Shell nut-shaped, tuberculate, without external sagittal stricture. Pores circular, not numerous. Basal plate with four large collar pores. Feet large, cylindrical, three to four times as long as the shell, strongly curved and divergent.

Dimensions.—Shell 0.05 long, 0.07 broad; feet 0.15 to 0.2 long.

Habitat.—Fossil in Barbados.

Subgenus 2. Tristylospyrium, Haeckel.

Definition.—Feet forked or branched.

5. Tristylospyris furcata, n. sp.

Shell subspherical, rough, with slight sagittal stricture. Pores subregular circular. Basal plate with three large collar pores. Feet cylindrical, three to four times as long as the shell, strongly curved and divergent, at the distal end forked, with two short (sometimes ramified) branches.

Dimensions.—Cephalis 0.08 long, 0.09 broad; feet 0.2 to 0.3 long.

Habitat.—South Atlantic (off Patagonia), Station 318, surface.

6. Tristylospyris ramosa, n. sp. (Pl. 52, fig. 23).

Shell subspherical, tuberculate, with a prominent sagittal ring. Pores irregular roundish. Basal plate with three large pores. Feet large, straight, widely divergent, about twice as long as the shell, prismatic, irregularly branched. (Compare the following species.)

Dimensions.—Shell 0.08 in diameter; feet 0.15 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

7. Tristylospyris tripodiscium, n. sp. (Pl. 52, fig. 22).

Shell subovate, tuberculate, very similar to the preceding species. It differs from this in the very different size of the irregular pores and the greater breadth of the pedal branches. The basal plate in a complete specimen (observed afterwards from the base) exhibited four large collar pores of the usual form, whilst in the similar preceding species it had three pores. In the similar Tripodiscium sphærocephalum (Pl. 52, fig. 21) the basal mouth is quite simple and open.

Dimensions.—Shell 0.09 long, 0.1 broad; feet 0.12 long.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 444. Cephalospyris,^[62] Haeckel, 1881, Prodromus, p. 441 (sensu emend.).

Definition.—Zygospyrida with three basal feet and two large apical openings or coryphal holes, one on each side of the ring-apex. No true horns.

The genus Cephalospyris comprises some few Tripospyrida of very peculiar shape, differing from all other Zygospyrida in the possession of two large apical holes or coryphal apertures, lying on each side of a latticed sagittal septum, which is formed by the upper part of the sagittal ring. The sagittal stricture is deep, with a complete primary ring. The vertical axis of the slender ovate shell is much greater than the transverse. The network is very delicate, with very small and numerous triangular or polygonal pores. The central capsule encloses peculiar concrements (Pl. 96, fig. 28).

1. Cephalospyris cancellata, n. sp. (Pl. 83, fig. 10).

Shell slender ovate, two and a half times as long as broad, with deep sagittal stricture and complete ring. Network very delicate, with very small and numerous, irregular polygonal pores. The two large apical holes are separated by a latticed triangular sagittal septum, the apex of which represents a rudimentary horn. Basal plate with two large collar holes. Three feet slightly curved, divergent, about half as long as the breadth of the shell; the caudal foot slender, much thinner than the two stout pyramidal pectoral feet.

Dimensions.—Shell 0.32 long, 0.13 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Cephalospyris ovata, n. sp.

Shell slender, ovate, twice as long as broad, with deep sagittal stricture and complete ring. Network very delicate, with very small and numerous triangular pores (on both poles intermingled with irregular polygonal pores). The two large apical holes are separated by a latticed triangular sagittal septum, the upper edge of which is concave and bears two rudimentary horns. Basal plate with four large collar holes. Three feet latticed, slightly curved, convergent, scarcely one-eighth as long as the breadth of the shell. The central capsule filled up by concrements.

Dimensions.—Shell 0.32 long, 0.16 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Cephalospyris triangulata, n. sp. (Pl. 96, fig. 28).

