit._

{1546}_Dimensions._--Diameter of the central capsule 0.15 to 0.25, of the

nucleus 0.06 to 0.1, of the calymma 0.8 to 1.2.

_Habitat._--Mediterranean; Portofino, near Genoa (Haeckel); Messina

(Hertwig).

2. _Phæodina cannopylea_, n. sp.

Central capsule subspherical, scarcely depressed in the direction of the

main axis. Astropyle with a finely ribbed radiate operculum, about as broad

as the radius of the capsule, prolonged into a slender, tubular proboscis

which is S-shaped, about as long as the radius, and similar to that of

_Phæocolla primordialis_, Pl. 101, fig. 1. Parapylæ also tubular, with two

slender prolongations, half as long and broad as the proboscis of the

parapyle. Nucleus spheroidal, about half as broad as the capsule. This

species differs from the preceding mainly in the cylindrical slender

prolongations of the three apertures, which are similar to those of

_Aulosphæra_ and _Aularia_ (Pl. 111, fig. 2).

_Dimensions._--Diameter of the central capsule 0.2, of the nucleus 0.1, of

the calymma 1.2 to 1.5.

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

Family LXXII. #CANNORRHAPHIDA#, Haeckel, 1879 (Pl. 101, figs. 3-14; Pl.

114, figs. 7-13).

_Cannorrhaphida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena,

Dec. 12, p. 4.

_Definition._--PHÆODARIA with an incomplete skeleton, composed of numerous

separate, not radially arranged pieces, which are either hollow tangential

spicula or cap-shaped dishes, or fenestrated rings, scattered loosely in

the calymma. Central capsule placed in the centre of the spherical calymma.

The family #Cannorrhaphida# comprises those PHÆODARIA in which the

incomplete skeleton is represented by numerous separate pieces of silica,

which exhibit very different forms, and are scattered tangentially on the

surface of the spherical calymma, sometimes also throughout its jelly-mass.

They agree in this peculiar character with the Thalassosphærida (among the

SPUMELLARIA) and bear the same relation to the skeletonless Phæodinida as

the Thalassosphærida do to the Thalassicollida (compare pp. 10 and 29). The

Cannorrhaphida represent the former group among the PHÆODARIA. They differ

from the following family, the Aulacanthida, in the arrangement and

position of the hollow spicula, which are never directed radially and never

touch the central capsule, as is constantly the case in the latter.

Two genera of Cannorrhaphida have been hitherto known. The first species

observed in a complete and living state (at Messina in 1859) was

_Cannobelos cavispicula_, described in 1862 in my Monograph as

_Thalassoplancta cavispicula_ (_loc. cit._, p. 261, Taf. iii. figs. 10-13).

I there figured a complete living specimen with expanded pseudopodia and a

double central capsule (in the stage of self-division). The latter was

surrounded by an {1547}alveolar calymma and by a voluminous mass of

blackish-brown pigment, the phæodium; numerous, long, hollow, cylindrical

tubes were scattered on the surface of the calymma. At that time I did not

know the tripylean character of the central capsule and the peculiar

radiate operculum in the PHÆODARIA, and therefore placed _Thalassoplancta

cavispicula_ among the Thalassosphærida.

The second description of a complete form of Cannorrhaphida was given in

1879 by R. Hertwig, under the name _Dictyocha fibula_ (Organismus d.

Radiol., p. 89, Taf. ix. fig. 5). The genus _Dictyocha_ had been already

founded by Ehrenberg in 1838, with the following definition:--"Lorica

simplex, univalvis, silicea, laxe reticulata aut stellata" (Abhandl. d. k.

Akad. d. Wiss. Berlin, 1838, p. 128). Ehrenberg had found only scattered

pieces of the skeleton, fossil in Tertiary rocks. He placed them among the

_Bacillaria_ (= _Diatomaceæ_), but added, that they may be possibly

scattered spicula of Sponges ("forsan Spongiarum ossicula").

In 1859 I myself observed similar forms of _Dictyocha_ at Messina, and

first recognised them as true Radiolaria. But I placed them at that time

among the Acanthodesmida, beside _Prismatium_, supposing that a small

spherical body which I had sometimes seen in the cavity of the pileated

pieces (probably a phæodellum) was the small central capsule (Monogr. d.

Radiol., 1862, p. 271, Taf. xii. figs. 3-6). The complete body of

_Dictyocha_ was not described till 1879, when R. Hertwig gave a full

description of its peculiar structure, and especially of the great central

capsule, which resembles that of the other PHÆODARIA. He first stated that

the singular pileated pieces described by Ehrenberg were not complete

shells, but isolated pieces of the skeleton, which are scattered in the

jelly-envelope around the central capsule in a mode similar to the spicula

of _Thalassoplancta_, _Thalassosphæra_ and _Sphærozoum_. Hertwig also first

recognised that the thin rods, which compose the reticular pileated pieces

of the skeleton in _Dictyocha_, are not solid bars, but thin hollow

tubules, similar to the hollow rods of _Aulacantha_ and of other PHÆODARIA.

Numerous complete and well-preserved specimens of _Dictyocha_, which I

found in the collection of the Challenger, have convinced me that the

accurate description of R. Hertwig is correct in every respect, and that

these remarkable bodies are true PHÆODARIA, most closely allied to

_Cannobelos_ (= _Thalassoplancta_) and to _Aulacantha_ (compare Pl. 101,

fig. 10). I now regard them as representatives of a peculiar subfamily of

Cannorrhaphida, which I call Dictyochida. To the same subfamily also belong

the small annular bodies which Ehrenberg described in 1841 as _Mesocena_

(_loc. cit._, p. 401), and the elegant, more complicated, reticular and

pileated bodies, which Stöhr figured in 1880 under the name _Distephanus_

(Palæontogr., vol. xxvi. p. 121). These peculiar bodies are also only

isolated pieces of the siliceous skeleton, and are scattered tangentially

in great numbers in the calymma, around the tripylean central capsule. A

still higher degree of development is attained by the interesting forms

{1548}which I describe here as _Cannopilus_ (Pl. 114, figs. 7-13). All

these peculiar forms may be derived from the simple annular pieces of

skeleton, which are aggregated in great numbers in the calymma of

_Mesocena_. The pieces of the skeleton of these Dictyochida never assume

the form of slender, cylindrical, tangential tubules which is

characteristic of the Cannobelida.

A third subfamily of Cannorrhaphida, the Catinulida, is represented by the

remarkable new genus _Catinulus_ (Pl. 117, fig. 8). The single pieces of

the skeleton, scattered in hundreds or thousands throughout the calymma,

are here not composed of hollow rods, as in the two former subfamilies, but

are solid hemispherical caps, or small, more flatly vaulted dishes, with a

peculiar radial striation. All the complete specimens of _Catinulus_ which

I could examine possessed four equal central capsules, united in one

spherical calymma.

The common character which unites the three rather different subfamilies,

the Cannobelida, Dictyochida and Catinulida into a single family, and which

separates this family, the Cannorrhaphida, from the other PHÆODARIA, is to

be found in the composition of the rudimentary skeleton from numerous

single pieces, which are loosely scattered either on the surface of the

calymma, or throughout its jelly-mass, and which are never arranged

radially and never touch the central capsule as is always the case in the

closely allied Aulacanthida.

The slender spicula of the Cannobelida are cylindrical or spindle-shaped,

tubular, scattered in variable numbers, but always in a tangential

direction on the surface of the calymma. Usually they are 0.2 to 0.5 long,

and 0.005 to 0.03 broad; either straight or slightly curved; smooth and

simple in _Cannobelos_, spiny or branched in _Cannorrhaphis_ (Pl. 101,

figs. 3-5). Their wall is thin and fragile, their diameter sometimes equal

throughout their whole length, at other times tapering towards both ends.

Their cavity is filled by jelly, and seems to be open at both ends, since

the purified and dried spicula constantly become filled by air.

The peculiar pieces of silica which compose the skeleton of the Catinulida

are not hollow, like the rods of the other Cannorrhaphida, but concave

hemispherical cups or more flatly vaulted little dishes, the thin flinty

wall of which is slightly thickened at the circular margin, and radially

striped above it. In all three species of _Catinulus_ observed they were

scattered throughout the calymma in hundreds or thousands (Pl. 117, fig.

8). Their relation to the Dictyochida is doubtful. Perhaps the small cups

of _Catinulus_ may be derived from the simple rings of _Mesocena_, by

development of an operculum on one side of the ring.

The skeleton of the Dictyochida is much more developed and possesses a

higher morphological interest; the numerous different forms, however, which

its pieces here assume, may be all derived from the simple circular ring of

_Mesocena_. This ring is formed by a thin, hollow, cylindrical, or

prismatic rod, sometimes circular or elliptical, at {1549}other times

polygonal. From its margin small, hollow, radial spines often proceed (Pl.

101, fig. 9). In _Dictyocha_ there arise from the ring two, three, four or

more siliceous bars or arches, which form one or more bulges over one side

of the ring; usually the little fenestrated shell thus produced assumes the

form of a three-sided or four-sided pyramid, or of a little hat with three

or four meshes (Pl. 101, figs. 10-14). From this _Dictyocha_ (in a

restricted sense) we separate the genus _Distephanus_, in which the little

pyramids become truncated, so that one central apical mesh (the apical or

upper ring) is surrounded by four, five, six or eight lateral meshes, the

sides of the pyramid (Pl. 114, figs. 7-9). The edges of the small pyramid

are formed by the same number of siliceous bars arising from the ring and

alternating with the meshes. Radial spines in different numbers and

arrangements arise from the corners of the two parallel rings, as well from

the smaller apical as from the larger basal ring. The simple apical ring of

_Distephanus_ becomes divided or fenestrated in the highest developed genus

of this subfamily, in _Cannopilus_ (Pl. 114, figs. 10-13); each pileated

piece of the skeleton exhibits here two rows of alternating lateral meshes,

an upper row of smaller and a lower row of larger meshes.

The majority of Dictyochida are armed with spines or thorns, which arise in

a regular manner from different points of the annular or pileated pieces.

In the ancestral genus, _Mesocena_, radial spines start from the corners of

the simple ring in centrifugal direction, and lie horizontally in its

plane. As these primary corner-spines determine the radial composition of

the more highly developed genera we call them perradial (lying in rays of

the first order). In _Dictyocha_ and _Distephanus_ commonly (but not quite

constantly) these perradial spines alternate with the ascending bars which

bisect the sides of the basal ring; these bars are therefore interradial

(lying in rays of the second order); consequently also the corners of the

apical ring of _Distephanus_ are interradial. The latter also often bear

small thorns or teeth. Other teeth frequently start in centripetal

direction from the lower or basal ring, on the side of the perradial

spines, and frequently they are directed obliquely downwards.

In _Dictyocha_ and _Distephanus_ are frequently found remarkable twin

pieces, composed of two pileated and reticulated skeleton pieces. These are

united by their basal rings loosely in such a way that they form together a

small fenestrated subspherical body; the union is strengthened by those

small teeth of the basal rings, which are directed downwards and catch one

into the other (Pl. 101, fig. 12; Pl. 114, fig. 8). A similar twin piece

has been already observed by Stöhr in the fossil _Distephanus rotundus_,

and upon this was founded this genus. Since the teeth of the two opposed

basal rings, catching one into the other, seem to be specially adapted for

the composition of those small double pyramids, it is probable that the

latter possess a special protective function in these PHÆODARIA, and

perhaps envelop their phæodella or their flagellate spores (?). In every

case these formations are very remarkable.

{1550}_The Central Capsule_ of the Cannorrhaphida seems to possess the same

shape in the three subfamilies, and to agree in general with that of the

Aulacanthida. In a living specimen of _Dictyocha stapedia_, which I

observed at Ceylon (Pl. 101, fig. 10), the three openings of the TRIPYLEA

were distinct; the radiate operculum of the astropyle (on the oral pole)

was surrounded by the granules of the dark phæodium, whilst on the opposite

aboral side, two parapylæ or conical secondary openings were visible. The

voluminous spherical calymma (about four times as broad as the central

capsule) contained numerous large alveoles (as in _Aulosphæra_) and its

surface was protected by numerous pileated pieces of the skeleton; the

basal ring of the latter was placed tangentially in the spherical surface

of the calymma, their apical spine being directed outwards. The

pseudopodia, arising from the central capsule and forming a network between

the alveoles of the calymma, radiated outwards in great number from its

surface (Pl. 101, fig. 10).

The propagation by self-division seems to be very frequent in the

Cannorrhaphida. I frequently found two equal central capsules in one

calymma, as in the first observed species, _Cannobelos cavispicula_, and in

_Cannorrhaphis spinulosa_ (Pl. 101, fig. 3), sometimes also in _Dictyocha_

and _Distephanus_. As already mentioned, _Catinulus_ constantly exhibited

four central capsules united in each calymma.

_Synopsis of the Genera of Cannorrhaphida._

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

I. Subfamily Cannobelida.

Pieces of the skeleton cylindrical or spindle-shaped tangential

tubules.

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

Tubules simple, smooth, 658. _Cannobelos_.

Tubules spiny or branched, 659. _Cannorrhaphis_.

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

II. Subfamily Catinulida.

Pieces of the skeleton hemispherical or cap-shaped, solid.

