Each pileated piece of the skeleton is a reticulated four-sided pyramid. The base of it (or the lower ring) is a square, from the four perradial corners of which start four centrifugal horizontal spines. In the centres of the four basal bars (or the sides of the square) arise four interradial beams, which unite in the second (or upper) square ring. This latter forms a second (but much smaller) four-sided pyramid, the apex of which is truncated. Therefore the little hat bears nine meshes; around the large central opening four upper smaller and four lower larger quadrangular meshes.

Dimensions.—Diameter of the basal ring 0.03, of the apical ring 0.01.

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta).

2. Cannopilus diplostaurus, n. sp. (Pl. 114, fig. 10).

Each pileated piece of the skeleton is a truncated quadrangular pyramid. From the corners of the square basal ring start four perradial, nearly horizontal, spines. Between these arise four interradial beams, which are united above by an upper square ring. This latter is divided into four small square meshes by a regular cross of perradial bars, the distal ends of which are prolonged into four short ascending spines. In the centre of the cross arises a vertical apical spine.

Dimensions.—Diameter of the basal ring 0.04, of the apical ring 0.016.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Cannopilus calyptra, Haeckel.

Each pileated piece of the skeleton is a truncated six-sided pyramid, like that of Dictyocha speculum, but distinguished by the reticulation of the upper (smaller) ring, which is divided by six beams into six meshes, lying in the horizontal plane of the upper ring. Six peripheral spines on the corners of the lower ring. (The irregular form, figured by Ehrenberg as Dictyocha heptacanthus, loc. cit., is probably only an individual abnormality with seven peripheral spines, instead of six; similar abnormalities occur also among the regular hexagonal forms which I found in the Tertiary rocks of Caltanisetta (Sicily).

Dimensions.—Diameter of the basal ring 0.05, of the apical ring 0.02.

Habitat.—Fossil in Tertiary deposits of Greece and Sicily.

4. Cannopilus hemisphæricus (Haeckel).

Each pileated piece of the skeleton is nearly hemispherical, with thirteen meshes; six lower and larger meshes in the sides of the truncated six-sided pyramid, seven others in the convex surface of the upper ring (one central with six surrounding it). From the six corners of the lower ring arise six horizontal perradial spines. From the inside of the same ring (probably on the side of the six ascending interradial beams) spring six centripetal teeth.

Dimensions.—Diameter of the basal ring 0.02, of the apical ring 0.01.

Habitat.—North Atlantic; Bermuda (Bailey).

5. Cannopilus cyrtoides, n. sp. (Pl. 114, figs. 11, 12).

Each pileated piece of the skeleton is an eight-sided truncated pyramid, or nearly hemispherical. From the basal ring arise twenty-four thorns or teeth, eight longer perradial centrifugal teeth placed almost horizontally, and between these sixteen shorter adradial teeth, directed downwards and somewhat centripetally. The network of the small hat is composed of seventeen meshes, arranged in two rows. The eight lower meshes are hexagonal, separated by six interradial ascending beams, and twice as large as the eight upper pentagonal meshes, which are separated by eight perradial beams, and enclose an apical central mesh.

Dimensions.—Diameter of the basal ring 0.04, of the apical ring 0.005.

Habitat.—Central area of the Pacific, Station 266, depth 2750 fathoms.

Family LXXIII. Aulacanthida, Haeckel (Pls. 102-105).

Definition.—Phæodaria with an incomplete skeleton, composed of numerous hollow radial tubes, which pierce the spherical calymma and touch with their proximal ends the surface of the tripylean central capsule.

The family Aulacanthida represents a large and interesting group of Phæodaria, differing from all other families of this legion in the possession of numerous large radial tubes, which pierce the gelatinous and alveolated calymma in a radial direction, and come in contact with the outer surface of the central capsule by their inner or proximal ends, whilst their outer or distal ends project over the surface of the spherical calymma, and develop a great variety of manifold branches and terminal appendages. Usually (with the exception of a single genus only) the surface of the calymma is covered by an arachnoidal veil or mantle, composed of thousands of very fine, hollow, tangential needles. The skeleton therefore is incomplete, without any direct connection between the isolated pieces, just as in the preceding Cannorrhaphida, but the latter never possess the large, hollow, cylindrical, radial tubes, which are characteristic of all Aulacanthida.

