1. Orona maxima, n. sp. (Pl. 107, fig. 5).
Shell spherical, with very irregular polygonal meshes. Bars of the loose network smooth or slightly spinulate, very thick, with a pinnulate axial canal.
Dimensions.—Diameter of the sphere 5.0 to 5.5, of the meshes 0.2 to 0.4, of the bars 0.01.
Habitat.—Central Pacific, Station 265, depth 2900.
2. Orona robusta, n. sp.
Shell spherical, with irregular quadrangular meshes (intermingled with single triangular, pentagonal, and hexagonal meshes). Bars of the coarse network very thick, spinulate.
Dimensions.—Diameter of the sphere 3.0 to 3.6, of the meshes 0.05, of the bars 0.012.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
3. Orona crassissima, n. sp. (Pl. 107, fig. 7).
Shell ellipsoidal, slightly prolonged in the main axis, with irregular polygonal meshes of very different sizes and unequal forms. Bars of the coarse network very thick, thorny and dimpled, their surface being covered with a network of prominent polygonal crests.
Dimensions.—Diameter of the sphere 3.0 to 4.0, of the meshes 0.2 to 0.5, of the bars 0.02 to 0.06.
Habitat.—South Pacific, Station 289, depth 2550 fathoms.
Definition.—Orosphærida with a simple, spherical (sometimes slightly ellipsoidal or polyhedral) lattice-shell without pyramidal elevations, but with numerous radial spines.
The genus Orosphæra differs from the preceding Orona, its ancestral form, in the development of simple or branched radial spines. It bears, therefore, the same relation to the latter that Acanthosphæra has to Cenosphæra. In the two latter genera, however, the bars of the network are solid, in the two former hollow. The species referred to Orosphæra are closely allied and require a further accurate examination.
Definition.—Radial spines simple, smooth or spiny, but neither branched nor arborescent.
1. Orosphæra hastigera, n. sp.
Radial spines cylindrical, straight, smooth, simple, about as long as the diameter of the spherical shell, and as broad as its smooth bars. Meshes of the network irregularly polygonal, the majority quadrangular, of different sizes.
Dimensions.—Diameter of the sphere 1.0 to 1.2, length of the radial spines 1.1 to 1.5, middle breadth 0.004.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
2. Orosphæra spinigera, n. sp.
Radial spines cylindrical, irregularly curved, thorny, simple, two to three times as long as the diameter of the spherical shell, and as broad as its spiny bars. Meshes of the network irregularly polygonal, the majority pentagonal.
Dimensions.—Diameter of the sphere 1.5 to 1.8, length of the spines 3.0 to 5.0, breadth 0.006.
Habitat.—North Atlantic, Station 353, depth 2965 fathoms.
3. Orosphæra fusigera, n. sp.
Radial spines slender, spindle-shaped, straight, smooth, about as long as the diameter of the spherical or slightly ellipsoidal shell, in the thicker middle part five times as broad as the bars, and tapering equally towards both ends. Meshes of the network irregularly polygonal, the majority quadrangular, separated by smooth bars.
Dimensions.—Diameter of the shell 1.0 to 1.2, length of the spines 1.2 to 1.6, basal breadth 0.02, middle breadth 0.1.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
4. Orosphæra foveolata, n. sp.
Radial spines spindle-shaped, straight, dimpled, half as long as the radius of the spherical shell and three to five times as thick as the bars. Meshes irregular, polygonal, of very different shapes, separated by dimpled bars. (Similar to Oroscena gegenbauri, Pl. 106, fig. 4, but with spherical dimpled shell, without pyramidal elevations.)
Dimensions.—Diameter of the shell 2.0 to 2.4, length of the spines 0.5, breadth 0.15.
Habitat.—Central Pacific, Station 267, depth 2700 fathoms.
5. Orosphæra serpentina, n. sp. (Pl. 106, fig. 1).
Radial spines cylindrical, dimpled, undulate or curved in a snake-like manner, about as long as the diameter of the ellipsoidal or spherical shell and four to six times as broad as its smooth bars. Meshes very irregular, polygonal.
Dimensions.—Diameter of the shell 1.0 to 1.2, length of the spines 0.12 to 0.15, breadth 0.12.
