1. Spongolonche conostyla, n. sp..

Spongy disk circular, with irregular framework, without concentric rings. Both opposite radial spines conical, about as long as the radius of the disk, and four times as long as broad at the base. Margin of the disk nearly smooth.

Dimensions.—Diameter of the disk 0.16; length of the radial spines 0.18, basal thickness 0.045.

Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.

2. Spongolonche amphistyla, n. sp.

Spongy disk circular, with four to six concentric rings in the inner part, with quite an irregular framework in the outer part. Both opposite radial spines cylindrical, twice to three times as long as the diameter of the disk, at the base about as broad as two meshes of the framework. Margin of the disk ciliated.

Dimensions.—Diameter of the disk 0.2; length of the radial spines 0.4 to 0.6, basal thickness 0.01.

Habitat.—Pacific, central area, Station 271, depth 2425 fathoms.

Genus 256. Spongotripus,^[295] Haeckel, 1881, Prodromus, p. 461.

Definition.—Spongodiscida with three solid radial spines on the margin of the circular or triangular disk.

The genus Spongotripus is characterised by three marginal spines, which are commonly regularly disposed, more rarely in a bilateral or an irregular manner. It corresponds to Trigonocyclia among the Coccodiscida, to Tripodictya among the Porodiscida.

Subgenus 1. Spongotripodiscus, Haeckel.

Definition.—Radial spines of equal size and distance; triangle regular.

1. Spongotripus regularis, n. sp.

Spongy disk circular; three radial spines on its margin of equal size and equidistant, strong, conical, about as long as the diameter of the disk, and five times as long as broad at the base.

Dimensions.—Diameter of the disk 0.15; length of the spines 0.16, basal breadth 0.03.

Habitat.—Pacific, central area, Station 272, surface.

2. Spongotripus neumayri, Haeckel.

Spongy disk circular, nearly spherical; three radial spines on its margin of equal size and equidistant, pyramidal, nearly as long as the diameter of the disk, and three times as long as broad at the base.

Dimensions.—Diameter of the disk 0.15 to 0.2; length of the spines 0.11, basal breadth 0.04.

Habitat.—Fossil in the Jura of the Alps and in Tertiary rocks of Barbados.

3. Spongotripus strepsiceros, n. sp.

Spongy disk circular; three radial spines on its margin of equal size and equidistant, angular, twice as long as the diameter of the disk, spirally twisted like the horns of Antilope strepsiceros.

Dimensions.—Diameter of the disk 0.15; length of the spines 0.3, basal breadth 0.02.

Habitat.—Pacific, central area, Station 272, depth 2600 fathoms.

Subgenus 2. Spongotripodium, Haeckel.

Definition.—Radial spines of different size or at different distances; triangle either isosceles or irregular.

4. Spongotripus ypsilon, n. sp.

Spongy disk triangular, isosceles, with convex sides; three spines angular, of different size and at different distances; the odd spine straight and twice as long as the two paired spines, which are more approximated and curved concavely one to the other, like Y.

Dimensions.—Diameter of the disk 0.12; length of the odd spine 0.2, of the paired spines 0.1, basal breadth 0.04.

Habitat.—Pacific, central area, Station 274, depth 2750 fathoms.

5. Spongotripus irregularis, n. sp.

Spongy disk circular; three spines conical, irregularly curved, all three of different size, and at irregular distances; once to three times as long as the diameter of the disk; margin of the disk thorny.

Dimensions.—Diameter of the disk 0.1; length of the spines 0.1 to 0.3, basal breadth 0.05.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Genus 257. Spongostaurus,^[296] Haeckel, 1881, Prodromus, p. 461.

Definition.—Spongodiscida with four solid radial spines on the margin of the circular or square disk, commonly crossed in two equatorial diameters perpendicular one to another.

The genus Staurodictya exhibits four marginal spines in cross form. Commonly the cross is regular and rectangular, the four spines being opposite in pairs in two perpendicular diameters; sometimes more or less irregular. The genus repeats Staurodictya among the Porodiscida, Staurocyclia among the Coccodiscida.