The spherical body of the Aulacanthida has usually a diameter of 1 to 2 mm., and including the radial tubes, of 4 to 5 mm. or more. Some species are very common and cosmopolitan, and some genera contain numerous species, distributed widely over all oceans. In spite of their considerable size and wide distribution, only one species of this great family has been hitherto known, having been discovered by me at Messina in 1859, and described in my Monograph as Aulacantha scolymantha (1862, p. 263, Taf. ii. figs. 1, 2, and Taf. iv. figs. 1-5). I there founded for it the peculiar subfamily Aulacanthida, and annexed it to the Thalassicollida. The same cosmopolitan species has been subsequently observed at Messina by R. Hertwig, who first recognised the three openings in its central capsule, and therefore united it with his Tripylea (Organism. d. Radiol., 1879, p. 88, Taf. ix. figs. 3, 4; Taf. x. figs. 7, 10). The rich collection of the Challenger has added an astonishing number of new and interesting forms of Aulacanthida, so that I can describe here not less than six genera and fifty-eight species. The majority are inhabitants of the colder parts of the South Pacific and South Atlantic, at great depths, whilst a few species only are found in the tropics.

The structure of the body in all Aulacanthida seems to be similar in all important points, and the differences by which we are enabled to separate this great number of species are mainly produced by differences in the development of the radial tubes, their form and their polymorphous apophyses. The entire body represents a rather firm jelly-sphere of 1 to 2 mm. diameter (rarely less or more); the peripheral layer of the spherical calymma is rather clear and transparent, whilst its central part is dark and opaque, containing the big phæodium and the enclosed central capsule. The diameter of the latter is usually between 0.1 and 0.3, often 0.4 to 0.5, or even more. The gelatinous calymma, in the centre of which the capsule is placed, always contains numerous, large, spherical or roundish alveoles, similar to those of Thalassicolla, and between them a delicate network of sarcode (Pl. 102, fig. 1; Pl. 103, fig. 1; Pl. 104, fig. 1).

The spherical surface of the calymma is nearly always protected by that characteristic arachnoidal veil or mantle, which is composed of thousands of very fine tangential needles, densely interwoven in all tangential directions but never directly connected. They are wanting in a single genus only, in Aulactinium (Pl. 101, figs. 6-8). This genus, therefore, may represent a separate subfamily, the Aulactinida, whilst all other genera protected by that mantle constitute the subfamily Aulographida. The tangential needles always seem to have the same shape as I have accurately described, in 1862, of Aulacantha scolymantha. They are constantly smooth, very thin and fragile, but also very elastic cylinders of silica, of equal breadth throughout their whole length, and seem to be open at both ends, since they are easily and constantly filled by air when dried. Their length is usually between 0.2 and 0.3 mm., rarely less than 0.15 or more than 0.5; their diameter is always less than 0.001, usually less than 0.0005.

The large radial tubes of the Aulacanthida constitute the most characteristic structures of this family, and are always so placed that their inner or proximal ends are in loose contact with the outer surface of their central capsule (upon which they rest), whilst their outer or distal ends are more or less prominent over the spherical surface of the calymma. Their position, therefore, is rather loose and movable, since they are fixed only by the consistence of the jelly of the surrounding calymma, and on the surface of the latter by the covering veil or the mantle of tangential needles (compare Pl. 102, fig. 1; Pl. 103, fig. 1; Pl. 104, fig. 1). Their number seems never to be fixed, and is probably very variable in different species. I found, in 1859, in the common Aulacantha scolymantha, the number varying from thirty to one hundred and fifty (loc. cit., p. 264). So also in Aulographis pandora, Aulospathis variabilis, and some other common species, numerous specimens of which I could compare, I found their number very variable, being in one and the same species sometimes only from ten to twenty, at other times from fifty to eighty, and sometimes even from one hundred to one hundred and fifty or more. Perhaps the number increases with the age and the increasing size of the calymma.