Habitat.—South Pacific, Station 289, depth 2550 fathoms.
6. Orosphæra horrida, n. sp. (Pl. 106, fig. 2).
Radial spines club-shaped, very strong, straight, about as long as the diameter of the polyhedral shell, ovate and smooth in the distal half, slenderly conical, and armed with recurved spines in the proximal half; their outer third is the thickest, and five times as broad as the smooth bars of the coarse network. Meshes of the latter irregularly quadrangular.
Dimensions.—Diameter of the shell 1.2 to 1.6, length of the spines 1.2 to 2.0, breadth 0.2.
Habitat.—South Pacific, Station 291, depth 2250 fathoms.
7. Orosphæra clavigera, n. sp.
Radial spines club-shaped, thickened towards the distal end, more or less curved, spinulate, about as long as the diameter of the spherical shell; in the distal third four to six times as broad as the spinulate bars. Meshes irregularly polygonal, the majority pentagonal.
Dimensions.—Diameter of the shell 2.0 to 2.5, length of the spines 1.8 to 2.2, breadth 0.16.
Habitat.—Central Pacific, Station 263, depth 2650 fathoms.
Definition.—Radial spines branched or arborescent.
8. Orosphæra ramigera, n. sp.
Radial spines cylindrical, spinulate, straight, about twice as long as the diameter of the spherical shell and as thick as its spinulate bars. Numerous simple spinulate branches, straight or slightly curved, and two to four times as long as the meshes, are irregularly scattered, and arise nearly perpendicularly from the bars.
Dimensions.—Diameter of the shell 2.0 to 2.2, length of the spines 4 to 5, breadth 0.05.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
9. Orosphæra furcata, n. sp.
Radial spines cylindrical, smooth, irregularly curved, about as long as the radius of the spherical shell and as thick as its smooth bars, forked at the distal end, with two or three terminal branches of various lengths. Meshes irregularly polygonal (the majority hexagonal).
Dimensions.—Diameter of the shell 1.2, length of the spines 0.7, breadth 0.03.
Habitat.—Indian Ocean, Madagascar (Rabbe), surface (?).
10. Orosphæra confluens, n. sp.
Radial spines cylindrical, smooth, irregularly curved, two to three times as long as the diameter of the polyhedral shell, twice as broad as its smooth bars, bearing numerous irregular, lateral branches, which are partly confluent and fenestrated (similarly as in Pl. 107, fig. 1), but not forming an outer lattice-shell. Meshes irregularly polygonal.
Dimensions.—Diameter of the shell 3.3, length of the spines 6 to 9, breadth 0.03.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
11. Orosphæra arborescens, n. sp. (Pl. 106, fig. 3).
Orothamnus arborescens, Haeckel, 1881, Atlas, loc. cit.
Radial spines cylindrical, rough, more or less curved, somewhat longer than the diameter of the subspherical or slightly ellipsoidal shell, and at the thicker base three times as broad as its smooth bars, bearing numerous irregularly branched and curved, sometimes confluent, lateral branches. Meshes irregularly quadrangular.
Dimensions.—Diameter of the shell 1.2 to 1.6, length of the spines 1.5 to 2.2, breadth 0.06.
Habitat.—South Atlantic, Station 335, depth 1425 fathoms.
Definition.—Orosphærida with a simple, polyhedral or subspherical lattice-shell, and with numerous pyramidal elevations on its surface, the top of which bears a radial spine.
The genus Oroscena differs from the preceding Orosphæra in the possession of numerous pyramidal or tent-shaped elevations, each of which bears on its top a radial spine. It exhibits therefore the same relation to the latter that Sagoscena does to Sagosphæra and Auloscena to Aulosphæra. The bases of the radial spines are usually connected by prominent concave crests, the edges of the pyramids. The species described of Oroscena seem to be very variable and transformistic.
Definition.—Radial spines simple, smooth or spiny, but neither branched nor forked.
