Chapter XI: Literature and History (2)

The difference between the two legions of Holotrypasta is determined by the skeleton, which in the SPUMELLARIA is either siliceous or wanting, whilst in the Acantharia it consists of the peculiar organic substance, acanthin.

The legion SPUMELLARIA is by far the largest and most important of the four legions of Radiolaria, as well with respect to the number of different forms, as to the enormous masses of individuals, which we encounter living and fossil. We distinguish in this legion not less than thirty-two different families, three hundred and sixteen genera, and more than seventeen hundred species.

The classification of this large group requires for its better comprehension a careful division into larger and smaller groups. We divide it therefore first of all into two orders, #Collodaria# and #Sphærellaria#, as proposed in the paper mentioned above.[3]

The #Collodaria# have no perfect latticed skeleton, and comprise two suborders or sections: in the #Colloidea# the skeleton is entirely wanting, in the #Beloidea# it is represented by a variable number of siliceous needles or spicules, scattered in the calymma around the central capsule.

{7}The #Sphærellaria# differ from the #Collodaria# in the possession of a perfect siliceous skeleton, which is originally a latticed spherical shell, enveloping the central capsule. By modification of this fenestrated sphere arises an enormous mass of different forms, which we dispose in twenty-eight families, and these in four larger groups, suborders or sections,--#Sphæroidea#, #Prunoidea#, #Discoidea#, and #Larcoidea#.

The #Sphæroidea#, the common ancestral group of the #Sphærellaria#, possess a skeleton which is either a simple fenestrated sphere, or composed of two or more concentric latticed spheres, which are united by radial beams; more rarely it becomes more or less spongy.

The #Prunoidea# are derived from the #Sphæroidea# by prolongation of the latticed sphere in one axis; the skeleton therefore becomes here ellipsoidal or cylindrical (often with annular transversal constrictions).

The #Discoidea# on the contrary must be derived from the #Sphæroidea# by shortening in one axis; here therefore the fenestrated shell becomes more or less lenticular or iscoidal (often with radial spines or arms in the equatorial plane, on the circular margin).

The #Larcoidea#, the fourth section, differ from the three foregoing sections by the different growth of the shell in three different dimensions of space; therefore here the fenestrated shell becomes "lentelliptical," or a "triaxial ellipsoid," its length, breadth, and height being different.

_The Skeleton_ consists in all SPUMELLARIA either of pure _silica_ or of a peculiar silicate. The siliceous bars and beams constituting it are invariably _solid_, as also in the NASSELLARIA, never hollow, as in the PHÆODARIA. Never is the skeleton composed of acanthin, as in all ACANTHARIA. Whilst in the first order of SPUMELLARIA, #Collodaria#, the form of the spicula, or the scattered needles, composing the skeleton, is very simple, _never latticed_, in the second order, the #Sphærellaria#, it is constantly latticed or fenestrated, often also spongy.

The geometrical fundamental form of the lattice-shell in the #Sphærellaria# is originally spherical (homaxon), as preserved in all #Sphæroidea#; in the #Prunoidea# and #Discoidea# it becomes monaxon, with one single axis (prolonged in the former, shortened in the latter); in the #Larcoidea# it becomes triaxon, by different growth in three principal axes, perpendicular one to another. The further development of radial parts of the skeleton in these three axes is very important for the "promorphology" of the Radiolaria.

_The Malacoma_, or the whole soft body of the SPUMELLARIA as opposed to the skeleton, exhibits some differences of structure in two different groups, which were separated formerly (1862) as Monocyttaria and Polycyttaria, corresponding to the "Radiolaria monozoa and polyzoa" of Johannes Müller (1858).

The #Monocyttaria# (or the Spumellaria solitaria) live isolated as single cells--like {8}all other Radiolaria--and are never aggregated in colonies; the calymma includes one single central capsule, and this again one central nucleus, which does not become divided until full maturity.

The #Polycyttaria# on the contrary (or the Spumellaria socialia) live aggregated in large colonies; the calymma includes a variable number of associated central capsules and each of these commonly one central oil-globule, whilst the original simple nucleus commonly becomes very early divided into numerous small nuclei.

_The Nucleus_ of the SPUMELLARIA is originally constantly _central_, placed quite in the centre of the concentric capsule, and it retains this central position in all Monocyttaria or solitary Peripylea; whereas in the Polycyttaria--in consequence of its early division--its place is commonly taken by a central oil-globule. Whilst the numerous nuclei of the latter are very small, the single nucleus of the former is comparatively large, extremely large (more than a millimeter in diameter) in some gigantic #Collodaria#.

_The Endoplasm_ or the intracapsular sarcode exhibits in the greater number of SPUMELLARIA a more or less distinct radial striation. It encloses a great variety of different parts; vacuoles, oil-globules, pigment-granules, crystals, &c.

_The Membrane_ of the capsule in all SPUMELLARIA is simple (never double as in the _Phæodaria_) and everywhere equally perforated by innumerable small pores; in the thick, double-edged membrane of many large #Collodaria# these pores appear (in the optical section of the capsule-wall) as distinct fine radial canals, very densely and regularly disposed.

_The Central Capsule_ in the SPUMELLARIA is originally a _geometrical sphere_, and this simple globular form is preserved in all #Sphæroidea#, and in the greatest part of #Colloidea# and #Beloidea#. By prolongation of one axis the form becomes _ellipsoidal_ (or even cylindrical) in the #Prunoidea#, and in some few forms of #Colloidea#. By shortening of one axis it becomes _lenticular_ (or even discoidal) in the _Discoidea_, and in some few forms of #Colloidea#. By unequal growth in three different axes, perpendicular one to another, the capsule becomes _lentelliptical_ in all #Larcoidea#. Very rarely the capsule assumes in the SPUMELLARIA a polyhedral or irregular (sometimes even amoeboid) form, only in a few #Colloidea#.

_The Calymma_, or the jelly-veil including the central capsule, is very voluminous in many SPUMELLARIA of gigantic size, mainly in the large #Colloidea#, and in all Polycyttaria or social Radiolaria. It includes here a considerable number of large vacuoles or "alveoli." The calymma never exhibits in this legion the dark voluminous phæodium, possessed by all PHÆODARIA.

_Xanthellæ_ or "zooxanthellæ" are numerous in the calymma of most SPUMELLARIA, but by no means constant; they are very variable in number and size.

_The Matrix_, placed between the calymma and central capsule, is, in the majority of the SPUMELLARIA, a rather thick layer of granular exoplasm.

_The Pseudopodia_ arising from it are very numerous, equally disposed over the whole {9}surface, and are in general rather fluid, exhibiting a considerable tendency to ramify, anastomose, and form networks. The movement of granules is commonly lively. In the Polycyttaria all capsules of one colony or "coenobium" are connected by the dense variable network of anastomosing pseudopodia.

_Synopsis of the Orders and Suborders of_ SPUMELLARIA.

I. COLLODARIA. { Skeleton entirely wanting, 1. #Colloidea.#
Skeleton wanting or {
quite imperfect, { Skeleton represented by
not latticed. { numerous scattered spicules, 2. #Beloidea.#

II. SPHÆRELLARIA. { Lattice-shell spherical or
{ composed of concentric spheres, 3. #Sphæroidea.#
Skeleton a perfect {
shell of lattice { Lattice-shell ellipsoidal or
work, or spongy and { prolonged in one axis, 4. #Prunoidea.#
resembling {
wicker-work. { Lattice-shell discoidal or
{ shortened in one axis, 5. #Discoidea.#
{
{ Lattice-shell lentelliptical,
{ with different extent of growth
{ in three axes, 6. #Larcoidea.#

----

Order I. COLLODARIA, Haeckel, 1881.