The radial tubes are always cylindrical (circular in transverse section), never angular or prismatic. Usually they are straight, more rarely slightly curved (Pl. 105, figs. 1, 2; Pl. 101, fig. 6). The cylinders are usually more or less tapering towards both ends, sometimes even spindle-shaped; the inner or proximal end is always simple and rounded, often slightly swollen or inflated, and ovate; the outer or distal end is often thickened, club-shaped, and exhibits the greatest variety in form and ramification. The length of the radial tubes is usually from 1 to 3 mm., rarely less than 0.8, or more than 3.2; their diameter is usually between 0.02 and 0.03, rarely less than 0.01 or more than 0.05. The smallest radial tubes are found in Aulactinium, the largest in Aulospathis.

The siliceous wall of the cylindrical radial tubes is usually very thin, fragile, and perfectly structureless. Only in a few species, mainly of Aulographis, does the wall become very thick and composed of concentric cylindrical layers (Pl. 105, figs. 6-11). Their cavity is wide and simple, and filled up by jelly (not by sarcode, as I supposed in my first description). The simple cavity of the tubes, though not smaller than in the radial tubes of the Aulosphærida, Circoporida and Tuscarorida, never contains the characteristic axial filament with its branches, which is constantly found in the latter families. According to the description of R. Hertwig, the tubes are perfectly closed and have no opening. I suppose, however, that a small opening always exists in the centre of the rounded base, and perhaps a second on the distal apex. Otherwise the circumstance that the entire and well-preserved tubes become easily and constantly filled up by air, when purified by hot mineral acids and afterwards dried, cannot be explained. I suppose that the jelly contained in the cavity of the tubes remains in constant connection by these openings with the jelly of the surrounding calymma.

The distal ends of the radial tubes exhibit in the Aulacanthida the greatest variety in the production of different branches and capturing apparatus, and this serves for the distinction of the genera and subgenera here described. In two genera only (in Aulactinium Pl. 101, figs. 6-8; and in Aulacantha, Pl. 105, fig. 16), the distal ends are simple, not branched. In the four other genera they are armed with terminal branches, which are usually arranged in elegant verticils. The greatest variety in the formation of these verticils is developed in Aulographis (Pl. 103). The single branches of the terminal verticils are here simple, whilst in the closely allied Auloceros they are forked or elegantly ramified (Pl. 102). Aulospathis, the biggest of all Aulacanthida, is distinguished by the possession of a verticil of lateral branches, placed beyond the terminal verticil, immediately above the veil of tangential needles (Pl. 104). Aulodendron, finally, possesses lateral and terminal branches, which are irregularly scattered.

The branches of the radial tubes are rarely straight, usually more or less curved, either simple or again ramified. Their surface is either smooth or armed with small spines or recurved teeth, often elegantly dentated or serrated (Pl. 103, figs. 20-27; Pl. 105, figs. 7-13). Their distal ends are either simply pointed or armed with a spathilla, or a small crown of verticillate, usually recurved teeth (Pl. 104, figs. 4-17). The variety and elegance of these minute armatures are very interesting, the more so as they occur in very similar and analogous forms among the Aulosphærida, the Cœlographida, and other Phæodaria.

The central capsule of the Aulosphærida and its large nucleus ("Binnenbläschen"), as well as the surrounding alveolate calymma ("Alveolen-Hülle"), and the enclosed dark phæodium ("dunkels Pigment") were first described in my Monograph (1862, loc. cit., p. 362). Their minute structure has been examined afterwards very accurately by R. Hertwig (1879, loc. cit., p. 95). The numerous well-preserved preparations of the Challenger (stained with carmine and preserved in glycerine) which I could examine, confirmed in all respects the detailed description of Hertwig (compare Pl. 102, fig. 1; Pl. 103, fig. 1; Pl. 104, fig. 1).

The spherical or subspherical central capsule is usually slightly depressed in the shortened main axis. Its diameter is usually between 0.1 and 0.3, rarely less than 0.08 or more than 0.4 mm. Its outer membrane (e) is thick and double-contoured, separated by a clear interval from the very thin but firm inner membrane (i). The large astropyle, or the main-opening on the oral pole of the main axis, is closed by a large, convex, radiate operculum (o), from which arises a short tubular proboscis. On both sides of the opposite aboral pole (to the right and left) are two conical parapylæ or secondary openings (u, u). The space between the inner membrane of the capsule and the nucleus is filled up by protoplasm, containing numerous spherical vacuoles of equal size (v); each vacuole encloses a small, dark, fat-granule. The large nucleus (n) is either spherical or lenticular, and more or less depressed in the main axis; its diameter is usually about half as great as that of the enclosing capsule, 0.05 to 0.15, rarely less or more; it contains, enclosed in a clear mass, numerous dark, roundish or oblongish nucleoli (l).

