Legion III. NASSELLARIA, (continued 10)

Dimensions.—Cephalis 0.035 long, 0.03 broad; thorax 0.15 long, 0.1 broad.

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

Genus 567. Anthocyrtium,^[184] n. gen.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) without thoracic ribs, with numerous terminal feet around the mouth (twelve to fifteen or more). Cephalis free, with an apical horn.

The genus Anthocyrtium has been derived from the two preceding genera by further multiplication of the terminal feet, the number of which is at least twelve to fifteen, often twenty or more. It may be that some species have arisen directly from Patagospyris by loss of the sagittal ring.

Subgenus 1. Anthocyrtarium, Haeckel.

Definition.—Feet of the peristome-corona divergent, their basal distance less than their terminal distance.

1. Anthocyrtium chrysanthemum, n. sp. (Pl. 62, fig. 14).

Shell smooth, with distinct collar stricture. Length of the two joints = 3 : 7, breadth = 4 : 9. Cephalis hemispherical, with small, circular pores, and a large, straight, cylindro-conical horn, about as long as the shell. Thorax campanulate, hemispherical, with six to eight transverse rows of squarish pores, increasing in size downwards. Mouth little constricted, with twelve to fifteen divergent, curved, slender feet, about as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09 broad.

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

2. Anthocyrtium centaurea, Haeckel.

Anthocyrtis mespilus, var. major, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. vi. fig. 5.

Shell smooth, with sharp collar stricture. Length of the two joints = 2 : 6, breadth = 3 : 7. Cephalis hemispherical, with irregular, roundish pores, and a very large pyramidal horn, longer than the shell, with contorted edges. Thorax hemispherical, with six to eight transverse rows of regular, circular pores of equal size. Mouth little constricted, with fifteen to twenty divergent, curved, slender feet, about as long as the shell.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.07 broad.

Habitat.—Fossil in Barbados.

3. Anthocyrtium anthemis, n. sp.

Shell papillate, with obliterated collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis hemispherical, with very small and scarce pores, and a conical horn of the same length. Thorax conical, as long as broad, with conical papillæ, and eight to ten transverse rows of roundish pores, gradually increasing in size downwards. Mouth scarcely constricted, with fifteen to twenty divergent, straight, conical feet, half as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.09 broad.

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

4. Anthocyrtium collare, Haeckel.

Anthocyrtis collaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 8.

Shell rough, conical, with obliterated collar stricture. Length of the two joints = 3 : 5, breadth = 4 : 7. Cephalis conical, with a pyramidal horn of the same length, and with two transverse rows of rather oblong, narrow pores. Thorax truncate, conical, in the lower part thorny, with six to eight transverse rows of regular, circular pores, increasing in size downwards.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.05 long, 0.07 broad.

Habitat.—Fossil in Barbados.

5. Anthocyrtium adonis, n. sp. (Pl. 62 fig. 20).

Shell rough, with sharp collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 12. Cephalis subspherical, with very small circular pores, and a very long, straight cylindrical, horn, twice to three times as long as the shell. Thorax inflated, ovate, or subspherical, with small regular, circular, hexagonally-framed pores. Mouth strongly constricted, half as broad as the thorax, with fifteen to twenty divergent, broad, lamellar, rectangular feet, as long as the thorax, and so densely placed that their margins come in contact with one another.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Central Pacific, Station 263 to 268, depth 2650 to 3000 fathoms.

6. Anthocyrtium anemone, n. sp.

Shell spiny, with sharp collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 4. Cephalis subspherical, with a conical horn of half the length, hyaline, without pores. Thorax spiny, pear-shaped, inflated, with small and numerous, regular, circular pores. Mouth constricted, half as broad as the thorax, with twelve to fifteen divergent, slender, conical, denticulate feet, half as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.14 long, 0.12 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil in Barbados.

Subgenus 2. Anthocyrtonium, Haeckel.

Definition.—Feet of the peristome-corona parallel, vertical; their basal and apical distances equal.

7. Anthocyrtium campanula, n. sp. (Pl. 62, fig. 17).

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis spherical, with a conical horn of the same length. Thorax campanulate, thin-walled, with delicate network of regular, hexagonal pores and thin bars. Mouth little constricted, with twenty to twenty-four parallel, vertical, lanceolate feet, about as long as the cephalis.

Dimensions.—Cephalis 0.03 diameter, thorax 0.09 long, 0.1 broad.

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

8. Anthocyrtium reticulatum, Haeckel.

Thyrsocyrtis reticulata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 10.

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis hemispherical, with a prismatic, denticulate horn of the same length, and small, irregular pores. Thorax campanulate, thorny, thin-walled, with delicate network of irregular, polygonal pores. Mouth little constricted, with twelve (or more) small, parallel, vertical, triangular feet, shorter than the cephalis.

Dimensions.—Cephalis 0.015 long, 0.02 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Fossil in Barbados.

9. Anthocyrtium leptostylum, Haeckel.

Anthocyrtis leptostyla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 1.

Shell thorny, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 4. Cephalis hemispherical, with small, scarce pores and a slender conical horn of the same length. Thorax spiny, with regular, circular, quincuncial pores. Mouth constricted, half as broad, with twelve to eighteen slender, parallel, vertical feet, about as long as the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.1 long, 0.08 broad.

Habitat.—Central Pacific, Stations 266 to 270, depth 2550 to 2925 fathoms; also fossil in Barbados.

10. Anthocyrtium hispidum, Haeckel.

Anthocyrtis hispida, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. viii. fig. 2.

Anthocyrtis hispida, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 30.

Shell thorny, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 5. Cephalis hemispherical, hyaline, with few very small pores, or without any; with a stout conical horn of twice the length. Thorax spiny, with regular, circular, hexagonally-framed pores (half as broad as the bars between them). Mouth wide open, scarcely constricted, with twelve to fifteen parallel, vertical, broad, lamellar, rectangular feet, reaching nearly the length of the thorax.

Dimensions.—Cephalis 0.02 to 0.03 long, 0.03 to 0.05 broad; thorax 0.07 to 0.09 long, 0.1 to 0.12 broad.

Habitat.—Central Pacific, Stations 263 to 265, depth 2650 to 3000 fathoms; also fossil in Barbados.

11. Anthocyrtium turris, n. sp.

Shell thorny, very similar to Calocyclas turris, Ehrenberg (1875, loc. cit., Taf. xviii. fig. 7), but without fenestrated abdomen. Collar stricture deep. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis subspherical, hyaline, without pores, with a stout conical horn of twice the length. Thorax nearly spherical, spiny, with regular, circular, quincuncial pores. Mouth little constricted, with fifteen to twenty parallel, vertical, broad, lamellar, rectangular feet, about as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.1 broad.

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

12. Anthocyrtium doronicum, n. sp. (Pl. 62, fig. 18).

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 3. Cephalis hemispherical, with small, circular pores and a stout conical horn of twice the length. Thorax campanulate, subcylindrical, with regular, circular, quincuncial pores, three to four times as broad as the bars. Mouth scarcely constricted, with twenty-four to thirty vertical, nearly parallel, little curved feet, which are about half as long as the shell, broad, lamellar, rectangular, and in close contact with their edges.