1. Oroscena gegenbauri, n. sp. (Pl. 106, fig. 4).
Radial spines club-shaped, about half as long as the radius of the shell, cylindrical and finely sulcate in the basal third, ovate and elegantly dimpled in the distal two-thirds. The bases of the radial spines are connected by prominent concave crests, which form the edges of the polyhedral shell. Meshes irregularly polygonal, the majority quadrangular, separated by denticulate bars.
Dimensions.—Diameter of the shell (without spines) 1.2 to 1.8, of the meshes 0.04 to 0.1; length of the spines 0.3 to 0.5.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
2. Oroscena mülleri, n. sp. (Pl. 107, fig. 8).[292]
Radial spines club-shaped, very similar to that of the preceding species, but much larger, about as long as the radius of the shell. Meshes irregularly polygonal, the majority pentagonal, separated by smooth bars.
Dimensions.—Diameter of the shell 2.0 to 2.4, length of the spines 1.0 to 1.2.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
3. Oroscena cuvieri, n. sp. (Pl. 107, fig. 6).
Radial spines club-shaped, compressed and smooth in the proximal half, spindle-shaped and dimpled in the distal half, about as long as the radius of the shell. Meshes irregularly polygonal, the majority hexagonal, separated by denticulate bars.
Dimensions.—Diameter of the shell 1.5, length of the spines 0.8.
Habitat.—South Pacific, Station 289, depth 2550 fathoms.
4. Oroscena bærii, n. sp. (Pl. 107, fig. 4).
Radial spines nearly spindle-shaped, undulate, tapering from the thicker middle towards both ends, coarsely dimpled, about one-third as long as the radius of the shell. Meshes irregularly polygonal, the majority pentagonal, separated by spinulate bars.
Dimensions.—Diameter of the shell 3.2, length of the spines 1.0 to 1.2, breadth 0.1.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
5. Oroscena wolffii, n. sp.
Radial spines cylindrical, spinulate, more or less curved, longer than the diameter of the shell and about twice as broad as its bars. Meshes irregularly polygonal, of very variable form and unequal size, separated by smooth bars.
Dimensions.—Diameter of the shell 2.5, length of the spines 3.0 to 3.5, breadth 0.02.
Habitat.—Indian Ocean, Zanzibar (Pullen), depth 2200 fathoms.
Definition.—Radial spines branched or arborescent.
6. Oroscena huxleyi, n. sp. (Pl. 12, figs. 1, 1a).
Radial spines cylindrical, obliquely ascending and irregularly curved, about as long as the diameter of the shell and somewhat thicker than its thorny bars. A variable number of short, irregular, partly simple, partly forked, lateral branches arises from the spines. Meshes of the network very irregular, partly solid, partly hollow (fig. 1a*), the majority quadrangular. This species, the first observed form of Orosphærida (captured the 21st February 1873 at Station 5), was at the beginning of my observations, in 1876, and when I had no knowledge of the central capsule, erroneously regarded by me as a gigantic Sphæroid (of the Monosphærida) and therefore placed in Pl. 12. The long branched spines, afterwards observed complete in another specimen, were broken off in the specimen first figured.
Dimensions.—Diameter of the shell 2.0 to 2.5, length of the spines 2 to 3 mm., breadth 0.03.
Habitat.—North Atlantic (west of Canary Islands), Station 5, depth 2740 fathoms.
7. Oroscena darwinii, n. sp.
Radial spines cylindrical, irregularly curved and branched, about twice as long as the diameter of the shell; the branches are all again ramified and partly confluent (as in Pl. 107, fig. 1). The branches and the bars of the network are of equal breadth, smooth (not thorny as in the similar preceding species). Meshes rather subregular, quadrangular.
Dimensions.—Diameter of the shell 2.4 to 2.8, length of the spines 4 to 5 mm., breadth 0.015.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.
8. Oroscena duncanii, n. sp.
? Hexactinellida dictyonina, Martin Duncan, 1881, Journ. Roy. Micr. Soc., p. 175, pl. iii. figs. 4, 6.
Radial spines cylindrical, thorny, arborescent, somewhat shorter than the diameter of the shell, with irregular ramified branches (similar to Orosphæra arborescens, Pl. 106, fig. 3). The size and ramification of the arborescent spinulate branches decrease towards the apex. The thicker branches are from two to three times as broad as the spinulate bars of the network. Meshes of the latter irregular, the majority quadrangular.
