Chapter XXXIV: Section IV: STICHOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., p. 280, 312 (9)

Radial spines simple, straight, smooth, a single one at each nodal point of the surface of the spongy sphere, bearing on its distal end a spinulate knob, or a bunch of numerous radial bristles. (Similar to _Sagenoscena penicillata_, Pl. 108, fig. 10.) Bars of the spongy framework smooth.

_Dimensions._--Diameter of the sphere 3.0 to 3.5, length of the bars 0.15 to 0.2, breadth 0.003 to 0.006.

_Habitat._--Antarctic Ocean, Station 256, surface.

2. _Sagmidium tricorne_, n. sp.

Radial spines simple, smooth, usually three divergent united at each nodal point of the surface (sometimes two or four instead of three). Each spine bears on its distal end three short divergent conical teeth. (Similar to the terminal teeth of _Sagoscena tentorium_, Pl. 108, fig. 6.) Bars of the spongy framework smooth.

_Dimensions._--Diameter of the sphere 1.6 to 2.4, length of the bars 0.06 to 0.09, breadth 0.001 to 0.002.

_Habitat._--Central Pacific, Stations 263 to 268, surface.

3. _Sagmidium crucicorne_, n. sp. (Pl. 108, fig. 9).

Radial spines slender, verticillate, three or four divergent arising from each nodal point of the surface. Each spine bears three to six cruciate verticils of lateral branches; each verticil being {1614}composed of four crossed small branches with a spinulate terminal knob. Bars of the spongy framework partly covered with similar verticils.

_Dimensions._--Diameter of the sphere 2.0 to 3.0, length of the bars 0.2 to 0.3, breadth 0.002 to 0.003.

_Habitat._--North Pacific, Stations 240 to 244, surface.

4. _Sagmidium quadricorne_, n. sp. (Pl. 108, fig. 12).

Radial spines stout, smooth, cylindrical, usually four divergent arising from each nodal point of the surface (sometimes three, five, or six, instead of four). Each spine bears on its distal end a club-shaped stellate knob. Bars of the spongy framework smooth.

_Dimensions._--Diameter of the sphere 4.5, length of the bars 0.2 to 0.3, breadth 0.003 to 0.005.

_Habitat._--South Pacific, Station 293, depth 2025 fathoms.

5. _Sagmidium multicorne_, n. sp.

Radial spines slender, more or less curved, verticillate, in variable number (three to six) divergent, arising from the nodal points of the surface. The spines as well as the bars of the spongy framework are partly simple, partly covered with irregularly scattered cruciate verticils, very similar to those of _Sagmarium trigonizon_ (or _Dictyosoma trigonizon_), figured in my Monograph, pl. xxvi. figs. 4, 5.

_Dimensions._--Diameter of the sphere 5.0, length of the bars 0.2 to 0.3, breadth 0.003.

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

Genus 681. _Sagoplegma_,[300] n. gen.

_Definition._--#Sagosphærida# with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework, and bears on its surface numerous pyramidal elevations.

The genus _Sagoplegma_ differs from _Sagmarium_, its ancestral form, in the development of pyramidal or tent-shaped elevations on the surface of the spongy hollow sphere. It exhibits, therefore, the same relation to the latter as the similar _Sagoscena_ bears to _Sagena_. The wall of the spherical shell is in the two latter genera a thin simple lattice-plate, in the former a thickened spongy framework.

1. _Sagoplegma pyramidophora_, n. sp.

Pyramids on the surface of the spongy sphere subregular, mostly tetrahedral, of nearly equal size and similar form. The three edges of each pyramid are prolonged over its top into three {1615}short, divergent, apical spines which are forked at the distal end. (Very similar to _Sagoscena castra_ and _Sagoscena tentorium_, Pl. 108, figs. 1, 6, probably derived from them, but differing in the spongy structure of the thickened shell-wall, which is half as thick as the radius of its cavity.)

_Dimensions._--Diameter of the sphere 2.0 to 2.5, length of the bars 0.15 to 0.2, breadth 0.002.

_Habitat._--North Pacific, Stations 231 to 239, surface.

2. _Sagoplegma scenophora_ n. sp. (Pl. 108, fig. 13).

Pyramids on the surface of the spongy sphere irregular, with three to six sides, unequal in size and different in form. The edges of each pyramid are prolonged over its top into three to six divergent apical spines, which bear three to six cruciate verticils, each composed of four small, crossed, lateral branches, armed with a spinulate knob at the distal end.

_Dimensions._--Diameter of the sphere 3.0 to 3.5, length of the bars 0.25 to 0.35, breadth 0.003.

_Habitat._--North Pacific, Stations 252, 253, surface.

Family LXXVI. #AULOSPHÆRIDA#, Haeckel (Pls. 109-111).

_Aulosphærida_, Haeckel, 1862, Monogr. d. Radiol., p. 357.

_Definition._--PHÆODARIA with a large spherical or subspherical (rarely spindle-shaped) articulated shell, which is composed of hollow tangential tubes. Nodal points of the loose network stellate, with a nodal cavity and astral septa. Meshes either triangular or polygonal. Hollow radial spines arise usually at the nodal points of the surface. No peculiar mouth in the shell. Central capsule tripylean, placed in the centre of the shell.

The family #Aulosphærida# comprises a great number of splendid and widely distributed PHÆODARIA, which have a special interest on account of the peculiarly complicated structure of their large lattice-shell, of the extraordinary beauty of their form and of their remarkable relations to the other PHÆODARIA. They differ from all the other Radiolaria in the peculiar articulate composition of the spherical skeleton of hollow tangential tubes, which are connected (and at the same time separated) by sutural or astral septa and filled up by jelly. The same peculiar structure recurs only in the closely allied Cannosphærida, which, however, differ in the possession of a second internal concentric shell, connected with the outer by radial beams. The similar Sagosphærida, which exhibit corresponding forms in various genera, differ from the Aulosphærida in the simpler structure of the delicate lattice-sphere, which is composed of very thin solid threads of silica, without astral septa. The Orosphærida, finally, also nearly related to the preceding families, differ from them in the coarse structure of the lattice-sphere, which is composed of very thick tangential, concentrically stratified rods, with an internal axial canal, but without astral septa at the nodal points.

{1616}One genus only, and two species, of Aulosphærida have been hitherto known, having been discovered by me in 1859 at Messina, and described in my Monograph in 1862 as _Aulosphæra trigonopa_ and _Aulosphæra elegantissima_ (_loc. cit._, p. 357, Taf. x. figs. 4, 5; Taf. ix. figs. 5, 6). The characteristic structure of their central capsule, as true TRIPYLEA, was afterwards, in 1879, described more accurately by Richard Hertwig (Organism. d. Radiol., p. 90, Taf. x. figs. 2, 8, 14). The rich collection of the Challenger has demonstrated that the Aulosphærida belong to the most common and most widely distributed PHÆODARIA; many of them are distinguished by the admirable elegance and astonishing regularity of their large and delicate shell. Nine genera and fifty-six species of this great family are described in the following pages, which, however, may represent only a small part of the numerous forms which are found on the surface as well as in different depths of all oceans and in all zones.