_Collodaria_, Haeckel, Prodromus, 1881, p. 469.
_Collida_ et _Sphærozoida_, Haeckel, 1862, Monogr. d. Radiol., pp. 246,
522.

_Definition._--SPUMELLARIA without latticed shell.

The order #Collodaria#, the first order of Radiolaria, comprises all those SPUMELLARIA in which the skeleton is either entirely wanting, or represented by numerous single, solid, siliceous needles or spicules, loosely scattered in the calymma around the central capsule. Never in this order is there any trace of the latticed or fenestrated shell, which characterises the second order, #Sphærellaria#. The skeleton exhibits no trace of phylogenetic connection in the two orders.

In my monograph (1862) two families appertaining to this order are described, the Collida (p. 244) and the Sphærozoida (p. 521). Both families contain forms with and without a skeleton. Of the solitary or monozous Collida the Thalassicollida are devoid of a skeleton, whilst the Thalassosphærida are provided with a skeleton. Of the social or polyzous Sphærozoida the Collozoida are without a skeleton, the Rhaphidozoida provided with one. As the special form in both skeletophorous subfamilies is exactly the same, I prefer now to associate them in the suborder #Beloidea#, and to oppose them to the other two skeletonless subfamilies, which are united under the name of #Colloidea#.

{10}_Synopsis of the four Families of Collodaria._

Suborder I. { Solitary cells, living
COLLOIDEA. { as isolated individuals
{ (_Colloidea monozoa_), 1. THALASSICOLLIDA.
Skeleton entirely {
wanting. { Associated cells, living
{ in colonies or coenobia
{ (_Colloidea polyzoa_), 2. COLLOZOIDA.

Suborder II. { Solitary cells, living as
BELOIDEA. { isolated individuals
{ (_Beloidea monozoa_), 3. THALASSOSPHÆRIDA.
Skeleton composed {
of numerous { Associated cells, living in
needles or { colonies or coenobia
spicula, scattered { (_Beloidea polyzoa_), 4. SPHÆROZOIDA.
in the calymma. {

----

Suborder I. COLLOIDEA, Haeckel.

_Definition._--SPUMELLARIA without skeleton.

The suborder #Colloidea# comprises all those SPUMELLARIA in which no skeleton is developed. The whole body is therefore soft--a true malacoma--and is composed only of two essential parts, the central capsule and the enveloping extracapsulum. The suborder contains only two different families, the solitary #Thalassicollida# (or Colloidea monozoa) and the associated #Collozoida# (or Colloidea polyzoa). Both families are very nearly allied, and differ only in one single essential character: the solitary life of the former, the social union of the latter. It seems to be merely in consequence of this difference that the cleavage of the nucleus commonly takes place very late in the former, very early in the latter.

Therefore the full-grown Thalassicollida (till immediately before propagation) commonly exhibit one single nucleus in the centre of the capsule, whilst in the Collozoida the capsule is distended by numerous small nuclei. In these latter the centre of the capsule usually contains one large oil-globule, whilst in the former oil-globules are either wanting, or scattered in large numbers in the endoplasm, or disposed in one layer on the inside of the capsule membrane.

In the solitary Thalassicollida each capsule is enclosed in its own peculiar spherical calymma, whilst in the associated Collozoida all capsules of the colony are united in one common, very voluminous calymma.

Family I. #THALASSICOLLIDA#, Haeckel, 1862.

_Thalassicollida_, Haeckel, 1862, Monogr. d. Radiol., p. 246.
_Thalassicollida_, Haeckel, 1881, Prodromus, p. 469.

_Definition._--#Colloidea# solitaria.

The family Thalassicollida comprises all solitary SPUMELLARIA without a skeleton. The oldest and best known form of this family is the genus _Thalassicolla_, as restricted by {11}Johannes Müller.[4] The most common representative of it, the cosmopolitan _Thalassicolla nucleata_, was first described by Huxley in 1851. But as early as 1834 another large Radiolarian, appertaining either to this or to a nearly allied family, had been described by Meyen as _Physematium atlanticum_. A third genus was detected by me in 1859 at Messina and figured under the name _Thalassolampe margarodes_.[5] A very accurate histological description of these forms was given in 1876 by Richard Hertwig.[6] The same author figured in his Organismus in 1879 a very interesting simpler form under the name _Thalassolampe primordialis_ (Taf. iii. fig. 5). Some similar forms had already been observed by me, and are here united with it to form the first genus _Actissa_.[7]

_Actissa_ is of the highest general interest as the most simple and typical form of all Radiolaria, and as the common ancestral form, from which all other forms of this large class may be derived. Its unicellular body exhibits neither the extracapsular alveoli of _Thalassicolla_, nor the intracapsular alveoli of _Thalassolampe_, and shows all essential characters of the Radiolarian type in its most simple form (Pl. 1, figs. 1 to 1_c_). The simple cell-body is composed of a spherical central capsule and a concentric, spherical, enveloping calymma, both separated by a thin membrane which is perforated by innumerable pores. The capsule includes the endoplasm and in the centre a simple spherical nucleus with nucleolus; at the time of propagation this latter becomes cleft into numerous small nuclei, each of which, together with a small piece of the surrounding endoplasm, forms a flagellated zoospore (fig. 1_c_). The extracapsulum is formed by the large, structureless, spherical calymma or concentric jelly-veil enveloping the capsule, and by the thin granular matrix or the layer of exoplasm which separates the calymma from the membrane. From this matrix or maternal tissue arise innumerable very long and thin pseudopodia, as simple radiating filaments, the proximal part of which is included in the calymma, whilst the distal part floats freely in the sea-water (Pl. 1, fig. 1).

The other Thalassicollida differ from their common ancestral form, _Actissa_, mainly by the higher histological differentiation of the unicellular body. Whilst in _Thalassicolla_ and _Thalassolampe_ the nucleus remains a single sphere as in _Actissa_, it becomes branched or covered with radial blind saccules in _Thalassopila_ and _Thalassophysa_; also the intracapsular protoplasm develops here a great variety of peculiar different corpuscles, as oil-globules, pigment-granules, concentric concretions, crystals, &c. But the most striking peculiarity by which the other Thalassicollida differ from _Actissa_ is the development of large vesicular alveoli, either within or without the capsule; the unicellular body reaches by this inflation the extraordinary size of 5 to 10 mm. or more.

{12}_Synopsis of the Genera of Thalassicollida._

A. Alveoli neither { Nucleus spherical
within nor without { (sometimes ellipsoidal),
the central capsule. { not branched, 1. _Actissa_.

B. Numerous large { Nucleus spherical, 2. _Thalassolampe_.
alveoli within the {
central capsule (not { Nucleus branched or
in the calymma). { covered with radial
{ sacs, 3. _Thalassopila_.

C. Numerous large { Nucleus spherical, 4. _Thalassicolla_.
alveoli without the {
central capsule, { Nucleus branched, or
within the jelly-veil { covered with radial
or calymma. { sacs, 5. _Thalassophysa_.

Genus 1. _Actissa_,[8] n. gen.

_Definition._--#Thalassicollida# with simple spherical nucleus, without any alveoli (either within or outside the central capsule).