Dimensions.—Diameter of the shell 3.2, length of the spines 3.5 to 4.5, breadth 0.02 to 0.3.
Habitat.—South Atlantic, Station 318, depth 2040 fathoms; coast of Portugal, 1095 fathoms.
Definition.—Orosphærida with a spongy, spherical or slightly polyhedral lattice-shell, which is enveloped by a loose spongy framework and bears numerous radial spines.
The genus Oroplegma differs from the other Orosphærida in the development of an external lattice-work enveloping the internal primary shell, and produced by the union of the branches of the radial spines. This outer shell is either a simple lattice-plate (comparable to the cortical shell of Diplosphæra), or a spongy framework (as in Rhizoplegma).
Definition.—External shell a simple fenestrated lamella, forming an outer concentric lattice-sphere around the inner primary shell.
1. Oroplegma diplosphæra, n. sp. (Pl. 107, fig. 1).
Radial spines slender, cylindrical, smooth, more or less curved, about twice as broad as the smooth bars of the network. External shell a simple irregular lattice-sphere, with loose polygonal meshes, which are on an average three to four times as broad as the irregular meshes of the internal shell. The free prominent parts of the radial spines are irregularly branched, very long, with partly confluent branches.
Dimensions.—Diameter of the inner sphere 1.5 to 2.0, of the outer 2.5 to 3.0; length of the free spines 1.2, breadth 0.04.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
2. Oroplegma spinulosum, n. sp.
Radial spines slender, cylindrical, thorny, more or less curved, very similar to those of the preceding species; the shell also much resembles that of Oroplegma perplexum. It differs from the latter in the more regular fenestration of both shells, and mainly in the shape of the bars and the spine-branches, which are all spinulate and densely studded with small conical thorns.
Dimensions.—Diameter of the inner sphere 1.5 to 2.0, of the outer 2.5 to 3.0; length of the spines 1.2, breadth 0.03.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
3. Oroplegma velatum, n. sp.
Radial spines stout, cylindrical, somewhat club-shaped, spiny, slightly curved, about three to four times as broad as the thorny bars of the network. External shell a simple lattice-sphere with irregular polygonal meshes, which are for the most part pentagonal and about four times as broad as the polygonal meshes of the inner shell. The free prominent parts of the radial spines are thickened, club-shaped, and about as long as the radius.
Dimensions.—Diameter of the inner sphere 2.0 to 2.4, of the outer 2.8 to 3.6; length of the free spines 0.5 to 0.7, breadth 0.12 to 0.15.
Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.
Definition.—External shell a complex framework, forming an outer spongy envelope around the inner primary shell.
4. Oroplegma spongiosum, n. sp. (Pl. 107, fig. 3).
Radial spines stout, cylindrical, spinulate, slightly curved, three to five times as broad as the inner rough bars. External shell with pyramidal elevations, forming a loose spongy framework, the irregular polygonal meshes of which are two to five times as broad as those of the enclosed internal shell; the thickness of the spongy envelope equals about half the radius of the inner shell. External free prolongations of the radial spines about equal to the radius.
Dimensions.—Diameter of the inner sphere 2 to 2.5, of the outer 3 to 3.5; length of the free radial spines 0.5 to 2.0, breadth 0.1.
Habitat.—North Pacific, Station 241, depth 2300 fathoms.
5. Oroplegma giganteum, n. sp. (Pl. 107, fig. 2).
Radial spines slender, cylindrical, spinulate, irregularly curved, about twice as broad as the spinulate tubular bars of the network (fig. 2). External shell an irregular, loose, spongy framework, the polygonal meshes of which are three to six times as broad as the rounded irregular meshes of the inner shell; the thickness of the spongy envelope about equals the radius of the inner shell. External free prolongation of the radial spines irregularly branched.
Dimensions.—Diameter of the inner sphere 3.2 to 3.5, of the outer 5.4 to 6.6; length of the free spines 1.4 to 1.5, breadth 0.03.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
Definition.—Phæodaria with a large spherical (or sometimes polyhedral), very delicate shell, which is composed of solid, very thin and long threads. Nodal points of the arachnoidal network without astral septa. Meshes large, triangular. Surface of the shell usually armed with radial spines and often studded with pyramidal elevations. No peculiar mouth in the shell. Central capsule tripylean, in the centre of the shell.