Shell ovate, one and a half times as long as broad, with deep sagittal stricture and complete ring. Network very delicate and regular, with small triangular pores of equal size. The two large apical holes are separated by a latticed semilunar septum, the upper edge of which is concave, and bears two rudimentary horns. Basal plate with three large collar holes (?). Three feet latticed, conical, nearly parallel and vertical (the caudal curved), about half as long as the breadth of the shell. The ovate central capsule contains peculiar amyloidal concentric concrements.

Dimensions.—Shell 0.2 long, 0.14 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subfamily 2. Dipospyrida, Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida dipoda, with two descending lateral basal feet (probably corresponding to the pectoral feet of Cortina).

Genus 445. Dipospyris,^[63] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two simple free basal feet and one apical horn.

The genus Dipospyris and the following five genera represent together the interesting subfamily of Dipospyrida, which always bear two opposite lateral feet only. Therefore in this bipedal group the biradial or bilateral type of the Spyroidea is particularly expressed. Such bipedal forms never occur in the Cyrtoidea. The topographical relation of the two lateral feet to the rods of the collar-plate, and to the cortinar pores separated by these, leaves no doubt that they correspond to the pectoral feet of Cortina and Tripospyris, and therefore that the Dipospyrida have originated from the Tripospyrida by loss of the caudal foot. Dipospyris is the simplest form of the Dipospyrida, with two simple free feet.

1. Dipospyris bipes, n. sp.

Shell thorax-shaped, smooth, with deep sagittal stricture, two vaulted bosoms, and subregular circular pores. Basal plate with two large collar pores only. Horn and feet equal, conical, straight, about as long as the shell; the feet widely divergent.

Dimensions.—Shell 0.08 long, 0.12 broad; horn and feet 0.1 to 0.15 long.

Habitat.—Fossil in Barbados.

2. Dipospyris mystax, Haeckel.

Shell elliptical spinulate, with slight collar stricture and large subregular circular pores. Basal plate with three pores (?) Horn small conical, oblique, shorter than the shell. Feet slender conical, longer than the shell, slightly curved, divergent. At the base of the columella, between the two feet, a small rudiment of the last caudal foot is visible.

Dimensions.—Shell 0.06 long, 0.1 broad; horn 0.02, feet 0.12 long.

Habitat.—Fossil in Barbados.

3. Dipospyris cubus, n. sp. (Pl. 83, fig. 18).

Shell box-shaped, subcubical, papillate, without external sagittal stricture, with numerous subregular circular pores. Basal plate with three very large collar pores, surrounded by a circle of smaller pores. Apical horn short and thick, scarcely half as long as the shell. Feet of the same form, longer than the shell, widely divergent.

Dimensions.—Shell 0.08 long, 0.11 broad; horn 0.03 long, feet 0.14 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Dipospyris chelifer, n. sp. (Pl. 85, fig. 3).

Shell elliptical, compressed, nodose, with deep sagittal stricture and irregular roundish pores. Basal plate with three pores (?). Apical horn stout, conical, twice to four times as long as the shell (often much longer than in the figured specimen). Feet scarcely longer then the shell, cylindrical, slightly curved towards one another.

Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.2 to 0.3 long, feet 0.1 to 0.15 long.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Dipospyris irregularis, n. sp. Pl. 85, fig. 2.

Shell subspherical, without external sagittal stricture, with small circular pores. Basal plate with four pores. Apical horn small, conical, shorter than the shell. Feet three to four times as long as the shell, cylindrical, irregularly curved, very variable in size and form.

Dimensions.—Shell 0.08 long, 0.1 broad; horn 0.02 to 0.04 long, feet 0.2 to 0.3 long.

Habitat.—Central Pacific, Stations 266 to 268, depth 2700 to 2900 fathoms.

6. Dipospyris sigmopodium, n. sp.

Shell violin-shaped, thorny, with deep sagittal stricture and irregular roundish pores. Basal plate with four collar pores. Horn straight, conical, about as long as the shell. Feet twice as long, cylindrical, markedly divergent, S-shaped, curved.

Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.06 long, feet 0.2 long.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; also fossil in Barbados.