Dimensions.—Cephalis 0.025 long, 0.035 broad, thorax 0.12 long, 0.1 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subgenus 3. Anthocyrturium, Haeckel.

Definition.—Feet of the peristome-corona convergent, their basal distance greater than their apical distance.

13. Anthocyrtium pyrum, n. sp. (Pl. 62, fig. 12).

Shell smooth, with obliterated collar stricture. Length of the two joints = 2 : 7, breadth = 3 : 8. Cephalis hemispherical, with a small, bristle-shaped horn of half the length. Thorax inflated, subglobose, with regular, circular, quincuncial pores and thin bars. Mouth constricted, only half as broad, with fifteen to twenty small, triangular, convergent feet, shorter than the cephalis. (In another specimen the feet were twice as long, stronger and more convergent, than in the one figured.)

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.8 broad.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

14. Anthocyrtium setosum, Haeckel.

Anthocyrtis setosa, Haeckel, 1862, Monogr. d. Radiol., p. 311.

? Lithopera setosa, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B., B. iv. fig. 23.

Shell spiny, with sharp collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis hemispherical, with a conical horn of the same length and some accessory spines. Thorax campanulate, with subregular, circular pores. Mouth little constricted, with twenty to thirty small, triangular, convergent feet, about as long as the cephalis. (In Ehrenberg's incomplete figure they are mostly broken off.)

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.04 long, 0.06 broad.

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

15. Anthocyrtium ehrenbergii, Haeckel.

Anthocyrtis ehrenbergii, Stöhr, 1880, Palæontogr., vol. xxvi. p. 100, Taf. iii. fig. 21, a, b.

Shell smooth, with obliterated collar stricture. Length of the two joints = 3 : 10, breadth = 2 : 8. Cephalis subcylindrical, with an excentric, stout, pyramidal horn of the same length. Thorax bottle-shaped, with small, regular, circular pores of equal size. Mouth little constricted, with twenty to thirty small, triangular, convergent feet, about half as long as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.1 long, 0.08 broad.

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

16. Anthocyrtium zanguebaricum, Haeckel.

Anthocyrtis zanguebarica, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ix. fig. 12.

Shell smooth, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 2 : 7. Cephalis subspherical, with an excentric conical horn of the same length. Thorax slender, ovate or bottle-shaped, with irregular, roundish pores increasing in size downwards. Mouth little constricted, with twelve to fifteen small, triangular, convergent feet, about half as long as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.1 long, 0.07 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.

17. Anthocyrtium ficus, Haeckel.

Anthocyrtis ficus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 3.

Shell rough, with obliterated collar stricture. Length of the two joints = 2 : 12, breadth = 3 : 10. Cephalis conical, with a large, cylindrical horn, pyramidal at the base, about as long as the thorax. Thorax subovate, truncate, papillate, with small, regular, circular, quincuncial pores of the same breadth as the bars. Mouth constricted, two-thirds as broad as the thorax, with fifteen to twenty strongly convergent, lamellar, rectangular or sword-shaped feet, nearly as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.12 long, 0.1 broad.

Habitat.—Fossil in Barbados.

18. Anthocyrtium flosculus, n. sp. (Pl. 62, fig. 19).

Anthocyrtis flosculus, Haeckel, 1881, Prodromus et Atlas, pl. lxii. fig. 19.

Shell ribbed, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 4. Cephalis hemispherical, with small, circular pores and a large cylindrical horn, twice as long as the thorax and half as broad at the base as the cephalis. Thorax subovate, truncate, with twenty-four to thirty longitudinal ribs and alternating rows of circular pores. Mouth constricted, two-thirds as broad as the thorax, with twenty-four to thirty slender, convergent feet, which are as long as the entire shell, with their edges in close contact and their distal ends pointed.

Dimensions.—Cephalis 0.03 long, 0.05 broad; thorax 0.12 long, 0.12 broad.

Habitat.—Central Pacific, Stations 265 to 274, depth 2350 to 2925 fathoms.

Genus 568. Anthocyrtidium,^[185] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethophormida, (vel Dicyrtida multiradiata aperta) without thoracic ribs, with numerous (twelve to fifteen or more) subterminal feet, which are separated from the constricted mouth by a ring of lattice-work. Cephalis free, with an apical horn.

The genus Anthocyrtidium has been derived from the preceding Anthocyrtium by further growth and constriction of the peristome, which becomes separated from the subterminal corona of feet by a more or less broad ring of lattice-work.

1. Anthocyrtidium cineraria, n. sp. (Pl. 62, fig. 16).

Shell campanulate, smooth, with obliterated collar stricture. Length of the two joints = 5 : 11, breadth = 3 : 13. Cephalis subcylindrical-ovate, with a conical straight horn of half the length. Thorax hemispherical, inflated, nearly twice as broad as the constricted mouth. Pores subregular, circular, double-contoured. Above the mouth, separated from it by two rows of pores, a corona of twelve to fifteen short conical feet, which are directed downwards, slightly curved, and as long as the cephalic horn.

Dimensions.—Cephalis 0.05 long, 0.03 broad; thorax 0.11 long, 0.13 broad.

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

2. Anthocyrtidium ligularia, n. sp. (Pl. 62, fig. 15).

Shell campanulate, rough, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a slender, conical, slightly curved horn, about as long as the shell. Thorax hemispherical, three times as broad as the cephalis, nearly twice as broad as the constricted mouth, which is prolonged into a prominent smooth ring. Above the mouth, separated from it by one row of pores, a corona of twelve to fifteen slender linear feet, which are slightly curved, divergent, and emarginate at the truncated distal end.

Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.06 long, 0.09 broad.

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

3. Anthocyrtidium matricaria, n. sp.

Shell campanulate, rough, very similar to the preceding species, but differing in the straight, large, pyramidal horn of the cephalis (as long as the shell), and in the longer feet, which are twelve to fifteen in number, little curved at the distal end, pointed, and about as long as the shell. Length of the two joints = 2 : 6, breadth = 3 : 8. Differs from the similar Anthocyrtium centaurea, Ehrenberg (1875, loc. cit., Taf. vi. fig. 5), mainly in the prominent ring of the peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Fossil in Barbados.

Genus 569. Carpocanium,^[186] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) without thoracic ribs, with numerous terminal feet around the mouth (six to twelve or more). Cephalis hidden in the thorax, without apical horn.

The genus Carpocanium, very common, and rich in numerous living and fossil species, was formerly placed by me among the true Monocyrtida, since an external constriction is not visible (Monogr., 1862, p. 290). Afterwards (in 1879) Richard Hertwig demonstrated that the cavity of the ovate shell, externally simple, is divided by an internal transverse septum into two joints, the upper of which is the flat rudimentary cephalis (Organism. d. Radiol., p. 79; compare also Bütschli, 1882, loc. cit., p. 535). Indeed this septum, with four central crossed cortinar beams, is a true collar septum, and Carpocanium has been derived from Anthocyrtis or Desmospyris by reduction of the cephalis, which is very flat and perfectly hidden in the uppermost part of the thorax. The apical horn is lost. If the internal septum were to become lost, the genus would pass over into Carpocanistrum.