The shell is in the great majority of Aulosphærida a regular sphere or an endospherical polyhedron. Two genera only, both rather rare, exhibit a different monaxonial form, one vertical main axis being developed either more or less than all the other ones of the sphere:--_Aulatractus_ is spindle-shaped or ellipsoidal, with prolonged main axis; _Aulophacus_ is lenticular or discoidal, with shortened main axis. The former may be compared to the #Prunoidea#, the latter to the #Discoidea#, in opposition to the common regular #Sphæroidea#. The size of the lattice-shell is very considerable in all Aulosphærida, its diameter varying usually between 1 and 3 mm., often it amounts to 4 or 5 mm.; very rarely the diameter is more than 5 or less than 1 mm. The largest form observed is the spindle-shaped _Aulatractus_, in which the vertical prolonged main axis attains 6 to 10 mm., the horizontal equatorial axis 3 to 5 mm.

The network of the lattice-shell exhibits in the Aulosphærida two different types, according to which we distinguish two different subfamilies: Aularida and Aulonida; the former are much more common and richer in remarkable forms than the latter. The meshes of the network are in the Aularida constantly triangular, regular or subregular, and very similar to those of the Sagosphærida; at each nodal point six tangential tubes are usually united, so that the network may be regarded also as composed of regular hexagonal meshes, each of which is divided into six smaller triangular meshes (Pl. 109, figs. 1, 3, 5). The second subfamily, the Aulonida, are much rarer than the former, and are distinguished by the polygonal meshes of the network; these are usually more or less irregular, pentagonal and hexagonal intermingled, more rarely tetragonal, heptagonal, or octagonal; usually three or four, rarely five or more tangential tubes are united at each nodal point (Pl. 111, figs. 1, 3). The size of the meshes is very considerable, and agrees with that of the Sagosphærida; their diameter being usually between 0.1 and 0.3, rarely less or more.

The hollow tubes which compose the loose network are usually cylindrical, straight or slightly curved, smooth (Pl. 111, fig. 2), more rarely somewhat spinulate (Pl. 109, {1617}fig. 5). Their length is usually between 0.1 and 0.2 mm., rarely less than 0.08, or more than 0.24 mm.; their diameter usually between 0.003 to 0.005, sometimes only 0.002 or less, at other times 0.006 or more. In several species the tangential tubes are thinner in the middle part, and thickened towards the two ends (Pl. 109, figs. 3, 4). Each tube consists of a thin cylindrical wall of silex, and of a jelly-mass filling up its cavity; in its axis runs a very thin, straight or slightly curved thread of silica, the axial filament.

The arrangement of the tangential tubes, which originally, in the simplest Aulosphærida, lie tangentially in the spherical face of a simple lattice-sphere, exhibits various secondary modifications, leading to various interesting generic forms. Two genera only, _Aularia_ (with triangular meshes, Pl. 111, fig. 2) and _Aulonia_ (with polygonal meshes, Pl. 111, fig. 1) possess a smooth, perfectly simple lattice-sphere, and may therefore be regarded as the ancestral genera of the two subfamilies. Two other corresponding genera, the common _Aulosphæra_ (Pl. 109) and the rarer _Aulastrum_ (Pl. 111, fig. 3), differ from the former in the development of radial spines at the nodal points of the simple lattice-sphere. _Aulophacus_ may be developed from _Aulosphæra_ by shortening, _Aulatractus_, however, by prolongation of the vertical main axis (Pl. 111, figs. 6, 7). In two genera, _Auloplegma_ and _Aulodictyum_, the latticed wall of the spherical shell becomes thickened and spongy, an irregular framework being formed by tubes connected in different directions (Pl. 111, fig. 8). The most remarkable and the most elegant form, however, of the whole family is represented by _Auloscena_ (Pl. 110). The entire surface of the spherical lattice-shell is here covered with numerous regular or subregular pyramids, or tent-shaped elevations. Usually each pyramid is six-sided, and surrounded by six other six-sided pyramids, their bases being separated by six triangular meshes, which lie in the spherical face. A similar elegant form is developed among the Sagosphærida in the genera _Sagoscena_, _Sagenoscena_ and _Sagoplegma_ (Pl. 108, fig. 1). The structure of _Auloscena_, however, is usually more regular, and in the top of each pyramid a radial tube arises.

The junction of the cylindrical tubes at the nodal points of the network is very remarkable. _Aularia_, the simplest form of the family, exhibits at each nodal point the union of six tangential tubes (Pl. 111, fig. 2); their ends are so pointed and truncated that they are connected in the form of a regular six-radiate star; the conical end of each tube is separated from, and at the same time closely connected with, the adjacent conical ends of the two neighbouring tubes by a thin septum, the astral or sutural septum. The six astral septa compose together a six-radiate star, and in the centre of this star the six axial filaments of the tubes are united. Their central union is surrounded by a small, double-contoured circle, and this circle seems to be the perimeter of a small and flat cavity on the inside of the star, which we call shortly the "nodal cavity" ("die kleine Vertiefung" according to Hertwig, _loc. cit._, p. 90). The nodal cavity of _Aularia_ probably possesses a central opening on its inside and six small surrounding pores, which {1618}lead into the six connected tangential tubes. In _Aulosphæra_ and _Auloscena_, where a radial spine arises at each nodal point, its axial filament arises from the centre of the star, and is usually prolonged on the inside into a free centripetal beam (Pl. 109, figs. 6, 7; Pl. 110, figs. 4, 6). This centripetal beam is a slender, very thin, conical tube (often with a six-sided pyramidal base) and perhaps of great morphological interest as a rudiment, being homologous to the hollow radial beams which connect the two concentric spheres of the Cannosphærida. Possibly the Aulosphærida have been derived from the latter by loss of the inner shell and reduction of the radial beams; the centripetal beams which are found in many (but not in all) Aulosphærida, may be the last remnant of those radial beams. They contain also an axial filament, as a direct internal prolongation of that of the external radial spine. The axial filaments of the radial spines are usually connected with their thin wall by a variable number of scattered transverse threads, or sometimes even by thin transverse septa (Pl. 110, figs. 4-7, &c.). This structure corresponds to the similar axial filaments and their thin filiform transverse branches which we have found in other PHÆODARIA, _e.g._, in the Tuscarorida and Circoporida.

The Aulonida (with polygonal meshes) exhibit in general the same structure as the Aularida (with triangular meshes). But whilst in the latter usually six tangential tubes are united at each nodal point, in the former only three or four tubes become united. Therefore also the number of the small sutural partitions or astral septa, which radiate from the central openings of the nodal cavity, is six in the latter, three or four in the former. Correspondingly three or four small pores lead from the nodal cavity into the surrounding tangential tubes.