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

Caps or hemispherical pieces of the skeleton

solid, with radiate margin and circular opening, 660. _Catinulus_.

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

III. Subfamily Dictyochida.

Pieces of the skeleton either simple rings or pileated or pyramidal

bodies, composed of thin hollow rods and reticular meshes.

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

Flinty pieces simple { Basal ring simple, not

or arched rings, not { arched or fenestrated, 661. _Mesocena_.

truncated pyramids, {

with a basal ring, { Basal ring fenestrated,

but without apical { with two or more arches,

ring. { vaulted over one side, 662. _Dictyocha_.

Flinty pieces of the { Apical ring simple, not

skeleton resembling { fenestrated (one girdle

a truncated pyramid, { of meshes on each piece), 663. _Distephanus_.

with an upper smaller {

apical ring, and a { Apical ring fenestrated

lower larger basal { (two girdles of meshes

ring. { on each piece), 664. _Cannopilus_.

{1551}Subfamily 1. CANNOBELIDA, Haeckel.

_Definition._--#Cannorrhaphida# with numerous hollow cylindrical or

spindle-shaped tubes, which lie tangentially scattered on the surface of

the spherical calymma.

Genus 658. _Cannobelos_,[276] n. gen.

_Definition._--#Cannorrhaphida# with a skeleton composed of tubular

acicular pieces, which are smooth, cylindrical or spindle-shaped tangential

needles, without spines and branches.

The genus _Cannobelos_, and the following closely allied _Cannorrhaphis_,

represent the peculiar subfamily Cannobelida, differing from the other

Cannorrhaphida in the acicular form of the pieces of the skeleton, which

are tangentially scattered on the surface of the spherical calymma. The

cylindrical or spindle-shaped hollow needles are smooth in _Cannobelos_,

whilst in _Cannorrhaphis_ they are studded with lateral spines or branches.

1. _Cannobelos cavispicula_, Haeckel.

_Thalassoplancta cavispicula_, Haeckel, 1862, Monogr. d. Radiol., p. 261,

Taf. iii. figs. 10-13.

_Thalassicolla cavispicula_, Haeckel, 1860, Monatsber. d. k. preuss.

Akad. d. Wis. Berlin, p. 798.

_Cannorrhaphis cavispicula_, Haeckel, 1881, Prodromus, p. 470.

Tangential tubes cylindrical, more or less curved, gradually tapering

towards the two pointed ends. Calymma with a voluminous phæodium.

_Dimensions._--Length of the tubular spicule 0.25, breadth 0.003.

_Habitat._--Mediterranean, Messina, surface.

2. _Cannobelos calymmata_, n. sp.

Tangential tubes cylindrical, straight, of equal breadth throughout their

whole length, closed by a hemispherical cap on the two rounded ends.

Calymma very voluminous, with a small phæodium.

_Dimensions._--Length of the tubular spicula 0.3 to 0.5, breadth 0.004 to

0.008.

_Habitat._--Central Pacific, Stations 263 to 274, surface.

3. _Cannobelos thalassoplancta_, n. sp.

Tangential tubes spindle-shaped, straight, gradually tapering towards the

two pointed ends. Calymma and the included phæodium rather voluminous.

_Dimensions._--Length of the tubular spicula 0.15 to 0.2, breadth in the

middle part 0.02.

_Habitat._--Tropical Atlantic, Station 347, surface.

{1552}Genus 659. _Cannorrhaphis_,[277] Haeckel, 1879, Sitzungsb. med.-nat.

Gesellsch. Jena, Dec. 12, p. 4.

_Definition._--#Cannorrhaphida# with a skeleton composed of tubular

acicular pieces, which are spiny, cylindrical or spindle-shaped tangential

needles, either with lateral spines or branches.

The genus _Cannorrhaphis_ differs from the preceding closely allied

_Cannobelos_ in the spiny shape of the tangential acicular spicula, which

are studded either with short spines or with longer lateral branches.

1. _Cannorrhaphis spinulosa_, n. sp. (Pl. 101, figs. 3, 4).

Tangential tubes cylindrical, straight, gradually tapering towards the two

pointed ends, densely studded with conical spines, arising perpendicularly.

(The specimen figured, fig. 3, exhibited two ovate central capsules, each

of which contained two large nuclei, with numerous nucleoli.)

_Dimensions._--Length of the tubular spicula 0.3 to 0.5, breadth 0.01 to

0.015.

_Habitat._--North Pacific, Station 244, surface.

2. _Cannorrhaphis lampoxanthium_, n. sp.

Tangential tubes cylindrical, more or less curved, suddenly tapering

towards the two pointed ends, densely studded with irregular conical spines

of unequal length, which arise obliquely from their surface.

_Dimensions._--Length of the tubular spicula 0.4 to 0.5, breadth 0.005 to

0.008.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

3. _Cannorrhaphis lappacea_, n. sp.

Tangential tubes spindle-shaped, gradually tapering towards the two pointed

ends, densely studded with irregular lateral branches, which are partly

simply, partly forked, more or less curved, and arise obliquely from their

surface.

_Dimensions._--Length of the tubular spicula 0.2 to 0.3, breadth 0.015 to

0.025.

_Habitat._--Central Pacific, Station 271, surface.

4. _Cannorrhaphis spathillata_, n. sp. (Pl. 101, fig. 5).

Tangential tubes cylindrical, thin and straight, regularly zigzag, with

pointed, regularly alternating lateral spines, with an elegant spathilla,

or a cap-shaped verticil of eight to ten recurved spines on the two ends.

_Dimensions._--Length of the tubular spicula 0.3, breadth 0.003.

_Habitat._--Indian Ocean, Cocos Islands (Rabbe), surface.

{1553}Subfamily 2. CATINULIDA, Haeckel.

_Definition._--#Cannorrhaphida# with a skeleton composed of numerous

cap-shaped pieces, which lie tangentially scattered on the surface of the

spherical calymma. Each piece is a hemispherical or flatly cap-shaped

siliceous body, often with radial striations, and with a thin solid wall.

Genus 660. _Catinulus_,[278] n. gen.

_Definition._--#Cannorrhaphida# with a skeleton composed of solid,

cap-shaped or hemispherical, not fenestrated, pieces.

The genus _Catinulus_ differs from all the other Cannorrhaphida in the

peculiar shape of the numerous siliceous pieces, which are scattered on the

surface of the calymma and compose their rudimentary skeleton. These pieces

are neither hollow rings (as in the Dictyochida), nor hollow tubes (as in

the Cannobelida), but solid hemispherical caps or more flatly vaulted small

dishes. All the complete specimens of this genus which I observed exhibited

four equal central capsules in the spherical calymma.

1. _Catinulus quadrifidus_, n. sp. (Pl. 117, figs. 8, 8_a_).

Cap-shaped pieces of the skeleton flatly vaulted, three times as broad as

high, smooth; the marginal ring with fine radial ribs and with smooth

margin.

_Dimensions._--Diameter of the calymma 0.6 to 0.8, of the four central

capsules 0.12 to 0.2; breadth of the concave caps 0.024, height 0.008.

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

2. _Catinulus catillum_, n. sp.

Cap-shaped pieces of the skeleton flatly vaulted, three times as broad as

high, rough, covered with numerous small spinules; the marginal ring with

stout radial ribs and a corona of denticles on the margin.

_Dimensions._--Breadth of the concave caps 0.03, height 0.01.

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

3. _Catinulus lopadium_, n. sp.

Cap-shaped pieces of the skeleton hemispherical, twice as broad as high,

smooth; the marginal ring smooth, slightly radiate, with thickened smooth

margin.

_Dimensions._--Diameter of the calymma 1.2, of the central capsule 0.22;

breadth of the concave caps 0.024, height 0.012.

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

{1554}Subfamily 3. DICTYOCHIDA, Haeckel.

_Definition._--#Cannorrhaphida# with a skeleton composed of numerous

annular pieces, which lie tangentially scattered on the surface of the

calymma. Each piece is either a simple hollow ring or a pileate and

reticulate cap, composed of a ring and several connected bars.

Genus 661. _Mesocena_,[279] Ehrenberg, 1841, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 401.

_Definition._--#Cannorrhaphida# with a skeleton composed of simple annular

pieces, each of which is a circular, elliptical or polygonal, not

fenestrated, ring, with or without radial spines.

The genus _Mesocena_ is the simplest form of the Dictyochida, and no doubt

the common ancestral form of this subfamily. The siliceous pieces, which

are scattered in variable and indefinite number in the calymma, are simple

hollow rings, with or without spines on the periphery. Ehrenberg, who first

described and figured such rings (found fossil in different Tertiary rocks)

has mistaken them for Diatoms. Some species, which I found in the

Challenger preparations, leave no doubt that these rings are the siliceous

pieces of the skeleton of the simplest Dictyochida. They are scattered in

great numbers in the spherical calymma, which surrounds a tripylean central

capsule with all the characters of the PHÆODARIA. In the living body the

rings probably always lie in the spherical periphery of the extracapsular

jelly-veil, in tangential planes, whilst in some of the Challenger

preparations the rings were scattered in hundreds throughout the whole

jelly-mass. In a few species the rings are quite simple, circular or

elliptical, smooth, and without teeth or spines. In the majority of species

some teeth or radial spines, regularly disposed, arise from the periphery

of each ring (two, three, four to eight; sometimes sixteen, eight smaller

alternating with eight larger spines). In some species small teeth occur on

the inner margin of the rings. The number of radial spines seems to be

rather constant in all the rings of one and the same individual, with the

exception of a few variations. Thus in _Mesocena octogona_ I found here and

there single rings with seven or nine teeth, instead of the usual number

eight. Ehrenberg enumerated sixteen different species of _Mesocena_; many,

however, of these are synonymous, being founded on slight variations in the

number of the teeth; of others he has given only the name, but neither a

figure nor a description (_e.g._, _Mesocena stephanolithis_, _Mesocena

spongolithis_, &c.).

{1555}1. _Mesocena circulus_, Ehrenberg.

_Mesocena circulus_, Ehrenberg, 1840, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 208.

_Mesocena circulus_, Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 44.

Rings of the skeleton circular, smooth or slightly denticulate on the outer

margin, without spines. This simple form is probably the ancestral form of

the Dictyochida.

_Dimensions._--Diameter of the rings 0.02 to 0.03, thickness of the hollow

rod 0.001 or less.

_Habitat._--Fossil in Tertiary rocks of Barbados and of the Mediterranean

(Ægina, Greece; Caltanisetta, Sicily).

2. _Mesocena annulus_, n. sp.

? _Mesocena crenulata_, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 822.

Rings of the skeleton elliptical, smooth or slightly denticulate on the

outer margin, without spines. This species is possibly identical with

_Mesocena crenulata_ of Ehrenberg, of which, however, no figure is given.

The major axis of the ellipse is one and a half times as long as the minor.

_Dimensions._--Diameter of the rings in the major axis 0.03, in the minor

0.02; thickness of the bars 0.002.

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

3. _Mesocena diodon_, Ehrenberg.

_Mesocena diodon_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 84.

_Mesocena diodon_, Ehrenberg, 1854, Mikrogeol., Taf. xxxiii., Nr. xv.

fig. 18.

Rings of the skeleton elliptical, smooth, with two opposite spines on the

poles of the major axis, which is about one and one-third as long as the

minor axis.

_Dimensions._--Diameter of the rings in the major axis 0.04, in the minor

0.03; length of the spines 0.01.

_Habitat._--Fossil in Barbados, and in North America (Virginia).

4. _Mesocena triangula_, Ehrenberg.

_Mesocena triangula_, Ehrenberg, 1840, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 208.

_Mesocena triangula_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 41.

_Dictyocha triangula_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 46.

_Lithocircus triangularis_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 121,

Taf. vii. fig. 10.

Rings triangular, with small peripheral thorns, and three larger teeth on

the corners of the equilateral triangle.

_Dimensions._--Diameter of the rings 0.03 to 0.05, length of the spines

0.01.

_Habitat._--Fossil in Tertiary deposits of the Mediterranean; Caltanisetta,

Sicily (Ehrenberg, Stöhr).

{1556}5. _Mesocena quadrangula_, Ehrenberg.

? _Mesocena quadrangula_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.

Berlin, pp. 145, 273.

? _Mesocena quaternaria_, Ehrenberg, 1855, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 302.

Rings square, with four radial spines on the corners of the square.

Ehrenberg has given only the name of this species, but neither diagnosis

nor figure. I think it may be identical with the species described, which I

found in the North Atlantic.

_Dimensions._--Diameter of the rings 0.02 to 0.025, length of the spines

0.007 to 0.01.

_Habitat._--North Atlantic, Færöe Channel, Gulf Stream (John Murray), depth

600 fathoms.

6. _Mesocena elliptica_, Ehrenberg.

_Mesocena elliptica_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 84.

_Mesocena elliptica_, Ehrenberg, 1854, Mikrogeol., vol. i. Taf. xx. fig.

44.

_Dictyocha elliptica_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 44.

Rings elliptical or ovate, with four peripheral spines which lie in two

diameters, perpendicular to one another, two opposite in the major, the two

others in the minor axis of the ellipse.

_Dimensions._--Diameter of the rings 0.015 to 0.03, length of the spines

0.005.

_Habitat._--Fossil in Tertiary rocks of the Mediterranean (Placca di furni,

from Zante, Greece); Caltanisetta, Sicily.