1. Spongostaurus cruciatus, n. sp.

Spongy disk circular; four radial spines on its margin opposite in two crossed equatorial diameters, perpendicular one to another, conical, about as long as the diameter of the disk.

Dimensions.—Diameter of the disk 0.16; length of the spines 0.18, basal breadth 0.04.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

2. Spongostaurus serratus, n. sp.

Spongy disk circular; four crossed radial spines very large, twice to three times as long as the diameter of the central disk, serrated on both edges, with two rows of strong conical perpendicular teeth (similar to the saw of Pristis antiquorum).

Dimensions.—Diameter of the disk 0.1; length of the spines 0.2 to 0.3, breadth 0.02.

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

3. Spongostaurus hastatus, n. sp.

Spongy disk square, with concave sides; four crossed radial spines cylindrical, on the broader distal end spear-shaped or nearly lanceolate, one and a half times as long as the diameter of the disk.

Dimensions.—Diameter of the disk 0.13; length of the spines 0.2, basal breadth 0.01, distal breadth 0.03.

Habitat.—Tropical Atlantic, Station 347, surface.

4. Spongostaurus quadratus, n. sp.

Spongy disk square, with rectilinear sides; four crossed radial spines pyramidal, arising from the corners of the square, about as long as its half diagonal.

Dimensions.—Diameter of the disk 0.16; length of the spines 0.08, basal breadth 0.02.

Habitat.—Pacific, central area, Station 271, surface.

Genus 258. Stylotrochus,^[297] Haeckel, 1862, Monogr. d. Radiol., p. 463.

Definition.—Spongodiscida with numerous solid radial spines on the margin of the disk (five to ten or more), all situated in the equatorial plane.

The genus Stylotrochus comprises those Spongodiscida in which the margin of the circular disk bears numerous radial spines. All these spines lie in the same equatorial plane, whilst in the following genus they are disposed over the whole surface of the disk. Stylotrochus corresponds to Astrocyclia among the Coccodiscida, to Stylodictya among the Porodiscida. The spongy framework of the disk is either quite irregular (Stylotrochiscus), or includes in the middle part some concentric circular rings (Stylospongia).

Subgenus 1. Stylotrochiscus, Haeckel.

Definition.—Spongy framework of the whole disk irregular, without concentric circular rings or spiral convolutions.

1. Stylotrochus arachnius, Haeckel.

Spongy framework of the whole disk irregular. Eight to twelve marginal spines very long and thin, bristle-shaped, twice to four times as long as the diameter of the disk. (Very similar to the common Stylodictya arachnia, but without concentric circular rings and sieve-plates, with quite irregular network of fine bars.)

Dimensions.—Diameter of the disk 0.12 to 0.15; length of the radial spines 0.2 to 0.6, basal breadth 0.001.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface; also fossil in Tertiary rocks of Barbados and the Mediterranean.

2. Stylotrochus craticulatus, Haeckel.

Spongy framework of the whole disk irregular. Sixteen to twenty short marginal spines (twice to four times as long as the diameter of one mesh of the framework), free prolongations of internal radial beams which arise from the darker centre of the disk. (The interruption of the disk-margin on one point of its circumference, figured by Stöhr as osculum or "Mündungs-Oeffnung," is probably an accidental abnormality; I did not find it in other specimens.)

Dimensions.—Diameter of the disk 0.2 to 0.25; length of the radial spines 0.005 to 0.018, basal breadth 0.001 to 0.003.

Habitat.—Pacific, central area, Stations 266 to 268, surface; fossil in Barbados and Sicily.

3. Stylotrochus helianthus, n. sp.

Spongy framework of the whole disk irregular. Thirty to fifty very large, conical radial spines, about as long as the diameter of the disk, and at the base two to four times as broad as one mesh of the framework (without internal prolongations).

Dimensions.—Diameter of the disk 0.15 to 0.2; length of the radial spines 0.16 to 0.24, basal breadth 0.008 to 0.016.

Habitat.—Pacific, central area, Station 272, surface.