The true nature of the nodal points, and the intimate structure of the different parts here united, is a matter which it is very difficult to explain. It is a certain fact, well established by hundreds of observations, that in the complete and well-preserved skeletons which are perfectly purified by fire, or by hot mineral acids, and afterwards dried, all the tubes of the skeleton, the tangential as well as the radial cylinders, become filled up by air. Each tube contains usually one large cylindrical air-bubble, with two hemispherical ends. But the air-bubbles of the neighbouring tubes are completely separated one from another by the thin astral or sutural septa, and the air-bubble of the radial tubes is also separated from the former. The central cavity of each nodal point is therefore surrounded in the Aularida by six, in the Aulonida by three or four separate cylinders of air. This fact seems to be explained only on the supposition that each single tube has two terminal pores or fissures, which open into the two nodal cavities on its two ends. The radial tubes must also possess at least one small opening, probably on their base, and probably they have another on their distal apex. In no other way can it be explained, that in all complete, well-preserved and purified skeletons, each single tube constantly becomes easily filled by an air-bubble after drying.

In the living Aulosphærida the cavities of all tubes are filled up by a jelly-substance, {1619}which may be stained by carmine and is probably identical with the jelly of the calymma. The latter is probably in direct connection with the former by the central pore of the nodal cavity, which is placed on its inside and surrounded by the astral septa; these separate the tangential tubes, radiating from one nodal point, completely, and are thin and simple, but very solid lamellæ of silica. Therefore the nodal stars of broken shells usually remain united, whilst the single radiating tubes composing them are broken off (Pl. 110, figs. 3, 8, 10). But it happens only rarely (and only in certain individual species) that complete single tubes separate; usually the fragments of the connected neighbouring tubes remain on their ends. The two small terminal openings of each tangential tube, which lead from its cavity into the nodal cavity, and are surrounded on each end by the truncated ends of two neighbouring astral septa, are very difficult to observe (Pl. 110, figs. 8-10).

The wonderful elegance and the high complication of these regular skeletons of the Aulosphærida, produced by a single cell, becomes increased by the graceful and manifold appendages and apophyses which are usually developed on the radial tubes. In only a few species these are simple, as in the common and cosmopolitan _Aulosphæra trigonopa_. Usually lateral or terminal appendages are developed in great variety, a selection of which is figured in Pls. 109-111. The lateral branches are either irregularly scattered spines (Pl. 110, figs. 3-7) or regular verticils of cruciate or radiate spines; each verticil is usually composed of four perpendicularly crossed horizontal branches (Pl. 109, figs. 3, 4, 7, 10, &c.), more rarely of a greater number of radiating transverse branches.

The terminal appendages of the radial spines exhibit a striking similarity with those of the Aulacanthida (Pls. 102-105). They are either forks with two or three divergent branches (Pl. 111, figs. 3, 4), or regular crosses with four branches opposite in pairs (Pl. 109, figs. 2, 6, 7, 10), or elegant crowns or verticils, composed of numerous radiating branches (Pl. 110, figs. 1-6). The distal ends of the terminal as well as of the lateral branches are either simple, pointed, or armed with a spinulate knob, or with a terminal spathilla. The variety and elegance of these terminal ornaments, the function of which is that of capturing tentacles, is in the Aulosphærida not less admirable than in the Aulacanthida and Coelodendrida.

The _central capsule_ of the Aulosphærida (Pl. 111, fig. 2) was first figured in my Monograph (1862, Taf. xi. fig. 5) of _Aulosphæra elegantissima_, as a sphere of 0.2 to 0.3 mm. in diameter. I described there the large nucleus (of half that size) as a spherical "Binnenblase," and the numerous pseudopodia which arise from the capsule and radiate through the meshes of the lattice-shell. But I had not observed at that time the three typical openings of the capsule, which were first discovered and accurately described by R. Hertwig (1879, _loc. cit._, p. 94, Taf. x. figs. 2, 4, 5, 8, 14). The large astropyle with its radiate operculum and proboscis, and the two smaller lateral parapylæ, provided with {1620}a smaller tubule, have in general the same shape as in the closely allied Sagosphærida and Orosphærida, and agree in their strong development with that of the Aulacanthida. The collection of the Challenger contains numerous well-preserved preparations of Aulosphærida, which were stained by carmine immediately after being captured, and in which the central capsule and its nucleus exhibit the same intimate structure already accurately described by R. Hertwig. The diameter of the capsule is usually between 0.2 and 0.3, rarely less than 0.15 or more than 0.35 mm., the nucleus has half that size. The phæodium has usually about the same volume (Pl. 109, fig. 1), but seems to be in many Aulosphærida less developed than in the other PHÆODARIA.

_Synopsis of the Genera of Aulosphærida._

-------------------------------------------------------------------------
I. Subfamily Aularida.
Meshes of the network triangular, regular or subregular. Six
tangential tubes united at each nodal point of the net.
-------------------------------------------------------------------------
{ Without radial tubes, 682. _Aularia_.
Shell spherical, with {
a simple network. { With radial tubes in
{ the nodes of the net, 683. _Aulosphæra_.

{ Shell covered with pyramidal
{ elevations, the top of
Shell spherical, with { which bears a radial tube, 684. _Auloscena_.
pyramidal elevations {
or with spongy { Shell with spongy framework,
framework. { the surface of which bears
{ radial tubes, 685. _Auloplegma_.

{ Shell lenticular, with
Shell not spherical, { shortened main axis and
either lenticular or { radial tubes, 686. _Aulophacus_.
spindle-shaped, with {
simple network. { Shell spindle-shaped, with
{ prolonged main axis and
{ radial tubes, 687. _Aulatractus_.
-------------------------------------------------------------------------
II. Subfamily Aulonida.
Meshes of the network polygonal, usually irregular. Three or four
(rarely more) tangential tubes united at each nodal point.
-------------------------------------------------------------------------
{ Without radial tubes, 688. _Aulonia_.
Shell spherical, with {
a simple network. { With radial tubes in the
{ nodes of the net, 689. _Aulastrum_.

Shell spherical, with { Without radial tubes, 690. _Aulodictyum_.
a spongy framework. {

Subfamily 1. AULARIDA, Haeckel.

_Definition._--Network of the shell with triangular, regular or subregular meshes; six tangential tubes being united at each nodal point.

{1621}Genus 682. _Aularia_,[301] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form a simple smooth lattice-sphere. No radial tubes at the nodal points.

The genus _Aularia_ is the simplest form of the subfamily Aularida, or of those Aulosphærida in which the network of the shell is composed of regular or subregular triangular meshes; they are the main group of the family, much more common and far richer in distinct forms than the Aulonida (or the Aulosphærida with polygonal meshes). The shell of _Aularia_, the probable ancestral form of the family, is a simple lattice-sphere with smooth surface, and differs from the common _Aulosphæra_ in the absence of radial tubes, arising at the nodal points.

1. _Aularia ternaria_, n. sp. (Pl. 111, fig. 2).

Tangential tubes of the network cylindrical, straight, smooth, of equal breadth. Triangular meshes of the reticular sphere very regular, equilateral triangular. This species is the simplest of all Aulosphærida and similar to the common _Aulosphæra trigonopa_, but has no radial tubes.

_Dimensions._--Diameter of the sphere 1.0 to 2.0; tubes 0.1 to 0.15 long, 0.007 to 0.01 broad.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

2. _Aularia tubularia_, n. sp.