The genus _Actissa_ is the most simple and typical form of all Radiolaria, and may be regarded as the common ancestral form of the whole class. The spherical body is composed of a simple spherical capsule and a concentric spherical calymma or jelly-envelope. Neither the former nor the latter contains alveoli. The central capsule possesses a strong membrane perforated by small pores, and contains in the intracapsular sarcode numerous small pellucid vacuoles, and in its middle a simple, concentric, spherical nucleus (often with some nucleoli); sometimes also one or more oil-globules. The extracapsularium forms a soft, voluminous, structureless calymma or enveloping jelly-sphere, perforated by the numberless, fine pseudopodia, which radiate outwards from the matrix or the thin granulated sarcode-layer, surrounding the capsule. Often (but not constantly) xanthellæ or yellow cells are scattered in it. _Actissa_ differs from the following skeletonless genera in the absence of all alveoli; it has neither intracapsular alveoli (like _Thalassolampe_) nor extracapsular alveoli (like _Thalassicolla_). The first observed species of this genus is that which I found in 1866 at the Canary Islands, _Actissa prototypus_; the second is that which Hertwig accurately described in 1879, from the Mediterranean (Messina), _Actissa primordialis_; the third I observed in 1881 at Ceylon, frequent and sporiparous, _Actissa princeps_. A fourth species (_Actissa radiata_) exhibited a distinct radial segmentation of the capsule-contents. These four species are quite spherical. Six other species, occurring in different preparations from the Challenger, are distinguished by modifications of the spherical capsule-form and may represent three different subgenera (or, perhaps better, genera?)--_Actiprunum_ ellipsoidal, _Actidiscus_ lenticular, _Actilarcus_ lentelliptical; perhaps these are the ancestral forms of the three sections: #Prunoidea#, #Discoidea#, #Larcoidea#.

{13}Subgenus 1. _Procyttarium_, Haeckel, 1879.

_Procyttarium_, Haeckel, Natürl. Schöpfungsgeschichte, ed. vii. p. 705.

_Definition._--Central capsule spherical.

1. _Actissa princeps_, n. sp. (Pl. 1, fig. 1).

Central capsule spherical, colourless or a little reddish, transparent, with a thick double-edged membrane. Nucleus central, spherical, one-third as broad as the central capsule, containing a single, central, glossy nucleolus. Protoplasm finely granulated, without oil-globules, with numerous clear spherical vacuoles of equal size and at equal distances; the superficial layer of protoplasm (immediately below the membrane) radially striated (fig. 1). In some older specimens the nucleus was divided into numerous small nuclei (fig. 1_a_), which by further division gave the nuclei of the flagellated spores (fig. 1_b_); each spore with a very thin lateral flagellum (fig. 1_c_). Jelly-like calymma twice as broad as the enclosed capsule, without xanthellæ or yellow cells, pierced by innumerable, very thin and long, undivided pseudopodia, which arise from the sarcode-matrix on the outside of the membrane (six to eight times longer than shown in fig. 1).

_Dimensions._--Diameter of the central capsule 0.1 to 0.12, of the nucleus 0.03 to 0.04, of the jelly calymma 0.2 to 0.3.

_Habitat._--Indian Ocean, Ceylon, Belligemma, Haeckel, 1881; also in a preparation from Station 271, Central Pacific, surface.

2. _Actissa primordialis_, Haeckel.

_Thalassolampe primordialis_, R. Hertwig, 1879, Organismus der
Radiolarien, p. 32, Taf. iii. fig. 5.

_Procyttarium primordiale_, Haeckel, 1879, Natürl. Schöpf., ed. vii. p.
705, Taf. xvi. fig. 1.

Central capsule spherical, dim-yellowish, with a thin, simple-edged but compact membrane. Nucleus large, central (about half as broad), with one or two dark nucleoli; on its side an excentric oil-globule, nearly of the same size. Protoplasm between nucleus and membrane, in the younger specimens finely granulated and radially striped; in the older specimens with numerous hyaline globules (vacuoles). Jelly-envelope or calymma very voluminous, ten to twelve times as broad as the central capsule, structureless, containing numerous yellow bodies (xanthellæ?), pierced by very numerous simple pseudopodia.

_Dimensions._--Diameter of the central capsule 0.11 to 0.18, of the nucleus 0.04 to 0.09, of the jelly-like calymma 1.2 to 1.5.

_Habitat._--Mediterranean, Messina, Hertwig, 1878, surface.

3. _Actissa prototypus_, n. sp.

Central capsule spherical, red-coloured, with a thick, double-edged membrane. Nucleus central, spherical, half as large as the radius of the capsule, containing a large number (forty to sixty) of small {14}dark nucleoli. Protoplasm filled up with numerous small clear vacuoles, and between them fine red pigment granules; on the inside of the membrane one layer of dark oil-globules. Jelly-like calymma four times as broad as the enclosed capsule, with very numerous small xanthellæ.

_Dimensions._--Diameter of the capsule 0.2, of the nucleus 0.05, of the calymma 0.8.

_Habitat._--Atlantic, Canary Islands (Lanzerote, Haeckel), 1866; also at Station 348, surface.

4. _Actissa radiata_, n. sp.

Central capsule spherical, dark, with a thick, double-edged membrane. Nucleus central, spherical, half as large as the capsule, transparent. Protoplasm divided into numerous cuneiform radial pieces which are separated by clear intervals, and filled with very fine dark granules (darker in the distal half). The equatorial optical section exhibits around the circular clear nucleus a coronal of twenty-five such wedge-shaped pieces (mother-cells of spores?) No oil-globules in the central capsule. Jelly-like calymma one and a half times as broad as the enclosed capsule, with numerous small xanthellæ.

_Dimensions._--Diameter of the capsule 0.15, of the nucleus 0.07, of the calymma 0.24.

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

Subgenus 2. _Actiprunum_, Haeckel, 1882.

_Definition._--Central capsule ellipsoidal, with one prolonged axis.

5. _Actissa prunoides_, n. sp.

_Actiprunum prunoideum_, Haeckel, 1882, Manuscript.

Central capsule ellipsoidal, colourless, with a thin, simple-edged membrane. Proportion of its major axis to the minor 4 : 3. Nucleus spherical, its diameter equal to one-third of the minor axis, in its centre a large, dark, spherical nucleolus. Protoplasm clear, containing numerous small vacuoles, separated by regular distances, and on the inside of the capsule-membrane, numerous (forty to fifty) small oil-globules. Calymma (or jelly-veil) ellipsoidal, with a thin sarcode-stratum on the outside of the capsule; its diameter twice as large as that of the central capsule.

_Dimensions._--Major axis of the capsule 0.16, minor 0.12; diameter of the nucleus 0.04; major axis of the calymma 0.32, minor 0.24.

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

6. _Actissa ellipsoides_, n. sp.

_Actiprunum ellipsoides_, Haeckel, 1882, Manuscript.

Central capsule ellipsoidal, red-coloured, with a thick, double-edged membrane. Proportion of its major axis to the minor 5 : 3. Nucleus ellipsoidal, one-third as large as the capsule, containing eight small dark nucleoli. Protoplasm dusky, filled with dark pink pigment-granules; in the {15}major axis, on both poles of the nucleus-axis, two large oil-globules, half as large as the nucleus. Calymma ellipsoidal, with numerous xanthellæ; its diameter four times as large as that of the capsule.

_Dimensions._--Major axis of the capsule 0.2, minor 0.12; major axis of the nucleus 0.07, minor 0.04; major axis of the calymma 0.8, minor 0.5.

_Habitat._--Mediterranean, Corfu, 1877, Haeckel, surface.

Subgenus 3. _Actidiscus_, Haeckel, 1882.

_Definition._--Central capsule lenticular, with one shortened axis.

7. _Actissa discoides_, n. sp.

_Actidiscus discoides_, Haeckel, 1882, Manuscript.