7. _Mesocena pentagona_, n. sp.

Rings regularly pentagonal, with smooth straight bars, and with five short

and straight radial spines on the five corners.

_Dimensions._--Diameter of the rings 0.02, length of the spines 0.005.

_Habitat._--Fossil in Barbados.

8. _Mesocena hexagona_, Haeckel.

? _Mesocena senaria_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.

Berlin, pp. 163, 273.

? _Mesocena septenaria_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.

Berlin, pp. 163, 273.

Rings regular, hexagonal, with six radial spines on the six corners

(sometimes between the usual six-radiate rings of one and the same

individual are intermingled single rings with five or seven spines).

_Dimensions._--Diameter of the rings 0.025 to 0.03, length of the spines

0.007 to 0.01.

_Habitat._--Mediterranean, Krim (Ehrenberg), Corfu (Haeckel).

{1557}9. _Mesocena octogona_, Ehrenberg.

_Mesocena octogona_, Ehrenberg, 1841, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 417, Taf. i., Nr. iii. fig. 27.

? _Mesocena heptagona_, Ehrenberg, 1841, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 417, Taf. i., Nr. iii. fig. 26.

? _Mesocena heptagona_, Ehrenberg, 1854, Mikrogeol., Taf. xx. fig. 49.

? _Mesocena octoradiata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.

Berlin, pp. 163, 273.

? _Mesocena nonaria_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.

Berlin, pp. 163, 273.

Rings regular, octagonal, with eight radial spines on the eight corners of

the ring (sometimes between the common octoradiate rings single rings with

seven or nine teeth are intermingled in one and the same calymma).

_Dimensions._--Diameter of the rings 0.02, length of the spines 0.005.

_Habitat._--Tropical Pacific; Peru, Ehrenberg; Station 272 to 274, surface.

10. _Mesocena bisoctona_, Ehrenberg.

_Mesocena bisoctona_, Ehrenberg, 1845, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 78; Mikrogeol., Taf. xxxv., Nr. xviii. figs. 9, 10.

_Mesocena binonaria_, Ehrenberg, 1845, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 78, _loc. cit._

Rings circular, with sixteen teeth; eight stronger teeth regularly disposed

on the outer margin, alternating with these eight smaller teeth on the

inner margin.

_Dimensions._--Diameter of the rings 0.02, length of the outer spines

0.005.

_Habitat._--Fossil in Guano from Peru and South Africa, also in Barbados.

11. _Mesocena stellata_, n. sp. (Pl. 101, fig. 9).

Rings circular, with sixteen teeth regularly disposed on the outer margin

of the rings, eight stronger teeth alternating with eight smaller.

_Dimensions._--Diameter of the rings 0.03, length of the larger spines

0.01.

_Habitat._--Central area of the Pacific, Station 270, depth 2925 fathoms.

Genus 662. _Dictyocha_,[280] Ehrenberg, 1838, Monatsber. d. k. preuss.

Akad. d. Wiss. Berlin, p. 128.

_Definition._--#Cannorrhaphida# with a skeleton composed of annular pieces,

which are fenestrated by one or more arches, arising on one side of the

simple ring, but do not form a truncated pyramid (therefore no apical

ring).

The genus _Dictyocha_ is a very remarkable and interesting form of

PHÆODARIA, which has had a curious history. Ehrenberg, who first observed

single pieces of it fossil in Tertiary rocks, supposed it to be the

siliceous carapace of a Diatom, and gave it the following {1558}diagnosis:

"Dictyocha, e familia Bacillariorum. Lorica simplex univalvis silicea, laxe

reticulata aut stellulata" (_loc. cit._). In my Monograph (1862, p. 271), I

placed it in the class Radiolaria, supposing that it might be a simple form

of Acanthodesmida, having found only isolated siliceous pieces. Afterwards

(in 1879) Richard Hertwig observed the entire living body, and demonstrated

that the hollow siliceous pieces are scattered in great numbers around a

tripylean central capsule, which exhibits all the essential characters of

PHÆODARIA (Organismus d. Radiol., 1879, p. 89). Hertwig describes the

position of the numerous siliceous pieces in the surface of the

extracapsular jelly-sphere so densely aggregated, that they touch one

another and produce the appearance of a reticulated sphere. In two

specimens, which I observed living (Pl. 101, fig. 10), and in numerous

complete specimens which I found in the collection of the Challenger, the

number of the siliceous pieces was much smaller, and they were scattered

irregularly in the surface of the alveolate jelly-sphere, being separated

by wide and unequal intervals. The regular position seems to be that the

basal rings lie tangentially in the spherical surface of the calymma,

whilst the bars of the reticulum are directed outwards, and the apical

spine radially in centrifugal direction. Very often two pieces are united

by their basal rings in such a manner that they form a little spheroidal

fenestrated body (as in _Distephanus_, Stöhr; compare p. 1550). The

characteristic reticular skeleton-pieces of _Dictyocha_ must be derived

from _Mesocena_; from its simple siliceous ring (on one side of its plane),

arise two, three, or four (rarely more) bars, which become united to a

loose framework (with two, three, or four meshes). When this network

assumes the form of a truncated pyramid (with a central mesh on the apex),

_Dictyocha_ passes over into _Distephanus_. From the corners of the

original basal ring several radial spines usually arise in a centrifugal

direction, and on the sides of these sometimes small teeth or thorns also

run in a centripetal direction. The number of the meshes and the separating

rods is usually four, more rarely two or three. The hollow rods are very

thin, either cylindrical or prismatic. As the ascending rods alternate

regularly with the corner-spines of the basal ring, we may call the latter

perradial, the former interradial. Ehrenberg has distinguished in his genus

_Dictyocha_ not less than fifty species, thirty-five living and twenty-five

fossil (ten species both living and fossil). The greater part of these

cannot be retained, as they are only slight varieties or abnormalities of

single pieces of the skeleton, such as very frequently occur associated

with the common regular forms in one and the same individual. Such abnormal

species are, _e.g._, _Dictyocha abnormis_, _Dictyocha binoculus_,

_Dictyocha bipartita_, _Dictyocha haliomma_, _Dictyocha hexathyra_,

_Dictyocha septenaria_, &c. One species (_Dictyocha splendens_), is the

fenestrated calcareous body of a Holothurian. Of some other species

Ehrenberg has only given the name, but neither a description nor a figure

(e.g., _Dictyocha borealis_, _Dictyocha cenostephania_, _Dictyocha compos_,

_Dictyocha coronata_, _Dictyocha socialis_, _Dictyocha specillum_). A

number of other species must be placed in the genera _Distephanus_ and

_Cannopilus_, so that only eight of his species of true _Dictyocha_ remain.

{1559}1. _Dictyocha navicula_, Ehrenberg.

_Dictyocha navicula_, Ehrenberg, 1838, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 129; Mikrogeol., Taf. xx., Nr. i. fig. 43.

_Dictyocha ponticulus_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 267.

Each individual ring elliptical or oblong, with one transverse arch in the

shorter axis, which bisects it into two meshes. No spines or teeth.

_Dimensions._--Diameter of the ring 0.02, of the bars 0.001.

_Habitat._--Fossil in Tertiary deposits, Barbados, Sicily, &c.; living in

the Atlantic, Stations 352, 354, and off Bermuda, surface.

2. _Dictyocha quadrata_, Ehrenberg.

_Dictyocha quadrata_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 267.

Each individual ring square or rhomboid, with one transverse arch in the

shorter axis, forming two meshes. Two peripheral opposite spines on the

poles of one axis.

_Dimensions._--Diameter of the ring 0.015.

_Habitat._--Atlantic, Bermuda Islands; fossil in Barbados.

3. _Dictyocha pons_, Ehrenberg.

_Dictyocha pons_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 80; Mikrogeol., Taf. xxi. fig. 40.

_Dictyocha tripyla_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 80; Mikrogeol., Taf. xxi. fig. 41.

Each individual ring elliptical or oblong, with one transverse arch in the

shorter axis, forming two meshes. Four peripheral spines, on the poles of

the longer and of the shorter axis. (The individual abnormality, figured as

_Dictyocha tripyla_, _loc. cit._, Taf. xxi. fig. 41, has the transverse

arch bifid at one end, therefore three meshes result; this forms an

interesting transition to _Dictyocha fibula_.)

_Dimensions._--Diameter of the ring 0.01, of the bars 0.001.

_Habitat._--Fossil in Tertiary rocks, Oran, Africa.

4. _Dictyocha triommata_, Ehrenberg.

_Dictyocha triommata_, Ehrenberg, 1845, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 76; Mikrogeol., Taf. xxxiii., Nr. xv. fig. 11.

_Dictyocha triactis_ (= _triacantha_), Ehrenberg, 1844, Monatsber. d. k.

preuss. Akad. d. Wiss. Berlin, p. 80.

_Dictyocha trifenestrata_, Ehrenberg, 1841, Monatsber. d. k. preuss.

Akad. d. Wiss. Berlin, p. 410; Mikrogeol., Taf. xix. fig. 38.

_Dictyocha abyssorum_, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 38.

Each pileated piece of the skeleton is a small three-sided pyramid, the

sides of which form three triangular meshes; the three edges between them

are three curved interradial beams, united in the {1560}centre (the apex of

the pyramid). Alternating with these, three horizontal, perradial,

centrifugal spines start from the base.

_Dictyocha trigona_, Zittel, 1876 (L. N. 29, p. 83, Taf. ii. fig. 6), is an

interesting Cretaceous species, perhaps a variety of _Dictyocha triommata_.

_Dimensions._--Diameter of the basal triangle 0.01, of the three meshes

0.005.

_Habitat._--Fossil in different Tertiary deposits (of Sicily, Greece, North

America); living in the Central Pacific, Stations 270 to 272, depth 2600 to

2925 fathoms.

5. _Dictyocha tripyla,_ Ehrenberg.

_Dictyocha tripyla,_ Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 80.

_Dictyocha tripyla,_ Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 38 (et

Taf. xxi. fig. 41?).

Each pileate piece of the skeleton is a small three-sided pyramid, similar

to that of _Dictyocha triommata_, but differs from it in the possession of

three small perpendicular teeth, which are directed downwards and start

from the basal ring near the origin of the three horizontal spines.

_Dimensions._--Diameter of the triangular basal ring 0.015, of the three

meshes 0.007.

_Habitat._--Fossil in Tertiary deposits. North Africa (Oran), Sicily

(Caltanisetta).

6. _Dictyocha medusa_, n. sp. (Pl. 101, figs. 13, 14).

Each pileated piece of the skeleton has four equal, cruciate, triangular

meshes. From the four corners of the square basal ring proceed four

perradial horizontal spines, and between these four interradial curved

bars, which correspond to the edges of a four-sided pyramid, arise from the

centre of the four sides and become united in the centre (on the apex of

the pyramid). No apical spine.

_Dimensions._--Diameter of the basal ring 0.02, of the four meshes 0.01.

_Habitat._--Central area of the Pacific, Station 272, depth 2600 fathoms.

7. _Dictyocha staurodon_, Ehrenberg.

_Dictyocha staurodon,_ Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 80.

_Dictyocha staurodon,_ Ehrenberg, 1854, Mikrogeol., Taf. xviii. fig. 58.

Each pileated piece of the skeleton is a small, regular, four-sided

pyramid, similar to the foregoing species. It differs from _Dictyocha

medusa_ in the development of a vertical apical spine, and of four small

centripetal teeth, which start from the inside of the basal square, between

the four perradial spines and the four ascending interradial beams.

_Dimensions._--Diameter of the basal ring 0.025, of the meshes 0.01.

_Habitat._--Fossil in Tertiary rocks; Tripel of Richmond, Virginia

(Ehrenberg); Barbados, (Haeckel); living in the Tropical Atlantic, Station

347, surface.

{1561}8. _Dictyocha fibula_, Ehrenberg.

_Dictyocha fibula_, Ehrenberg, 1839, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 149; Mikrogeol., Taf. xviii. fig. 54, _a_, _b_, _c_, Taf. xix.

fig. 43, Taf. xx. fig. 45, Taf. xxi. fig. 42, &c.

_Dictyocha abnormis_, Ehrenberg, 1845, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 76; Mikrogeol., 1854, Taf. xxxvA., Nr. xvii. fig. 9.

_Dictyocha bipartita_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 44.

_Dictyocha tenella_, Ehrenberg, 1841, Abhandl. d. k. Akad. d. Wiss.

Berlin, Taf. ii. fig. 11.

Each pileated piece of the skeleton stirrup-shaped, with two pairs of

meshes, and a square basal ring, the four corners of which are prolonged

into four perradial spines. Between the latter four interradial beams arise

from the sides in pairs, and the two pairs are connected by a diagonal

arch. Therefore the two opposite meshes are larger and pentagonal, the

other two meshes (alternating with these) are smaller and square. No

vertical spine on the apex.

_Dimensions._--Diameter of the basal square ring (diagonal) 0.01 to 0.02,

of the meshes 0.005.

_Habitat._--Fossil in different Tertiary rocks (Barbados, Oran, Greece,

Sicily, &c.), Ehrenberg.

9. _Dictyocha messanensis_, Haeckel.

_Dictyocha messanensis_, Haeckel, 1862, Monogr. d. Radiol., p. 272, Taf.

xii. figs. 3-6.