Numerous preparations of Aulacanthida exhibited a central capsule with two nuclei (Pl. 101, fig. 6), or a calymma with two central capsules (Pl. 104, figs. 1, 3); so that the process of propagation by self-division, observed already in many different Phæodaria, seems to happen very frequently in the Aulacanthida. The voluminous phæodium is usually about twice or three times as large as the central capsule, and covers its oral or anterior half; the colour of the roundish phæodella composing it is sometimes more green or brown, at other times more blackish. The roundish alveoles, which fill up the rather firm jelly of the calymma, exhibit nearly the same shape as in the common Thalassicolla nucleata. The surface of the calymma is usually protected by the dense veil of tangential needles, and often forms conical or tent-shaped elevations around the bases of the piercing radial tubes (Pl. 102, fig. 1).

Synopsis of the Genera of Aulacanthida.

Subfamily 1. Aulactinida, Haeckel.

Definition.—Aulacanthida without external veil of tangential needles on the surface of the calymma.

Genus 665. Aulactinium,^[283] n. gen.

Definition.—Aulacanthida without a veil of tangential needles, with simple radial tubes, which bear neither lateral nor terminal branches.

The genus Aulactinium differs from all the other Aulacanthida in the complete absence of the characteristic fine tangential needles, which constitute in the latter an arachnoidal veil or mantle around the spherical calymma. We accordingly divide the whole family into two subfamilies, the Aulactinida with a naked calymma, and the Aulographida with a veil of tangential needles. The radial tubes possess in the few species of Aulactinium observed a very simple shape, as in the closely allied Aulacantha.

1. Aulactinium actinastrum, n. sp. (Pl. 101, figs. 6, 7).

Radial tubes slenderly spindle-shaped, slightly curved, gradually tapering from the middle towards both ends. The proximal two-thirds of the tubes enclosed in the calymma are smooth; the distal freely prominent third is armed with six to eight equidistant verticils of small conical teeth (ten to fifteen in each verticil).

Dimensions.—Length of the tubes 0.5 to 1.5, breadth 0.02.

Habitat.—South Pacific, Station 289, depth 2550 fathoms.

2. Aulactinium actinelium, n. sp. (Pl. 101, fig. 8).

Radial tubes cylindrical, straight, slightly tapering towards both ends. Proximal two-thirds smooth, the distal third studded with numerous small recurved thorns.

Dimensions.—Length of the tubes 0.6 to 0.9, breadth 0.02.

Habitat.—South Pacific, Station 293, depth 2025 fathoms.

3. Aulactinium actinosphærium, n. sp.

Radial tubes cylindrical, straight, smooth, of nearly equal breadth throughout their whole length, without thorns and spathillæ, pointed at both ends.

Dimensions.—Length of the tubes 1.6 to 2.2, breadth 0.02 to 0.03.

Habitat.—Antarctic Sea, Station 157, depth 1950 fathoms.

Subfamily 2. Aulographida, Haeckel.

Definition.—Aulacanthida with an external veil of interwoven, very numerous and thin, hollow, tangential needles, entirely covering the surface of the calymma.

Genus 666. Aulacantha,^[284] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 799.

Definition.—Aulacanthida with a veil of tangential needles, and with simple radial tubes, which bear neither lateral nor terminal branches.

The genus Aulacantha, hitherto the only representative of this family, was founded by me in 1860 for the cosmopolitan Aulacantha scolymantha, the most common and most widely distributed of all the members of the family. It is the simplest form of the Aulographida, or of those Aulacanthida in which the spherical surface of the calymma is densely covered with interwoven tangential needles. The large radial tubes of Aulacantha possess a very simple shape, as in the preceding Aulactinium, and have neither lateral nor terminal branches.

1. Aulacantha scolymantha, Haeckel.

Radial tubes cylindrical, straight, of nearly equal breadth throughout their whole length, somewhat inflated on the proximal basal end, smooth throughout the greater part of their length, but in the distal third dentate, with numerous (ten to forty) small pointed teeth, which are curved outwards, and shorter than the thickness of the tube.