Central capsule lenticular, red-coloured, about twice as broad as high, with a thick, double-edged membrane. Nucleus spherical, one-third as broad as the capsule, with one single, large central nucleolus. Protoplasm dusky, filled with scarlet pigment; granules and small oil-globules between them. Calymma lenticular, three times as broad as the capsule.

_Dimensions._--Major axis of the capsule 0.16, minor 0.08; diameter of the nucleus 0.05; breadth of the calymma 0.5.

_Habitat._--North Pacific, Station 236, surface.

8. _Actissa lenticularis_, n. sp.

Central capsule lenticular, flattened, about three times as broad as high, with a thin, simple-edged membrane. Nucleus lenticular, one-third as large as the capsule, with ten small dark nucleoli. Protoplasm transparent, colourless, filled with small vacuoles at regular distances; on the inside of the membrane in the circular periphery of the lens twenty dark oil-globules. Calymma lenticular, twice as broad as the capsule.

_Dimensions._--Major axis of the capsule 0.15, minor 0.05; breadth of the nucleus 0.05, height 0.02; breadth of the calymma 0.03.

_Habitat._--East Pacific, Station 272, surface.

9. _Actissa phacoides_, n. sp.

_Actidiscus phacoides_, Haeckel, 1882, Manuscript.

Central capsule lenticular, strongly flattened, about four times as broad as high, with a thin, simple-edged membrane. Nucleus lenticular, one-fourth as broad as the capsule, with numerous (twenty or more) small nucleoli. Protoplasm filled with dark pigment-granules; on the inside of the membrane in the circular periphery of the lens thirty-two dark oil-globules. Calymma lenticular, three times as broad as the capsule.

{16}_Dimensions._--Major axis of the capsule 0.2, minor 0.05; breadth of the nucleus 0.05, height 0.015; breadth of the calymma 0.6.

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

Subgenus 4. _Actilarcus_, Haeckel.

_Definition._--Central capsule lentelliptical, with three different axes.

10. _Actissa larcoides_, n. sp.

Central capsule lentelliptical; with three different axes, bearing the proportion 4 : 3 : 2. Nucleus spherical; its diameter equal to the shortest radius of the capsule. No nucleoli visible. Protoplasm transparent, with small vacuoles; on the inside of the thin capsule-membrane numerous (fifty to sixty) small oil-globules, regularly disposed. Calymma lentelliptical, twice as large as the central capsule.

_Dimensions._--Major axis or length of the capsule 0.2, middle axis or breadth 0.15, minor axis or height 0.1; diameter of the nucleus 0.05, of the calymma 0.3-0.4.

_Habitat._--Central Pacific, Station 266, surface.

Genus 2. _Thalassolampe_,[9] Haeckel, 1862, Monogr. d. Radiol., p. 253.

_Definition._--#Thalassicollida# without extracapsular alveoles, but with large roundish or globular alveoles within the central capsule, with a simple spherical, not branched nucleus in the centre.

The genus _Thalassolampe_ is, next to _Actissa_, the most simple of all Radiolaria, but differs from it by the large intracapsular alveoles. By these the central capsule is inflated to an extraordinary size, which in _Thalassolampe maxima_ exceeds that of most other Radiolaria. From the nearly allied _Thalassopila_ it differs by the simple spherical nucleus, from _Physematium_ by the absence of spicula. Of the two species of the genus the first observed _Thalassolampe margarodes_, 1862, is Mediterranean, the second, _Thalassolampe maxima_, 1882, is Indian.

1. _Thalassolampe margarodes_, Haeckel.

_Thalassolampe margarodes_, Haeckel, 1862, Monogr. d. Radiol., p. 253,
Taf. ii. figs. 4, 5.

_Thalassolampe margarodes_, R. Hertwig, 1876, Histologie d. Radiol., p.
68, Taf. iii. figs. 1-5.

Spherical body very soft and limpid, somewhat pearl-like opalescent, yellowish or bluish. Central capsule with a very thin structureless membrane, its diameter six to eight times as large as that of the central spherical nucleus. Wall of the vesicular nucleus thick, perforated by fine {17}pore-canals; on its inside often numerous oval nucleoli. In the movable protoplasmic network between the large alveoles a considerable number of large yellowish or orange oil-globules. Extracapsular jelly-envelope very thin, contains small yellow bodies (zooxanthellæ). (Compare the accurate description of this Mediterranean species in my monograph and in Hertwig's work.) In the Canary Islands I found very often a large variety of it, of double and triple the size, distinguished by the delicate orange colour of the intracapsular oil-globules. This may be distinguished as _Thalassolampe aurantiaca_.

_Dimensions._--Diameter of the whole jelly-sphere 2 to 4 mm., of the central capsule 2 to 3 mm., of its nucleus 0.2 to 0.4 mm.

_Habitat._--Mediterranean, Messina, Haeckel, Hertwig; Canary Islands, Lanzerote, Haeckel; surface.

2. _Thalassolampe maxima_, n. sp. (Pl. 1, fig. 2).

Spherical body quite pellucid, like a glass globule, colourless. Central capsule with a moderately thick, but quite transparent, structureless membrane, its diameter ten to twelve times as large as that of the central spherical nucleus. Wall of the vesicular nucleus thick, perforated by fine pore-canals; on its inside numerous small spherical nucleoli. No large oil-globules in the movable protoplasmic network between the large alveoles. Extracapsular jelly-envelope very thin, containing no yellow bodies. This differs from the preceding nearly allied species in the want of the intracapsular oil-globules and of the extracapsular yellow bodies. It possesses the largest central capsule of all known Radiolaria. I found them living and floating in water taken from the surface of the Indian Ocean by a bucket.

_Dimensions._--Diameter of the whole jelly-body 12 to 15 mm., of the central capsule 10 to 12 mm., of the nucleus 0.8 to 1.2 mm.

_Habitat._--Indian Ocean, near the Maldive Islands, Haeckel, 1882, surface.

Genus 3. _Thalassopila_,[10] Haeckel, 1881, Prodromus, p. 469.

_Definition._--Thalassicollida without extracapsular alveoles, but with large roundish or globular alveoles within the central capsule, with a papillate or branched nucleus in its centre.

The genus _Thalassopila_ has, like _Thalassolampe_, a voluminous foamy central capsule, inflated by numerous large alveoles; but it differs in the complicated form of the nucleus, which is like that of _Thalassophysa_, and is either branched or occupied by conical or roundish papillæ.

1. _Thalassopila cladococcus_, n. sp. (Pl. 1, fig. 3).

Spherical body dark-spotted, with a thin yellowish jelly-envelope. Central capsule with a thick and firm membrane, perforated by pores; its diameter three times that of the central nucleus, {18}three-fourths that of the whole jelly-sphere. Nucleus profusely branched or papillated, its spherical surface covered with numerous (more than a hundred) finger-shaped obtuse blind sacs, about as long as its radius. Protoplasm of the central capsule forming a loose network between the large roundish alveoles, in the cortical zone radially striped and containing one layer of large dark oil-globules. These are regularly distributed on the inside of the capsule-membrane and separated by intervals, twice as broad as its diameter, giving to the capsule-surface a spotted appearance. Extracapsular jelly-envelope thin, yellowish, with very numerous and small xanthellæ.

_Dimensions._--Diameter of the whole jelly-sphere 5 mm., of the central capsule 4 mm., of the nucleus 1.3 mm.

_Habitat._--Antarctic Ocean, Station 154 (south of Kerguelen), surface.

Genus 4. _Thalassicolla_,[11] Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 433.