_Dictyocha fibula_, R. Hertwig (not Ehrenberg), 1879, Organismus d.

Radiol., p. 89, Taf. ix. fig. 5.

Each pileated piece of the skeleton stirrup-shaped, very similar to

_Dictyocha fibula_, but distinguished by a vertical apical spine in the

centre of the transverse arch, which connects the two pairs of ascending

bars.

_Dimensions._--Diameter of the basal ring 0.02 to 0.03, of the meshes 0.01

to 0.016.

_Habitat._--Mediterranean (Messina), North Atlantic (Canary Islands),

Station 354, surface.

10. _Dictyocha epiodon_, Ehrenberg.

_Dictyocha epiodon_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 79; Mikrogeol., Taf. xviii. fig. 55.

Each pileated piece of the skeleton stirrup-shaped, with four paired meshes

similar to the hats of _Dictyocha fibula_, but distinguished by four small

centripetal thorns, which start from the inside of the basal ring, at the

side of the four ascending beams. No apical spine.

_Dimensions._--Diameter of the basal ring 0.03, of the meshes 0.01.

_Habitat._--Fossil in Tertiary rocks of North America (Miocene Tripel of

Richmond, Virginia, &c.).

11. _Dictyocha stapedia_, n. sp. (Pl. 101, figs. 10-12).

Each pileated piece of the skeleton stirrup-shaped, with four paired

meshes, similar to the hats of _Dictyocha fibula_ and _Dictyocha

messanensis_, but distinguished by four small centripetal teeth, which

start from the inside of the basal ring, at the side of the four ascending

beams. In the centre of the diagonal arch arises a vertical apical spine

(differing from _Dictyocha epiodon_). This species seems {1562}to be the

most common of the living forms and widely distributed over all warmer

seas. I observed in Ceylon, taken on the surface, the living specimen

figured in Pl. 101, fig. 10, the numerous spicula were irregularly

scattered over the spherical surface of the alveolate calymma. Other

specimens occur in various preparations of the Challenger collection, from

the Atlantic and the Pacific. The majority of the siliceous little hats

exhibited the stirrup-form shown in fig. 11, and many were united in pairs,

forming a twin-piece (fig. 12). Intermingled with these are found some

irregular forms, representing the specific form of some allied species,

viz., _Dictyocha speculum_, _Dictyocha staurodon_, _Dictyocha epiodon_ and

_Dictyocha messanensis_.

_Dimensions._--Diameter of the basal ring 0.015 to 0.03, of the meshes

0.005 to 0.012.

_Habitat._--Cosmopolitan; Atlantic, Pacific, Indian Ocean, in the Tropical

and warmer regions; Stations 159, 244, 266-272, 318, 352, &c.

12. _Dictyocha rhombus_, n. sp.

Each pileated piece of the skeleton stirrup-shaped, similar to _Dictyocha

stapedia_, with four paired meshes. It differs from the latter in the

rhomboid form of the basal ring and the larger size of the two opposite

meshes, which are two to three times as large as the two others. Therefore

the four centripetal teeth of the basal ring do not stand in the four

single meshes, but in pairs only in the two larger meshes.

_Dimensions._--Diameter of the basal ring 0.02, of the meshes 0.005 to

0.01.

_Habitat._--North Atlantic; Færöe Channel, Gulf Stream, depth 50 to 600

fathoms, John Murray.

Genus 663. _Distephanus_,[281] Stöhr, 1880, Palæontogr., vol. xxvi. Taf.

ii. p. 121.

_Definition._--#Cannorrhaphida# with a skeleton composed of pileated

pieces, each of which is a small truncated pyramid with one girdle of

meshes (the apical ring being simple).

The genus _Distephanus_ was founded in 1880 by Stöhr (_loc. cit._) for a

single twin-piece of the skeleton of _Dictyocha speculum_. Among the common

fossil forms of this species he once found in the Tertiary rocks of

Caltanisetta, Sicily, a single piece (_loc. cit._, Taf. vi. fig. 9), which

seemed to be composed of two equal pieces so united that they formed a

little sphere with fourteen meshes; on each pole of the sphere lies a

central hexagonal mesh surrounded by six pentagonal meshes, and from the

six corners of the equatorial ring arise six centrifugal spines. No doubt

this was a mistake, and the apparent little sphere was one of the above

mentioned twin-forms, composed of two separate hexagonal truncated

pyramids, which were loosely connected by their basal rings. I have often

seen such twin-pieces of _Dictyocha speculum_ and of other species (Pl.

101, fig. 12, Pl. 114, fig. 8), and was always able to separate the two

loosely connected halves of the bivalve shell by slight compression.

{1563}The genus _Distephanus_ of Stöhr, therefore, is nothing other than

the _Dictyocha_ of Ehrenberg. But I think it is more convenient to retain

the name _Distephanus_ for those forms of _Dictyocha_ which possess a

simple apical mesh surrounded by a ring of lateral meshes, and in which

each piece of the skeleton forms a small truncated pyramid. The basal plane

of this pyramid is marked by the original basal ring (_Mesocena_), the

truncated upper plane by the parallel apical ring, and the edges of the

pyramid by the rising bars which connect both rings. In this sense, so far

as the two rings lying in parallel planes are concerned, the term

_Distephanus_ is correct (but not in the original sense of Stöhr). The

number of the rising bars between the two rings varies from four, five, six

to eight or more. It seems rather constant in each species, so that all the

pieces of the skeleton of one specimen possess either four or six or eight

lateral meshes, &c. But sometimes individual irregularities occur. In the

majority of species each skeleton-piece is armed with spines. Usually a

radial horizontal spine starts centrifugally from each corner of the basal

ring, and on the side of this a small tooth or thorn often starts

centripetally or downwards. In the twin-pieces, where the two basal rings

are united, these teeth catch into one another. In some species upper

spines also occur, starting from the corners of the apical ring. The

perradial spines of the corners of the basal ring alternate regularly with

the interradial ascending bars, which bisect the sides of the ring, as in

_Dictyocha_.

1. _Distephanus crux_, Haeckel.

_Dictyocha crux_, Ehrenberg, 1840, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 207; Mikrogeol., 1854, Taf. xviii. fig. 56, Taf. xx.

fig. 46, Taf. xxxiii. Nr. xv. fig. 9.

_Dictyocha bipartita_, Ehrenberg, 1844, _loc. cit._, p. 79, Taf. xxii.

fig. 44.

Each pileated piece of the skeleton exhibits four pentagonal lateral meshes

around one square central mesh, and is composed of two horizontal square

rings; the smaller upper square is connected with the larger lower square

by four ascending interradial beams, which start from the corners of the

former and bisect the sides of the latter; from the corners of the basal

ring arise four short perradial spines.

_Dimensions._---Diameter of the basal ring 0.02 to 0.03, of the apical ring

0.008.

_Habitat._---Tropical Atlantic, Station 347, surface; fossil in Tertiary

deposits of the Mediterranean (Sicily, Oran).

2. _Distephanus mesophthalmus_, Haeckel.

_Dictyocha mesophthalma_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 80; Mikrogeol., 1854, Taf. xxii. fig. 43.

Each pileated piece of the skeleton exhibits four lateral meshes around the

central mesh, and is composed of two parallel horizontal square rings, like

those of _Distephanus crux_, but distinguished {1564}from this by eight

short teeth, four centripetal on the larger lower ring and four perradial

centrifugal on the smaller upper ring.

_Dimensions._--Diameter of the basal ring 0.03, of the apical ring 0.015.

_Habitat._--Fossil in Tertiary rocks of Sicily, Caltanisetta (Ehrenberg);

living in the Central Pacific, Station 270 to 272, surface.

3. _Distephanus stauracanthus_, Haeckel.

_Dictyocha stauracanthus_, Ehrenberg, 1845, Monatsber. d. k. preuss.

Akad. d. Wiss. Berlin, p. 76; Mikrogeol., 1854, Taf. xxxiii., Nr. xv.

fig. 10.

Each pileated piece of the skeleton exhibits four lateral meshes around the

central mesh, and is composed of two horizontal rings, which are connected

by four perradial beams arising from the corners of the upper and smaller

square ring. Lower ring octagonal, with eight peripheral adradial spines,

and with four interradial centripetal teeth on the inside.

_Dimensions._--Diameter of the basal ring 0.03, of the apical ring 0.004.

_Habitat._--Fossil in Tertiary rocks of North America (Hollis Cliff,

Virginia; Norwich, Connecticut).

4. _Distephanus asteroides_, n. sp.

_Dictyocha asteroides_, Haeckel, 1881, Prodromus.

Each pileated piece of the skeleton exhibits five lateral meshes around the

central mesh (or the upper ring). Five peripheral spines (on the corners of

the lower ring) simple, not articulated.

_Dimensions._--Diameter of the basal ring 0.02, of the apical ring, 0.007.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.

5. _Distephanus pentasterias_, Haeckel.

_Dictyocha pentasterias_, Ehrenberg, 1839, Mikrogeol., Taf. xviii. fig.

61.

? _Dictyocha quinaria_, Ehrenberg, 1842, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 265.

? _Dictyocha elegans_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 80; Mikrogeol., 1854, Taf. xxii. fig. 51.

_Actiniscus elegans_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 51.

Each pileated piece of the skeleton exhibits five lateral meshes around the

central mesh (or the upper ring). Five peripheral spines (on the corners of

the lower ring) articulated, triangular, with three distinct joints

(tapering towards the distal end).

_Dimensions._--Diameter of the basal ring 0.012 to 0.018, of the apical

ring 0.002 to 0.003.

_Habitat._--Cosmopolitan; living in the depths of the Atlantic and Central

Pacific, Stations 247, 270 to 272, depths 2530 and 2600 to 2925 fathoms;

fossil in Tertiary deposits (Tripel of Caltanisetta, Sicily; Richmond,

Virginia).

{1565}6. _Distephanus speculum_, Haeckel.

_Dictyocha speculum_, Ehrenberg, 1837, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 150; Mikrogeol., 1854, Taf. xviii. fig. 57, Taf. xix.

fig. 41, Taf. xxi. fig. 44, Taf. xxii. fig. 47, &c.

_Dictyocha speculum_, Stöhr, 1880, Palæontogr., vol. xxvi., Taf. vii.

fig. 8.

_Dictyocha anacantha_, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 238.

_Dictyocha diommata_, Ehrenberg, 1854, Mikrogeol., Taf. xxxiii., Nr.

xvii. fig. 6.

_Dictyocha erebi_, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 238.

_Dictyocha haliomma_, Ehrenberg, 1844, Mikrogeol., 1854. Taf. xxi. fig.

46.

_Dictyocha hexathyra_, Ehrenberg, 1844, Mikrogeol., 1854, Taf. xxii. fig.

46.

_Dictyocha ubera_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 80.

_Dictyocha stella_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 52.

_Dictyocha rotundus_, Stöhr, 1880, Palæontogr., vol. xxvi., Taf. vii.

fig. 9.

Each pileated piece of the skeleton is a truncated, six-sided pyramid, and

composed of two regular hexagonal rings which lie in parallel plains, and

are connected by six ascending interradial beams; these start from the

corners of the upper smaller ring and bisect the sides of the lower larger

ring; from the corners of the latter start six perradial centrifugal

spines.

_Dimensions._--Diameter of the basal ring 0.03, of the apical ring 0.01.

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

in Barbados, Sicily, &c.

7. _Distephanus ornamentum_, Haeckel.

_Dictyocha ornamentum,_ Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 80; Mikrogeol., 1854, Taf. xxii. fig. 49.

_Dictyocha binoculus_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 79; Mikrogeol., 1854, Taf. xix. fig. 42.

Each pileated piece of the skeleton is a truncated, six-sided pyramid,

similar to that of _Distephanus speculum_, but distinguished by six small

(probably vertical) teeth, which start from the inside of the lower

(larger) ring, on the sides of the ascending beams.

_Dimensions._--Diameter of the basal ring 0.03, of the apical ring 0.015.

_Habitat._--Fossil in Tertiary deposits of Sicily, Caltanisetta

(Ehrenberg).

8. _Distephanus aculeatus_, Haeckel.

_Dictyocha aculeata_, Ehrenberg, 1839, Abhandl. d. k. preuss. Akad. d.

Wiss. Berlin, p. 149; Mikrogeol., 1854, Taf. xxii. Fig. 48, Taf. xix.

fig. 40.

_Dictyocha aculeata_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 120, Taf.

vii. fig. 7.

_Dictyocha bisternaria_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 201.

Each pileated piece of the skeleton is a truncated, six-sided pyramid,

similar to that of _Distephanus speculum_, but distinguished by six small

perradial, horizontal teeth, which start from the sides of the upper

(smaller) ring.

_Dimensions._--Diameter of the basal ring 0.02, of the apical ring 0.008.

_Habitat._--Fossil in Tertiary deposits of the Mediterranean; plastic clay

of Greece and Sicily; living in the Mediterranean and the Atlantic, Station

352, surface.

{1566}9. _Distephanus sirius_, Haeckel.

_Actiniscus sirius_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 68.

_Dictyocha sirius_, Ehrenberg, 1854, Mikrogeol., Taf. xviii. fig. 59.