Subgenus 1. Carpocanarium, Haeckel.

Definition.—Peristome-corona composed of six feet (three primary perradial alternating with three secondary interradial).

1. Carpocanium calycodes, Stöhr.

Carpocanium calycodes, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii. fig. 8.

Shell urceolate, smooth, nearly twice as long as broad, with hemispherical vaulted cephalis. Length of the two joints = 3 : 16, breadth = 5 : 10. Pores regular, circular, as broad as the bars, quincuncially disposed in about five longitudinal series at each side. Mouth constricted, half as broad as the thorax. Peristome with six vertical, equilateral, triangular feet.

Dimensions.—Cephalis 0.015 long, 0.025 broad; thorax 0.08 long, 0.05 broad.

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

2. Carpocanium setosum, Haeckel.

Halicalyptra setosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 160, Taf. ii. fig. 12.

Shell ovate, truncate at the mouth, thorny, exactly as long as broad. Length of the two joints = 1 : 8, breadth = 3 : 9. Cephalis hidden, with very small pores. Thorax inflated, with regular, circular pores, twice as broad as the bars, in about ten longitudinal series at each side. Mouth constricted, half as broad as the thorax. Peristome with six vertical, parallel, broad, lamellar, rectangular feet, separated by equal internals, half as long as the shell.

Dimensions.—Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.09 broad.

Habitat.—Fossil in Barbados.

3. Carpocanium laeve, Ehrenberg.

Carpocanium laeve, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287.

Shell subspherical, smooth, equal in length and breadth, with little vaulted, cap-shaped cephalis. Length of the two joints = 1 : 6, breadth = 4 : 7. Pores regular, circular, twice as broad as the bars, in nine longitudinal rows. Mouth constricted, only one-third as broad as the thorax. Peristome with six strong conical feet, which are slightly curved and convergent.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.06 long, 0.07 broad.

Habitat.—Mediterranean (Greece); Tropical Atlantic, Station 348, depth 2450 fathoms.

4. Carpocanium lanceolatum, n. sp.

Shell subspherical, thorny, with perfectly hidden cephalis. Length of the two joints = 1 : 3, breadth = 1 : 3. Pores regular, circular, hexagonally framed, half as broad as the bars, in about sixteen longitudinal rows at each side. Mouth constricted, half as broad as the thorax. Peristome with six large lanceolate, vertical, lamellar feet, half as long as the shell.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.09 long, 0.09 broad.

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

Subgenus 2. Carpocanidium, Haeckel.

Definition.—Peristome-corona composed of nine feet (three primary perradial and six secondary interradial).

5. Carpocanium diadema, Haeckel.

Carpocanium diadema, Haeckel, 1862, Monogr. d. Radiol., p. 290, Taf. v. fig. 1.

Carpocanium diadema, R. Hertwig, 1879, Organism. d. Radiol., p. 79, Taf. viii. figs. 7, 7a, 8, 8a, 8b.

Shell ovate, with little vaulted cephalis. Length of the two joints = 1 : 8, breadth = 3 : 6. Pores regular, circular, in about twelve longitudinal rows, twice as broad as the bars. Mouth constricted, half as broad as the thorax. Peristome with nine vertical, equilateral, triangular feet.

Dimensions.—Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; many stations, surface.

6. Carpocanium cylindricum, n. sp.

Shell cylindrical, with hemispherical, flatly vaulted cephalis. Length of the two joints = 1 : 4, breadth = 3 : 3. Pores regular, circular, double-contoured, as broad as the bars, in about fifteen longitudinal series. Mouth constricted, two-thirds as broad as the thorax. Peristome with nine vertical, slender, triangular, pointed feet.

Dimensions.—Cephalis 0.02 long, 0.06 broad; thorax 0.08 long, 0.06 broad.

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

7. Carpocanium enneaphyllum, n. sp.

Shell slenderly ovate, at the mouth truncate, thorny, with hemispherical, vaulted cephalis. Length of the two joints = 1 : 6, breadth = 2 : 4. Pores regular, circular, hexagonally framed, as broad as the bars, in about thirteen longitudinal rows. Mouth constricted, about two-thirds as broad as the thorax. Peristome with nine broad, lamellar, vertical, nearly square feet, half as long as the shell, with small intervals.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.09 broad.

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

8. Carpocanium solitarium, Ehrenberg.

Carpocanium solarium, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 28.

Lithocampe solitaria, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 65.

Shell slenderly ovate, twice as long as broad, with hidden spherical cephalis, completely enclosed in the summit of the thorax. Length of the two joints = 1 : 6, breadth = 1 : 4. Pores small, regular, circular, as broad as the bars, in about eleven longitudinal rows. Mouth gradually constricted, half as broad as the thorax. Peristome with nine ovate blunt feet, which are as long as the cephalis, little curved and convergent.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.12 long, 0.07 broad.

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

9. Carpocanium gemmula, n. sp.

Shell subspherical, smooth, equal in length and breadth, with hemispherical vaulted cephalis. Length of the two joints = 2 : 7, breadth = 4 : 9. Pores small, regular, circular, twice as broad as the bars, in about twenty longitudinal rows. Mouth strongly constricted, only one-fourth as broad as the thorax. Peristome with nine conical feet, which are twice as long as the cephalis, curved, and so convergent that their distal ends come nearly in contact.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.07 long, 0.09 broad.

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

10. Carpocanium microdon, Ehrenberg.

Carpocanium microdon, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 30.

Shell broad, ovate, rough, with perfectly hidden cephalis. Length of the two joints = 2 : 9, breadth = 4 : 7. Pores very small and scarce, smaller than the bars between them, irregularly scattered. Mouth constricted, one-third as broad as the thorax. Peristome with nine short, triangular, pointed, convergent feet.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.07 broad.

Habitat.—Mediterranean (Crete), Atlantic (Canary Islands), Station 354, surface.

Subgenus 3. Carpocanobium, Haeckel.

Definition.—Peristome-corona composed of twelve or more feet.

11. Carpocanium trepanium, n. sp. (Pl. 52, fig. 18).

Shell subcylindrical, with flatly vaulted cephalis. Length of the two joints = 1 : 6, breadth = 3 : 4. Pores regular, hexagonal, four to six times as broad as the bars. Mouth little constricted, two-thirds as broad as the thorax. Peristome with eighteen to twenty-four large, slender, triangular, vertical feet.

Dimensions.—Cephalis 0.02 long, 0.06 broad; thorax 0.12 long, 0.08 broad.

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

12. Carpocanium hexagonale, n. sp. (Pl. 52, fig. 15).

Shell broadly ovate or subconical, with vaulted, cap-shaped cephalis. Length of the two joints = 2 : 7, breadth = 6 : 9. Thorax subglobular, truncate. Pores subregular, hexagonal, three to four times as broad as the bars. Mouth constricted, two-thirds as broad as the thorax. Peristome with twenty to twenty-five small, triangular, vertical feet.