_Definition._--Thalassicollida without intracapsular alveoles, but with large roundish or globular alveoles within the extracapsular calymma. Nucleus in the centre of the capsule simple spherical, not branched.

The genus _Thalassicolla_ was proposed by Huxley in 1851, for a certain number of different voluminous jelly-like Radiolaria, which he had observed living during his voyage in the "Rattlesnake" through the tropical seas, and of which he gives an excellent description--the first accurate observations on living Radiolaria. Johannes Müller afterwards removed from this genus the social genera _Sphærozoum_ and _Collosphæra_ (formerly _Thalassicolla punctata_), and retained as type of the genus _Thalassicolla nucleata_. In 1862 in my Monograph I added two other species, _Thalassicolla pelagica_ and _Thalassicolla zanclea_, and later (1870) _Thalassicolla sanguinolenta_. Now I think it better to separate the last two species as a new genus, _Thalassophysa_, characterised by the papillate or branched nucleus, and to retain in _Thalassicolla_ only those forms with simple spherical nucleus. For both genera the extracapsular, voluminous, spherical calymma or jelly-envelope, with numerous large alveoles, is characteristic. The membrane of the central capsule in _Thalassicolla_ is now structureless (subgenus _Thalassicollarium_, with three species), now characterised by a peculiar structure, prominent ridges on the inside of the membrane, which form a network with polygonal plates, resembling an epithelium (Pl. 1, fig. 5_b_; subgenus _Thalassicollidium_, with four species). Of the seven species here described, two are cosmopolitan, widely distributed, and common; one is Mediterranean, one Atlantic, and three Pacific.

Subgenus 1. _Thalassicollarium_, Haeckel.

_Definition._--Membrane of the central capsule structureless, only perforated by innumerable very small radial pores.

{19}1. _Thalassicolla pellucida_, n. sp.

Spherical body very soft, transparent, clear and colourless, without any pigment. Central capsule soft, hyaline, with a thin, structureless, not areolated membrane. Diameter of the central capsule about three times that of the nucleus, one-fourth to one-sixth that of the jelly-envelope. Nucleus delicate, transparent, with one single central nucleolus, about one-third its diameter. Protoplasm of the central capsule contains only small, pellucid, densely packed globules (vacuoles?), no oil-globules. Extracapsular body quite transparent, without pigment or oil-globules, only composed of the large alveoles imbedded in the jelly-cover, and of the fine protoplasmic network between them. No xanthellæ.

_Dimensions._--Diameter of the central capsule 0.8 to 1.2, of the nucleus 0.3 to 0.4, of the calymma 3 to 6 mm.

_Habitat._--Cosmopolitan, Canary Islands, Haeckel; Cape, Australia, Pacific, Challenger; surface.

2. _Thalassicolla spumida_, n. sp.

Spherical body nearly transparent, yellowish, without dark pigment. Central capsule pellucid, with a thick, structureless, not areolated membrane. Diameter of the central capsule about twice that of the nucleus, one-sixth to one-eighth that of the jelly-cover. Nucleus delicate, somewhat opaque, with numerous small nucleoli. Protoplasm of the central capsule contains small pellucid globules (vacuoles?), and immediately under its membrane (on its inside) one single layer of large, dark, refractive oil-globules. Extracapsular body very voluminous, foamy, with innumerable alveoles in the jelly, and many xanthellæ between them.

_Dimensions._--Diameter of the central capsule 0.6 to 0.8, of the nucleus 0.3 to 0.4, of the calymma 3 to 5 mm.

_Habitat._--Atlantic, Canary Islands, Haeckel; Cape Verde Islands, Challenger Station 350; Brazil, Rabbe; surface.

3. _Thalassicolla zanclea_, Haeckel.

_Thalassicolla zanclea_, Haeckel, 1862, Monogr. d. Radiol., p. 252, Taf.
ii. fig. 3.

Spherical body opaque, transparent only in the periphery, with colourless central capsule, but with brown or black pigment-powder scattered everywhere through the extracapsular alveolated jelly-cover. Central capsule soft, transparent, colourless, with a thin structureless, not areolated membrane. Diameter of the central capsule about one and a half times that of the nucleus, one-half or one-third that of the jelly-cover. Nucleus delicate, transparent, with a thin, finely punctated membrane, with one or more nucleoli. Protoplasm of the central capsule contains only small, pellucid, densely packed globules (vacuoles?), no oil-globules. Extracapsular body very dark and opaque, with a great mass of brown or blackish-brown pigment between the alveoles of the jelly-cover. Numerous xanthellæ.

_Dimensions._--Diameter of the central capsule 0.1 to 0.12, of the nucleus 0.07 to 0.08, of the calymma 0.2 to 0.4.

_Habitat._--Mediterranean, Messina, Haeckel.

{20}Subgenus 2. _Thalassicollidium_, Haeckel.

_Definition._--Membrane of the central capsule areolated, with small polygonal plates, resembling an epithelial cell-tissue, spotted by innumerable fine radial pores.

4. _Thalassicolla australis_, n. sp.

Spherical body nearly transparent, without dark pigment. Central capsule colourless, somewhat opaque, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about three times that of the nucleus, one-third that of the jelly-cover. Nucleus thin-walled, with many small nucleoli. Protoplasm of the central capsule finely granulated, containing numerous hyaline globules (vacuoles?) of different size, and in each of these one single roundish, dark refringing corpuscle, concentrically lamellated like an amylum grain. Extracapsular body without pigment or oil-globules, only composed of the large alveoles imbedded in the jelly-cover, and of the fine protoplasmic network between them. No xanthellæ.

_Dimensions._--Diameter of the central capsule 1 to 2, of its nucleus 0.3 to 0.4, of the nucleoli 0.12 to 0.16, of the hyaline globules in the protoplasm of the capsule 0.02 to 0.05; calymma, 4 to 6 mm.

_Habitat._--South-west Pacific, east coast of Australia, New Zealand, &c.; Challenger Stations 163, 171; surface.

5. _Thalassicolla nucleata_, Huxley.

_Thalassicolla nucleata_, Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2,
vol. viii. p. 435, pl. xvi. fig. 4.

_Thalassicolla nucleata_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 28.

_Thalassicolla coerulea_, Schneider, 1858, Archiv f. Anat. u. Physiol.,
p. 40, Taf. iii. Bd. i. figs. 5-7.

_Thalassicolla nucleata_, Haeckel, 1862, Monogr. d. Radiol., p. 249, Taf.
iii. figs. 1-5.

_Thalassicolla nucleata_, R. Hertwig, 1876, Histologie d. Radiol., p. 43,
Taf. iii. figs. 61-5, Taf. iv., v.

_Thalassicolla nucleata_, R. Hertwig, 1879, Organismus d. Radiol., p. 34.

Spherical body in the central part opaque, black or dark coloured, in the periphery transparent, whitish, or yellowish. Central capsule rather compact, yellowish, opaque, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about twice as large as that of the nucleus, one-half to one-fourth that of the jelly-cover. Nucleus with a very thick, finely punctated membrane, containing a viscous fluid (when coagulated finely granular), and sometimes one large, central, spherical, or ramified nucleolus, sometimes a variable number of smaller roundish nucleoli. Protoplasm of the central capsule containing many very variable corpuscles, mostly pellucid (albuminous?) spherules, containing oil-globules, or concentric amyloid concretions, or crystals, &c. Extracapsular body with dark pigment-powder of variable colour (black, brown, violet, blue, &c.), densely aggregated around the central capsule, more loosely dissipated between the alveoles of the outer jelly-cover. Xanthellæ very numerous.