4. Stylotrochus rhabdostylus, Haeckel.

Spongy framework of the whole disk irregular. Four very large marginal primary spines crossed in two equatorial diameters, perpendicular one to another, and between them numerous (twelve to twenty or more) smaller secondary spines. The latter arise from the margin, whilst the former pierce the disk and are nearly united in its centre. All the spines are cylindrical, the smaller as broad as one mesh, the larger three to six times as broad.

Dimensions.—Diameter of the disk 0.2; length of the four main spines 0.15 to 0.3, breadth 0.01 to 0.02; length of the accessory spines 0.05 to 0.1, breadth 0.005.

Habitat.—Fossil in the rocks of Barbados.

5. Stylotrochus heteracanthus, Haeckel.

Spongy framework of the whole disk irregular. Ten very long needle-shaped marginal spines (symmetrically distributed), and between them numerous very fine, shorter, accessory, bristle-shaped spines.

Dimensions.—Diameter of the disk 0.16; length of the main spines 0.16, basal breadth 0.002; length of the secondary spines 0.03.

Habitat.—Mediterranean (Messina), surface.

Subgenus 2. Stylospongia, Haeckel, 1862, Monogr. d. Radiol., p. 473.

Definition.—Spongy framework of the disk in the inner part with concentric rings or spiral convolutions, in the outer part quite irregular.

6. Stylotrochus huxleyi, Haeckel.

Spongy framework of the disk in the inner part with five concentric rings, in the outer part quite irregular. Ten marginal spines, conical at the base, about as long as the radius of the disk, without inner piercing prolongations.

Dimensions.—Diameter of the disk 0.12; length of the radial spines 0.06, basal breadth 0.003.

Habitat.—Mediterranean (Messina), Haeckel.

7. Stylotrochus geddesii, n. sp. (Pl. 41, fig. 11).

Spongy framework of the disk in the inner part with four to eight concentric rings (or partially spiral convolutions), in the outer part quite irregular. Thirty to fifty pyramidal marginal spines of variable size, one-fourth to one-half as long as the radius of the disk, outer prolongations of inner piercing radial beams, which arise from various concentric rings. I call this interesting species, which is intermediate between Stylodictya and Stylotrochus, in honour of the morphologist Mr. Patrick Geddes of Edinburgh.

Dimensions.—Diameter of the disk 0.15 to 0.25; length of the radial spines 0.03 to 0.06, basal breadth 0.004 to 0.01.

Habitat.—Pacific, central area, Stations 270 to 274, in 2350 to 2925 fathoms.

Genus 259. Spongotrochus,^[298] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 844.

Definition.—Spongodiscida with numerous solid radial spines (five to ten or more), which are scattered over the whole surface and the margin of the disk, or regularly disposed on both sides of it.

The genus Spongotrochus differs from the foregoing and nearly allied genus by the distribution of the numerous radial spines. These are not confined to the margin of the disk, but also scattered on its whole surface, and sometimes symmetrically disposed on both its sides in a regular manner. Also in this genus the spongy framework is sometimes quite irregular (Spongotrochiscus), at other times in the middle part with enclosed concentric rings (Stylospongidium).

Subgenus 1. Spongotrochiscus, Haeckel, 1862, Monogr. d. Radiol., p. 463.

Definition.—Spongy framework of the whole disk irregular, without concentric rings or spiral convolutions.

1. Spongotrochus brevispinus, Haeckel.

Spongy framework of the whole disk irregular, everywhere equal. The whole surface of the disk covered with numerous short, needle-shaped, radial spines, about as long as the thickness of the disk, which is one-fifth of its diameter.

Dimensions.—Diameter of the disk 0.18; length of the radial spines 0.03 to 0.04, basal breadth 0.002.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

2. Spongotrochus multispinus, n. sp.

Spongy framework of the whole disk irregular, in the centre darker. The whole surface of the disk covered with numerous conical radial spines, about as long as the radius of the disk.

Dimensions.—Diameter of the disk 0.22; length of the radial spines 0.1, basal breadth 0.008.

Habitat.—Pacific, central area, Stations 271 to 274, surface.

3. Spongotrochus longispinus, Haeckel.

Spongy framework of the whole disk irregular, everywhere equal. Surface thorny. Twenty long, needle-shaped, radial spines, about as long as the diameter of the disk, symmetrically distributed in pairs on both flat sides of the disk, so that the opposite pairs lie in five equidistant, meridian planes (compare the figures).