Dimensions.—Cephalis 0.02 long, 0.05 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Tropical Atlantic, Station 347, surface.

13. Carpocanium petalospyris, n. sp. (Pl. 52, fig. 19).

Shell subspherical, smooth, with perfectly hidden cephalis. Length of the two joints = 1 : 6, breadth = 3 : 6. Pores regular, circular, hexagonally framed, twice as broad as the bars, in about sixteen longitudinal rows. Mouth slightly constricted, little narrower than the thorax. Peristome with twenty to twenty-four vertical, broad, lamellar feet, which are nearly as long as the shell, at the distal end truncate, and almost in contact at their edges.

Dimensions.—Cephalis 0.02 long, 0.05 broad; thorax 0.11 long, 0.12 broad.

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

14. Carpocanium polypterum, Haeckel.

Cryptoprora polyptera, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 17.

Carpocanium macropterum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 302.

Shell campanulate-conical, smooth, with perfectly hidden cephalis. Length of the two joints = 1 : 6, breadth = 4 : 6. Pores regular, circular, twice as broad as the bars, in about sixteen longitudinal rows. Mouth wide open, not constricted. Peristome with twenty to thirty vertical, slender, conical feet, about as long as the shell.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms (Pullen).

15. Carpocanium palmipes, n. sp.

Shell ovate, very thick-walled, smooth. Lower half of the subspherical cephalis hidden in the summit of the thorax, upper half free, with few small pores. Length of the two joints = 3 : 10, breadth = 3 : 10. Thorax foveolate, with oblong dimples, each of which encloses a small, circular, double-contoured pore, half as broad as the bars. Mouth little constricted, nearly as broad as the thorax. Peristome prolonged into a solid, cylindrical tube, nearly as long and as broad as the shell; the upper half of the tube is solid, the lower divided into from twelve to fifteen vertical, lamellar, pointed feet.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.1 broad.

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

16. Carpocanium peristomium, n. sp. (Pl. 52, figs. 16, 17).

Shell ovate, smooth, with perfectly hidden, flat cephalis (fig. 17). Length of the two joints = 2 : 10, breadth = 5 : 9. Pores small and very numerous, regular, circular, as broad as the bars, in about twenty longitudinal rows. Mouth little constricted. Peristome broad; in the upper half a hyaline, circular ring, in the lower half divided into from eighteen to twenty-four triangular, curved, little convergent feet.

Dimensions.—Cephalis 0.02 long, 0.05 broad; thorax 0.1 long, 0.09 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; many stations, at various depths.

17. Carpocanium coronatum, Ehrenberg.

Carpocanium coronatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. v. fig. 7.

Shell ovate, smooth, with perfectly hidden, subspherical cephalis. Length of the two joints = 2 : 9, breadth = 2 : 8. Pores small and very numerous, twice as broad as the bars, regular, circular, in about twenty longitudinal rows. Mouth little constricted, two-thirds as broad as the thorax. Peristome with twenty-five to thirty short, bristle-shaped feet, which are slightly curved, convergent, and in the upper half connected by a solid ring.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Fossil in Barbados.

18. Carpocanium dactylus, n. sp.

Shell slenderly ovate, twice as long as broad, with flat, perfectly hidden cephalis. Length of the two joints = 1 : 12, breadth = 4 : 8. Pores subregular, circular, as broad as the bars, in about twelve longitudinal rows, separated by prominent longitudinal ribs. Mouth constricted, two-thirds as broad as the thorax. Peristome with twelve large, lanceolate, lamellar, convergent feet.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.12 long, 0.08 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

19. Carpocanium irregulare, n. sp. (Pl. 52, fig. 14).

Shell irregular, roundish, subovate, with flat and oblique, perfectly hidden cephalis. Length of the two joints = 1 : 10, breadth = 3 : 9. Pores irregularly scattered, roundish, about as broad as the bars. Mouth wide open, not at all or little constricted. Peristome with twenty to thirty long, lamellar, pointed feet, which are irregularly curved and convergent.

Dimensions.—Cephalis 0.01 to 0.02 long, 0.03 to 0.04 broad; thorax 0.09 to 0.11 long, 0.08 to 0.09 broad.

Habitat.—Central Pacific, Station 263 to 274, surface, and at various depths.

20. Carpocanium verecundum, n. sp. (Pl. 52, figs. 12, 13).

Shell ovate, smooth, with flat, perfectly hidden cephalis (fig. 12). Length of the two joints = 1 : 9, breadth = 4 : 9. Pores subregular, circular, twice as broad as the bars, in about eighteen, partly interrupted, longitudinal rows, separated by prominent crests. Mouth little constricted. Peristome with twenty to twenty-four broad, lamellar, pointed feet, which are about as long as the shell, little curved, and convergent.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.09 long, 0.09 broad.

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

21. Carpocanium virgineum, n. sp. (Pl. 52, fig. 20).

Shell ovate, smooth, with flat perfectly hidden cephalis. Length of the two joints = 1 : 8, breadth = 3 : 9. Pores regular, circular, hexagonally framed, as broad as the bars, in about sixteen longitudinal rows on each side. Mouth little constricted. Peristome with eighteen to twenty-four very large, lamellar, pointed feet, which are longer than the shell, and so curved and convergent that their distal points come nearly in contact.

Dimensions.—Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.09 broad.

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

Subfamily 2. Sethophænida, Haeckel, 1881, Prodromus, p. 433.

Definition.—Anthocyrtida with the basal mouth of the shell fenestrated (vel Dicyrtida multiradiata clausa).

Genus 570. Sethophæna,^[187] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethophænida (vel Dicyrtida multiradiata clausa) with lateral apophyses. Cephalis with a horn.

The genus Sethophæna and the following Clistophæna form together the small subfamily of Sethophænida, comprising those Dicyrtida in which the thorax bears numerous radial appendages (four to six or more), and the mouth is closed by a lattice-plate. In Sethophæna the apophyses are lateral wings, as in Micromelissa, from which it may be derived by development of secondary wings, interpolated between the three primary wings.

1. Sethophæna tetraptera, n. sp.

Shell smooth, with deep collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 9. Cephalis subspherical, without horn. Thorax ovate, with rounded hemispherical base, and subregular, hexagonal pores. From its upper half (below the collar stricture) arise four divergent, conical, straight wings, of half the length, opposite in pairs in two meridional planes, perpendicular to one another (compare Tetralacorys, Pl. 65, figs. 4, 5).

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.09 broad.

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

2. Sethophæna hexaptera, n. sp. (Pl. 97, fig. 13).

Shell rough, pear-shaped, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 4. Cephalis hemispherical, with a conical horn of the same length. Thorax inflate, inversely ovate, nearly pear-shaped, with subregular, circular pores. From its upper half arise, by a broad base, six divergent, strong, conical wings, which are horn-like, curved downwards, and half as long as the thorax.