Tangential tubes of the network cylindrical, straight, of equal breadth, thorny, covered with numerous short bristle-shaped thorns, which are all of the same length and perpendicular to the tube.

_Dimensions._--Diameter of the sphere 3.0; tubes 0.15 long, 0.005 broad.

_Habitat._--South Pacific, Station 291, depth 2250 fathoms.

3. _Aularia trigonaria_, n. sp.

Tangential tubes of the network smooth, very thin in the middle part, gradually dilated towards both ends, so that the nodal points of the network are inflated. (Similar to _Aulosphæra sceptrophora_, Pl. 109, fig. 3, but without radial tubes.)

_Dimensions._--Diameter of the sphere 2.2; tubes 0.1 long, 0.002 broad in the middle part, 0.01 on both sides.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.

{1622}Genus 683. _Aulosphæra_,[302] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 802.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form a simple lattice-sphere. Radial tubes arise at its nodal points.

The genus _Aulosphæra_, the first observed form of all Aulosphærida, is also the most common form of the whole family, the richest in distinct species, and widely distributed over all oceans, in the tropical as well as in the temperate and Arctic zones.

The twenty-one species here enumerated may be only a small part of the numerous forms, which may be distinguished according to the different forms of the tubes. One of the two Mediterranean species, which I first described in my Monograph, is cosmopolitan. The shell is in all species a simple regular lattice-sphere with triangular meshes; it differs from the preceding _Aularia_ in the development of radial tubes at the nodal points of the lattice-work.

Subgenus 1. _Aulosphærantha_, Haeckel.

_Definition._--Radial tubes simple, smooth, without terminal teeth and without lateral branches.

1. _Aulosphæra trigonopa_, Haeckel.

_Aulosphæra trigonopa_, Haeckel, 1862, Monogr. d. Radiol., p. 359, Taf.
x. fig. 4.

Radial tubes of the spherical shell cylindro-conical, straight, smooth, of the same length as the tangential tubes of the network, which are also smooth, straight, cylindrical.

_Dimensions._--Diameter of the sphere 1.0 to 2.0; tangential tubes 0.1 to 0.2 long, 0.002 to 0.004 broad.

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

2. _Aulosphæra flexuosa_, n. sp.

Radial tubes slenderly conical, smooth, gradually tapering towards the distal end, more or less irregularly curved, two to three times as long as the tangential tubes, which are cylindrical, straight and smooth.

_Dimensions._--Diameter of the sphere 2.2; tangential tubes 0.15 long, 0.006 broad.

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

{1623}Subgenus 2. _Aulosphærella_, Haeckel.

_Definition._--Radial tubes smooth, without lateral branches or spines, but armed with a verticil of teeth at the distal end.

3. _Aulosphæra diodon_, n. sp.

Radial tubes cylindro-conical, straight, smooth, of the same length as the smooth, cylindrical, tangential tubes; armed at the distal end with two divergent terminal teeth, which are slightly curved, pincer-shaped, and about one-fourth as long as the tube.

_Dimensions._--Diameter of the sphere 2.5; tangential tubes 0.16 long, 0.003 broad.

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

4. _Aulosphæra triodon_, n. sp. (Pl. 109, fig. 8).

Radial tubes cylindrical, straight, smooth, two to three times as long as the smooth, cylindrical, tangential tubes; armed at the distal end with three divergent terminal teeth, which are straight or slightly curved and about one-third as long as the tube.

_Dimensions._--Diameter of the sphere 1.2; tangential tubes 0.1 long, 0.01 broad.

_Habitat._--North-Eastern Pacific (off Japan), Station 231, surface.

5. _Aulosphæra tetrodon_, n. sp.

Radial tubes slender, cylindrical, straight, smooth, about three times as long as the smooth, cylindrical, tangential tubes; armed at the distal end with a regular cross of four terminal teeth, which are directed almost horizontally, and are slightly recurved (just as in _Aulosphæra spathillata_, Pl. 109, fig. 7, but longer and without lateral verticils).

_Dimensions._--Diameter of the sphere 1.6; tangential tubes 0.15 long, 0.005 broad.

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

6. _Aulosphæra polyodon_, n. sp.

Radial tubes slender, spindle-shaped, gradually tapering towards the two ends, smooth, about twice as long as the cylindrical, smooth, tangential tubes; armed at the distal end with a verticil of twelve to twenty or more divergent, conical, slightly curved teeth.

_Dimensions._--Diameter of the sphere 3.3; tangential tubes 0.2 long, 0.01 broad.

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

Subgenus 3. _Aulosphærissa_, Haeckel.

_Definition._--Radial tubes verticillate, armed with a variable number of regular verticils of lateral branches.

{1624}7. _Aulosphæra verticillata_, n. sp.

Radial tubes slender, cylindro-conical, straight, tapering towards the distal end, about as long as the smooth, cylindrical, tangential tubes; armed with eight to twelve verticils of three curved, simple, lateral branches. (Very similar to the tubes of _Aulastrum trichoceros_, Pl. 111, fig. 5_a._)

_Dimensions._--Diameter of the sphere 1.6; tangential tubes 0.15 long, 0.008 broad.

_Habitat._--South Pacific, Station 300, surface.

8. _Aulosphæra spathillata_, n. sp. (Pl. 109, figs. 7, 7_a_).

Radial tubes slender, cylindro-conical, straight, tapering towards the distal end, two to three times as long as the smooth, cylindrical, tangential tubes; armed with two or three distal alternate verticils, each of which forms a horizontal cross of four (sometimes three or five) equidistant branches; their distal ends are on the terminal cross simple hooks, on the proximal cross spathillæ.

_Dimensions._--Diameter of the sphere 3.2; tangential tubes 0.12 to 0.16 long, 0.01 broad.

_Habitat._--South-Eastern Pacific (off Valparaiso), Station 298, depth 2225 fathoms.

9. _Aulosphæra cruciata_, Haeckel (Pl. 109, fig. 10).

_Aulosphæra elegantissima_, R. Hertwig (_non_ Haeckel), 1879, Organism.
d. Radiol., p. 90, Taf. ix. fig. 1; Taf. x. figs. 2, 4, 5, 8, 14, 15.

? _Aulosphæra pourtalesii_, Duncan, 1881, Journ. Roy. Micr. Soc., p. 175,
pl. iii. figs. 1-3.

Radial tubes slender, cylindro-conical, straight, tapering towards the distal end, twice as long as the smooth, cylindrical, tangential tubes; armed with four to eight cruciate equidistant verticils, each of which forms a regular cross of four equal, horizontal, lateral branches, bearing at the end a small knob or spathilla.

_Dimensions._--Diameter of the sphere 1.2 to 1.8; tangential tubes 0.1 to 0.15 long, 0.003 broad.

_Habitat._--Mediterranean (Messina), North Atlantic (Canary Islands), Caribbean Sea.

10. _Aulosphæra elegantissima_, Haeckel.

_Aulosphæra elegantissima_, Haeckel, 1862, Monogr. d. Radiol., p. 359,
Taf. x. fig. 5; Taf. xi. figs. 5, 6.