The family Sagosphærida comprises a rather large number of common and widely distributed Phæodaria, which in respect of the special form and differentiation of the shell exhibit the greatest similarity to the common Aulosphærida, but differ essentially from them in the peculiar structure of the network. This is not composed of stout hollow cylindrical tubes, but of solid, very thin threads; and these fine arachnoidal threads are simply united or confluent at the nodal points, and are not connected by a radial or stellate septal junction, as in the Aulosphærida. There are, therefore, neither astral septa nor a nodal cavity in each nodal point. The delicate shape of the thin and fragile threads separates the Sagosphærida from the closely allied Orosphærida, the thick bars of which contain a central axial canal and exhibit a concentric structure. Another difference between these two similar families is indicated by the form of the meshes of the network, which are constantly triangular in the Sagosphærida, but irregularly polygonal or quadrangular in the Orosphærida. The general habit of these two families, however, is very different, since the big and stout spheres of the Orosphærida are the coarsest and rudest spherical shells of all Radiolaria, whilst the fragile and delicate spheres of the Sagosphærida represent the finest and most tender in the whole class.
The spherical lattice-shell of the Sagosphærida has a considerable size, its diameter being usually between one and three millimetres, rarely less or more. Some species are very common and widely distributed, usually accompanying the common Aulosphærida; very frequently the similar shells of the two are found interwoven. But in spite of this frequency and visible size, the Sagosphærida have hitherto almost completely escaped the attention of observers. The main cause of this strange fact may be their extreme delicacy and fragibility, so that complete and intact shells occur very rarely, the majority being more or less broken and incomplete. It seems that only two species of Sagosphærida have been hitherto observed.
The first form described is Sagmarium trigonizon, observed by me in 1859 living at Messina, and figured in 1862 in my Monograph as Dictyosoma trigonizon (Taf. xxvi. figs. 4-6), but afterwards called Spongodictyum trigonizon (loc. cit., p. 459). I supposed at that time (now twenty-five years ago), that this remarkable and in many respects distinct form might belong to the Spongosphærida, and that an internal, triple, spherical lattice-shell, found entangled in its spongy framework, might be its central "medullary shell." But at present, having found many shells of different Radiolaria accidentally entangled in the arachnoidal framework of various Sagosphærida, I think it much more probable, that that "triple medullary shell," composed of three simple concentric lattice-spheres, was really a species of Plegmosphæra or Actinomma, accidentally entangled in the arachnoidal spongy framework of Sagmarium. This is the more probable, as I had observed very frequently at Messina, in 1859, fragments of that framework, but only once the triple lattice-shell which I supposed to be the "triple medullary shell" of the former. The peculiar structure of the loose framework, its very large triangular meshes and thin arachnoidal bars, partly provided with cruciate verticils (loc. cit., Taf. xxvi. figs. 4, 5) have been very frequently observed by me during the last ten years in various Sagosphærida (Phæodaria), but never in any true Sphæroidea (Spumellaria).
The second species of Sagosphærida hitherto observed, is Sagoscena gracilis, described and figured in 1879 by Richard Hertwig as Aulosphæra gracilis (Organism. d. Radiol., p. 91, Taf. ix. fig. 4). He too observed only fragments of destroyed and incomplete shells, and was led by their striking similarity to fragments of Aulosphæra elegantissima to unite it with the genus Aulosphæra. But the accurate description and the figure given by him of the fragments observed leaves no doubt that it was a true Sagoscena.
In the collection of the Challenger the Sagosphærida are so common and so richly represented, that we may describe here not less than seven genera and thirty-three species, but this may be a small part only of the numerous species of this family, which seems to be widely distributed over all oceans, in the Arctic and Antarctic as well as in temperate and tropical zones. The majority are inhabitants of the surface, but a few species have been found only in deep-sea soundings. A striking fact is their usual association with the similar Aulosphærida. The majority of shells of both families were found entangled in one another.