Dimensions.—Cephalis 0.025 long, 0.04 broad; thorax 0.09 long, 0.08 broad.

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

3. Sethophæna enneaptera, n. sp.

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 6, breadth = 1 : 3. Cephalis subspherical, with a stout conical horn of twice the length. Thorax inversely ovate, with pointed, conical, basal part, and irregular, roundish pores. From its middle part arise, by a broad triangular base, nine compressed, divergent wings, which are a little curved, slender, and about as long as the thorax.

Dimensions.—Cephalis 0.025 long, 0.03 broad; thorax 0.17 long, 0.1 broad.

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

4. Sethophæna polyptera, n. sp.

Shell thorny, with slight collar stricture. Length of the two joints = 1 : 10, breadth = 3 : 8. Cephalis flat, cap-shaped, without horn. Thorax pear-shaped, with hemispherical base and regular, circular pores. From its lower half (beyond the equator) arises a corona of numerous short conical wings (eighteen to twenty-four), which are a little curved, and divergent downwards, scarcely one-third as long as the thorax.

Dimensions.—Cephalis 0.015 long, 0.04 broad; thorax 0.15 long, 0.12 broad.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Genus 571. Clistophæna,^[188] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethophænida (vel Dicyrtida multiradiata clausa) with terminal apophyses. Cephalis with a horn.

The genus Clistophæna agrees with the preceding Sethophæna in the mouth of the thorax being closed by a lattice-plate. But the appendages of the thorax are terminal feet, not lateral wings; their number is commonly six or nine, rarely more. Clistophæna may be derived either from Tetrahedrina by interpolation of secondary feet between the three primary, or from Sethamphora by development of a basal lattice-plate closing the mouth.

1. Clistophæna rüstiana, n. sp. (Pl. 57, fig. 6).

Shell rough, with distinct collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 11. Cephalis hemispherical, with small, circular pores and a stout oblique horn three times the length, which is three-sided prismatic, and at the top denticulate. Thorax subconical, inflate, with regular, circular, quincuncial pores, increasing in size towards the base. Margin of the flat base, with six divergent, stout feet of the same prismatic form as the cephalic horn, with denticulate distal ends, about as long as the thorax. This elegant species is dedicated to Dr. Rüst of Freiburg, the discoverer of numerous fossil Radiolaria in the Liassic and Jurassic formations.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.11 broad.

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

2. Clistophæna hexolena, n. sp.

Shell smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 5. Cephalis subspherical, small, with a large, vertical, cylindrical horn, about as long as the shell, and small, circular pores. Thorax nearly three-sided pyramidal or tetrahedral, with three rounded edges and sub-regular, circular pores. Margin of the flat base with six conical, divergent, straight feet, somewhat shorter than the thorax. (Three on the corners, one on the middle of each side of the triangular base.)

Dimensions.—Cephalis 0.03 diameter, thorax 0.12 long, 0.14 broad.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

3. Clistophæna pyramidalis, n. sp.

Shell smooth, with slight collar stricture. Length of the two joints = 2 : 8, breadth = 3 : 10. Cephalis hemispherical, with a stout pyramidal horn of twice the length. Thorax six-sided pyramidal, with regular, circular pores of equal size, and six prominent, straight edges, which are prolonged into six divergent, pyramidal feet of half the length.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.1 broad.

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

4. Clistophæna armata, n. sp. (Pl. 57, fig. 7).

Shell spiny, with deep collar stricture. Length of the two joints = 4 : 18, breadth = 5 : 15. Cephalis subspherical, with small, circular, hexagonally-framed pores, and a stout, three-sided prismatic, cuspidate horn of the same length. Thorax pear-shaped, with regular, circular pores and three pairs of stout pyramidal wings, placed in the three primary meridional planes of the collar beams; three of them lie in the upper, and three in the lower third of the thorax. Margin of the flat base with nine cylindrical, somewhat club-shaped, divergent feet.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.18 long, 0.15 broad.

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

5. Clistophæna enneolena, n. sp.

Shell spiny, with sharp collar stricture. Length of the two joints = 4 : 20, breadth 5 : 16. Cephalis hemispherical, hyaline, with a stout conical horn of the same length and some small accessory horns. Thorax ovate, spiny, with subregular, circular pores. Margin of the vaulted base with nine divergent, conical feet, half as long as the thorax.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.2 long, 0.16 broad.

Habitat.—South Pacific, Station 296, depth 1825 fathoms.

6. Clistophæna polyolena, n. sp.

Shell smooth, conical, with obliterated collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 5. Cephalis hemispherical, with small, circular pores and two divergent conical horns (a major occipital and a smaller frontal horn). Thorax obtusely conical, with regular, hexagonal pores at the mantle, and circular pores in the basal plate, the margin of which bears eighteen vertical, parallel, conical feet, as long as the cephalis.

Dimensions.—Cephalis 0.015 long, 0.025 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

Family LXIV.—Sethocyrtida, n. fam.

Definition.—Dicyrtida eradiata. (Cyrtoidea with a two-jointed shell, divided by a transverse constriction into cephalis and thorax, without radial apophyses).

The family Sethocyrtida, composed of the Sethocorida and Sethocapsida of my Prodromus, comprises those Cyrtoidea in which the shell is two-jointed and bears no radial apophyses. The two subfamilies differ in the shape of the mouth, which in the Sethocorida is a simple wide opening, and in the Sethocapsida is closed by a lattice-plate. The former are here divided into eight, the latter into three genera.

Numerous living and fossil forms of Sethocyrtida were previously described by Ehrenberg, partly in his genera Dictyocephalus and Lophophæna, partly (intermingled with three-jointed and many-jointed forms) in the genera Eucyrtidium and Lithocampe. A larger number of new forms has been found in the Radiolarian ooze collected by the Challenger, and others fossil in Barbados. Many of these Sethocyrtida are common and widely distributed. When a new third joint is formed on their basal mouth, they pass over into Theocyrtida.

The cephalis is usually subspherical or hemispherical, and much smaller than the thorax, the form of which exhibits all possible intermediate stages between flat, discoidal, conical, cylindrical, and ovate forms. The wide open mouth becomes more and more constricted, and finally closed in the Sethocapsida. The majority of the Sethocyrtida may have been derived either from the Tripocyrtida, or from the Anthocyrtida by reduction and loss of the radial apophyses.

Synopsis of the Genera of Sethocyrtida.

I. Subfamily Sethocorida. Terminal mouth of the thorax a simple wide opening. Thorax conical or campanulate, gradually dilated. Shell simple, without mantle, 572. Sethoconus.

Shell double, with an arachnoid mantle, 573. Periarachnium.

Thorax discoidal, flatly expanded. Cephalis very large, without horn, 574. Sethocephalus.

Thorax cylindrical or ovate, with truncate, constricted or tubular mouth. Cephalis with a single horn. Mouth simple, 575. Sethocyrtis.

Mouth tubular, 576. Sethocorys.

Cephalis with two horns or a bunch of horns, 577. Lophophæna.