{21}_Dimensions._--Diameter of the central capsule 0.4 to 0.8, of the nucleus 0.02 to 0.05, of the calymma 1 to 5 mm.

_Habitat._--Cosmopolitan; common in all warmer seas; Mediterranean, Atlantic, Indian Ocean, Pacific, mainly between lat. 40° N. and lat. 40° S.; surface.

6. _Thalassicolla maculata_, n. sp. (Pl. 1, fig. 4).

Spherical body in the central part opaque, black or dark coloured, in the periphery semi-transparent, spotted. Central capsule compact, yellowish, opaque, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about twice that of the nucleus, one-third to one-fifth that of the jelly-cover. Nucleus thin-walled, with one large spherical nucleolus. Protoplasm of the central capsule contains innumerable very small, hyaline, spherical vesicles of equal size (or vacuoles?), two to four times as broad as the separating bridges of protoplasm. Extracapsular body with dark pigment-powder of black or brown colour, densely accumulated around the central capsule (in the matrix), loosely scattered between the alveoles of the outer jelly-cover. The latter appears spotted by numerous large, roundish lumps of protoplasm, scattered between the alveoles. No xanthellæ.

_Dimensions._--Diameter of the central capsule 0.3 to 0.6, of the nucleus 0.2 to 0.3, of the hyaline globules in the protoplasm of the capsule 0.02 to 0.03; calymma, 2 to 3 mm.

_Habitat._--South Pacific, Challenger Station 289.

7. _Thalassicolla melacapsa_, n. sp. (Pl. 1, fig. 5).

Spherical body in the central part opaque, black or dark coloured, in the periphery semi-transparent, spotted. Central capsule compact, black, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about twice that of the nucleus, one-third or half that of the jelly-cover. Nucleus thin-walled, transparent, containing very numerous and small nucleoli. Protoplasm of the central capsule filled with small black pigment-granules, quite intransparent, contains densely packed hyaline (albuminous?) globules of equal size; every pellucid globule includes a smaller globule (one-third or one-fourth its diameter), which appears to be composed of aggregated oil-bubbles. Extracapsular body without pigment, contains between its alveoles in the inner half numerous, dark refractive oil-globules, in the outer half numerous amoeboid lumps of protoplasm, irregularly scattered. No xanthellæ.

_Dimensions._--Diameter of the central capsule 2 to 2.5, of the nucleus 1 to 1.5, of the hyaline globules in the protoplasm of the capsule 0.03 to 0.04; calymma, 3 to 5 mm.

_Habitat._--South-east Pacific (near Valparaiso), Challenger Station 300, surface.

Genus 5. _Thalassophysa_,[12] Haeckel, 1881, Prodromus, p. 470.

_Definition._--Thalassicollida without intracapsular alveoles, but with large roundish or globular alveoles within the extracapsular calymma. Nucleus in the centre of the capsule papillate or branched.

{22}The genus _Thalassophysa_ contains those species of Thalassicollida formerly associated with _Thalassicolla_, which are distinguished by the complicated, ramose, or papillate form of the large nucleus. All three species here described are found in the Mediterranean and the Atlantic. To this genus appertains also that strange form of Radiolaria which I described in 1870 as _Myxobrachia_ (compare _Thalassophysa sanguinolenta_).

1. _Thalassophysa papillosa_, n. sp.

_Thalassicolla papillosa_, Haeckel, 1867, Manuscript.

Spherical body transparent, colourless, or somewhat yellowish. Central capsule soft, colourless, with a very thin but firm, elastic, structureless membrane. Diameter of the central capsule about twice that of the nucleus, one-fourth to one-sixth that of the jelly-envelope. Nucleus papillated, its spherical surface covered with a great number (50 to 80) of conical or finger-like protuberances or blind sacs, not longer than half its radius. Protoplasm of the central capsule filled with very small and numerous spherical vacuoles, without oil-globules. Extracapsular jelly-body, without dark pigment, oil-globules, and large protoplasmic lumps, contains between its alveoles very numerous xanthellæ.

_Dimensions._--Diameter of the whole jelly sphere 4 to 5 mm., of the central capsule 0.8 to 1 mm., of its nucleus 0.4 to 0.5.

_Habitat._--Canary Islands, Lanzerote, common, Haeckel; Cape Verde Islands, Challenger; surface.

2. _Thalassophysa sanguinolenta_, Haeckel.

_Thalassicolla sanguinolenta_, Haeckel, 1870, Jenaische Zeitschr., Bd. v.
p. 526, Taf. 18.

_Thalassicolla sanguinolenta_, Haeckel, 1870, Biolog. Studien, i. p. 113,
Taf. iv.

_Thalassicolla sanguinolenta_, R. Hertwig, 1879, Organismus d. Radiol.,
p. 37, Taf. iii. fig. 1.

_Myxobrachia rhopalum_, Haeckel, 1870, Jenaische Zeitschr., Bd. v. p.
519, Taf. 18 (et in Biol. Stud., _loc. cit._).

_Myxobrachia pluteus_, Haeckel, 1870, Jenaische Zeitschr., Bd. v. p. 520,
Taf. 18 (et in Biol. Stud., _loc. cit._).

Spherical body in the central part opaque, reddish, in the periphery transparent, yellowish. Central capsule compact, white, red spotted, with a thick elastic membrane, perforated by pores, but not areolated. Diameter of the central capsule three times that of the nucleus, one-fifth to one-eighth that of the jelly-envelope. Nucleus papillated, its spherical surface covered with numerous (80 to 120) conical or finger-like protuberances not longer than one-fourth or one-third of its radius. On the inside of these blind sacs lie numerous small roundish nucleoli. Protoplasm of the central capsule in the outer (cortical) zone (on the inside of the membrane) radially striped, with one layer of very numerous red oil-globules of equal size, producing its blood-spotted appearance; in the inner (medullary) zone foamy, with numerous small spherical vacuoles. Extracapsular jelly-body without dark pigment, contains between its alveoles no large protoplasmic lumps (as in _Thalassophysa pelagica_), but numerous small oil-globules and xanthellæ. This species sometimes amasses in its jelly-envelope large accumulations of Coccoliths and Coccospheres, {23}which are much heavier than the jelly-body, and produce arm-like protuberances of it; this modified form, often of very regular and peculiar appearance, I formerly described as _Myxobrachia_ (compare my Biolog. Studien, _loc. cit._, and Hertwig, _loc. cit._, p. 37). Compare also _Myxobrachia cienkowski_, Wagner, 1872, L. N. 23.

_Dimensions._--Diameter of the whole jelly-sphere 5 to 8 mm., of the central capsule 1 to 1.2 mm., of its nucleus 0.3 to 0.4.

_Habitat._--Canary Islands, Lanzerote; common, Haeckel; Mediterranean, Messina, Hertwig; surface.

3. _Thalassophysa pelagica_, Haeckel.

_Thalassicolla pelagica_, Haeckel, 1862, Monogr. d. Radiol., p. 247, Taf.
i.

_Thalassicolla pelagica_, R. Hertwig, 1879, Organismus d. Radiol., p. 35,
Taf. iii. fig. 4.