Each pileated piece of the skeleton is a truncated six-sided pyramid,

similar to that of _Distephanus speculum_, but distinguished by the six

broad, triangular, peripheral spines, which are articulated and connected

by a thin siliceous membrane (like a web-membrane); each spine has three

articulations (as in _Dictyocha pentasterias_).

_Dimensions._--Diameter of the basal ring 0.02, of the apical ring 0.005.

_Habitat._--Fossil in Tertiary rocks (Richmond, Virginia), but also living

in the Atlantic Ocean, Gulf Stream, Færöe Channel, John Murray, 1880.

10. _Distephanus corona_, n. sp. (Pl. 114, figs. 7-9).

_Dictyocha corona_, Haeckel, 1881, Prodromus.

Each pileated piece of the skeleton is a truncate six-sided pyramid like

that of _Distephanus speculum_, but differing in the number (twenty-four)

of teeth or spines. Six interradial ascending beams connect the two

horizontal rings between these, and six nearly vertical spines arise from

the perradial corners of the upper hexagonal ring. In the same meridional

(perradial) plains six larger spines descend downwards from the corners of

the lower larger ring. Between these six descending spines and the six

ascending beams arise from the upper edge of the lower ring twelve shorter

teeth of unequal size (the right tooth in each pentagonal lateral mesh

being smaller and directed upwards, the left tooth being larger and

directed nearly horizontally outwards). The lower ring is nearly

dodecagonal.

_Dimensions._--Diameter of the basal ring 0.025 to 0.03, of the apical ring

0.012 to 0.02.

_Habitat._--North-west Pacific, Sea of Japan, Station 231, depth 2250

fathoms.

11. _Distephanus octonarius_, Haeckel.

_Dictyocha octonaria_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 201.

_Dictyocha polyactis_, Ehrenberg, 1844, _loc. cit._, p. 80; Mikrogeol.,

1854, Taf. xxii. fig. 50.

_Dictyocha septenaria_, Ehrenberg, 1844, _loc. cit._, p. 80; Mikrogeol.,

1854, Taf. xxi. fig. 45.

Each pileate piece of the skeleton is a truncated eight-sided pyramid,

composed of two regular octagonal rings, which lie in parallel plains, and

are connected by eight radial beams. From the eight outer corners of the

lower ring (or from the eight interradial meshes, between the eight

perradial beams) start eight basal centrifugal spines. (This species is

similar to _Distephanus speculum_, but has eight beams instead of six. In

single pieces the number of the beams and meshes varies between seven and

nine, the constant number being eight.) A seven-rayed variety is _Dictyocha

septenaria_ (_loc. cit._), a nine-rayed _Dictyocha polyactis_.

_Dimensions._--Diameter of the basal ring 0.02 to 0.03, of the apical ring

0.01 to 0.015.

_Habitat._--Fossil in Tertiary rocks (Tripel and Marne from Caltanisetta,

Sicily; Oran, Africa); living in the depths of the Atlantic, Station 348,

and Pacific, Station 270, &c.

{1567}12. _Distephanus octogonius_, n. sp.

_Dictyocha septenaria_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvA., Nr.

xxi. fig. 8.

Each pileated piece of the skeleton is a truncated eight-sided pyramid,

like that of _Distephanus octonarius_, but differs from it by having eight

short erect teeth, which arise from the corners of the upper smaller ring

and lie in the same perradial plains as the eight horizontal spines

starting from the corners of the lower larger ring. Ehrenberg has figured

only an individual abnormality with seven beams instead of eight, taken

from the Antarctic ice; but I found the same form frequent in deep-sea

soundings from the Antarctic, almost constantly with eight beams, isolated

hats with six, seven, or nine beams being intermingled.

_Dimensions._--Diameter of the basal ring 0.02, of the apical ring 0.012.

_Habitat._--Antarctic Ocean; in smolten "Pancake-Ice," taken by Sir James

Clark Ross in lat. 78° 10' S., long. 162° W. (Ehrenberg); Station 156,

depth 1975 fathoms.

13. _Distephanus diadema_, n. sp.

_Dictyocha diadema_, Haeckel, 1881, Prodromus.

Each pileated piece of the skeleton is an eight-sided pyramid, like that of

the two foregoing species, but differing in the number and distribution of

the teeth or spines, which are thirty-two. From the eight corners of the

basal ring start eight long, nearly horizontal perradial spines, which bear

on each side a smaller, nearly vertically descending spine. From the eight

corners of the upper ring ascend also eight perradial spines, alternating

with the eight interradial beams, which connect the two rings.

_Dimensions._--Diameter of the basal ring 0.04, of the apical ring 0.02.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

Genus 664. _Cannopilus_,[282] n. gen.

_Definition._--#Cannorrhaphida# with a skeleton composed of pileated

pieces, each of which is a small truncated pyramid with two girdles of

meshes (the apical ring being fenestrated).

The genus _Cannopilus_ represents the most highly developed form of

Dictyochida. Each piece of the skeleton is a little fenestrated hat or

topped pyramid, as in _Distephanus_. But the apical mesh is simple in the

latter, in the former it is divided into several meshes by bars which start

in a centripetal direction from the upper ring. Therefore we find two

annular rows of meshes, one above the other; an apical or upper row of

smaller meshes and a basal or lower row of larger meshes. In the apex of

the little {1568}hat is either a central mesh or an apical spine. Other

spines arise from the basal ring, as in the former genera. The number of

corner-spines on the basal ring is either four, six, or eight (in

individual abnormalities also five or seven).

1. _Cannopilus superstructus_, Haeckel.

_Dictyocha superstructa_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 80; Mikrogeol., Taf. xxii. fig. 45.

Each pileated piece of the skeleton is a reticulated four-sided pyramid.

The base of it (or the lower ring) is a square, from the four perradial

corners of which start four centrifugal horizontal spines. In the centres

of the four basal bars (or the sides of the square) arise four interradial

beams, which unite in the second (or upper) square ring. This latter forms

a second (but much smaller) four-sided pyramid, the apex of which is

truncated. Therefore the little hat bears nine meshes; around the large

central opening four upper smaller and four lower larger quadrangular

meshes.

_Dimensions._--Diameter of the basal ring 0.03, of the apical ring 0.01.

_Habitat._--Fossil in Tertiary rocks of Sicily (Caltanisetta).

2. _Cannopilus diplostaurus_, n. sp. (Pl. 114, fig. 10).

Each pileated piece of the skeleton is a truncated quadrangular pyramid.

From the corners of the square basal ring start four perradial, nearly

horizontal, spines. Between these arise four interradial beams, which are

united above by an upper square ring. This latter is divided into four

small square meshes by a regular cross of perradial bars, the distal ends

of which are prolonged into four short ascending spines. In the centre of

the cross arises a vertical apical spine.

_Dimensions._--Diameter of the basal ring 0.04, of the apical ring 0.016.

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

3. _Cannopilus calyptra_, Haeckel.

_Dictyocha heptacanthus_, Ehrenberg, 1840, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 208; Mikrogeol., 1854, Taf. xix. fig. 39 (?).

Each pileated piece of the skeleton is a truncated six-sided pyramid, like

that of _Dictyocha speculum_, but distinguished by the reticulation of the

upper (smaller) ring, which is divided by six beams into six meshes, lying

in the horizontal plane of the upper ring. Six peripheral spines on the

corners of the lower ring. (The irregular form, figured by Ehrenberg as

_Dictyocha heptacanthus_, _loc. cit._, is probably only an individual

abnormality with seven peripheral spines, instead of six; similar

abnormalities occur also among the regular hexagonal forms which I found in

the Tertiary rocks of Caltanisetta (Sicily).

_Dimensions._--Diameter of the basal ring 0.05, of the apical ring 0.02.

_Habitat._--Fossil in Tertiary deposits of Greece and Sicily.

{1569}4. _Cannopilus hemisphæricus_ (Haeckel).

_Dictyocha hemisphærica_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 266.

Each pileated piece of the skeleton is nearly hemispherical, with thirteen

meshes; six lower and larger meshes in the sides of the truncated six-sided

pyramid, seven others in the convex surface of the upper ring (one central

with six surrounding it). From the six corners of the lower ring arise six

horizontal perradial spines. From the inside of the same ring (probably on

the side of the six ascending interradial beams) spring six centripetal

teeth.

_Dimensions._--Diameter of the basal ring 0.02, of the apical ring 0.01.

_Habitat._--North Atlantic; Bermuda (Bailey).

5. _Cannopilus cyrtoides_, n. sp. (Pl. 114, figs. 11, 12).

_Dictyocha cyrtoides_, Haeckel, 1881, Prodromus.

Each pileated piece of the skeleton is an eight-sided truncated pyramid, or

nearly hemispherical. From the basal ring arise twenty-four thorns or

teeth, eight longer perradial centrifugal teeth placed almost horizontally,

and between these sixteen shorter adradial teeth, directed downwards and

somewhat centripetally. The network of the small hat is composed of

seventeen meshes, arranged in two rows. The eight lower meshes are

hexagonal, separated by six interradial ascending beams, and twice as large

as the eight upper pentagonal meshes, which are separated by eight

perradial beams, and enclose an apical central mesh.

_Dimensions._--Diameter of the basal ring 0.04, of the apical ring 0.005.

_Habitat._--Central area of the Pacific, Station 266, depth 2750 fathoms.

Family LXXIII. #AULACANTHIDA#, Haeckel (Pls. 102-105).

_Aulacanthida_, Haeckel, 1862, Monogr. d. Radiol., p. 262.

_Definition._--PHÆODARIA with an incomplete skeleton, composed of numerous

hollow radial tubes, which pierce the spherical calymma and touch with

their proximal ends the surface of the tripylean central capsule.

The family #Aulacanthida# represents a large and interesting group of

PHÆODARIA, differing from all other families of this legion in the

possession of numerous large radial tubes, which pierce the gelatinous and

alveolated calymma in a radial direction, and come in contact with the

outer surface of the central capsule by their inner or proximal ends,

whilst their outer or distal ends project over the surface of the spherical

calymma, and develop a great variety of manifold branches and terminal

appendages. Usually (with the exception of a single genus only) the surface

of the calymma is covered by an {1570}arachnoidal veil or mantle, composed

of thousands of very fine, hollow, tangential needles. The skeleton

therefore is incomplete, without any direct connection between the isolated

pieces, just as in the preceding Cannorrhaphida, but the latter never

possess the large, hollow, cylindrical, radial tubes, which are

characteristic of all Aulacanthida.

The spherical body of the Aulacanthida has usually a diameter of 1 to 2

mm., and including the radial tubes, of 4 to 5 mm. or more. Some species

are very common and cosmopolitan, and some genera contain numerous species,

distributed widely over all oceans. In spite of their considerable size and

wide distribution, only one species of this great family has been hitherto

known, having been discovered by me at Messina in 1859, and described in my

Monograph as _Aulacantha scolymantha_ (1862, p. 263, Taf. ii. figs. 1, 2,

and Taf. iv. figs. 1-5). I there founded for it the peculiar subfamily

Aulacanthida, and annexed it to the Thalassicollida. The same cosmopolitan

species has been subsequently observed at Messina by R. Hertwig, who first

recognised the three openings in its central capsule, and therefore united

it with his TRIPYLEA (Organism. d. Radiol., 1879, p. 88, Taf. ix. figs. 3,

4; Taf. x. figs. 7, 10). The rich collection of the Challenger has added an

astonishing number of new and interesting forms of Aulacanthida, so that I

can describe here not less than six genera and fifty-eight species. The

majority are inhabitants of the colder parts of the South Pacific and South

Atlantic, at great depths, whilst a few species only are found in the

tropics.

The structure of the body in all Aulacanthida seems to be similar in all

important points, and the differences by which we are enabled to separate

this great number of species are mainly produced by differences in the

development of the radial tubes, their form and their polymorphous

apophyses. The entire body represents a rather firm jelly-sphere of 1 to 2

mm. diameter (rarely less or more); the peripheral layer of the spherical

calymma is rather clear and transparent, whilst its central part is dark

and opaque, containing the big phæodium and the enclosed central capsule.

The diameter of the latter is usually between 0.1 and 0.3, often 0.4 to

0.5, or even more. The gelatinous calymma, in the centre of which the

capsule is placed, always contains numerous, large, spherical or roundish

alveoles, similar to those of _Thalassicolla_, and between them a delicate

network of sarcode (Pl. 102, fig. 1; Pl. 103, fig. 1; Pl. 104, fig. 1).

The spherical surface of the calymma is nearly always protected by that

characteristic arachnoidal veil or mantle, which is composed of thousands

of very fine tangential needles, densely interwoven in all tangential

directions but never directly connected. They are wanting in a single genus

only, in _Aulactinium_ (Pl. 101, figs. 6-8). This genus, therefore, may

represent a separate subfamily, the Aulactinida, whilst all other genera

protected by that mantle constitute the subfamily Aulographida. The

tangential needles always seem to have the same shape as I have accurately

described, in 1862, of _Aulacantha scolymantha_. They are constantly

smooth, very thin and fragile, but also very elastic cylinders of silica,

of equal breadth throughout their whole length, and seem {1571}to be open

at both ends, since they are easily and constantly filled by air when

dried. Their length is usually between 0.2 and 0.3 mm., rarely less than

0.15 or more than 0.5; their diameter is always less than 0.001, usually

less than 0.0005.