Dimensions.—Length of the tubes 0.5 to 2.0, breadth 0.01 to 0.02.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; at many Stations; surface and at various depths; the most common of all Aulacanthida.

2. Aulacantha tubulosa, n. sp.

Radial tubes cylindrical or nearly spindle-shaped, straight, gradually tapering towards the two pointed ends, twice as broad in the middle third as in the outer and inner third, smooth in the inner half, dentate in the outer half, with very numerous (one hundred to two hundred) short conical teeth, which are scarcely one-fourth as large as the greatest breadth of the tube.

Dimensions.—Length of the tubes 0.4 to 0.5, breadth in the middle part 0.02 to 0.03.

Habitat.—Central Pacific, Stations 271 to 274, surface.

3. Aulacantha spinosa, n. sp. (Pl. 105, fig. 4).

Radial tubes cylindrical, straight, of equal breadth throughout their whole length, rounded on the proximal base, smooth in the inner proximal half, dentate or spinescent in the outer distal half, with numerous (fifty to eighty) slender conical teeth, which are curved forwards, increasing in size towards the distal end, and somewhat longer than the breadth of the tube.

Dimensions.—Length of the tubes 0.8 to 1.2, breadth 0.015 to 0.02.

Habitat.—North Pacific, Stations 241 to 253, surface.

4. Aulacantha cannulata, n. sp. (Pl. 105, fig. 16).

Radial tubes cylindrical in the inner proximal half, prismatic in the outer distal half, with from three to six, usually four, prominent, thick, parallel edges, which are dentate towards the thicker distal end; their teeth short, conical, directed outwards, scarcely one-fourth as long as the thickness of the tube. The edges are separated in the distal third by more or less deep furrows, like a channelled column.

Dimensions.—Length of the tubes 1.2 to 2.5, breadth 0.03 to 0.04.

Habitat.—South Pacific, Stations 291 to 293, surface.

5. Aulacantha clavata, n. sp.

Radial tubes more or less irregularly curved, in the inner proximal half slenderly conical, and gradually tapering towards the inflated base, in the outer distal half club-shaped, armed with a few (five to twenty) short conical teeth.

Dimensions.—Length of the tubes 1.0 to 1.2, breadth in the middle pact 0.01, in the distal part 0.04.

Habitat.—South Atlantic, Station 318, depth 2040 fathoms.

6. Aulacantha lævissima, n. sp.

Radial tubes cylindrical, straight, of nearly equal breadth throughout their whole length; the inner proximal end rounded, the outer distal end pointed. Surface of the tubes perfectly smooth, without any teeth. The thickness and length of the simple spicula, as well as the thickness of their wall, are very variable in this species.

Dimensions.—Length of the tubes 0.5 to 4.2, breadth 0.003 to 0.02.

Habitat.—North Atlantic, Station 253, Færöe Channel, surface, John Murray.

Genus 667. Aulographis,^[285] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

Definition.—Aulacanthida with a veil of tangential needles, and with radial tubes, which bear no lateral branches, but at the distal end a verticil of simple terminal branches.

The genus Aulographis, the richest in the number of species among all Aulacanthida, differs from the preceding Aulacantha, its ancestral form, in the development of simple terminal branches, which form either a fork or a verticil. The branches are either smooth or spiny, but not ramified as in the following genus, Auloceros. Their distal ends are either simply pointed or bear a terminal spathilla, or a little crown of recurved teeth. According to these differences we may dispose the twenty-six species described into four subgenera.

Subgenus 1. Aulographantha, Haeckel.

Definition.—Terminal branches of the radial tubes simple, smooth, without lateral teeth and terminal spathillæ. Tubes usually thin and fragile.

1. Aulographis pandora, n. sp. (Pl. 103, figs. 2-9).

Radial tubes cylindrical, slender, straight or slightly curved, of equal breadth. Terminal branches of the tubes very variable in size and number (two to six, usually three or four), without lateral teeth and terminal spathillæ, slender, conical, slightly curved, directed outwards, twice to four times (rarely five to eight times) as long as the breadth of the tubes. This species is extraordinarily variable in the number and size of the simple terminal branches; the eight tubes, shown in figs. 2 to 9, are all found in one and the same specimen.