Radial tubes cylindrical, straight, twice as long as the smooth, cylindrical, tangential tubes; armed with four to eight equidistant verticils, each of which is composed of eight to twelve simple, horizontal, lateral branches.

_Dimensions._--Diameter of the sphere 1.5 to 2; tangential tubes 0.12 to 0.16 long, 0.004 broad.

_Habitat._--Mediterranean (Messina), surface.

11. _Aulosphæra bisternaria_, n. sp. (Pl. 109, figs. 11, 12).

Radial tubes cylindrical, straight, about as long as the cylindrical tangential tubes, smooth or somewhat thorny, armed at the distal end with two alternate verticils of three branches, which bear {1625}a terminal spathilla; the proximal branches are twice as long as the distal, and alternate with them regularly, so that the six branches lie in six different meridional planes.

_Dimensions._--Diameter of the sphere 2.5; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--Antarctic Ocean, Station 156, surface.

12. _Aulosphæra dendrophora_, n. sp. (Pl. 109, figs. 1, 2).

Radial tubes cylindrical, straight, about as long as the cylindrical, smooth, tangential tubes, armed in the distal half with three verticils of four crossed branches; the four proximal branches are three times as long as the four distal, and twice as long as the four intermediate branches. All twelve branches bear a terminal spinulate knob, and lie in two perpendicularly crossed meridian planes.

_Dimensions._--Diameter of the sphere 2.2 to 2.8; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

13. _Aulosphæra sceptrophora_, n. sp. (Pl. 109, figs. 3, 4).

Radial tubes straight, in the proximal half conical, with inflated base; in the distal half cylindrical, with five or six cruciate verticils, each of which has four perpendicularly crossed teeth. Tangential tubes half as long as the radial tubes, in the middle part very thin, thickened towards both ends.

_Dimensions._--Diameter of the sphere 1.2; tangential tubes 0.1 long, 0.002 broad in the middle part, 0.012 on both ends.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.

14. _Aulosphæra spathophora_, n. sp.

Radial tubes slender, cylindrical, more or less curved, about three times as long as the tangential tubes, in the distal half with eight to twelve verticils of six to eight lateral branches, which are forked, decrease in length towards the distal end, and bear on each ramule a terminal spathilla. Tangential tubes slightly curved and thorny. (Similar to _Auloplegma perplexum_, Pl. 111, fig. 8_a_, but with a simple lattice-sphere.)

_Dimensions._--Diameter of the sphere 2.2; tangential tubes 0.2 long. 0.006 broad.

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

Subgenus 4. _Aulosphæromma_, Haeckel.

_Definition._--Radial tubes spiny or thorny, with irregular lateral branches, often with forked distal ends.

{1626}15. _Aulosphæra bifurca_, n. sp.

Radial tubes cylindrical, straight, thorny, twice as long as the smooth, cylindrical, tangential tubes, forked at the distal end, with two curved, convergent, thorny, terminal branches. (Similar to _Aulastrum dendroceros_, Pl. 111, figs. 4_a_-4_c_, but with longer and more spinulate branches.)

_Dimensions._--Diameter of the sphere 3.2; tangential tubes 0.25 long, 0.01 broad.

_Habitat._--North Pacific, Station 239, surface.

16. _Aulosphæra trifurca_, n. sp. (Pl. 109, fig. 9).

Radial tubes cylindrical, straight, thorny, about as long as the smooth, cylindrical, tangential tubes, forked at the distal end, with three curved, convergent, terminal branches.

_Dimensions._--Diameter of the sphere 2.5 to 3.0; tangential tubes 0.2 long, 0.01 broad.

_Habitat._--North Pacific, Station 240, surface.

17. _Aulosphæra quadrifurca_, n. sp.

Radial tubes cylindro-conical, straight, about as long as the smooth, cylindrical, tangential tubes; studded with numerous irregular lateral branches in the distal half, and armed at the distal end with a cross of four divergent, forked, terminal branches.

_Dimensions._--Diameter of the sphere 4.2; tangential tubes 0.2 long, 0.01 broad.

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

18. _Aulosphæra multifurca_, n. sp.

Radial tubes cylindrical, more or less curved, three to four times as long as the smooth, often curved, tangential tubes; studded with numerous forked, irregular, lateral branches, and armed at the distal end with a verticil of twelve to sixteen divergent, forked, terminal branches.

_Dimensions._--Diameter of the sphere 1.2; tangential tubes 0.06 long, 0.003 broad.

_Habitat._--Arctic Ocean, Greenland (Olrik), surface.

19. _Aulosphæra coronata_, n. sp.

Radial tubes spindle-shaped, tapering from the thicker middle part towards both ends, twice as long as the thorny tangential tubes, studded with numerous irregular, curved, lateral spines, and bearing at the distal end a corona of twenty to twenty-five divergent, curved, terminal branches. (Similar to _Auloscena flammabunda_, Pl. 110, fig. 4.)

_Dimensions._--Diameter of the sphere 3.0; tangential tubes 0.2 long, 0.08 broad.

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

{1627}20. _Aulosphæra undulata_, n. sp. (Pl. 109, fig. 6).

Radial tubes slender, cylindro-conical, undulate, about twice as long as the spinulate and undulate tangential tubes; studded with numerous short, perpendicular, lateral branches which are partly simple, partly forked, and bear small terminal spathillæ. The distal end of each radial tube bears usually a verticil of four to eight similar pediculate spathillæ.

_Dimensions._--Diameter of the sphere 2.4; tangential tubes 0.2 long, 0.005 broad.

_Habitat._--North Pacific, Station 252, surface.

21. _Aulosphæra spinosa_, n. sp. (Pl. 109, fig. 5).

Radial tubes and tangential tubes equal in size and similar in form, more or less curved, slender, cylindrical, densely studded with numerous irregular spines.

_Dimensions._--Diameter of the sphere 1.6; tangential tubes 0.1 long, 0.004 broad.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

Genus 684. _Auloscena_,[303] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which arise in pyramidal groups of six over the surface of the spherical shell. Radial tubes arise at the tops of the six-sided pyramids, which cover the whole surface.

The genus _Auloscena_ differs from the preceding _Aulosphæra_, its ancestral form, in a very remarkable and elegant character. The tangential tubes of the network here lie not on a spherical face (as in the latter), but arise over the surface of the spherical calymma in the form of numerous, regular, hexagonal pyramids; each pyramid being composed of six convergent ascending tubes, which are united in a common nodal point; at the latter arises a radial tube, which usually bears an elegant corona of radially divergent terminal branches. Therefore the base of each hexagonal pyramid is in contact at its six corners with the basal corners of six similar neighbouring pyramids, whilst the neighbouring sides of the bases are separated by six regular triangular meshes, which lie on the spherical face. In some species this remarkable and elegant structure is quite regular, whilst in others it becomes more or less irregular.

Subgenus 1. _Auloscenium_, Haeckel.

_Definition._--Radial tubes smooth, without lateral branches or spines, bearing a terminal verticil at the distal end.

{1628}1. _Auloscena mirabilis_, n. sp. (Pl. 110, figs. 1, 2).