The large radial tubes of the Aulacanthida constitute the most

characteristic structures of this family, and are always so placed that

their inner or proximal ends are in loose contact with the outer surface of

their central capsule (upon which they rest), whilst their outer or distal

ends are more or less prominent over the spherical surface of the calymma.

Their position, therefore, is rather loose and movable, since they are

fixed only by the consistence of the jelly of the surrounding calymma, and

on the surface of the latter by the covering veil or the mantle of

tangential needles (compare Pl. 102, fig. 1; Pl. 103, fig. 1; Pl. 104, fig.

1). Their number seems never to be fixed, and is probably very variable in

different species. I found, in 1859, in the common _Aulacantha

scolymantha_, the number varying from thirty to one hundred and fifty

(_loc. cit._, p. 264). So also in _Aulographis pandora_, _Aulospathis

variabilis_, and some other common species, numerous specimens of which I

could compare, I found their number very variable, being in one and the

same species sometimes only from ten to twenty, at other times from fifty

to eighty, and sometimes even from one hundred to one hundred and fifty or

more. Perhaps the number increases with the age and the increasing size of

the calymma.

The radial tubes are always cylindrical (circular in transverse section),

never angular or prismatic. Usually they are straight, more rarely slightly

curved (Pl. 105, figs. 1, 2; Pl. 101, fig. 6). The cylinders are usually

more or less tapering towards both ends, sometimes even spindle-shaped; the

inner or proximal end is always simple and rounded, often slightly swollen

or inflated, and ovate; the outer or distal end is often thickened,

club-shaped, and exhibits the greatest variety in form and ramification.

The length of the radial tubes is usually from 1 to 3 mm., rarely less than

0.8, or more than 3.2; their diameter is usually between 0.02 and 0.03,

rarely less than 0.01 or more than 0.05. The smallest radial tubes are

found in _Aulactinium_, the largest in _Aulospathis_.

The siliceous wall of the cylindrical radial tubes is usually very thin,

fragile, and perfectly structureless. Only in a few species, mainly of

_Aulographis_, does the wall become very thick and composed of concentric

cylindrical layers (Pl. 105, figs. 6-11). Their cavity is wide and simple,

and filled up by jelly (not by sarcode, as I supposed in my first

description). The simple cavity of the tubes, though not smaller than in

the radial tubes of the Aulosphærida, Circoporida and Tuscarorida, never

contains the characteristic axial filament with its branches, which is

constantly found in the latter families. According to the description of R.

Hertwig, the tubes are perfectly closed and have no opening. I suppose,

however, that a small opening always exists in the centre of the rounded

base, and perhaps a second on the distal apex. Otherwise the circumstance

that the entire and well-preserved tubes become easily and constantly

filled {1572}up by air, when purified by hot mineral acids and afterwards

dried, cannot be explained. I suppose that the jelly contained in the

cavity of the tubes remains in constant connection by these openings with

the jelly of the surrounding calymma.

The distal ends of the radial tubes exhibit in the Aulacanthida the

greatest variety in the production of different branches and capturing

apparatus, and this serves for the distinction of the genera and subgenera

here described. In two genera only (in _Aulactinium_ Pl. 101, figs. 6-8;

and in _Aulacantha_, Pl. 105, fig. 16), the distal ends are simple, not

branched. In the four other genera they are armed with terminal branches,

which are usually arranged in elegant verticils. The greatest variety in

the formation of these verticils is developed in _Aulographis_ (Pl. 103).

The single branches of the terminal verticils are here simple, whilst in

the closely allied _Auloceros_ they are forked or elegantly ramified (Pl.

102). _Aulospathis_, the biggest of all Aulacanthida, is distinguished by

the possession of a verticil of lateral branches, placed beyond the

terminal verticil, immediately above the veil of tangential needles (Pl.

104). _Aulodendron_, finally, possesses lateral and terminal branches,

which are irregularly scattered.

The branches of the radial tubes are rarely straight, usually more or less

curved, either simple or again ramified. Their surface is either smooth or

armed with small spines or recurved teeth, often elegantly dentated or

serrated (Pl. 103, figs. 20-27; Pl. 105, figs. 7-13). Their distal ends are

either simply pointed or armed with a spathilla, or a small crown of

verticillate, usually recurved teeth (Pl. 104, figs. 4-17). The variety and

elegance of these minute armatures are very interesting, the more so as

they occur in very similar and analogous forms among the Aulosphærida, the

Coelographida, and other PHÆODARIA.

The _central capsule_ of the Aulosphærida and its large nucleus

("Binnenbläschen"), as well as the surrounding alveolate calymma

("Alveolen-Hülle"), and the enclosed dark phæodium ("dunkels Pigment") were

first described in my Monograph (1862, _loc. cit._, p. 362). Their minute

structure has been examined afterwards very accurately by R. Hertwig (1879,

_loc. cit._, p. 95). The numerous well-preserved preparations of the

Challenger (stained with carmine and preserved in glycerine) which I could

examine, confirmed in all respects the detailed description of Hertwig

(compare Pl. 102, fig. 1; Pl. 103, fig. 1; Pl. 104, fig. 1).

The spherical or subspherical central capsule is usually slightly depressed

in the shortened main axis. Its diameter is usually between 0.1 and 0.3,

rarely less than 0.08 or more than 0.4 mm. Its outer membrane (_e_) is

thick and double-contoured, separated by a clear interval from the very

thin but firm inner membrane (_i_). The large astropyle, or the

main-opening on the oral pole of the main axis, is closed by a large,

convex, radiate operculum (_o_), from which arises a short tubular

proboscis. On both sides of the opposite aboral pole (to the right and

left) are two conical parapylæ or secondary openings (_u, u_). The space

between the inner membrane of the capsule and {1573}the nucleus is filled

up by protoplasm, containing numerous spherical vacuoles of equal size

(_v_); each vacuole encloses a small, dark, fat-granule. The large nucleus

(_n_) is either spherical or lenticular, and more or less depressed in the

main axis; its diameter is usually about half as great as that of the

enclosing capsule, 0.05 to 0.15, rarely less or more; it contains, enclosed

in a clear mass, numerous dark, roundish or oblongish nucleoli (_l_).

Numerous preparations of Aulacanthida exhibited a central capsule with two

nuclei (Pl. 101, fig. 6), or a calymma with two central capsules (Pl. 104,

figs. 1, 3); so that the process of propagation by self-division, observed

already in many different PHÆODARIA, seems to happen very frequently in the

Aulacanthida. The voluminous phæodium is usually about twice or three times

as large as the central capsule, and covers its oral or anterior half; the

colour of the roundish phæodella composing it is sometimes more green or

brown, at other times more blackish. The roundish alveoles, which fill up

the rather firm jelly of the calymma, exhibit nearly the same shape as in

the common _Thalassicolla nucleata_. The surface of the calymma is usually

protected by the dense veil of tangential needles, and often forms conical

or tent-shaped elevations around the bases of the piercing radial tubes

(Pl. 102, fig. 1).

_Synopsis of the Genera of Aulacanthida._

{ Surface of the calymma

{ naked, without tangential

{ needles, 665. _Aulactinium_.

Radial tubes simple, {

without lateral and { Surface of the calymma

terminal branches. { covered by a veil of

{ tangential needles, 666. _Aulacantha_.

Radial tubes without { Terminal branches simple, 667. _Aulographis_.

lateral branches, but {

with a verticil of { Terminal branches forked

terminal branches. { or again ramified, 668. _Auloceros_.

{ Lateral branches

Radial tubes with { verticillate, 669. _Aulospathis_.

lateral and with {

terminal branches. { Lateral branches

{ irregularly scattered,

{ not verticillate, 670. _Aulodendron_.

Subfamily 1. AULACTINIDA, Haeckel.

_Definition._--#Aulacanthida# without external veil of tangential needles

on the surface of the calymma.

Genus 665. _Aulactinium_,[283] n. gen.

_Definition._--#Aulacanthida# without a veil of tangential needles, with

simple radial tubes, which bear neither lateral nor terminal branches.

{1574}The genus _Aulactinium_ differs from all the other Aulacanthida in

the complete absence of the characteristic fine tangential needles, which

constitute in the latter an arachnoidal veil or mantle around the spherical

calymma. We accordingly divide the whole family into two subfamilies, the

Aulactinida with a naked calymma, and the Aulographida with a veil of

tangential needles. The radial tubes possess in the few species of

_Aulactinium_ observed a very simple shape, as in the closely allied

_Aulacantha_.

1. _Aulactinium actinastrum_, n. sp. (Pl. 101, figs. 6, 7).

Radial tubes slenderly spindle-shaped, slightly curved, gradually tapering

from the middle towards both ends. The proximal two-thirds of the tubes

enclosed in the calymma are smooth; the distal freely prominent third is

armed with six to eight equidistant verticils of small conical teeth (ten

to fifteen in each verticil).

_Dimensions._--Length of the tubes 0.5 to 1.5, breadth 0.02.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

2. _Aulactinium actinelium_, n. sp. (Pl. 101, fig. 8).

Radial tubes cylindrical, straight, slightly tapering towards both ends.

Proximal two-thirds smooth, the distal third studded with numerous small

recurved thorns.

_Dimensions._--Length of the tubes 0.6 to 0.9, breadth 0.02.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

3. _Aulactinium actinosphærium_, n. sp.

Radial tubes cylindrical, straight, smooth, of nearly equal breadth

throughout their whole length, without thorns and spathillæ, pointed at

both ends.

_Dimensions._--Length of the tubes 1.6 to 2.2, breadth 0.02 to 0.03.

_Habitat._--Antarctic Sea, Station 157, depth 1950 fathoms.

Subfamily 2. AULOGRAPHIDA, Haeckel.

_Definition._--#Aulacanthida# with an external veil of interwoven, very

numerous and thin, hollow, tangential needles, entirely covering the

surface of the calymma.

Genus 666. _Aulacantha_,[284] Haeckel, 1860, Monatsber. d. k. preuss. Akad.

d. Wiss. Berlin, p. 799.

_Definition._--#Aulacanthida# with a veil of tangential needles, and with

simple radial tubes, which bear neither lateral nor terminal branches.

{1575}The genus _Aulacantha_, hitherto the only representative of this

family, was founded by me in 1860 for the cosmopolitan _Aulacantha

scolymantha_, the most common and most widely distributed of all the

members of the family. It is the simplest form of the Aulographida, or of

those Aulacanthida in which the spherical surface of the calymma is densely

covered with interwoven tangential needles. The large radial tubes of

_Aulacantha_ possess a very simple shape, as in the preceding

_Aulactinium_, and have neither lateral nor terminal branches.

1. _Aulacantha scolymantha_, Haeckel.

_Aulacantha scolymantha_, Haeckel, 1862, Monogr. d. Radiol., p. 263, Taf.

ii. figs. 1, 2, Taf. iv. figs. 1-5.

_Aulacantha scolymantha_, R. Hertwig, 1879, Organism. d. Radiol., p. 88,

Taf. ix. fig. 3, Taf. x. figs. 7-10.

Radial tubes cylindrical, straight, of nearly equal breadth throughout

their whole length, somewhat inflated on the proximal basal end, smooth

throughout the greater part of their length, but in the distal third

dentate, with numerous (ten to forty) small pointed teeth, which are curved

outwards, and shorter than the thickness of the tube.

_Dimensions._--Length of the tubes 0.5 to 2.0, breadth 0.01 to 0.02.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; at many

Stations; surface and at various depths; the most common of all

Aulacanthida.

2. _Aulacantha tubulosa_, n. sp.

Radial tubes cylindrical or nearly spindle-shaped, straight, gradually

tapering towards the two pointed ends, twice as broad in the middle third

as in the outer and inner third, smooth in the inner half, dentate in the

outer half, with very numerous (one hundred to two hundred) short conical

teeth, which are scarcely one-fourth as large as the greatest breadth of

the tube.

_Dimensions._--Length of the tubes 0.4 to 0.5, breadth in the middle part

0.02 to 0.03.

_Habitat._--Central Pacific, Stations 271 to 274, surface.

3. _Aulacantha spinosa_, n. sp. (Pl. 105, fig. 4).

Radial tubes cylindrical, straight, of equal breadth throughout their whole

length, rounded on the proximal base, smooth in the inner proximal half,

dentate or spinescent in the outer distal half, with numerous (fifty to

eighty) slender conical teeth, which are curved forwards, increasing in

size towards the distal end, and somewhat longer than the breadth of the

tube.

_Dimensions._--Length of the tubes 0.8 to 1.2, breadth 0.015 to 0.02.

_Habitat._--North Pacific, Stations 241 to 253, surface.

{1576}4. _Aulacantha cannulata_, n. sp. (Pl. 105, fig. 16).

Radial tubes cylindrical in the inner proximal half, prismatic in the outer

distal half, with from three to six, usually four, prominent, thick,

parallel edges, which are dentate towards the thicker distal end; their

teeth short, conical, directed outwards, scarcely one-fourth as long as the

thickness of the tube. The edges are separated in the distal third by more

or less deep furrows, like a channelled column.

_Dimensions._--Length of the tubes 1.2 to 2.5, breadth 0.03 to 0.04.

_Habitat._--South Pacific, Stations 291 to 293, surface.

5. _Aulacantha clavata_, n. sp.