Dimensions.—Diameter of the disk 0.2; length of the twenty radial spines 0.2, basal breadth 0.001.

Habitat.—Mediterranean (Messina), surface.

Subgenus 2. Stylospongidium, Haeckel, 1881, Prodromus, p. 460.

Definition.—Spongy framework of the disk in the inner part with concentric rings or spiral convolutions, in the outer part quite irregular.

4. Spongotrochus scutella, n. sp.

Spongy framework of the disk in the inner part with four to six concentric rings, in the outer part quite irregular. The whole surface of the disk covered with bristle-shaped radial spines, about half as long as the radius of the disk.

Dimensions.—Diameter of the disk 0.24; length of the radial spines 0.06, basal breadth 0.02.

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

5. Spongotrochus parma, n. sp.

Spongy framework of the disk in the inner part with five to eight spiral convolutions (or partly concentric rings), in the outer part quite irregular. Thirty to forty long, bristle-shaped, radial spines, about as long as the diameter of the disk, disposed on both flat sides of the disk, but not on the margin.

Dimensions.—Diameter of the disk 0.16; length of the radial spines 0.18, basal breadth 0.003.

Habitat.—South Atlantic, Station 325, surface.

Subfamily 3. Spongobrachida, Haeckel, 1881, Prodromus, p. 461.

Definition.—Spongodiscida with two or more (commonly three or four) spongy radial arms on the margin of the disk, situated in its equatorial plane (with or without a connecting patagium between the arms).

Genus 260. Spongolena,^[299] n. gen.

Definition.—Spongodiscida with two opposite spongy arms on the margin of the disk, without a connecting patagium.

The genus Spongolena opens the series of the Spongobrachida, or of the Spongodiscida provided with radial spongy arms on the margin of the disk. Spongolena is the most simple form of this subfamily, and bears only two simple opposite arms, without a connecting patagium. It corresponds to Amphibrachium (Porodiscida) and to Diplactura (Coccodiscida). Also there is no patagium. Spongolena may easily be confounded with Spongurus (compare my Prodromus, 1881, p. 461); but in the true Spongurus (an ellipsoid) the transverse section is circular, in Spongolena elliptical.

1. Spongolena rhopalura, n. sp.

Arms club-shaped, three times as long as broad, at the rounded distal end twice as broad as at the base, and twice as long as the diameter of the circular central disk. Surface nearly smooth.

Dimensions.—Radius of the arms (or the distance from the centre to the distal arm-end) 0.16, distal breadth 0.05, basal breadth 0.03.

Habitat.—Pacific, central area, Station 273, depth 2350 fathoms.

2. Spongolena spongura, n. sp.

Arms nearly cylindrical, twice as long as broad, and a little longer than the diameter of the elliptical central disk. Surface thorny, some longer bristle-shaped spines on the distal end of the arms. (Very similar to the ellipsoid Spongurus cylindricus, Monogr. d. Radiol., p. 465, Taf. xxvii. fig. 1, but differs in the compressed lenticular (not ellipsoidal) form of the central disk; the transverse section of the arm is elliptical, not circular.)

Dimensions.—Radius of the arms 0.1, breadth 0.04.

Habitat.—Pacific, central area, Station 270, depth 2925 fathoms.

3. Spongolena cypselura, n. sp.

Arms nearly triangular, not longer than broad, about half as large as the elliptical central disk, at the broader distal end with two very large, widely divergent lateral spines, and between them several smaller, like the tail of a swallow. Surface thorny.

Dimensions.—Radius of the arms 0.2, distal breadth (without spines) 0.15, basal breadth 0.07.

Habitat.—Pacific, central area, Station 272, depth 2600 fathoms.

Genus 261. Spongobrachium,^[300] Haeckel, 1881, Prodromus, p. 461.

Definition.—Spongodiscida with two opposite spongy arms on the margin of the disk, connected by a spongy patagium of different texture.