Radial tubes cylindrical, straight, smooth, about as long as the smooth pyramidal tubes (or the convergent tubes which form the edges of the six-sided pyramids of the network). The distal end of each radial tube bears an elegant spathillate terminal corona (fig. 2), or a verticil of fifteen to twenty curved radial branches, the distal end of which is armed with a spinulate knob.

_Dimensions._--Diameter of the sphere 2.0 to 3.0; pyramidal tubes 0.16 to 0.24 long, 0.008 broad.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

2. _Auloscena spectabilis_, n. sp. (Pl. 110, figs. 8, 9).

Radial tubes cylindro-conical, straight, smooth, twice as long as the smooth pyramidal tubes, armed at the distal end with a conical terminal corona, or a verticil of twelve to sixteen divergent, straight, pointed, terminal branches.

_Dimensions._--Diameter of the sphere 4.0 to 5.0; pyramidal tubes 0.25 to 0.3 long, 0.012 broad.

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

3. _Auloscena pyramidalis_, n. sp.

Radial tubes slender, conical, straight, smooth, of the same length as the smooth pyramidal tubes, armed at the distal end with a hexagonal terminal corona, or a verticil of six divergent, straight, pointed, terminal branches, which correspond to the six sides of a pyramid; the proximal apex of this terminal pyramid is opposed to the distal apex of the similar basal pyramid.

_Dimensions._--Diameter of the sphere 3.0 to 4.0; pyramidal tubes 0.2 to 0.3 long, 0.01 broad.

_Habitat._--Tropical Atlantic, Stations 347 to 349, surface.

Subgenus 2. _Auloscenidium_, Haeckel.

_Definition._--Radial tubes thorny, with lateral branches or spines, usually with a terminal verticil at the distal end.

4. _Auloscena tentorium_, n. sp. (Pl. 110, fig. 6).

Radial tubes spindle-shaped, tapering towards both ends, nearly smooth, of the same length as the smooth pyramidal tubes. The distal part of the radial tubes is thorny, and bears a verticil or a corona of twenty to thirty slender terminal branches, which are about one-third as long as the tube, sabre-shaped, with concave outer edge and pointed distal end.

_Dimensions._--Diameter of the sphere 4.0; radial tubes 0.3 to 0.4 long, 0.02 to 0.03 broad.

_Habitat._--North-Western Pacific (off Japan), Station 231, surface.

{1629}5. _Auloscena verticillus_, n. sp. (Pl. 110, figs. 10, 11).

Radial tubes slender, cylindrical, twice as long as the smooth or somewhat thorny pyramidal tubes, armed in the distal part with two or three irregular verticils of three to six perpendicular spines, and on the distal end with a corona of twelve to eighteen straight, divergent, pointed, terminal branches, which often arise in pairs.

_Dimensions._--Diameter of the sphere 3.2; pyramidal tubes 0.15 long, 0.01 broad.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

6. _Auloscena penicillus_, n. sp. (Pl. 110, fig. 3).

Radial tubes slender, cylindrical, thorny, one and a half times as long as the thin and smooth pyramidal tubes, armed in the distal half with densely crowded perpendicular spines and a terminal corona of numerous (twenty to thirty or more) bristle-shaped branches, like a brush.

_Dimensions._--Diameter of the sphere 2.0 to 2.5; radial tubes 0.15 to 0.2 long, 0.005 to 0.01 broad.

_Habitat._--Antarctic Ocean, Stations 156, 157, surface.

7. _Auloscena flammabunda_, n. sp. (Pl. 110, fig. 4).

Radial tubes cylindro-conical, twice as long as the thorny pyramidal tubes, studded with numerous curved spines, and armed with a verticil or corona of numerous (twenty to thirty or more) undulate, divergent, pointed, terminal branches.

_Dimensions._--Diameter of the sphere 3.0; radial tubes 0.3 to 0.4 long, 0.02 to 0.03 broad.

_Habitat._--North Pacific, Station 252, surface.

8. _Auloscena gigantea_, n. sp. (Pl. 110, fig. 7).

Radial tubes cylindrical, thorny, about as long as the thorny pyramidal tubes, armed in the distal half with four to eight verticils of short curved ciliæ, and at the distal end with a similar small terminal verticil.

_Dimensions._--Diameter of the sphere 5.2; pyramidal tubes 0.2 to 0.3 long, 0.01 broad.

_Habitat._--Central Pacific, Stations 265 to 268, surface.

9. _Auloscena arboretum_, n. sp.

Radial tubes cylindrical, straight or slightly curved, about the same length as the smooth pyramidal tubes; armed in the distal half with three or four verticils, tapering in size towards the distal end; each verticil is composed of four crossed and curved branches, which bear a terminal spinulate knob. (This species is very similar to _Aulosphæra dendrophora_, Pl. 109, fig. 1, and may {1630}be derived from it by elevation of the hexagonal pyramids, which in the latter lie in the spherical plane).

_Dimensions._--Diameter of the sphere 4.4; pyramidal tubes 0.25 long, 0.01 broad.

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

10. _Auloscena serrata_, n. sp. (Pl. 110, fig. 5).

Radial tubes spindle-shaped, tapering towards both ends, thorny, twice as long as the thorny pyramidal tubes; armed at the distal end with an elegant corona which is composed of twelve to sixteen curved terminal branches. Each branch bears two opposite series of small recurved teeth and a terminal spathilla of six to eight larger recurved teeth.

_Dimensions._--Diameter of the sphere 3.0; pyramidal tubes 0.3 long, 0.012 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.

Genus 685. _Auloplegma_,[304] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tubes of which are connected in different directions, and form the spongy wall of a spherical shell. Radial tubes arise on the surface at the nodal points.

The genus _Auloplegma_, one of the rarest forms of Aulosphærida, differs from the preceding genera in the spongy structure of the lattice-sphere, the thickened wall of which is composed of a loose framework. Numerous tubes, irregularly disposed in different directions, are connected at the nodal points of this loose spongy framework, whilst radial tubes arise on the surface of the latter. _Auloplegma_ exhibits therefore a relation to _Aulosphæra_, its probable ancestral form, similar to that which _Plegmosphæra_ does to _Acanthosphæra_ among the #Sphæroidea#.

1. _Auloplegma perplexum_, n. sp. (Pl. 111, figs. 8, 8_a_).

Radial tubes straight, cylindro-conical, armed with six to eight verticils of lateral branches, which increase in size towards the base; each verticil is a cross of four dichotomous delicate ramules, ending with a spinulate knob. The length of the radial tube is about equal to the radial diameter of the spongy framework, which forms the thick wall of the spherical shell, and is composed of smooth and straight cylindrical tubes.

_Dimensions._--Diameter of the shell 1.5 to 2.0, of its wall 0.3 to 0.4; length of the radial tubes 0.2 to 0.3, basal breadth 0.015.

_Habitat._--North Pacific, Station 237, surface.

{1631}2. _Auloplegma spongiosum_, n. sp. (Pl. 111, fig. 9).

Radial tubes slender, straight, cylindro-conical, studded irregularly with lateral branches, which are short, simple, slightly curved, partly verticillate in the distal third, and ending with a small spinulate knob. The length of the radial tubes is about twice as great as the radial diameter of the spongy framework, which forms the wall of the spherical shell, and is composed of thorny or verticillate cylindrical tubes.