Dimensions.—Length of the tubes 0.5 to 1.5, breadth 0.01 to 0.03; branches 0.02 to 0.12.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; surface and in various depths.

2. Aulographis bovicornis, n. sp. (Pl. 103, figs. 12-14).

Radial tubes cylindrical, slender, straight, of equal breadth. Terminal branches usually two (rarely three), smooth, without lateral teeth and terminal spathillæ, eight to ten times as long as the breadth of the tube, pointed, S-shaped, or curved like the horns of an ox.

Dimensions.—Length of the tubes 0.6 to 0.8, breadth 0.015 to 0.02; branches 0.1 to 0.2.

Habitat.—South Atlantic (east of Buenos Ayres), Stations 323 to 325, surface.

3. Aulographis taumorpha, n. sp. (Pl. 103, fig. 16).

Radial tubes cylindrical, slender, straight, gradually tapering towards the pointed proximal end. Terminal branches constantly two, opposite in a tangential, slightly concave or nearly straight line, ten to twelve times as long as the breadth of the tube, smooth, straight in the proximal part, recurved in the distal part.

Dimensions.—Length of the tubes 0.7 to 0.8, breadth 0.01 to 0.015; branches 0.1 to 0.15.

Habitat.—North Pacific, Station 231, depth 2250 fathoms.

4. Aulographis triglochin, n. sp. (Pl. 103, fig. 17).

Radial tubes robust, club-shaped at the distal end. Terminal branches three (rarely two or four), widely divergent, geniculated and recurved, smooth, without lateral teeth and terminal spathillæ.

Dimensions.—Length of the tubes 1.2 to 1.8, breadth 0.02; branches 0.12 to 0.15.

Habitat.—Central Pacific, Stations 271 to 274, surface.

5. Aulographis cruciata, n. sp. (Pl. 103, fig. 25).

Radial tubes slender, cylindrical, of equal breadth. Terminal branches almost constantly four, equal, regularly crossed (very rarely three or five), slender, straight or slightly curved, smooth, divergent outwards, six to eight times as long as the breadth of the tube.

Dimensions.—Length of the tubes 1.0 to 1.5, breadth 0.02; branches 0.12 to 0.15.

Habitat.—South Atlantic, Stations 325 to 332, surface.

6. Aulographis ancorata, n. sp. (Pl. 103, fig. 21).

Radial tubes slender, cylindrical, straight. Terminal branches constantly four, equal, regularly crossed, arcuato-recurved or nearly semicircular, smooth, six to eight times as long as the breadth of the tube. Resembling an anchor with four teeth.

Dimensions.—Length of the tubes 0.5 to 0.7, breadth 0.012 to 0.015; branches 0.07 to 0.09.

Habitat.—South-west Atlantic, Station 318, depth 2040 fathoms.

7. Aulographis stellata, n. sp. (Pl. 103, figs. 23, a-c).

Radial tubes club-shaped, gradually thickened towards the distal end. Terminal branches stellate, numerous (five to ten or more), diverging in all directions, smooth, straight or slightly curved, slenderly conical, three to five times as long as the distal breadth of the tube. The branches are very variable in size, sometimes very small (figs. a, b).

Dimensions.—Length of the tubes 0.4 to 0.8, breadth 0.02; branches 0.01 to 0.02.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

8. Aulographis penicillata, n. sp.

Radial tubes slender, cylindrical, of equal breadth. Terminal branches pencil-shaped, smooth, very numerous (twenty to thirty or more), diverging outwards, curved, eight to ten times as long as the breadth of the tube, very thin and fragile, resembling a brush.

Dimensions.—Length of the tubes 1.0 to 1.5, breadth 0.02; branches 0.15 to 0.2.

Habitat.—North Atlantic (Antilles), Weber, surface.

9. Aulographis pistillum, n. sp. (Pl. 105, fig. 6).

Radial tubes club-shaped, robust, straight, gradually thickened towards the distal end. Terminal branches eight to ten (usually nine), conical, smooth, slightly curved, divergent outwards like a regular corona.

Dimensions.—Length of the tubes 0.5 to 0.6, distal breadth 0.04; branches 0.08.

Habitat.—North Atlantic, Station 354, depth 1675 fathoms.

Subgenus 2. Aulographella, Haeckel.