Spherical body in the central part opaque, yellowish, in the periphery semi-transparent, spotted. Central capsule compact, yellowish-white, with a thick and compact membrane, perforated by pores, but not areolated. Diameter of the central capsule about twice that of the nucleus, one-half to one-sixth that of the jelly-envelope. Nucleus papillated, its spherical surface covered with numerous (20 to 60) conical, roundish, or finger-like protuberances, not longer than its radius (commonly only one-half or one-third as long). Enclosed in the semi-fluid substance of the nucleus are very long and thin cylindrical nucleoli snake-like, contorted, and penetrating into the protuberances of the nucleus. Protoplasm of the central capsule in the outer (cortical) zone (on the inside of the membrane) radially striped, with one layer of large oil-globules of different sizes; in the inner (medullary) zone foamy, with numerous small spherical vacuoles, mostly of equal size. Extracapsular jelly-body without dark pigment, contains between its alveoles a large number of large roundish or amoeboid lumps of protoplasm, and very numerous yellow cells or xanthellæ (compare the detailed description in my Monograph, and in R. Hertwig's work).

_Dimensions._--Diameter of the whole jelly-sphere 1 to 4 mm., of the central capsule 0.5 to 0.6, of the nucleus 0.2 to 0.3.

_Habitat._--Mediterranean--Messina, Corfu, Nizza, Genoa, Haeckel; Messina, R. Hertwig; surface.

Family II. #COLLOZOIDA#, Haeckel, 1862 (Pl. 3).

_Collozoida_, Haeckel, 1862, Monogr. d. Radiol., p. 522.

_Definition._--#Colloidea# socialia.

The family Collozoida comprises all associated or colony-building Radiolaria without skeleton. We unite here all these skeletonless Radiolarian colonies into one single genus _Collozoum_, constituted (1862) in my Monograph (p. 522). The oldest known form of it was the _Collozoum inerme_, described firstly by Johannes Müller (1856) as _Sphærozoum inerme_. Two other species of the genus were figured (1862) in my Monograph (p. 522, Tafn. xxxii., xxxv.). A most accurate description of its histological structure and {24}development was given in 1876 by Richard Hertwig in his Histologie der Radiolarien (pp. 12-42, Tafn. i., ii.). A number of other very remarkable forms of _Collozoum_ have been observed by me during the last few years, and partly figured in Pl. 3.

_Collozoum_, as the only representative of this family, is sufficiently distinguished from all other Radiolaria by the definition "_Skeletonless Radiolarian Colonies._" These occur floating on the surface of all warmer seas, often in astonishing masses, and may be easily confounded, owing to their external resemblance, with the jelly-like egg-masses of certain Mollusca. _Collozoum_ is derived either from _Actissa_ or from _Thalassicolla_, simply by multiplication of the unicellular body and by reunion of the associated capsules in one common calymma or jelly-veil; this is constantly alveolated, as in _Thalassicolla_. As in _Actissa_, the form of the central capsule remains either spherical, or it becomes ellipsoidal or discoidal, rarely polyhedral or amoeboid. In _Collozoum_ as in all colonial Radiolaria, the original central nucleus commonly undergoes cleavage very early into numerous small nuclei, whilst its place is usually taken by a central oil-globule. This peculiarity may serve often (but not constantly) for the distinction of isolated capsules of _Collozoum_ from _Actissa_.

Genus 6. _Collozoum_,[13] Haeckel, 1862, Monogr. d. Radiol., p. 522.

_Definition._--Skeletonless colonies of Radiolaria.

The genus _Collozoum_, as already mentioned, is the only representative of its family, and comprises all Radiolaria living associated in colonies, and having no skeleton. Therefore _Collozoum_ possesses all the peculiarities described above. Although the floating colonies of this genus occur in enormous masses on the surface of all warmer seas, nevertheless the number of different species in this genus is not great, and amounts only to thirteen. If this number increase by further investigations, the subgenera distinguished in the following description can be advanced to the range of genera; in which case _Collodinium_ (or _Collozoum_ sensu restricto) will be characterised by the spherical form of its central capsules, _Colloprunum_ by the ellipsoidal form (Pl. 3, fig. 9), _Collophidium_ by the cylindrical, very prolonged form (figs. 2, 3), _Collodiscus_ by the lenticular or discoidal form, and _Collodastrum_ by the indefinite, polyhedral, or amoeboid form (figs. 4, 5).

Subgenus 1. _Collodinium_, Haeckel.

_Definition._--Form of the central capsules spherical or subspherical, never polyhedral, ellipsoidal, or cylindrical.

{25}1. _Collozoum inerme_, Haeckel (Pl. 3, figs. 10-12).

_Collozoum inerme_, Haeckel, 1862, Monogr. d. Radiol., p. 522, Taf. xxxv.

_Collozoum inerme_, Cienkowski, 1871, Archiv. f. mikrosk. Anat., vol.
vii. p. 376, Taf. xxix. figs. 18-36.

_Collozoum inerme_, R. Hertwig, 1876, Histologie der Radiol., p. 12, Taf.
i., ii.

_Collozoum inerme_, R. Hertwig, 1879, Organismus d. Radiol., p. 31, Taf.
iii. fig. 12.

_Sphærozoum inerme_, J. Müller, 1856, Monatsber. d. k. Akad. d. Wiss.
Berlin, p. 478; Abhandl., p. 54.

_Sphærozoum bicellulare_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 54, Taf. viii. fig. 5.

_Thalassicolla punctata_, Huxley (_pro parte_), 1851, Ann. and Mag. Nat.
Hist., ser. 2, vol. viii. p. 433.

Central capsules spherical, with thin, simple-edged membrane, with one single oil-globule in the centre. (If the capsules multiply by division, the spherical form becomes violin-shaped, constricted in the middle; and in this condition the number of oil-globules increases; but in the ordinary mature state the capsule of this species remains spherical, and its oil-globule solitary. In quite young capsules the oil-globules are wanting; Pl. 3, fig. 12.)

_Dimensions._--Diameter of the central capsules 0.04 to 0.16.

_Habitat._--Cosmopolitan, common in all warmer seas (Mediterranean, Atlantic, Indian, and Pacific), surface.

2. _Collozoum nostochinum_, n. sp.

Central capsules spherical, very large, opaque, distended with red pigment-granules and with very numerous (two hundred to three hundred) small oil-globules. Membrane thick, double-edged.

_Dimensions._--Diameter of the central capsules 0.3 to 0.5.

_Habitat._--Indian Ocean, off Socotra, surface, Haeckel.

3. _Collozoum volvocinum_, n. sp.

Central capsules spherical, very large, opaque, containing a great number (ten to thirty) of large oil-globules, and between them densely packed masses of dark pigment. Membrane thick, double-edged. This species differs from _Collozoum inerme_, mainly by the great size of the central capsules (three to five times as big as in the former) and the great number of oil-globules in them.

_Dimensions._--Diameter of the central capsules 0.2 to 0.3.

_Habitat._--Central Pacific, Station 272, surface.

Subgenus 2. _Colloprunum_, Haeckel.

_Definition._--Form of the central capsules ellipsoidal, with one prolonged axis.

4. _Collozoum ovatum_, n. sp.

_Colloprunum ovatum_, Haeckel, 1882, Manuscript.

Central capsules ovate or ellipsoidal, its longer diameter twice to three times as large as the shorter. In the centre of every capsule one single oil-globule.

{26}_Dimensions._--Length of the central capsules 0.2 to 0.3, breadth of them 0.1 to 15.

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

5. _Collozoum ellipsoides_, n. sp. (Pl. 3, figs. 8, 9).

_Colloprunum ellipsoides_, Haeckel, 1882, Manuscript.

Central capsules regularly ellipsoidal, very large; their longer diameter once and a half to twice as large as the shorter. In every capsule fifty to eighty oil-globules.

_Dimensions._--Length of the central capsules 0.3 to 4, breadth of them 0.2.

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

Subgenus 3. _Collophidium_, Haeckel.

