Subfamily 2. Spongotrochida, Haeckel, 1881, Prodromus, p. 461

Definition.—Spongodiscida with a circular disk, the margin of which is armed with solid radial spines, situated in the equatorial plane (rarely also on both sides of the disk with radial spines).

Genus 255. Spongolonche, Haeckel, 1881, Prodromus, p. 461.

Definition.—Spongodiscida with two solid marginal spines, opposite in one equatorial diameter of the disk.

The genus Spongolonche opens the series of the Spongotrochida, or of those Spongodiscida in which the margin of the disk is armed with solid radial spines, situated in the equatorial plane. Spongolonche possesses only two such spines, opposite in one equatorial diameter of the disk; it corresponds therefore to Stylocyclia among the Coccodiscida, to Xiphodictya among the Porodiscida.

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, 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.

Spongechinus neumayri, Dunikowski, 1882, Denskchr. d. k. Akad. d. Wiss. Wien, xlv. p. 28, Taf. v. fig. 59.

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, 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, 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.

Spongotrochus arachnius, Haeckel, 1862, Monogr. d. Radiol., p. 464.

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.

Spongotrochus craticulatus, Stöhr, 1880, Palæontogr., vol. xxvi. p. 118, Taf. vi. fig. 12.

? Spongodiscus aculeatus, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 246.

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.

Spongosphæra rhabdostyla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 256, Taf. xxvi. figs. 1, 2.

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.

Spongotrochus heteracanthus, Haeckel, 1862, Monogr. d. Radiol., p. 464.

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.

Stylospongia huxleyi, Haeckel, 1862, Monogr. d. Radiol., p. 473, Taf. xxviii. fig. 7.

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. , fig. 11).

Stylospongidium geddesii, Haeckel, 1881, Atlas (pl. xli. 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, 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.

Spongotrochus brevispinus, Haeckel, 1862, Monogr. d. Radiol., p. 462, Taf. xxvii. figs. 4, 5.

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.

Spongotrochus longispinus, Haeckel, 1862, Monogr. d. Radiol., p. 463, Taf xxvii. figs. 2, 3.

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.

Spongotrochus ehrenbergii, Bütschli, 1882, L. N. , Taf. xxvi. figs. 1a, 1b.

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.