The genus Spongobrachium differs from the foregoing only in the loose spongy patagium, which envelops both opposite spongy arms. It corresponds to Amphymenium among the Porodiscida and to Amphiactura among the Coccodiscida.

1. Spongobrachium ellipticum, Haeckel.

Arms nearly square, scarcely as long and broad as the radius of the circular central disk, at the broader distal end truncated. Patagium complete, enveloping the whole disk with the arms, and forming a larger elliptical disk of looser framework. (In my Monograph, 1862, loc. cit., I had not distinguished the opposite darker arms, opposite in the longer axis of the elliptical disk, from the enveloping looser framework of the patagium. In larger specimens of the Challenger collection this distinction is very evident.)

Dimensions.—Radius of the arms 0.12, breadth 0.05; major axis of the elliptical patagium 0.24, minor 0.16.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

2. Spongobrachium lanceolatum, n. sp.

Arms club-shaped, twice as long as broad, at the distal end pointed, five times as long as the radius of the circular central disk. Patagium complete, enveloping the whole disk with the arms, and forming a larger lanceolate disk of looser framework. (Similar in form to Amphymenium pupula, Pl. 44, fig. 8, but with an irregular spongy framework and pointed ends.)

Dimensions.—Radius of the arms 0.16, breadth 0.05; major axis of the lanceolate patagium 0.32, minor axis 0.12.

Habitat.—Pacific, central area, Station 270, surface.

Genus 262. Rhopalodictyum,^[301] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830.

Definition.—Spongodiscida with three spongy arms on the margin of the circular or triangular disk, without a connecting patagium.

The genus Rhopalodictyum comprises those very common forms of Spongodiscida in which the margin of the disk is provided with three simple, free, spongy arms. It corresponds to Dictyastrum and Rhopalastrum among the Porodiscida, to Trigonactura among the Coccodiscida. The typical species of this genus is Rhopalodictyum abyssorum of Ehrenberg, the only species figured by him. His diagnosis of the genus was very insufficient, and agreed with that of his Dictyastrum (compare above the improved diagnosis of this genus, p. 526, and my Monograph, p. 466).

Subgenus 1. Rhopalodictya, Haeckel.

Definition.—Triangular shell regular, with three arms of equal size and equidistant.

1. Rhopalodictyum abyssorum, Ehrenberg.

Arms of equal size and equidistant, club-shaped, about as long as the diameter of the triangular central disk, and a little longer than the breadth of the pear-shaped rounded distal end. Surface rough.

Dimensions.—Radius of the arms 0.11, basal breadth 0.03, distal breadth 0.06.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; tropical zone, surface.

2. Rhopalodictyum truncatum, Ehrenberg.

Arms of equal size and equidistant, nearly square, with straight edges, towards the truncated end a little broader, about of the same diameter as the central triangular disk. This species is indicated by Ehrenberg only by the short diagnosis, "Radiis stellæ tribus apice truncatis." It is probably identical with his figure of Dictyastrum angulatum (loc. cit.). This latter name I have retained for the similar Porodiscid (above, p. 526), mainly because the genera Dictyastrum and Rhopalodictyum, according to the insufficient diagnosis of Ehrenberg, seem to be identical. (Compare my Monograph, 1862, p. 466.)

Dimensions.—Radius of each arm 0.13, basal breadth 0.09, distal breadth 0.1.

Habitat.—Tropical Pacific, Philippine Sea, Station 200, depth 250 fathoms; Atlantic (Mexican Gulf Stream).

3. Rhopalodictyum subacutum, Ehrenberg.

Arms of equal size and equidistant, club-shaped, three times as long as the diameter of the central disk, which equals the breadth of the thickened distal end; the latter is armed with a strong pyramidal terminal spine. (The diagnosis of Ehrenberg is "Radiis stellæ tribus, apice cuneatis subacutis.")

Dimensions.—Radius of the arms 0.2, basal breadth 0.04, distal breadth 0.07.

Habitat.—North Atlantic, surface and various depths; Greenland; Mexican Gulf Stream; Færöe Channel (John Murray).

4. Rhopalodictyum bifidum, n. sp.

Arms of equal size and equidistant, in the distal half forked, twice as long as the diameter of the central disk; both fork branches half as broad as the simple basal part, truncated at the distal end.