7. Dipospyris forcipata, n. sp. (Pl. 85, fig. 1).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four larger and a circle of six to ten smaller pores. Horn cylindrical, straight, two to three times as long as the shell. Feet three to five times as long as the shell, cylindrical, semicircular, with convergent and crossed distal ends. (If these ends grow together, Gamospyris arises.)

Dimensions.—Shell 0.08 long, 0.11 broad; horn 0.15 to 0.2 long, feet 0.2 to 0.4 long.

Habitat.—Central Pacific, Stations 263 to 268, depth 2600 to 3000 fathoms.

Genus 446. Brachiospyris,^[64] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two simple free basal feet, without apical horn.

The genus Brachiospyris differs from the preceding Dipospyris, its ancestral form, only in the absence of the reduced apical horn, and therefore bears to it a similar relation to that which the hornless Tristylospyris, among the Tripospyrida, bears to the horned Tripospyris. Brachiospyris may therefore also be derived from Tristylospyris by loss of the caudal foot.

1. Brachiospyris ocellata, Haeckel.

Shell nut-shaped, thorny, with slight sagittal stricture and irregular roundish pores. Basal plate with four large and four alternate pairs of smaller pores. Two feet cylindrical, straight, divergent, two to three times as long as the shell.

Dimensions.—Shell 0.08 long, 0.11 broad; feet 0.2 to 0.3 long.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms; also fossil in Barbados.

2. Brachiospyris diacantha, n. sp. (Pl. 95, fig. 5).

Shell nut-shaped, tuberculate, compressed in the sagittal axis, convex on the frontal face, concave on the sagittal face, with a slight sagittal stricture; with large irregular roundish pores. Basal plate with three very large pores. Two feet cylindrical, curved, S-shaped, about twice as long as the shell.

Dimensions.—Shell 0.06 long, 0.09 broad; feet 0.1 to 0.15 long.

Habitat.—Western Tropical Pacific (Philippine Sea), Station 206, depth 2100 fathoms.

Genus 447. Dendrospyris,^[65] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two free lateral feet, forked or branched like a tree. Apex with a horn.

The genus Dendrospyris differs from its ancestral form Dipospyris in the ramification of the two large lateral feet, which descend from the base of the shell, and are usually very large and stout, sometimes simply forked.

1. Dendrospyris stylophora, Haeckel.

Shell nut-shaped, thorny, with subregular circular pores. Basal plate with four pores. Apical horn and the two divergent feet straight, cylindrical, larger than the shell, forked at the distal end. (The size and number of the fork-branches is variable; the horn is sometimes simple. In some specimens a rudimentary remnant of the lost caudal foot is visible.)

Dimensions.—Shell 0.08 long, 0.09 broad; horn and feet 0.1 to 0.12 long.

Habitat.—Fossil in Barbados.

2. Dendrospyris dirrhiza, Haeckel.

Shell nut-shaped, spiny, very similar to the preceding species. It differs from that mainly in the growth of the cylindrical feet, which are not straight and divergent, but more or less curved and convergent; their distal ends are sometimes simply forked, sometimes repeatedly dichotomous. The size and form of the apical horn are also very variable.

Dimensions.—Shell 0.06 long, 0.08 broad; horn and feet 0.07 to 0.09 long.

Habitat.—Fossil in Barbados.

3. Dendrospyris bibrachiata, Haeckel.

Shell nut-shaped, smooth, with sharp stricture and numerous very small circular pores. Apical horn and the two feet very large and stout, straight, prismatic, with irregular lateral branches on their edges, twice to four times as long as the shell (The horn in the Ehrenberg's figure is broken off.) This species is closely allied to Tripospyris tribrachiata.

Dimensions.—Shell 0.05 long, 0.06 broad; horn and feet 0.1 to 0.2 long.

Habitat.—Fossil in Barbados.

4. Dendrospyris furcata, n. sp.

Shell subspherical, tuberculate, with irregularly roundish pores. Basal plate with two large pores. Apical horn simple, conical, as long as the shell. Feet cylindrical, twice as long, in the proximal half parallel, vertical, in the distal half with two stout divergent equal fork-branches, one of which is directed dorsally, the other ventrally.