Cephalis without horn, 578. Dictyocephalus.

II. Subfamily Sethocapsida. Terminal mouth closed by a lattice-plate. Cephalis free, not hidden in the thorax. One horn, 579. Sethocapsa.

No horn, 580. Dicolocapsa.

Cephalis hidden in the upper part of the thorax. No horn, 581. Cryptocapsa.

I. Subfamily Sethocorida. Terminal mouth of the thorax a simple wide opening.

Thorax conical or campanulate, gradually dilated.

Shell simple, without mantle,

572. Sethoconus.

Shell double, with an arachnoid mantle,

573. Periarachnium.

Thorax discoidal, flatly expanded.

Cephalis very large, without horn,

574. Sethocephalus.

Thorax cylindrical or ovate, with truncate, constricted or tubular mouth.

Cephalis with a single horn.

Mouth simple,

575. Sethocyrtis.

Mouth tubular,

576. Sethocorys.

Cephalis with two horns or a bunch of horns,

577. Lophophæna.

Cephalis without horn,

578. Dictyocephalus.

II. Subfamily Sethocapsida. Terminal mouth closed by a lattice-plate.

Cephalis free, not hidden in the thorax.

One horn,

579. Sethocapsa.

No horn,

580. Dicolocapsa.

Cephalis hidden in the upper part of the thorax.

No horn,

581. Cryptocapsa.

Subfamily 1. Sethocorida, Haeckel, Prodromus, p. 430.

Definition.—Sethocyrtida with the basal mouth of the shell open (vel Dicyrtida eradiata aperta).

Genus 572. Sethoconus,^[189] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with conical or campanulate, gradually dilated thorax and wide open mouth. Cephalis with one or more horns.

The genus Sethoconus is the oldest and simplest form of the Sethocorida, or of those Dicyrtida in which the simple thorax bears no apophyses and has the mouth open and not closed by a basal lattice-plate. Probably all those eradiate Sethocorida have been derived either from triradiate Sethopilida (Lychnocanium), or from multiradiate Sethophormida (Sethophormis, Anthocyrtis ?) by loss of the radial ribs and feet. In Sethoconus the thorax is more or less conical, sometimes more campanulate, commonly smooth, in some species covered with spines. The cephalis is usually small, with rudimentary collar septum, at other times large, with distinct cortinar septum. Correspondingly, the genus may be divided into different groups, which here are enumerated as subgenera.

Subgenus 1. Conarachnium, Haeckel, 1881, Prodromus, p. 430. (= Ceratocyrtis, Bütschli), 1882, loc. cit., p. 536.

Definition.—Cephalis relatively large, with distinct collar septum and numerous pores. Thorax smooth.

1. Sethoconus trochus, Haeckel.

Eucyrtidium trochus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii, fig. 17.

Conarachnium trochus, Haeckel, 1881, Prodromus, p. 430.

Cephalis ovate, relatively large, with a pyramidal horn of the same length, and three pairs of large opposite pores, on each side of a vertical septum. Thorax wide, conical, about as long as broad, with nearly straight outlines; its pores regular, circular, hexagonally framed, of the same size as the cephalic pores.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Tropical Pacific, Stations 200 to 281, surface.

2. Sethoconus cucullaris, Haeckel.

Cornutella cucullaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 7.

Ceratocyrtis cucullaris, Bütschli, 1882, Zeitschr. f. wiss Zool., Bd. xxvi. p. 536, Taf. xxxiii. fig. 36, a., b.

Cephalis subspherical, thorny, relatively large, with a conical horn of the same length, and small circular pores. Thorax wide, conical, enveloping the lower hidden half of the cephalis, about as long as broad, with slightly convex outlines; its pores subregular, circular, half as broad as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.15 long, 0.14 broad.

Habitat.—Fossil in Barbados.

3. Sethoconus pileus, n. sp.

Cephalis subspherical, free, with distinct collar stricture, a conical oblique horn of the same length, and small, irregular, roundish pores. Thorax flatly conical, about half as long as broad, with straight outlines; its pores subregular, hexagonal, half as broad as the cephalis, with very thin bars.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.16 broad.

Habitat.—Central Pacific, Stations 262 to 274, surface.

4. Sethoconus ampliatus, Haeckel.

Cornutella ampliata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 5.

Ceratocyrtis ampliata, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 536.

Cephalis, hemispherical, thorny, with a conical horn of twice the length; it is separated from the thorax by a complete internal collar septum, but without external collar stricture. Thorax flatly conical, about half as long as broad, with straight outlines; its pores subregular, hexagonal, about as large as the cephalis, with thin bars.

Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.08 long, 0.18 broad.

Habitat.—Fossil in Barbados.

5. Sethoconus mitra, Haeckel.

Cornutella mitra, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 8.

Ceratocyrtis mitra, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 536.

Cephalis ovate, with slight collar stricture (not distinct enough in Ehrenberg's figure), with few large pores, and a conical stout horn of the same length. Thorax campanulate, conical, twice as long as broad, with slightly convex outlines; its pores subregular, roundish, increasing in size towards the mouth, the largest as broad as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.12 long, 0.07 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; fossil in Barbados.

6. Sethoconus rayianus, n. sp. (Pl. 58, fig. 6).

Conarachnium rayianum, Haeckel, 1881, Prodromus, p. 430.

Cephalis ovate, with obliterated collar stricture (but distinct internal septum), with small, irregular pores, and two to four divergent horns, which are longer than the cephalis, and two or three of which are forked. Thorax tent-shaped, conical, two-thirds as long as broad, with slightly concave outlines, and subregular, hexagonal pores, gradually increasing towards the mouth, the largest half as broad as the cephalis. This elegant species is dedicated to Dr. Ray, the discoverer of many rare Radiolarians in the Challenger collection.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.08 long, 0.12 broad.

Habitat.—Central Pacific, Stations 266 to 272, surface.

7. Sethoconus cervus, Haeckel.

? Eucyrtidium cervus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 21.

Conarachnium cervus, Haeckel, 1881, Prodromus, p. 430.

Cephalis subspherical, with slight collar stricture, small circular pores, and two to four divergent horns, one or two of which are forked. Thorax wide, conical, about as long as broad, with straight outlines and irregular, polygonal pores, gradually increasing towards the mouth; the largest as broad as the cephalis.

Dimensions.—Cephalis 0.015 long, 0.02 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Indian Ocean; Maldive Islands, surface (Haeckel); Zanzibar, depth 2200 fathoms (Pullen).

8. Sethoconus lophophæna, n. sp.

Conarachnium lophophæna, Haeckel, 1881, Prodromus, p. 430.

Cephalis subspherical, with distinct collar stricture, small circular pores, and numerous (twelve to sixteen) radial, bristle-shaped horns of different lengths. Thorax wide, conical, somewhat longer than broad, with slightly convex outlines, and subregular, hexagonal pores, increasing gradually in size towards the mouth; the largest twice as broad as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.2 long, 0.16 broad.

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

9. Sethoconus larvatus, Haeckel.

Lophophæna larvata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 10.