Radial tubes more or less irregularly curved, in the inner proximal half

slenderly conical, and gradually tapering towards the inflated base, in the

outer distal half club-shaped, armed with a few (five to twenty) short

conical teeth.

_Dimensions._--Length of the tubes 1.0 to 1.2, breadth in the middle pact

0.01, in the distal part 0.04.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

6. _Aulacantha lævissima_, n. sp.

Radial tubes cylindrical, straight, of nearly equal breadth throughout

their whole length; the inner proximal end rounded, the outer distal end

pointed. Surface of the tubes perfectly smooth, without any teeth. The

thickness and length of the simple spicula, as well as the thickness of

their wall, are very variable in this species.

_Dimensions._--Length of the tubes 0.5 to 4.2, breadth 0.003 to 0.02.

_Habitat._--North Atlantic, Station 253, Færöe Channel, surface, John

Murray.

Genus 667. _Aulographis_,[285] Haeckel, 1879, Sitzungsb. med.-nat.

Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Aulacanthida# with a veil of tangential needles, and with

radial tubes, which bear no lateral branches, but at the distal end a

verticil of simple terminal branches.

The genus _Aulographis_, the richest in the number of species among all

Aulacanthida, differs from the preceding _Aulacantha_, its ancestral form,

in the development of simple terminal branches, which form either a fork or

a verticil. The branches are either smooth or spiny, but not ramified as in

the following genus, _Auloceros_. Their distal {1577}ends are either simply

pointed or bear a terminal spathilla, or a little crown of recurved teeth.

According to these differences we may dispose the twenty-six species

described into four subgenera.

Subgenus 1. _Aulographantha_, Haeckel.

_Definition._--Terminal branches of the radial tubes simple, smooth,

without lateral teeth and terminal spathillæ. Tubes usually thin and

fragile.

1. _Aulographis pandora_, n. sp. (Pl. 103, figs. 2-9).

Radial tubes cylindrical, slender, straight or slightly curved, of equal

breadth. Terminal branches of the tubes very variable in size and number

(two to six, usually three or four), without lateral teeth and terminal

spathillæ, slender, conical, slightly curved, directed outwards, twice to

four times (rarely five to eight times) as long as the breadth of the

tubes. This species is extraordinarily variable in the number and size of

the simple terminal branches; the eight tubes, shown in figs. 2 to 9, are

all found in one and the same specimen.

_Dimensions._--Length of the tubes 0.5 to 1.5, breadth 0.01 to 0.03;

branches 0.02 to 0.12.

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

and in various depths.

2. _Aulographis bovicornis_, n. sp. (Pl. 103, figs. 12-14).

Radial tubes cylindrical, slender, straight, of equal breadth. Terminal

branches usually two (rarely three), smooth, without lateral teeth and

terminal spathillæ, eight to ten times as long as the breadth of the tube,

pointed, S-shaped, or curved like the horns of an ox.

_Dimensions._--Length of the tubes 0.6 to 0.8, breadth 0.015 to 0.02;

branches 0.1 to 0.2.

_Habitat._--South Atlantic (east of Buenos Ayres), Stations 323 to 325,

surface.

3. _Aulographis taumorpha_, n. sp. (Pl. 103, fig. 16).

Radial tubes cylindrical, slender, straight, gradually tapering towards the

pointed proximal end. Terminal branches constantly two, opposite in a

tangential, slightly concave or nearly straight line, ten to twelve times

as long as the breadth of the tube, smooth, straight in the proximal part,

recurved in the distal part.

_Dimensions._--Length of the tubes 0.7 to 0.8, breadth 0.01 to 0.015;

branches 0.1 to 0.15.

_Habitat._--North Pacific, Station 231, depth 2250 fathoms.

{1578}4. _Aulographis triglochin_, n. sp. (Pl. 103, fig. 17).

Radial tubes robust, club-shaped at the distal end. Terminal branches three

(rarely two or four), widely divergent, geniculated and recurved, smooth,

without lateral teeth and terminal spathillæ.

_Dimensions._--Length of the tubes 1.2 to 1.8, breadth 0.02; branches 0.12

to 0.15.

_Habitat._--Central Pacific, Stations 271 to 274, surface.

5. _Aulographis cruciata_, n. sp. (Pl. 103, fig. 25).

Radial tubes slender, cylindrical, of equal breadth. Terminal branches

almost constantly four, equal, regularly crossed (very rarely three or

five), slender, straight or slightly curved, smooth, divergent outwards,

six to eight times as long as the breadth of the tube.

_Dimensions._--Length of the tubes 1.0 to 1.5, breadth 0.02; branches 0.12

to 0.15.

_Habitat._--South Atlantic, Stations 325 to 332, surface.

6. _Aulographis ancorata_, n. sp. (Pl. 103, fig. 21).

Radial tubes slender, cylindrical, straight. Terminal branches constantly

four, equal, regularly crossed, arcuato-recurved or nearly semicircular,

smooth, six to eight times as long as the breadth of the tube. Resembling

an anchor with four teeth.

_Dimensions._--Length of the tubes 0.5 to 0.7, breadth 0.012 to 0.015;

branches 0.07 to 0.09.

_Habitat._--South-west Atlantic, Station 318, depth 2040 fathoms.

7. _Aulographis stellata_, n. sp. (Pl. 103, figs. 23, _a_-_c_).

Radial tubes club-shaped, gradually thickened towards the distal end.

Terminal branches stellate, numerous (five to ten or more), diverging in

all directions, smooth, straight or slightly curved, slenderly conical,

three to five times as long as the distal breadth of the tube. The branches

are very variable in size, sometimes very small (figs. _a_, _b_).

_Dimensions._--Length of the tubes 0.4 to 0.8, breadth 0.02; branches 0.01

to 0.02.

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

8. _Aulographis penicillata_, n. sp.

Radial tubes slender, cylindrical, of equal breadth. Terminal branches

pencil-shaped, smooth, very numerous (twenty to thirty or more), diverging

outwards, curved, eight to ten times as long as the breadth of the tube,

very thin and fragile, resembling a brush.

_Dimensions._--Length of the tubes 1.0 to 1.5, breadth 0.02; branches 0.15

to 0.2.

_Habitat._--North Atlantic (Antilles), Weber, surface.

{1579}9. _Aulographis pistillum_, n. sp. (Pl. 105, fig. 6).

Radial tubes club-shaped, robust, straight, gradually thickened towards the

distal end. Terminal branches eight to ten (usually nine), conical, smooth,

slightly curved, divergent outwards like a regular corona.

_Dimensions._--Length of the tubes 0.5 to 0.6, distal breadth 0.04;

branches 0.08.

_Habitat._--North Atlantic, Station 354, depth 1675 fathoms.

Subgenus 2. _Aulographella_, Haeckel.

_Definition._--Terminal branches of the radial tubes without terminal

spathillæ, but with lateral teeth or secondary spines. (Tubes usually very

stout and robust, club-shaped.)

10. _Aulographis triæna_, n. sp. (Pl. 105, fig. 8).

Radial tubes club-shaped, straight, tapering gradually towards the rounded

proximal end. Terminal branches constantly three, divergent, very stout,

eight to ten times as long as the breadth of the tube, each studded with

three to six irregular, conical, secondary spines. Sometimes the branches

become forked, the species passing over into _Auloceros cervinus_.

_Dimensions._--Length of the tubes 1.2 to 1.5, breadth 0.004 to 0.06;

branches 0.3 to 0.5.

_Habitat._--South Pacific, Station 299, depth 2160 fathoms.

11. _Aulographis martagon_, n. sp. (Pl. 105, fig. 7).

Radial tubes club-shaped or slenderly conical, strongly thickened towards

the distal end. Terminal branches six to nine, conical, slightly curved,

divergent outwards, studded outside with small, conical, secondary spines,

twice to three times as long as the breadth of the tube.

_Dimensions._--Length of the tubes 1.0 to 1.2, breadth 0.04 to 0.05;

branches 0.1 to 0.15.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

12. _Aulographis flammabunda_, n. sp. (Pl. 105, fig. 9).

Radial tubes club-shaped, more or less curved, with thickened distal ends.

Terminal branches three to six, conical, very stout, three to four times as

long as the breadth of the tube, densely studded with numerous, crowded,

conical, secondary spines, which are very irregular and more or less

curved, resembling the flames of a fire.

_Dimensions._--Length of the tubes 1.0 to 1.2, distal breadth 0.08 to 0.1;

branches 0.2 to 0.4.

_Habitat._--South Pacific, Station 302, depth 1450 fathoms.

{1580}13. _Aulographis gemmascens_, n. sp. (Pl. 105, fig. 11).

Radial tubes club-shaped, more or less curved, with thickened distal end.

Terminal branches three to nine (usually three larger and six smaller)

stout, conical, studded with irregular, straight, conical, secondary

spines, crowded and densely aggregated, like the leaves in a bud.

_Dimensions._--Length of the spines 1.5 to 1.8, distal breadth 0.07 to 0.1;

branches 0.2 to 0.6.

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

14. _Aulographis flosculus_, n. sp. (Pl. 105, fig. 10).

Radial tubes club-shaped, straight, tapering gradually towards the rounded

proximal end. Terminal branches nine to twelve, stout, conical, twice to

three times as long as the breadth of the tube, studded with irregular

secondary spines, connected in the proximal half by a solid, cap-shaped,

flinty lamella, so that the terminal corona resembles a flower. The hollow

canal of the tube sends a thin branch into each branch of the crown.

_Dimensions._--Length of the tubes 1.2 to 1.8, distal breadth 0.04 to 0.05;

branches 0.1 to 0.2.

_Habitat._--North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth

600 fathoms.

Subgenus 3. _Aulographidium_, Haeckel.

_Definition._--Terminal branches of the radial tubes armed with terminal

spathillæ (or whorls of small radial teeth), but without lateral denticles

or spines.

15. _Aulographis furcula_, n. sp. (Pl. 103, figs. 10, 11).

Radial tubes cylindrical, slender, slightly curved. Terminal branches

usually two, sometimes on single tubes three, eight to ten times as long as

the tube is broad, strongly curved, ascending vertically from a horizontal

base, with a terminal spathilla of four crossed teeth at the distal end.

_Dimensions._--Length of the tubes 0.6 to 0.8, breadth 0.006 to 0.008;

branches 0.06 to 0.08.

_Habitat._--North-west Pacific (off Japan), Station 231, depth 2250

fathoms.

16. _Aulographis triangulum_, n. sp. (Pl. 103, fig. 15).

Radial tubes cylindrical, slender, straight. Terminal branches constantly

three, slender, slightly curved, nearly horizontally (tangentially)

expanded, eight to ten times as long as the tube is broad, with a terminal

spathilla of four recurved teeth which are opposite in pairs. Since the

angles between the three branches are equal (= 120°) they correspond to the

axes of an equilateral triangle.

_Dimensions._--Length of the tubes 1.2, breadth 0.015 to 0.02; branches 0.1

to 0.12.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

{1581}17. _Aulographis tetrancistra_, n. sp. (Pl. 103, fig. 22).

Radial tubes slender, cylindrical, straight. Terminal branches four to six

(usually four), eight to ten times as long as the tube is broad, slightly

curved and widely divergent, with a terminal spathilla of four crossed

recurved teeth.

_Dimensions._--Length of the tubes 0.5 to 0.7, breadth 0.01; branches 0.08

to 0.1.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.

18. _Aulographis hexancistra_, n. sp. (Pl. 103, figs. 18, 19).

Radial tubes club-shaped, slightly curved, gradually thickened from the

proximal to the distal end. Terminal branches four to eight (usually six in

the majority of tubes), widely divergent, nearly straight, three to four

times as long as the tube is broad, with a terminal spathilla of six

(rarely five) recurved teeth.

_Dimensions._--Length of the tubes 0.4 to 0.6, breadth 0.01 to 0.02;

branches 0.04 to 0.08.

_Habitat._--North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.

19. _Aulographis polyancistra_, n. sp.

Radial tubes club-shaped, straight, thickened towards the distal end.

Terminal branches ten to twenty, smooth, strongly curved, disposed in a

corona, six to eight times as long as the tube is broad, each with a

terminal spathilla of eight to twelve radial teeth.

_Dimensions._--Length of the tubes 0.6 to 0.8, distal breadth 0.02;

branches 0.12 to 0.16.

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

20. _Aulographis asteriscus_, n. sp. (Pl. 103, fig. 24).

Radial tubes slender, cylindrical, straight, equally broad. Terminal

branches six to nine, widely divergent, disposed in a radiate corona,

around a central branch, which is the distal prolongation of the tube

itself. Each branch bears a stellate terminal spathilla, composed of ten to

twenty conical teeth, which radiate in all directions.

_Dimensions._--Length of the tubes 0.5 to 0.8, breadth 0.02; branches 0.06

to 0.09.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

Subgenus 4. _Aulographonium_, Haeckel.

_Definition._--Terminal branches of the radial tubes armed with numerous

lateral denticles, and with terminal spathillæ (or whorls of small radial

teeth).

{1582}21. _Aulographis dentata_, n. sp. (Pl. 103, fig. 20).

Radial tubes slender, cylindrical, equally broad, scarcely inflated at the

distal end. Terminal branches six to eight, curved, disposed in a corona

around a straight central branch, eight to ten times as long as the tube is

broad, armed with numerous stout recurved lateral denticles and with a

terminal spathilla of five or six recurved teeth.