Dimensions.—Radius of the arms 0.16, basal breadth 0.08, distal breadth 0.04.

Habitat.—North Pacific, Station 237, surface.

Subgenus 2. Triactinosphæra, Dunikowski, 1882, Denkschr. d. k. Akad. d.

Definition.—Triangular shell bilateral or irregular, with three arms of different size or distance.

5. Rhopalodictyum zittelii, Haeckel.

Arms of different size and at unequal distances, one odd arm being a little shorter than the two paired arms; the odd angle between the latter is larger than the paired angles between them and the former. Arms club-shaped, their basal semi-cylindrical, half as broad as the spherical distal half, which bears a strong, conical, terminal spine. The discoverer of this remarkable, very old, Liassic species, Dunikowski, supposes that it is not a true Discoid, from the absence of a central disk; in my opinion the central disk (nearly spherical) has the same relation to the arms as in many other Discoidea, their equatorial plane is the same.

Dimensions.—Radius of the odd arm 0.18, of the paired arms 0.24; basal breadth 0.08, distal breadth 0.16.

Habitat.—Fossil in the Alpine Lias, Schafberg, near Salzburg, Dunikowski.

6. Rhopalodictyum elongatum, n. sp.

Arms of different size and at unequal distances, one odd arm being twice as long as both paired arms; the odd angle between the latter much larger than both equal paired angles. Arms nearly cylindrical, little flattened, three to six times as long as broad, with rounded blunt distal end.

Dimensions.—Radius of the arms 0.15 to 0.3, breadth 0.05.

Habitat.—Pacific, central area, Station 274, surface.

7. Rhopalodictyum curvatum, n. sp.

Arms of different size and at unequal distances, irregular, more or less curved, nearly cylindrical, five to ten times as long as broad, with rounded blunt distal end. (There were observed only two specimens of this remarkable irregular species; in one specimen all three arms were simple, in the other one odd arm forked. The length of the arms and the size of the angles between them seems to be very different and variable.)

Dimensions.—Radius of the arms 0.3 to 0.6 to 1.15, breadth 0.06 to 0.12.

Habitat.—Pacific, central area, Station 271, surface.

Genus 263. Dictyocoryne,^[302] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830.

Definition.—Spongodiscida with three spongy arms on the margin of the circular or triangular disk, connected by a spongy patagium of different texture.

The genus Dictyocoryne differs from the foregoing Rhopalodictyum only in the patagium, connecting the three spongy arms, and bears to it the same relation as in the Porodiscida Euchitonia does to Rhopalastrum. The typical species of this genus is Dictyocoryne profunda, the only species figured by Ehrenberg. After his insufficient diagnosis Dictyocoryne was identical with his Spongaster (compare my Monograph, p. 467); but as the type of this latter genus (Spongaster tetras) figured by him, 1872, had four crossed arms, we retain this genus here separate.

Subgenus 1. Dictyocorynula, Haeckel.

Definition.—Triangular shell regular, with three arms of equal size and equal distance.

1. Dictyocoryne profunda, Ehrenberg.

Arms of equal size and equidistant, club-shaped, in the outer circular half three times as broad as in the inner cylindrical half, and much larger than the small triangular central disk. Patagium complete, forming an equilateral triangle with rounded corners.

Dimensions.—Radius of the arms 0.14, basal breadth 0.025, distal breadth 0.07.

Habitat.—Pacific, Philippine Sea, depth 3300 fathoms, Ehrenberg; Station 198, depth 2150 fathoms; Station 274, depth 2750 fathoms.

2. Dictyocoryne tetradiscus, n. sp.

Arms of equal size and equidistant, club-shaped, their outer circular half is quite as large as the circular central disk, and is connected with it by the thin cylindrical inner half, which is scarcely one-fourth as broad. Patagium complete, forming an equilateral triangle with rounded corners and convex sides.

Dimensions.—Radius of the arms 0.16, basal breadth 0.02, distal breadth 0.08.

Habitat.—Pacific, central area, Stations 271 to 274, in 2350 to 2750 fathoms.