_Definition._--Form of the central capsules cylindrical, often snake-like, contorted, with one axis much prolonged, several times longer than the transverse axis.

6. _Collozoum contortum_, n. sp.

_Collophidium contortum_, Haeckel, 1882, Manuscript.

Central capsules cylindrical, three to four times as long as broad, C- or S-like curved, transparent, without oil-globules.

_Dimensions._--Length of the central capsules 0.2 to 0.3, breadth 0.06 to 0.08.

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

7. _Collozoum serpentinum_, n. sp. (Pl. 3, figs. 1-3).

_Collophidium serpentinum_, Haeckel, 1882, Manuscript.

Central capsules cylindrical, filiform, much elongated, ten to one hundred times, sometimes two hundred to four hundred times as long as broad, snake-shaped or worm-shaped, curved and contorted in the most irregular manner, often spiral or twisted into a large nodule. Numerous oil-vesicles constantly present, forming one series of globules in the axis of every capsule; distance of the globules, one from another, and also from the capsule-membrane, about equal to their diameter. (This interesting and very curious form was very frequently observed living by me in the Canary Islands, in January 1867; the jelly-colonies were commonly spherical, and contained fifty to two hundred or more capsules of very different size and form.)

_Dimensions._--Length of the central capsules 1 to 10, sometimes 20 to 40 mm.; average breadth 0.1 mm.

_Habitat._--Canary Islands, Lanzerote, Haeckel, surface.

{27}8. _Collozoum vermiforme_, n. sp. (Pl. 3, figs. 6, 7).

_Collophidium vermiforme_, Haeckel, 1882, Manuscript.

Central capsules cylindrical, much elongated, five to ten times (sometimes twenty to fifty times) as long as broad, snake-shaped or worm-shaped, very irregularly curved and contorted. Numerous oil-globules constantly present, forming in the axis of every capsule a double series of alternating rose-coloured globules. (This species is nearly allied to the preceding; but its capsules are thicker and shorter, and the oil-vesicles in them are arranged not in a single, but in a double row.)

_Dimensions._--Length of the central capsules 0.6 to 1.2 mm., sometimes 3 to 6 mm.; breadth 0.12.

_Habitat._--Tropical Atlantic, near the west coast of Africa, Station 349, Canary Islands, surface.

Subgenus 4. _Collodiscus_, Haeckel.

_Definition._--Form of the central capsules discoidal or lenticular, with one shortened axis.

9. _Collozoum coeruleum_, Haeckel.

_Collozoum coeruleum_, Haeckel, 1862, Monogr. d. Radiol., p. 523, Taf.
xxxii. figs. 6-8.

_Collodiscus coeruleus_, Haeckel, 1882, Manuscript.

Central capsule lenticular or discoidal, flattened, blue coloured, with one single oil-globule in the centre. Protoplasm containing numerous crystals and dark blue pigment-granules. Membrane very thick, double-edged. (Whilst at Messina in 1859 I found this form not constantly discoidal, in 1867 in the Canary Islands I observed it constantly lenticular.)

_Dimensions._--Breadth of the central capsules 0.1 to 0.15, height 0.04 to 0.08.

_Habitat._--Mediterranean (Messina), Atlantic (Canary Islands), surface.

10. _Collozoum discoideum_, n. sp.

_Collodiscus discoideus_, Haeckel, 1882, Manuscript.

Central capsule discoidal, flattened, transparent, with a ring of twenty to twenty-five oil-globules in its circular periphery (on the inside of the thin membrane).

_Dimensions._--Breadth of the central capsules 0.2, height 0.05.

_Habitat._--South Pacific (Juan Fernandez), Station 300, surface.

Subgenus 5. _Collodastrum_, Haeckel.

_Definition._--Form of the central capsules irregular and indefinite, variable, commonly polyhedral or polygonal, or amoeboid, often with irregular, finger-like processes.

{28}11. _Collozoum pelagicum_, Haeckel.

_Collozoum pelagicum_, Haeckel, 1862, Monogr. d. Radiol., p. 525, Taf.
xxxii. figs. 4, 5.

_Sphærozoum pelagicum_, Haeckel, 1860, Monatsber. d. k. Akad. d. Wiss.
Berlin, 1860, p. 845.

Central capsules small, quite irregularly formed, roundish-polyhedral or depressed-polygonal, transparent, without oil-globules. Often many extracapsular oil-vesicles in the common jelly-body between the central capsules. Membrane very thin and delicate.

_Dimensions._--Diameter of the central capsules 0.02 to 0.08.

_Habitat._--Mediterranean, Messina, Haeckel; Naples, Brandt; surface.

12. _Collozoum stellatum_, n. sp.

_Collodastrum stellatum_, Haeckel, 1882, Manuscript.

Central capsules star-shaped, irregularly radiating, with a great number (eight to twenty or more) of radial, short, conical, acute processes, very variable in size and number. Membrane thin. In every capsule several (four to eight) oil-globules.

_Dimensions._--Diameter of the central capsules 0.12 to 0.2.

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

13. _Collozoum amoeboides_, n. sp. (Pl. 3, figs. 4, 5).

_Collodastrum amoeboides_, Haeckel, 1882, Manuscript.

Central capsules amoebiform, of moderate size, quite irregularly formed, with a variable number of finger-like, obtuse, irregular prolongations (commonly three to six), very variable in size and form. Membrane thin. In the centre of every capsule one single oil-globule.

_Dimensions._--Diameter of the central capsules 0.04 to 0.08.

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

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Suborder II. BELOIDEA, Haeckel.

_Definition._--SPUMELLARIA with an imperfect skeleton, composed of numerous solid needles or spicula, scattered irregularly in the calymma.

The suborder #Beloidea# comprises all those SPUMELLARIA which possess an imperfect or rudimentary skeleton, composed of a variable number of isolated spicula scattered in the extracapsulum. The suborder contains only two different families, the solitary Thalassosphærida (or Beloidea monozoa) and the associated Sphærozoida (or Beloidea polyzoa). Both families are very nearly allied, and differ only in one single character: the solitary life of the former, the social union of the {29}latter. It seems to be merely a consequence of this difference that the cleavage of the nucleus commonly takes place very late in the former, very early in the latter.

Commonly, therefore, the full-grown Thalassosphærida (until immediately before their propagation) exhibit one single nucleus in the centre of the capsule, whilst in the Sphærozoida the capsule is distended with numerous small nuclei. In these latter the centre of the capsule usually contains one large oil-globule, whilst in the former oil-globules are either wanting or scattered in large numbers in the endoplasm, or disposed in one layer on the inside of the capsule membrane.

In the solitary Thalassosphærida each capsule is enclosed in its own peculiar spherical calymma, whilst in the associated Sphærozoida all the capsules of the colony are united into one common, very voluminous, alveolated calymma.

Family III. #THALASSOSPHÆRIDA#, Haeckel, 1862, (Pl. 2).

_Thalassosphærida_, Monogr. d. Radiol., p. 255.

_Definition._--#Beloidea# solitaria.

The family Thalassosphærida comprises all solitary SPUMELLARIA with an imperfect skeleton, composed of numerous solid needles or spicula, scattered around the central capsule in the calymma. The structure of the unicellular soft body is quite the same as in the Thalassicollida; it differs from these only in the possession of the extracapsular skeleton. All needles of this skeleton are solid siliceous spicula, never hollow, as in the similar Cannorrhaphida among the PHÆODARIA. In the special structure and form of the skeleton the Thalassosphærida agree perfectly with the well-known, colony-building Sphærozoida; they differ from these only by their hermit-like life and by some peculiarities derived from this solitary development.