Dimensions.—Shell 0.07 long, 0.08 broad; horn 0.06 long, feet 0.1 to 0.15 long.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

5. Dendrospyris polyrrhiza, n. sp. (Pl. 85, fig. 8).

Shell subspherical, rough, with subregular circular pores. Basal plate with three pores (?). Apical horn simple, conical, half as long as the shell. Feet cylindrical twice to three times as long as the shell, semicircular, with a strong conical tooth in the middle of their outer convex edge; their distal ends convergent, divided into a bunch of numerous short irregular branches.

Dimensions.—Shell 0.7 long, 0.08 broad; horn 0.03 long, feet 0.15 to 0.25 long.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

6. Dendrospyris ramosa, n. sp.

Shell nut-shaped, spiny, with irregular roundish pores. Basal plate with three pairs of pores. Apical horn cylindrical, spinulate, twice to three times as long as the shell. Feet as long as the horn, S-shaped, widely divergent, irregularly branched, with widely distant pointed branches.

Dimensions.—Shell 0.08 long, 0.12 broad; horn and feet 0.2 to 0.3 long.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

7. Dendrospyris arborescens, n. sp. (Pl. 85, fig. 9).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four central larger and ten to twelve peripheral smaller pores. Apical horn cylindrical, twice as long as the shell, in the distal half spinulate or tuberculate. Feet about three times as long as the shell, cylindrical, nearly vertical, in the distal half irregularly branched, with dense bunches of aggregated blunt branches.

Dimensions.—Shell 0.07 long, 0.09 broad; horn and feet 0.12 to 0.18 long.

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

Genus 448. Dorcadospyris,^[66] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two free lateral feet armed with a series of secondary spines. Apex with a horn.

The genus Dorcadospyris and the closely allied Stephanospyris differ from the other Dipospyrida in the development of a series of secondary spines on the convex outer margin of the two large curved lateral feet, which therefore appear semipinnate. In some species this peculiar armature attains an extraordinary size, whilst the shell itself is very small, as in Dorcadospyris dinoceras (Pl. 85, fig. 4).

1. Dorcadospyris dentata, n. sp. (Pl. 85, fig. 6).

Shell subspherical, tuberculate with small regular circular pores. Basal plate with four larger pores. Apical horn three to four times as long as the shell, slender conical, smooth. Feet more or less convexly curved towards one another; the distal ends not crossed. In the convex edge of each arm a series of five to ten smooth conical teeth, not longer than the shell. This common species is very variable and often asymmetrical; the figured specimen is an asymmetrical one, in which the two arms exhibit different curves; in the normal form both arms have the same curve, now more, now less convex.

Dimensions.—Shell 0.06 long, 0.08 broad; horn 0.2, feet 0.03 long.

Habitat.—Central Pacific, Stations 267 to 274, depth 2350 to 2925 fathoms.

2. Dorcadospyris antilope, n. sp. (Pl. 85, fig. 5).

Shell subspherical, tuberculate, with small regular circular pores. Basal plate with four larger pores. Apical horn four to six times as long as the shell, straight, cylindrical, smooth. Feet of the same length, crescentic or nearly semicircular, with crossed distal ends. On the convex edge of each foot a series of twelve to fifteen smooth conical teeth, partly longer than the shell. (Very variable in size and curvature of the feet, and number of their teeth.)

Dimensions.—Shell 0.09 long, 0.11 broad; horn and feet 0.4 to 0.6 long.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

3. Dorcadospyris lunulata, n. sp.

Shell subspherical spinulate, nearly of the same shape as in the preceding species, but with a short conical horn (scarcely as long as the shell); the feet are much mere slender, crescentic, and bear twenty to thirty smaller smooth conical teeth (shorter than the shell). The distal ends of the feet are crossed.

Dimensions.—Shell 0.08 long, 0.09 broad; horn 0.06 long, feet 0.03 to 0.06 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Dorcadospyris decussata, n. sp. (Pl. 85, fig. 7).