Dictyocephalus larvatus, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 535.

Cephalis subspherical, large, with sharp collar stricture, and numerous (five to ten or more) radial, conical (partly forked) horns of different lengths. Thorax wide, conical, somewhat broader than long, with straight outlines. Pores of both joints very irregular, roundish, of very different sizes and form.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Fossil in Barbados.

10. Sethoconus nassa, Haeckel.

Eucyrtidium nassa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 9.

Cephalis slenderly ovate, with sharp collar stricture, few scattered pores, and a very stout, pyramidal horn of the same length, which is surrounded at the base by three short, divergent, ascending spines (perhaps the remnants of the three cortinar rods of Eucecryphalus, &c. ?). Thorax slender, conical, with straight outlines, and small, dense, regular, circular pores of equal size.

Dimensions.—Cephalis 0.04 long, 0.02 broad; thorax 0.12 long, 0.08 broad.

Habitat.—Fossil in Barbados.

11. Sethoconus tabulatus, Haeckel.

Cycladophora tabulata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. iv. fig. 18.

Cephalis subspherical, with slight collar stricture, and numerous small, irregular pores, without horn, or with a small conical horn. Thorax slenderly conical, with straight outlines, and large, regular, hexagonal pores. Mouth truncate. (In the specimen I examined the thorax was longer and more conically dilated; the cephalis had a distinct small horn.)

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.06 broad.

Habitat.—North Atlantic, Antilles, depth 1600 fathoms (Ehrenberg); Station 347, depth 2250 fathoms.

Subgenus 2. Cornutellium (vel Ceratarachnium), Haeckel, 1881, Prodromus, p. 430.

Definition.—Cephalis very small, rudimentary, hyaline, without distinct collar septum, and without pores (or with scarce, rudimentary pores). Thorax smooth.

12. Sethoconus hexagonalis, Haeckel.

Cornutella trochus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 14.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the length. Thorax slenderly conical, or bottle-shaped, twice to three times as long as broad; in the lower half nearly cylindrical, with very thin, thread-like bars, and regular, hexagonal pores, increasing in size towards the mouth.

Dimensions.—Cephalis 0.005 diameter, thorax 0.12 long, 0.05 broad.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

13. Sethoconus verrucosus, Haeckel.

Cornutella verrucosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 16.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the length. Thorax slenderly conical, or bottle-shaped, with little convex outlines; three to four times as long as broad, papillate, with regular, circular pores, which are included by rhombic frames, and increase in size towards the mouth.

Dimensions.—Cephalis 0.004 diameter, thorax 0.12 long, 0.035 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms (Pullen).

14. Sethoconus orthoceras, n. sp. (Pl. 54, fig. 11).

Cornutella orthoceras, Haeckel, 1879, Atlas, loc. cit.

Cephalis very small, conical, hyaline, without pores, with a double internal stricture, and a very short, rudimentary horn. Thorax slenderly conical, with undulate outlines, three to four times as long as broad, with subregular, roundish pores, gradually increasing in size towards the mouth.

Dimensions.—Cephalis 0.02 long, 0.01 broad; thorax 0.16 long, 0.04 to 0.08 broad.

Habitat.—South Atlantic, Station 325, surface.

15. Sethoconus profundus, Haeckel.

Cornutella profunda, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B, Nr. B. iv. fig. 21.

Cornutella profunda, Bailey, 1856, Amer. Jour., vol. xxii. pl. i. fig. 23.

Cornutella profunda, Haeckel, 1862 Monogr. d. Radiol., p. 284.

Cephalis very small, spherical, hyaline without pores and internal stricture, with a very short, rudimentary horn. Thorax slenderly conical with straight outlines, three to four times as long as broad, with subregular, circular pores, gradually increasing in size towards the mouth.

Dimensions.—Cephalis 0.004 to 0.008 diameter, thorax 0.08 to 0.12 long, 0.03 to 0.04 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; at various depths.

16. Sethoconus trichostylus, Haeckel.

Cornutella trichostyla, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vi. fig. 2.

Cephalis very small, conical, hyaline, without pores, with a very long, bristle-shaped, spirally twisted horn, longer than the whole shell. Thorax slenderly conical, with straight outlines, and very small, regular, circular pores of nearly equal size, which are separated by broader bars and spirally ascending oblique crests (according to the figure).

Dimensions.—Cephalis 0.004 long, 0.002 broad; thorax 0.06 long, 0.04 broad.

Habitat.—North Pacific (California), depth 2600 fathoms.

17. Sethoconus longisetus, Haeckel.

Cornutella longiseta, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 15.

Cephalis very small, spherical, hyaline, without pores, with a very long, bristle-shaped horn, nearly as long as the shell. Thorax slenderly conical, rough, with straight outlines, and irregular, roundish pores, gradually increasing in size towards the mouth.

Dimensions.—Cephalis 0.01 diameter, thorax 0.09 long, 0.03 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms (Pullen).

18. Sethoconus gracilis, Haeckel.

Eucyrtidium gracile, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 15.

Cephalis small, subspherical, with few scarce pores, and a stout, pyramidal horn, of the same length. Thorax slenderly conical, three to four times as long as broad, with straight outlines, and very small and numerous circular pores of equal size.

Dimensions.—Cephalis 0.015 diameter, thorax 0.12 long, 0.04 broad.

Habitat.—Fossil in Barbados.

19. Sethoconus bimarginatus, n. sp. (Pl. 54, fig. 12).

Cornutella bimarginata, Haeckel, 1879, Atlas, loc. cit.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary, conical horn of the same length. Thorax slenderly conical, three times as long as broad, with undulated, little convex outlines, and irregular, roundish, double-contoured pores, arranged in nine longitudinal series, markedly increasing in size towards the mouth.

Dimensions.—Cephalis 0.01 diameter, thorax 0.16 long, 0.05 broad.

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

20. Sethoconus clathratus, Haeckel.

Cornutella clathrata, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 39a, b, c.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the length. Thorax slenderly conical, three to four times as long as broad, smooth, with curved axis and small, regular, circular pores, nearly equal in size. This common species differs from all others of the genus by the curvation of the axis of the shell, which is more or less crescentic, or curved like a cowherd's horn; it may, therefore, represent a peculiar genus, Sethodrepanum.

Dimensions.—Cephalis 0.003 to 0.006 diameter, thorax 0.08 to 0.16 long, 0.03 to 0.05 broad.

Habitat.—Cosmopolitan; Atlantic, Pacific, many stations; fossil in Barbados and Sicily.

Subgenus 3. Phlebarachnium, Haeckel (et Cladarachnium, Haeckel), 1881,

Definition.—Cephalis small, with very small pores, and internal collar septum. Thorax spiny or thorny.

21. Sethoconus facetus, n. sp. (Pl. 55, fig. 1).

Phlebarachnium facetum, Haeckel, 1881, Prodromus, p. 430.