_Dimensions._--Diameter of the shell 3.2, of its wall 0.1; length of the radial tubes 0.24, breadth 0.01.

_Habitat._--North Pacific, Station 231, surface.

Genus 686. _Aulophacus_,[305] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form a simple, lenticular, biconvex lattice-shell, with shortened vertical main axis. Radial tubes arise at its nodal points.

The genus _Aulophacus_ differs from the common _Aulosphæra_, its ancestral form, only in the lenticular compression of the spherical lattice-shell, the vertical axis of which is considerably shortened. It exhibits therefore to the latter the same relation as _Cenodiscus_ does to _Cenosphæra_ among the #Sphæroidea#. The contrary condition is shown in the following genus _Aulatractus_, in which the vertical axis is prolonged. In the two species of _Aulophacus_ observed the radial spines exhibit a remarkable peculiarity, being longer on the circular periphery of the lens, shorter on both its faces, and shortest in the vertical main axis.

1. _Aulophacus lenticularis_, n. sp. (Pl. 111, fig. 5_a_).

Shell biconvex, lenticular, with rounded circular margin; its horizontal diameter three times as great as its thickness (or its vertical main axis). Radial tubes cylindro-conical, straight, with six to nine triradiate verticils, those of the margin of the lens twice as long as the smooth tangential tubes, the others shorter.

_Dimensions._--Horizontal diameter of the lens 5.5 mm., vertical main axis 0.2; length of the radial tubes 0.2, breadth 0.01.

_Habitat._--Indian Ocean, Belligemma, Ceylon (Haeckel), surface.

2. _Aulophacus amphidiscus_, n. sp. (Pl. 111, fig. 5_b_).

Shell discoidal, slightly biconvex, with rounded circular margin; its horizontal diameter five times as great as its thickness. Radial tubes cylindrical, covered with numerous short thorns, those of the margin of the lens three times as long as the smooth tangential tubes, the others shorter.

{1632}_Dimensions._--Horizontal diameter of the lens 6.0, vertical main axis 1.2; length of the radial tubes 0.2, breadth 0.005.

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

Genus 687. _Aulatractus_,[306] n. gen.

_Definition._--#Aulosphærida# with triangular meshes in the network, the tangential tubes of which form an ellipsoidal or spindle-shaped, simple lattice-shell, with prolonged vertical main axis. Radial tubes arise at its nodal points.

The genus _Aulatractus_ differs from all the other Aulosphærida in the peculiar prolongation of the vertical axis of the lattice-sphere, by which the latter becomes ellipsoidal or spindle-shaped. The triangular meshes of the regular lattice-work become usually more or less irregular and polygonal at the two poles of the elongated main axis. _Aulatractus_ seems to be developed from _Aulosphæra_ in the opposite way from _Aulophacus_, the former by elongating, the latter by shortening of the vertical main-axis.

1. _Aulatractus fusiformis_, n. sp. (Pl. 111, figs. 6, 6_a_, 6_b_).

Shell spindle-shaped, about twice as long as broad, rounded at both poles of the main axis. Tangential tubes smooth, cylindrical. Radial tubes of the same length as the tangential tubes, but much thinner, slender cylindrical, studded with perpendicularly arising, short, lateral branches, which are scattered in the proximal part, verticillate in the distal part, and bear a spinulate terminal knob.

_Dimensions._--Length of the shell 7.5 to 10.0, breadth 3.5; length of the radial tubes 0.15 to 0.18, breadth 0.004.

_Habitat._--Tropical Atlantic, Stations 348, 349; surface, and in various depths.

2. _Aulatractus diploconus_, n. sp. (Pl. 111, fig. 7).

Shell diploconical or nearly spindle-shaped, about three times as long as broad, equally pointed at the two poles of the main axis, not inflated in the middle part. Radial tubes slenderly conical, thorny, only half as long as the smooth tangential tubes.

_Dimensions._--Length of the shell 6.0 to 8.0, breadth 2.2 to 4.5; length of the radial tubes 0.1 to 0.15, breadth 0.007.

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

3. _Aulatractus fusulus_, n. sp.

Shell spindle-shaped, about twice as long as broad, pointed at the two equal poles of the main axis. Radial tubes cylindro-conical, smooth, about as long as the smooth tangential tubes. This {1633}species resembles in its simple structure the common cosmopolitan _Aulosphæra trigonopa_, and differs from it only in the constant spindle-form of the shell.

_Dimensions._--Length of the shell 6 to 8, breadth 3 to 4; length of the radial tubes 0.16 to 0.2, breadth 0.008.

_Habitat._--North Atlantic, Færöe Channel, Gulf Stream (John Murray); Hebrides (Moebius).

4. _Aulatractus ellipsoides_, n. sp.

Shell ellipsoidal, about twice as long as broad, with equally rounded poles on the main axis. Radial tubes straight, cylindrical, verticillate, about twice as long as the smooth tangential bars; each verticil is cruciate, composed of four rectangularly crossed, short, lateral branches which bear a small spathilla at the distal end.

_Dimensions._--Length of the shell 6.6, breadth 3.6; length of the radial tubes 0.2, breadth 0.01.

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

Subfamily 2. AULONIDA, Haeckel.

_Definition._--Network of the shell with polygonal, usually irregular meshes; three or four tangential tubes usually being united at each nodal point.

Genus 688. _Aulonia_,[307] n. gen.

_Definition._--#Aulosphærida# with polygonal meshes in the network, the tangential tubes of which form a simple smooth lattice-sphere. No radial tubes at the nodal points.

The genus _Aulonia_ is the simplest form of the subfamily Aulonida, or of those Aulosphærida in which the lattice-work of the shell is composed not of triangular but of polygonal meshes; all these Aulonida are much rarer and much less differentiated than the Aularida or the common Aulosphærida with triangular meshes. _Aulonia_ has the same simple, smooth, spherical lattice-shell as _Aularia_, and differs from it only in the polygonal form of the meshes, which, however, is very constant.

1. _Aulonia tetragonia_, n. sp.

Meshes regular or subregular, square, sometimes intermingled with a variable number of irregular, triangular, and pentagonal meshes. Bars cylindrical, of equal breadth.

_Dimensions._--Diameter of the spherical shell 2.0 to 3.2, of the meshes 0.12 to 0.18; breadth of the bars 0.008.

_Habitat._--Antarctic Ocean, Station 154, depth 1800 fathoms.

{1634}2. _Aulonia pentagonia_, n. sp.

Meshes subregular, pentagonal, intermingled with a smaller number of quadrangular and triangular irregular meshes. Bars cylindrical, of equal breadth.

_Dimensions._--Diameter of the spherical shell 2.8 to 3.2, of the meshes 0.15 to 0.2; breadth of the bars 0.01.

_Habitat._--South Pacific, Stations 293 to 302, depth 1375 to 2270 fathoms.

3. _Aulonia hexagonia_, n. sp. (Pl. 111, fig. 1).