3. Dictyocoryne euchitonia, Haeckel.

Arms of equal size and equidistant, lanceolate, twice as long as broad in the distal part, and three times as long as the small circular central disk. Patagium complete, forming an equilateral triangle with pointed corners. (Very similar to Euchitonia köllikeri, Monograph, 1862, p. 511, Taf. xxxi. fig. 6, but quite spongy, not concentric.)

Dimensions.—Radius of the arms 0.15, basal breadth 0.03, distal breadth 0.06.

Habitat.—Mediterranean (Messina), Haeckel.

4. Dictyocoryne trigona, n. sp.

Arms of equal size and equidistant, lanceolate, three times as long as broad in the middle part, and as the diameter of the triangular central disk; their distal end armed with a strong conical radial spine. Patagium complete, forming an equilateral triangle with pointed corners.

Dimensions.—Radius of the arms 0.2, basal breadth 0.02, distal breadth 0.06.

Habitat.—North Atlantic, Canary Islands, surface.

Subgenus 2. Dictyocorynium, Haeckel.

Definition.—Triangular shell bilateral or irregular, with three arms of different sizes or at different distances.

5. Dictyocoryne charybdaea, Haeckel.

Arms at different distances, nearly equilateral triangular, scarcely half as long as the radius of the large circular central disk. Both paired arms touching at their bases, separated by a great distance from the opposite odd arm. Patagium complete, nearly pentagonal. (The illustration in my Monograph, in the coloured plate xxviii., is better than my description, as I had not exactly separated the arms from the patagium.)

Dimensions.—Radius of the arms 0.18, basal breadth 0.08.

Habitat.—Mediterranean (Messina), surface.

6. Dictyocoryne pentagona, Stöhr.

Arms at different distances, club-shaped, little longer than broad at their rounded distal end. Both paired arms smaller and more approximate than the opposite odd arm. Patagium complete, very large, enveloping the whole shell, and forming a pentagon with rectilinear base and transverse constriction, and with five rounded corners.

Dimensions.—Radius of the arms 0.1 to 0.15, middle breadth 0.04.

Habitat.—Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.

7. Dictyocoryne agrigentina, Stöhr.

Arms at different distances, club-shaped, about twice as long as broad, and smaller than the large triangular central disk. Both paired arms smaller and more approximate than the opposite odd arm. Patagium incomplete, enveloping only the basal half of the arms as a circular spongy disk of loose framework.

Dimensions.—Radius of the arms 0.18, basal breadth 0.05, distal breadth 0.08.

Habitat.—Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.

8. Dictyocoryne echinata, n. sp.

Arms unequal and at different distances, club-shaped, in the distal half twice as broad as in the basal half, three times as long as the small triangular central disk, at their distal end armed with one larger and several smaller conical spines. Both paired arms with touching bases, and only half as large as the doubly remote odd arm. Patagium incomplete, enveloping only the basal half of the arms, and forming a circular disk of looser framework. Surface thorny.

Dimensions.—Radius of the arms 0.15 to 0.2, basal breadth 0.03, distal breadth 0.06.

Habitat.—South Atlantic, Station 325, surface.

Genus 264. Spongasteriscus,^[303] Haeckel, 1862, Monogr. d. Radiol., p. 474 (sensu restricto).

Definition.—Spongodiscida with four spongy arms on the margin of the circular or quadrangular disk, crossed in two equatorial diameters, without a connecting patagium.

The genus Spongasteriscus (in the restricted definition here stated) exhibits on the margin of the disk four spongy arms, which form either a regular or a bilateral cross. It corresponds to Stauralastrum and Myelastrum among the Porodiscida, to Astractura among the Coccodiscida.

Subgenus 1. Spongasteriscinus, Haeckel.

Definition.—Cross formed by the four arms regular, rectangular, with equal-sized and equidistant arms.

1. Spongasteriscus ovatus, n. sp.

Arms at equal distances, forming a regular, rectangular cross, egg-shaped, with a broader rounded distal end, one and a third times as long as broad, and three times as long as the radius of the central disk; in the latter three to four concentric rings.

Dimensions.—Radius of the arms 0.1, greatest breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225.