The shell of all Sagosphærida seems to be spherical or nearly spherical in the complete state; but complete spheres can be observed only very rarely, and it is not impossible that deviations from the spherical form exist just as in some Aulosphærida (e.g., the lenticular Aulophacus and the spindle-shaped Aulatractus). The diameter of the spheres usually seems to be between 1 and 2, often also 3 millimetres; very rarely shells occur which are less than 1 or more than 3 (4 or 5) millimetres.
The siliceous network or lattice-work of the Sagosphærida exhibits a very characteristic shape, and this enables one to distinguish it at first sight from all the other Radiolaria. It is constantly composed of triangular, very large meshes, which are separated by very thin and delicate, flexible and elastic bars. With respect to the arrangement of these meshes we distinguish two different subfamilies; in the Sagenida the wall of the spherical shell is very thin and composed only of a simple lattice-plate; in the Sagmarida the wall is thickened and spongy, with a complete wicker-work of threads, interwoven in different directions.
The typical triangular form of the large meshes is usually regular or subregular in the fenestrated Sagenida, more or less irregular in the spongy Sagmarida. In many cases, however, irregular triangles also occur in the former, and regular triangles in the latter subfamily. Very rarely irregular polygonal meshes are found in a part of the network, small connecting bars being developed accidentally between two neighbouring sides of the triangles. The diameter of the meshes is usually between 0.1 and 0.2 mm., often also greater, between 0.2 and 0.3, rarely smaller, 0.05 to 0.09 mm. The triangular meshes of the Sagosphærida are therefore on an average ten times as large as the usual meshes in the network of the common Sphæroidea.
The filiform bars, or the thread-shaped, very long and thin rods between the triangular meshes, are scarcely less characteristic of the Sagosphærida than the form and size of the meshes. Their length is usually between 0.1 and 0.2 mm., often also from 0.2 to 0.3 mm., whilst their thickness is only 0.002 to 0.004 mm., often it is less than 0.001, rarely more than 0.005 mm. The nodal points of the network, in which six threads are usually united, are more or less thickened, often stellate (Pl. 108, figs. 9, 12, &c.). Sometimes they are pierced by a central pore. The thin threads are constantly cylindrical, never edged or prismatic, very elastic and flexible; usually they are perfectly smooth, rarely spiny or thorny, sometimes provided with scattered cruciate verticils of lateral branches, as in Sagena crucifera and in the first described form of this family, Sagmarium trigonizon (compare my Monograph, 1862, Taf. xxvi. fig. 5).
The surface of the spherical shell is smooth only in two genera of Sagosphærida, in Sagena and Sagmarium (Pl. 108, figs. 2, 8). In the five other genera it is covered either with radial spines, arising from the nodal points of the network, or with peculiar cortical pyramids or tent-shaped elevations (Pl. 108, figs. 1, 3-6, &c.). These pyramids are of the same characteristic shape as in the similar Auloscena among the Aulosphærida (Pl. 110, fig. 1); usually, however, they are less regular than in the latter. The pyramids or tents are usually six-sided, often, however, they are also four-sided or three-sided, more rarely five, seven or more sided. The edges of the pyramids are formed by filiform bars similar to those which compose the original lattice-work of the Sagosphærida. The cavity of the pyramids is quite simple in Sagoscena (figs. 1, 5, 6), whilst in Sagenoscena and Sagoplegma a radial column arises in its axis, the thickened axial rod (figs. 3, 4, 10).
The radial spines, which arise either from the tops of the pyramids or from the nodal points of the network, exhibit in the Sagosphærida a variety and elegance similar to the closely allied Aulosphærida. Sometimes a single radial spine arises in each nodal point or at the top of each pyramid (figs. 3, 4, 10); at other times two, three, or four (rarely more) divergent spines (figs. 6-9, 12, 13). These are rarely quite simple, usually provided with lateral and terminal branches. The lateral branches are either scattered irregularly, or regularly disposed in elegant verticils, each of which is usually composed of three or four short branches (Pl. 108, figs. 9, 13). The terminal branches form either a similar verticil, or a bunch or corona, composed of numerous radial secondary spines. The distal ends of the terminal as well as of the lateral branches are rarely simple, usually they are provided with a spinulate knob or with an elegant spathilla (Pl. 108, figs. 3, 9, 13).