_Dimensions._--Length of the tubes 1.5 to 2.5, breadth 0.03; branches 0.15

to 0.2 long.

_Habitat._--North Atlantic, Station 354, depth 1675 fathoms.

22. _Aulographis pulvinata_, n. sp. (Pl. 103, fig. 26).

Radial tubes club-shaped, straight, gradually thickened towards the distal

end, which bears a broad, circular, biconvex cushion. The margin of this

cushion bears two alternating verticils of radially divergent, straight,

terminal branches, which are twice to three times as long as the tube is

broad. Each branch is armed with two opposite lateral rows of numerous

small denticles, and bears a terminal spathilla with six to eight recurved

radial teeth.

_Dimensions._--Length of the tubes 2.0 to 2.4, distal breadth 0.03 to 0.07;

branches 0.05 to 0.08 long.

_Habitat._--South-east Pacific (off Valparaiso), Station 298, depth 2225

fathoms.

23. _Aulographis tripentas_, n. sp. (Pl. 105, fig. 13, 13_a_).

Radial tubes club-shaped, straight, thickened towards the inflated distal

end, which bears three alternating verticils of terminal branches, each

with five radial branches. The ten branches of the inner and outer

verticils are perradial, smooth; the alternating five branches of the

middle verticil are armed with recurved lateral denticles. Each of the

fifteen branches bears a terminal spathilla with five to seven recurved

teeth.

_Dimensions._--Length of the spines 2.0 to 2.5, distal breadth 0.03 to

0.06; branches 0.1 long.

_Habitat._--South-east Pacific (off Juan Fernandez), Station 299, depth

2160 fathoms.

24. _Aulographis verticillata_, n. sp. (Pl. 105, fig. 12, 12_a_).

Radial tubes cylindrical, equally broad, with an inflated ellipsoidal knob

at the distal end. This knob bears twenty to thirty slender, slightly

curved, terminal branches, which are regularly arranged in five radial or

meridional rows, and in four to six concentric verticils. The branches are

five to ten times as long as the tube is broad, and armed with two opposite

rows of lateral denticles, and with a terminal spathilla of six to eight

recurved teeth.

_Dimensions._--Length of the tubes 1.5 to 1.8, breadth 0.01 to 0.02;

branches 0.5 to 1.0 long.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

25. _Aulographis serrulata_, n. sp. (Pl. 103, fig. 27).

Radial tubes club-shaped, curved, thickened towards the inflated

ellipsoidal distal end, which bears a bunch of fifteen to twenty-five

terminal branches, arranged more or less regularly in radial {1583}or

meridional rows and concentric horizontal verticils. The branches are

irregularly curved, twice to four times as long as the distal end of the

tube, armed with two opposite rows of lateral denticles, and at the distal

end with a spathilla of six radial teeth.

_Dimensions._--Length of the tubes 1.5 to 1.8, breadth 0.02 to 0.04;

branches 0.1 to 0.15 long.

_Habitat._--North Pacific, Stations 253 and 254, depth 3025 to 3125

fathoms.

26. _Aulographis candelabrum_, n. sp. (Pl. 103, fig. 1).

Radial tubes club-shaped, straight, thickened towards the distal end and

constricted beyond the ovate, inflated, terminal knob. This knob is similar

to a candelabrum and bears a corona of six to nine strongly curved terminal

branches, which are eight to ten times as long as the tube is broad, armed

with scattered lateral denticles, and with a spathilla of five to seven

radial teeth.

_Dimensions._--Length of the tubes 1.6 to 2.4, breadth 0.03 to 0.05;

branches 0.2 to 0.3 long.

_Habitat._--South-east Pacific (off Juan Fernandez), Station 300, depth

1375 fathoms.

Genus 668. _Auloceros_,[286] n. gen.

_Definition._--#Aulacanthida# with a veil of tangential needles, and with

radial tubes, which bear no lateral branches, but at the distal end a

verticil of ramified or forked terminal branches.

The genus _Auloceros_ differs from the preceding closely allied

_Aulographis_, its ancestral form, in the ramification of the verticillate

terminal branches. They are either simply forked or again ramified, and

their distal ends are either simply pointed or armed with a terminal

spathilla, or a little crown of recurved teeth. Some forms of this genus

belong to the most elegant and graceful PHÆODARIA, as the _Auloceros

elegans_ figured, which I observed living in the Indian Ocean.

Subgenus 1. _Auloceræa_, Haeckel.

_Definition._--Distal ends of the terminal branches pointed, smooth,

without spathilla (or corona of radiate denticles).

1. _Auloceros furcosus_, n. sp. (Pl. 102, figs. 2-6).

Radial tubes slender, spindle-shaped or nearly cylindrical, more or less

tapering towards the two ends. Terminal branches slender, curved, twice to

four times as long as the tube is broad, very variable in number (usually

two or three, rarely four, five, or six; compare figs. 2-6), once or twice

forked; the secondary branches are short, irregular, and pointed. No

terminal spathillæ. {1584}In some specimens of this species all the tubes

bear two or three terminal branches, whilst in others there are tubes with

four, five, or six branches intermingled. When the number of the terminal

branches is constant in single localities, this transformistic or

"Darwinian" species may be divided into the following "subspecies:" (1)

_Auloceros pandora_ (with variable numbers); (2) _Auloceros bifurca_ (fig.

2); (3) _Auloceros trifurca_ (fig. 3); (4) _Auloceros quadrifurca_ (fig.

4); (5) _Auloceros quinquefurca_ (fig. 5); (6) _Auloceros sexfurca_ (fig.

6).

_Dimensions._--Length of the tubes 1.5 to 2.5, breadth 0.02 to 0.03;

branches 0.05 to 0.15 long.

_Habitat._--North Pacific, Stations 231 to 253, surface and at various

depths.

2. _Auloceros trigeminus_, n. sp. (Pl. 102, fig. 7).

Radial tubes club-shaped, gradually thickened towards the inflated distal

end. Terminal branches short, scarcely longer than the tube is broad, two

constantly opposite, each with three equal, conical, short secondary

branches. No terminal spathillæ.

_Dimensions._--Length of the tubes 0.6 to 0.8, breadth 0.02 to 0.03;

branches 0.04 to 0.08.

_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.

3. _Auloceros capreolus_, n. sp. (Pl. 102, fig. 8).

Radial tubes cylindrical, equally broad. Terminal branches in two opposite

clustered bunches, each with sixteen to eighteen unequal secondary

branches. The total length and breadth of each cluster is about four times

as great as the tube is broad. No terminal spathillæ.

_Dimensions._--Length of the tube 1.5 to 2.0, breadth 0.03; branches 0.07

to 0.1.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.

4. _Auloceros cervinus_, n. sp. (Pl. 102, figs. 9, 10).

Radial tubes slender, spindle-shaped, slightly curved, tapering gradually

from the middle towards the two ends. Terminal branches constantly three,

obliquely ascending, each twice or three times forked (often more or less

irregularly), with slender, curved, secondary and tertiary branches (twenty

to twenty-four on each tube); the latter are scarcely half as broad as the

three main branches of each tube. No terminal spathillæ.

_Dimensions._--Length of the tubes 2.0 to 3.5, breadth 0.03 to 0.04;

branches 0.12 to 0.15 long.

_Habitat._--South Atlantic, Station 325, depth 2650 fathoms.

5. _Auloceros elegans_, n. sp. (Pl. 102, fig. 1).

Radial tubes slender, cylindrical, straight, equally broad. Terminal

branches two or three, more or less irregularly branched, each with twelve

to eighteen curved and pointed secondary branches. No terminal spathillæ.

Differs from the preceding _Auloceros cervinus_ in the cylindrical form of

the thinner straight tubes, and the more irregular ramification; the

branches are nearly {1585}tangentially expanded, The specimen figured, with

expanded pseudopodia, red central capsule, and green phæodium, was observed

living by me in 1882 in Ceylon.

_Dimensions._--length of the tubes 1.0 to 2.0, breadth 0.02 to 0.03;

branches 0.15 to 0.3.

_Habitat._--Indian Ocean, Ceylon (south of Matura), Haeckel, surface.

Subgenus 2. _Auloceratium_, Haeckel.

_Definition._--Distal ends of the terminal branches with a spathilla, or a

small corona of radial, usually recurved teeth.

6. _Auloceros dicranaster_, n. sp. (Pl. 105, figs. 14, 15).

Radial tubes cylindrical, straight, equally broad. Terminal branches

tangential, forked, expanded horizontally, five to six times as long as the

tube is broad; their number is usually five (more rarely four or six), and

each is divided into two short, equal, divergent, secondary branches, armed

at the distal end with a spathilla of five or six unequal recurved teeth.

_Dimensions._--Length of the tubes 1.0 to 1.5, breadth 0.01 to 0.02;

branches 0.05 to 0.08.

_Habitat._--North Pacific, Stations 244 to 252, depth 2050 to 3050 fathoms.

7. _Auloceros spathillaster_, n. sp. (Pl. 102, fig. 12).

Radial tubes club-shaped or nearly cylindrical, straight, often thickened

towards the distal end. Terminal branches ascending, three to six, usually

four, partly simple, partly forked, slightly curved. The branches are from

twice to three times as long as the tube is broad, and much thinner; at the

distal end they are armed with a spathilla of five or six recurved teeth.

_Dimensions._--Length of the tubes 2.0 to 2.5, breadth 0.02 to 0.03;

branches 0.08 to 0.12.

_Habitat._--South Atlantic, Station 319, depth 2425 fathoms.

8. _Auloceros arborescens_, n. sp, (Pl. 102, figs. 11, 13).

Radial tubes club-shaped, irregularly curved, thickened towards the distal

end. Terminal branches two opposite (rarely three or four), forked near the

base, and either dichotomously or more irregularly branched; each tube

bears fifteen to thirty, usually twenty to twenty-four, secondary branches,

which are irregularly curved, and armed at the distal end with a spathilla

of four to eight recurved teeth. The tubes are more richly branched than in

the preceding, smaller, closely allied species, and the branches are more

flatly expanded.

_Dimensions._--Length of the tubes 2.6 to 3.3, breadth 0.03 to 0.04;

branches 0.1 to 0.2.

_Habitat._--South Pacific, Stations 288 to 295, depth 1500 to 3000 fathoms.

{1586}Genus 669. _Aulospathis_,[287] n. gen.

_Definition._--#Aulacanthida# with a veil of tangential needles, and with

radial tubes, which bear two verticils of branches, a distal verticil of

terminal branches, and a proximal verticil of lateral branches.

The genus _Aulospathis_ and the following _Aulodendron_ differ from the

preceding Aulacanthida in the possession of lateral branches; these are

usually similar to the terminal branches, and irregularly scattered along

the distal half of the tubes in _Aulodendron_. In _Aulospathis_, however,

the largest form in the family, each tube bears two whorls or verticils

only, a verticil of terminal branches at the distal end, and a verticil of

lateral branches beyond the latter, between the middle and distal third of

the tube. The number of branches in each verticil is usually from two to

four, rarely more; it is, however, very variable, so that the ten species

described in the sequel are "Darwinian species," derived either from

_Aulospathis polymorpha_, or from _Aulospathis variabilis_. Each branch

bears at the distal end a spathilla, the teeth of which are very variable

in form, number and arrangement.

Subgenus 1. _Aulospathessa_, Haeckel.

_Definition._--Distal ends of the radial tubes inflated, usually in the

form of an ovate or pyriform terminal knob.

1. _Aulospathis bifurca_, n. sp. (Pl. 104, figs. 1-5).

Radial tubes with an inflated ovate terminal knob at the distal end, which

bears two divergent, curved, terminal branches (often a few tubes bear

three or four branches instead of the usual two). Proximal whorl usually

cruciate, with four irregularly crossed lateral branches (but often with

five or six, more rarely with two or three).

_Dimensions._--Length of the tubes 0.15 to 25 mm., breadth 0.04 to 0.06;

branches 0.1 to 0.15.

_Habitat._--South Pacific, Stations 293 to 295, depth 1500 to 2270 fathoms.

2. _Aulospathis trifurca_, n. sp. (Pl. 104, figs. 6, 7, 7_a_).

Radial tubes with an inflated ovate terminal knob at the distal end, which

bears three divergent, straight, or slightly curved terminal branches

(often a few tubes bear two or four branches instead of the usual three).

Proximal whorl irregular, usually with six divergent, straight, lateral

branches.

_Dimensions._--Length of the tubes 2.2 to 3.4, breadth 0.03 to 0.05;

branches 0.1 to 0.15.

_Habitat._--South Pacific (off Valparaiso), Stations 298 to 300, depth 1375

to 2225 fathoms.

{1587}3. _Aulospathis quadrifurca_, n. sp.

Radial tubes with an inflated ovate terminal knob at the distal end, which

bears four crossed, divergent, curved terminal branches. Proximal whorl

also rather regular, with a cross of four straight lateral branches.

_Dimensions._--Length of the tubes 3.0 to 4.0, breadth 0.04 to 0.08;

branches 0.2 to 0.3.

_Habitat._--South Pacific, Station 291, depth 2250 fathoms.

Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, Second Part: Subclass Osculosa; Index Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII · 第 11 / 17 章

The physiological signification of the phæodella, therefore, is at present