Meshes regular or subregular, hexagonal, often intermingled with a variable number of pentagonal and heptagonal meshes. Bars cylindrical, of equal breadth.

_Dimensions._--Diameter of the spherical shell 2.5 to 3.3, of the meshes 0.15 to 0.25; breadth of the bars 0.012.

_Habitat._--Tropical Atlantic, Stations 347 to 349, surface.

4. _Aulonia metagonia_, n. sp.

Meshes subregularly alternating, larger octagonal and smaller tetragonal. The network of this remarkable species has a striking similarity to the arrangement of the radial tubes in some species of _Sycon_, figured in my Monograph of the Calcispongiæ (1872, Bd. iii., Taf. ix. fig. 12).

_Dimensions._--Diameter of the sphere 4.4, of the greater octagonal meshes 0.24 to 0.3, smaller tetragonal 0.1 to 0.12; breadth of the bars 0.007.

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

5. _Aulonia polygonia_, n. sp.

Meshes irregular, polygonal, variable in form and unequal in size; the majority usually pentagonal or hexagonal, but numerous intermingled meshes with three, four, seven, or eight sides. Very variable in the size of the bars and the form of the meshes.

_Dimensions._--Diameter of the sphere 2.5 to 5.5, of the meshes 0.1 to 0.2; breadth of the bars 0.008 to 0.12.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface.

Genus 689. _Aulastrum_,[308] n. gen.

_Definition._--#Aulosphærida# with polygonal meshes in the network, the tangential tubes of which form a simple lattice-sphere. Radial tubes arise at its nodal points.

{1635}The genus _Aulastrum_ differs from the preceding _Aulonia_, its ancestral form, only in the development of radial spines at the nodal points of the simple lattice-sphere. It exhibits therefore to the latter the same relation as _Aulosphæra_ does to _Aularia_. But the meshes of the spherical network are constantly triangular in the two latter genera, polygonal in the two former. The different species of _Aulastrum_ are much rarer, and are not so differentiated as those of the common _Aulosphæra_.

1. _Aulastrum monoceros_, n. sp.

Radial tubes simple, smooth, straight, cylindro-conical, about as long as the smooth tangential tubes or somewhat longer. Meshes of the network irregularly polygonal, the majority usually pentagonal or hexagonal.

_Dimensions._--Diameter of the sphere 3.0 to 4.0, of the meshes 0.15; breadth of the tubes 0.012.

_Habitat._--Tropical Atlantic, Stations 347, 348, depth 2250 to 2450 fathoms.

2. _Aulastrum dichoceros_, n. sp.

Radial tubes cylindrical, more or less curved, undulate, smooth, twice as long as the smooth tangential tubes, forked at the distal end, with two divergent curved branches. Meshes of the network subregular, hexagonal (as in _Aulonia hexagonia_, Pl. 111, fig. 1), intermingled with single pentagonal and square meshes.

_Dimensions._--Diameter of the sphere 2.0 to 2.5, of the meshes 0.12 to 0.18; breadth of the tubes 0.01.

_Habitat._--Antarctic Ocean, Station 157, depth 1950 fathoms.

3. _Aulastrum dendroceros_, n. sp. (Pl. 111, figs. 4_a_, _b_, _c_).

Radial tubes cylindrical, straight or slightly curved, thorny, forked at the distal end, two to three times as long as the thorny tangential tubes; the thorns are short and thin, partly simple, partly irregularly branched and scattered, arborescent. Meshes of the network irregularly polygonal, the majority pentagonal or tetragonal.

_Dimensions._--Diameter of the sphere 2.4; radial tubes 0.2 to 0.3 long, 0.02 broad.

_Habitat._--North Pacific, Station 241 to 244, surface.

4. _Aulastrum triceros_, n. sp. (Pl. 111, figs. 3, 3_a_).

Radial tubes cylindrical, straight, smooth, about twice as long as the smooth tangential tubes, armed with three divergent curved teeth at the distal end. Meshes subregular, pentagonal, intermingled with a small number of tetragonal and hexagonal meshes.

_Dimensions._--Diameter of the sphere 1.2 to 1.8; radial tubes 0.15 long, 0.01 broad.

_Habitat._--Tropical Atlantic, Station 349, depth 2450 fathoms.

{1636}5. _Aulastrum trichoceros_, n. sp.

Radial tubes slender, straight, cylindro-conical, about twice as long as the smooth tangential tubes, armed with six to eight verticils of lateral branches, each of which is composed of three short curved branches (similar to those of _Aulophacus lenticularis_, Pl. 111, fig. 5_a_). Meshes irregularly polygonal, the majority tetragonal, intermingled with pentagonal and triangular meshes.

_Dimensions._--Diameter of the sphere 2.2; tangential tubes 0.12 long, 0.007 broad.

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

6. _Aulastrum tetraceros_, n. sp.

Radial tubes straight, cylindrical, about three times as long as the smooth tangential meshes, armed with three to six subregular cruciate verticils of branches, each of which is composed of four short, regularly crossed branches, bearing at the end a spinulate knob (similar to those of _Aulatractus fusiformis_, Pl. 111, fig, 6_b_). Meshes subregular, square, intermingled with single pentagonal and hexagonal meshes.

_Dimensions._--Diameter of the sphere 1.5, of the meshes 0.12 to 0.16; breadth of the bars 0.008.

_Habitat._--South Atlantic, Station 318, depth 2040 fathoms.

7. _Aulastrum pentaceros_, n. sp.

Radial tubes straight, cylindrical, smooth, about as long as the smooth tangential tubes, armed at the distal end with a corona of five curved teeth (of the same shape as in _Cannosphæra atlantica_, Pl. 112, fig. 6). Meshes subregular pentagonal (intermingled with single tetragonal, hexagonal, and heptagonal meshes).

_Dimensions._--Diameter of the sphere 5.0, of the meshes 0.2; breadth of the bars 0.015.

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

8. _Aulastrum polyceros_, n. sp.

Radial tubes spindle-shaped, tapering from the broader middle towards both ends, spiny, twice as long as the spiny tangential tubes, armed at the distal end with a corona of twelve to twenty divergent curved teeth (similar to the radial tubes of _Auloscena tentorium_, Pl. 110, fig. 6). Meshes irregular, polygonal, very variable in size and form. All tubes of this species are armed with scattered, short, conical spines.

_Dimensions._--Diameter of the sphere 4.5, of the meshes 0.1 to 0.2; breadth of the bars 0.006.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

{1637}Genus 690. _Aulodictyum_,[309] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 6.

_Definition._--#Aulosphærida# with polygonal meshes in the network, the tubes of which are connected in different directions and form the spongy wall of a spherical shell. No radial tubes prominent over the surface.

The genus _Aulodictyum_ differs from _Aulonia_, its ancestral form, in the development of a spongy framework in the thickened wall of the spherical lattice-shell. It bears therefore to the latter the same relation as _Auloplegma_ does to _Aularia_. But the outer surface of the hollow sphere is in _Aulodictyum_ completely smooth, as well as the inner, and bears no radial tubes. Only one species of this genus has been observed.

1. _Aulodictyum hydrodictyum_, n. sp.