The central capsule of the Sagosphærida is comparatively small, as it also is in the Aulosphærida and Orosphærida. Its diameter is usually about one-third or one-fourth that of the enveloping shell, between 0.2 and 0.3, often only 0.12 to 0.18, rarely more than 0.3 mm. It is surrounded on the oral half by a red or dark phæodium and separated from the inner surface of the shell by the voluminous calymma. The subspherical nucleus is usually about half as broad as the capsule. The three openings of the latter, the large tubular astropyle and the two opposite lateral parapylæ, exhibit the same shape as in the closely allied Aulosphærida (Pl. 111, fig. 3). The pseudopodia arising from the central capsule form a loose network in the calymma, and proceed over its surface as numerous delicate radial filaments, often supported by the radial spines.
|
I. Subfamily Sagenida. Wall of the spherical shell composed of a simple lattice-plate with or without pyramidal elevations. |
brace | Surface of the spherical shell smooth or spiny, without pyramidal elevations. | brace | No radial spines, surface smooth, | 675. Sagena. |
| Radial spines in the nodal points, | 676. Sagosphæra. | ||||
| Surface of the spherical shell covered with pyramidal or tent-shaped elevations. | brace | Pyramids without internal axial rod, | 677. Sagoscena. | ||
| Pyramids with an internal radial axial rod, | 678. Sagenoscena. | ||||
|
II. Subfamily Sagmarida. Wall of the spherical shell spongy, composed of an irregular complicated wicker-work. |
brace | Surface of the spherical shell smooth or spiny, without pyramidal elevations. | brace | Surface smooth, without radial spines, | 679. Sagmarium. |
| Surface studded with radial spines, | 680. Sagmidium. | ||||
| Surface of the spherical shell covered with pyramidal elevations. | brace | Pyramids on the top with a radial spine or a bunch of divergent spines, | 681. Sagoplegma. |
|
I. Subfamily Sagenida. Wall of the spherical shell composed of a simple lattice-plate with or without pyramidal elevations. |
||||||
| Surface of the spherical shell smooth or spiny, without pyramidal elevations. | ||||||
| No radial spines, surface smooth, | ||||||
| 675. Sagena. | ||||||
| Radial spines in the nodal points, | ||||||
| 676. Sagosphæra. | ||||||
| Surface of the spherical shell covered with pyramidal or tent-shaped elevations. | ||||||
| Pyramids without internal axial rod, | ||||||
| 677. Sagoscena. | ||||||
| Pyramids with an internal radial axial rod, | ||||||
| 678. Sagenoscena. | ||||||
|
II. Subfamily Sagmarida. Wall of the spherical shell spongy, composed of an irregular complicated wicker-work. |
||||||
| Surface of the spherical shell smooth or spiny, without pyramidal elevations. | ||||||
| Surface smooth, without radial spines, | ||||||
| 679. Sagmarium. | ||||||
| Surface studded with radial spines, | ||||||
| 680. Sagmidium. | ||||||
| Surface of the spherical shell covered with pyramidal elevations. | ||||||
| Pyramids on the top with a radial spine or a bunch of divergent spines, | ||||||
| 681. Sagoplegma. | ||||||
Definition.—Sagosphærida with a delicate spherical shell, the thin wall of which is composed of a simple lattice-plate, not spongy.
Definition..—Sagosphærida with a delicate shell, the thin wall of which is composed of a simple smooth lattice-plate, without radial spines.
The genus Sagena is the simplest of the Sagosphærida and may be regarded as the common ancestral form of this family. The delicate wall of the simple spherical lattice-shell is composed of large, regular, or subregular, triangular meshes, the nodal points of which bear no radial spines. It agrees therefore perfectly with Aularia, and differs from this simplest form of Aulosphærida only in the structure of the skeleton, which is composed not of hollow articulated tubes, but of very thin solid threads. The skeleton may therefore also be confounded with Cenosphæra, but the central capsule of this latter is "peripylean," with numerous fine pores in the entire wall, whilst that of Sagena is "tripylean," having the proboscis of all Phæodaria.