Shell subspherical, smooth, very similar to that of the two preceding species. Horn small conical, about as long as the shell. Feet more than semicircular, more strongly curved than in any other species, each with four to eight small conical teeth, shorter than the shell; distal ends crossed. (In this species also, besides the normal symmetrical form, there often occurs an asymmetrical form of the two feet; one of these frequent anomalies is shown in fig. 7.)

Dimensions.—Shell 0.06 long, 0.08 broad; horn 0.05, feet 0.2 to 0.5 long.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

5. Dorcadospyris dinoceras, n. sp. (Pl. 85, fig. 4).

Shell subspherical, tuberculate, with subregular circular pores. Basal plate with four larger central and eight to twelve smaller peripheral pores. Horn about as long as the shell, in the basal half prismatic, smooth, in the distal half ovate or strobiliform, spiny. Feet very large and strongly curved, together nearly heart-shaped, four to six times as long as the shell. Each foot bears on its outer convex side a series of fifteen to twenty or more strong conical teeth, which are again spinulate, perpendicular to the foot, and longer than the shell.

Dimensions.—Shell 0.08 long, 0.09 broad; horn 0.07 long, feet 0.3 to 0.5 long.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 449. Gamospyris,^[67] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two simple lateral feet, forming a ring by union.

The genus Gamospyris and the similar Stephanospyris differ from all other Spyroidea in the possession of a large basal ring, placed in the frontal plane of the shell. This ring has been produced by concrescence of the distal ends of the two large curved lateral feet of Dipospyris.

1. Gamospyris circulus, n. sp. (Pl. 83, fig. 19).

Shell subspherical, tuberculate, with subregular circular pores. Basal plate with four larger collar pores. Apical horn pyramidal, about as long as the shell. The connected feet form together a circular or nearly circular smooth ring, the diameter of which is three to four times as great as that of the shell.

Dimensions.—Shell 0.08 long, 0.09 broad; diameter of the arm-ring 0.25 to 0.33.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Gamospyris annulus, n. sp.

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four large central and a circle of eight to twelve small peripheral pores. Apical horn conical, twice as long as the shell. The connected arms form together an elliptical smooth ring, which is five times as long and three times as broad as the shell.

Dimensions.—Shell 0.07 long, 0.09 broad; ring 0.33 long, 0.26 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 450. Stephanospyris,^[68] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two lateral feet bearing a series of secondary spines and forming a ring by union.

The genus Stephanospyris exhibits the same peculiar armature of the semipinnate lateral feet as its ancestral genus Dorcadospyris, but differs from it in the concrescence of the distal ends of the feet, to form a complete foot-ring. The former therefore bears to the latter the same relation that Gamospyris does to Dipospyris.

1. Stephanospyris cordata, n. sp. (Pl. 85, fig. 10).

Shell subspherical, tuberculate, with small regular circular pores. Basal plate with four larger pores. Apical horn cylindrical, three times as long as the shell, with three to four verticils of teeth. The connected feet form a heart-shaped ring, four times as long and three times as broad as the shell. Each foot bears on the outer convex edge four to six stout conical teeth, shorter than the shell. Distal ends crossed and prominent.

Dimensions.—Shell diameter 0.1; length of the arm-ring 0.4, breadth 0.3.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Stephanospyris verticillata, n. sp. (Pl. 85, fig. 11).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with numerous small pores. Apical horn cylindrical, four to six times as long as the shell, with six to ten verticils of teeth. The connected feet form a circular ring, the diameter of which is four times as great as that of the shell. Each foot bears ten to twelve conical teeth, about as long as the shell. Distal ends not crossed and not prominent.

Dimensions.—Diameter of the shell 0.1, of the arm-ring 0.4.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Stephanospyris excellens, n. sp. (Pl. 83, fig. 20).