Definition.—Terminal branches of the radial tubes without terminal spathillæ, but with lateral teeth or secondary spines. (Tubes usually very stout and robust, club-shaped.)

10. Aulographis triæna, n. sp. (Pl. 105, fig. 8).

Radial tubes club-shaped, straight, tapering gradually towards the rounded proximal end. Terminal branches constantly three, divergent, very stout, eight to ten times as long as the breadth of the tube, each studded with three to six irregular, conical, secondary spines. Sometimes the branches become forked, the species passing over into Auloceros cervinus.

Dimensions.—Length of the tubes 1.2 to 1.5, breadth 0.004 to 0.06; branches 0.3 to 0.5.

Habitat.—South Pacific, Station 299, depth 2160 fathoms.

11. Aulographis martagon, n. sp. (Pl. 105, fig. 7).

Radial tubes club-shaped or slenderly conical, strongly thickened towards the distal end. Terminal branches six to nine, conical, slightly curved, divergent outwards, studded outside with small, conical, secondary spines, twice to three times as long as the breadth of the tube.

Dimensions.—Length of the tubes 1.0 to 1.2, breadth 0.04 to 0.05; branches 0.1 to 0.15.

Habitat.—South Atlantic, Station 318, depth 2040 fathoms.

12. Aulographis flammabunda, n. sp. (Pl. 105, fig. 9).

Radial tubes club-shaped, more or less curved, with thickened distal ends. Terminal branches three to six, conical, very stout, three to four times as long as the breadth of the tube, densely studded with numerous, crowded, conical, secondary spines, which are very irregular and more or less curved, resembling the flames of a fire.

Dimensions.—Length of the tubes 1.0 to 1.2, distal breadth 0.08 to 0.1; branches 0.2 to 0.4.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

13. Aulographis gemmascens, n. sp. (Pl. 105, fig. 11).

Radial tubes club-shaped, more or less curved, with thickened distal end. Terminal branches three to nine (usually three larger and six smaller) stout, conical, studded with irregular, straight, conical, secondary spines, crowded and densely aggregated, like the leaves in a bud.

Dimensions.—Length of the spines 1.5 to 1.8, distal breadth 0.07 to 0.1; branches 0.2 to 0.6.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

14. Aulographis flosculus, n. sp. (Pl. 105, fig. 10).

Radial tubes club-shaped, straight, tapering gradually towards the rounded proximal end. Terminal branches nine to twelve, stout, conical, twice to three times as long as the breadth of the tube, studded with irregular secondary spines, connected in the proximal half by a solid, cap-shaped, flinty lamella, so that the terminal corona resembles a flower. The hollow canal of the tube sends a thin branch into each branch of the crown.

Dimensions.—Length of the tubes 1.2 to 1.8, distal breadth 0.04 to 0.05; branches 0.1 to 0.2.

Habitat.—North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth 600 fathoms.

Subgenus 3. Aulographidium, Haeckel.

Definition.—Terminal branches of the radial tubes armed with terminal spathillæ (or whorls of small radial teeth), but without lateral denticles or spines.

15. Aulographis furcula, n. sp. (Pl. 103, figs. 10, 11).

Radial tubes cylindrical, slender, slightly curved. Terminal branches usually two, sometimes on single tubes three, eight to ten times as long as the tube is broad, strongly curved, ascending vertically from a horizontal base, with a terminal spathilla of four crossed teeth at the distal end.

Dimensions.—Length of the tubes 0.6 to 0.8, breadth 0.006 to 0.008; branches 0.06 to 0.08.

Habitat.—North-west Pacific (off Japan), Station 231, depth 2250 fathoms.

16. Aulographis triangulum, n. sp. (Pl. 103, fig. 15).

Radial tubes cylindrical, slender, straight. Terminal branches constantly three, slender, slightly curved, nearly horizontally (tangentially) expanded, eight to ten times as long as the tube is broad, with a terminal spathilla of four recurved teeth which are opposite in pairs. Since the angles between the three branches are equal (= 120°) they correspond to the axes of an equilateral triangle.

Dimensions.—Length of the tubes 1.2, breadth 0.015 to 0.02; branches 0.1 to 0.12.

Habitat.—South Pacific, Station 289, depth 2550 fathoms.