Shell subspherical, tuberculate, with regular circular pores. Basal plate with numerous small pores. Apical horn cylindrical, twice as long as the shell, with eight verticils of teeth. The connected feet form an ovate ring, which is three times as long and two and a half times as broad as the shell. Each foot bears eight conical spinulate teeth, about as long as the shell. The crossed and prominent distal ends bear two parallel vertical teeth.

Dimensions.—Diameter of the shell 0.1, of the arm-ring 0.2 to 0.3.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subfamily 3. Tetraspyrida, Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida tetrapoda, with four descending basal feet, two of which are opposite in the sagittal plane (an odd caudal and an odd sternal foot), whilst the two others are paired lateral or pectoral feet.

Genus 451. Tetraspyris,^[69] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with four basal feet crossed in pairs (two sagittal and two lateral). Apex with a horn.

The genus Tetraspyris and the following closely allied Tessarospyris represent together the small subfamily of Tetraspyrida, characterised by the possession of four descending basal feet, three of which correspond to the three original feet of the ancestral genera Cortina and Tripospyris, whilst the fourth in an odd anterior or sternal foot, produced by anterior prolongation of the basilar segment of the sagittal ring. Here, therefore, two opposed feet lie in the sagittal plane (a caudal and a sternal foot), whilst the two others are the paired lateral or pectoral feet, as also in Stephanium and Stephaniscus, p. 965. The Tetraspyrida ought not to be confounded with the Therospyrida (sixth subfamily), in which the four feet have another signification.

Subgenus 1. Tetrarrhabda, Haeckel, 1881, p. 429.

Definition.—Feet simple, not branched nor forked.

1. Tetraspyris stephanium, n. sp. (Pl. 95, fig. 6).

Shell nut-shaped, tuberculate, with deep sagittal stricture and small roundish pores; three pairs of larger pores on each side of the ring. Basal plate with four large collar pores. Apical horn stout conical, half as long as the shell. Two pectoral feet somewhat longer than the two sagittal feet, one and a half times as long as the shell. All four feet straight, three-sided prismatic, strongly divergent.

Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.04 long, feet 0.08 to 0.12 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Tetraspyris cubica, n. sp.

Shell nearly cubical, smooth, with slight sagittal stricture and small polygonal pores; some larger pores on both sides of the ring. Basal plate with four large collar pores. Apical horn and the four feet of equal size and form, about as long as the shell, cylindrical in the basal, spindle shaped in the distal half.

Dimensions.—Shell 0.09 diameter; horn and feet 0.1 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.

Subgenus 2. Tetracorethra, Haeckel, 1831, Prodromus, p. 429.

Definition.—Feet branched or forked.

3. Tetraspyris tetracorethra, n. sp. (Pl. 53, figs. 19, 20).

Shell campanulate, tuberculate, with deep sagittal stricture and irregular polygonal pores; two pairs of larger pores at the flattened occipital face (fig. 20). Basal plate with four large collar pores. Apical horn very long, thirty to forty times as long as the shell, slender three-sided prismatic, straight, at the distal end irregularly branched, besom-shaped. Four basal feet half as thick as the horn, eight to twelve times as long as the shell, bristle-shaped, irregularly curved and branched, divergent, at the distal end besom-shaped. Central capsule very large; the enclosed small campanulate part sends out through the four collar pores four very long club-shaped basal lobes, half as long as the feet; each lobe contains a large oil-globule (fig. 19).

Dimensions.—Shell 0.036 diameter; horn 1 to 1.5 mm. long, feet 0.3 to 0.4 long.

Habitat.—Central Pacific, Station 270, surface.

4. Tetraspyris calcarata, n. sp.

Shell campanulate, smooth, very similar to that of the preceding species, but differing in the following characters:—the two inferior occipital pores are four times (in the preceding twice) as large as the two superior; the apical horn bears at its distal end only three simple branches; the sternal foot is smaller than the three others, arises higher, is more divergent and curved, and bears at its base a large horizontal conical spur.

Dimensions.—Shell 0.035 diameter; horn 1 to 1.2 long, feet 0.2 to 0.3 long.

Habitat.—Central Pacific, Station 266, surface.

5. Tetraspyris scoparia, n. sp.

Shell campanulate, rough, very similar to the two preceding species, but differing in the following characters:—the four occipital pores are of nearly equal size; the apical horn is simple, not branched; the four feet are forked near the base, so that apparently eight feet diverge, each in the distal half richly branched, besom-shaped.

Dimensions.—Shell 0.038 diameter; horn 1 to 1.1 long, feet 0.4 to 0.5 long.

Habitat.—Central Pacific, Station 268, surface.

Genus 452. Tessarospyris,^[70] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with four basal feet crossed in pairs (two sagittal and two lateral). Apex without horn.

The genus Tessarospyris differs from the preceding Tetraspyris, its ancestral genus, in the absence of the apical horn, and therefore bears to it the same relation that Tristylospyris does to Tripospyris.

1. Tessarospyris clathrobursa, n. sp. (Pl. 53, fig. 8).

Shell nearly ovate, strongly compressed, smooth, one and a half times as long as broad, with deep sagittal stricture in the basal half. Pores very small and numerous, irregularly roundish. Basal plate with four very large triangular holes, two larger (posterior) cardinal, and two smaller (anterior) jugular pores; above the latter (on the frontal face) two large mental pores. Two pectoral feet large, half as long as the shell, at the base fenestrated, vertical, and parallel. Two sagittal feet much smaller, nearly horizontal, pyramidal (the caudal larger than the sternal foot). Two longitudinal pectoral ribs arise on the frontal face.

Dimensions.—Shell 0.21 long, 0.14 broad; lateral feet 0.1, sagittal feet 0.02.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Tessarospyris nuciformis, n. sp.

Shell nut-shaped, papillate, with deep sagittal stricture. Pores irregular roundish, on both sides of the ring three to six times as large as on the lateral sides. Basal plate with four large pores. Two pectoral feet cylindrical curved, twice as long as the shell and as the two sagittal feet; the caudal is much stronger than the sternal foot.

Dimensions.—Shell 0.06 long, 0.09 broad; lateral feet 0.1, sagittal feet 0.05 long.

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

3. Tessarospyris seminulum, Haeckel.

Shell subspherical, smooth, with slight sagittal stricture and small circular pores; some larger pores on both sides of the ring. Basal plate with two large (lateral) pores only. Four feet nearly equal, short, conical, divergent, scarcely one-fourth as long as the shell.

Dimensions.—Shell 0.06 long, 0.08 broad; feet 0.016 long.

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

Subfamily 4. Hexaspyrida, Haeckel.

Definition.—Zygospyrida hexapoda, with six descending basal feet; three of these are primary (one odd caudal and two paired pectoral feet), the other three are secondary, opposed diametrically to the former and alternating with them (one odd sternal and two paired tergal feet).

Genus 453. Hexaspyris,^[71] n. gen.

Definition.—Zygospyrida with six basal feet and one apical horn.

The genus Hexaspyris and the two following closely allied genera represent together the peculiar subfamily of Hexaspyrida, and differ from the other Zygospyrida in the possession of six descending basal feet; three of these are the three original, perradial, or primary basal feet of Cortina, Cortiniscus, Plagoniscus, Plectaniscus, Tripospyris, &c.; the other three, usually opposed to the former diametrically, are secondary or interradial; an odd sternal foot (opposed to the odd caudal) and two paired tergal feet (opposed to the two paired pectoral).

Subgenus 1. Hexaspyridium, Haeckel.

Definition.—Feet simple, not branched nor forked.

1. Hexaspyris alterna, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture and irregular polygonal pores; on each side of the stricture two pairs of larger square annular pores. Basal plate also with four larger collar pores. Apical horn twice as long as the shell, conical. Three primary feet (the apical and the two pectoral) slender, curved, as long as the horn; three secondary feet (the sternal and the two tergal) are half as long as the former and more highly inserted; all six feet strongly divergent, cylindrical, pointed.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.15 long, feet 0.08 to 0.14 long.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

2. Hexaspyris setigera, Haeckel.