Cephalis small, hemispherical, with distinct collar septum, the same network as the thorax, and numerous bristle-shaped horns of the same length. Thorax wide, conical, about as long as broad, with slightly convex outlines; its network extremity delicate, with very small and numerous, regular, hexagonal pores, disposed in numerous divergent, longitudinal series, which are convoluted somewhat spirally around the shell axis. Surface covered with thin, scattered, bristle-shaped spines, about as long as the cephalis.

Dimensions.—Cephalis 0.02 diameter, thorax 0.2 long, 0.22 broad.

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

22. Sethoconus anthocyrtis, n. sp. (Pl. 62, fig. 21).

Anthocyrtis sethoconus, Haeckel, 1879, Atlas, loc. cit.

Cephalis small, subspherical, with very small pores and numerous radial, bristle-shaped spines of the same length. Thorax wide, conical, about as long as broad, with parabolic outlines, its network very delicate, with subregular, hexagonal meshes. Surface with scarce, bristle-shaped spines (not represented in the figure). Mouth with a corona of numerous small, vertical spines.

Dimensions.—Cephalis 0.025 diameter, thorax 0.26 long, 0.24 broad.

Habitat.—North Pacific, Station 248, surface.

23. Sethoconus virgultus, n. sp.

Cladarachnium virgultum, Haeckel, 1881, Prodromus, p. 430.

Cephalis and thorax nearly of the same form and stricture as in Sethoconus facetus, but larger and wider, with the same delicate, hexagonal network (Pl. 55, fig. 1); it differs from the latter by the wider, more convex and campanulate form, but mainly by the armature of the surface, which is densely covered with thin, arborescent, bristle-shaped spines, irregularly branched, and four to eight times as large as the cephalis.

Dimensions.—Cephalis 0.02 diameter, thorax 0.32 long, 0.4 broad.

Habitat.—South Pacific, Station 288, surface.

24. Sethoconus setosus, n. sp.

Phlebarachnium setosum, Haeckel, 1881, Prodromus, p. 430.

Cephalis small, subspherical, with distinct collar septum, and the same network as the thorax, with numerous bristle-shaped horns of the same length. Thorax slenderly conical, twice as long as broad, with irregular, polygonal pores of little different sizes, and very thin bars. Surface covered with perpendicular, simple, bristle-shaped spines, about as long as the cephalis.

Dimensions.—Cephalis 0.02 diameter, thorax 0.12 long, 0.22 broad.

Habitat.—Central Pacific, Stations 266 to 272, surface.

25. Sethoconus venosus, n. sp. (Pl. 55, fig. 2).

Phlebarachnium venosum, Haeckel, 1881, Prodromus, p. 430, et Atlas, loc. cit.

Cephalis subspherical, with a stout prismatic horn twice the length, bearing three denticulate edges. The uppermost part of the thorax is supported by three diverging, radial beams arising from the deep collar stricture. Thorax wide, conical, nearly twice as long as broad, with slightly convex, thorny outlines; its delicate network is composed of very irregular, polygonal meshes of different sizes, separated by stronger bars, and of numerous very small polygonal pores separated by very thin bars inside the former. The central capsule of the figured specimen exhibited in the upper third of the thorax four large club-shaped lobes, which arose from a very small sphere enclosed in the cephalis and containing the nucleus.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.4 long, 0.3 broad.

Habitat.—Central Pacific, Station 271, surface.

Genus 573. Periarachnium,^[190] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with conical or campanulate, gradually dilated thorax, and widely open mouth. Primary lattice-shell enveloped by an external arachnoidal mantle. Cephalis with one or more horns.

The genus Periarachnium has been derived from those forms of the preceding Sethoconus, in which the conical thorax is covered with simple spines (Phlebarachnium) or branched spines (Cladarachnium). By communication of the branches of these spines a second outer shell is formed, which, like an arachnoidal mantle, envelops the inner primary shell.

1. Periarachnium periplectum, n. sp. (Pl. 55, fig. 11).

Cephalis hemispherical, separated from the thorax by a sharp collar stricture, from which arise three internal, diverging beams supporting its upper third. Thorax campanulate, conical, about as long as broad, with slightly convex outlines. The delicate lattice-work of the entire shell is double; the inner composed of subregular, hexagonal meshes; the outer of larger, irregular, polygonal meshes. The bars of the inner are much thicker than the thin threads of the outer. Both shells are connected by numerous bristle-shaped beams. The central capsule of the figured specimen exhibited in the upper part of the thorax three club-shaped lobes, which arose from a sphere enclosed in the cephalis and containing the nucleus.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.15 long, 0.12 broad.

Habitat.—Central Pacific, Station 271, surface.

Genus 574. Sethocephalus,^[191] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with discoidal, flatly expanded thorax. Cephalis large, without horn.

The genus Sethocephalus (formerly proposed under the name Platycryphalus) contains some few and rare Sethocorida, distinguished by the very large cephalis, the collar opening of which is wide open, not closed by cortinar beams, and surrounded by a very flat, nearly discoidal thorax, like the brim of a hat. It is possible that this peculiar genus has been derived from a Tricyrtid (Theocalyptra?) by loss of the original cephalis, and that the apparent large cephalis is the original thorax.

1. Sethocephalus eucecryphalus, n. sp. (Pl. 56, fig. 13).

Cephalis very large, campanulate-conical, with irregular, polygonal pores and thin bars. Thorax short, scarcely broader than the cephalis, beyond the sharp collar stricture expanded like the brim of a hat, with few rows of irregular, polygonal pores. (In the specimen figured the thorax was only half as broad as in another specimen found afterwards.)

Dimensions.—Cephalis 0.12 long, 0.09 broad; thorax 0.02 long, 0.12 broad.

Habitat.—South Pacific, Station 285, surface.

2. Sethocephalus platycryphalus, n. sp.

Platycryphalus sethodiscus, Haeckel, 1881, Prodromus, p. 430.

Cephalis large, hemispherical, with irregular square pores and thin bars. Thorax flatly conical, three to four times as broad as the cephalis, beyond the collar stricture expanded nearly discoidally, with a delicate network of small, subregular, hexagonal pores. (Similar in general form to Sethophormis aurelia, Pl. 55, fig. 3, but without any trace of collar beams or radial ribs.)

Dimensions.—Cephalis 0.04 long, 0.08 broad; thorax 0.04 long, 0.3 broad.

Habitat.—South Pacific, Station 289, surface.

Genus 575. Sethocyrtis,^[192] n. gen.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or subcylindrical thorax, the mouth of which is constricted, simple, without prominent hyaline peristome. Cephalis with an apical horn.

The genus Sethocyrtis and the three following nearly allied genera differ from the three preceding genera of Sethocorida in the form of the thorax, which is not gradually dilated, conical, but cylindrical or ovate, with more or less constricted mouth. Sethocyrtis may be derived from Anthocyrtis by loss of the terminal feet. Its mouth is quite simple, without tubular or annular peristome.

1. Sethocyrtis oxycephalis, n. sp. (Pl. 62, fig. 9).

Shell rough, subconical, with slight collar stricture. Length of the two joints = 4 : 9, breadth = 3 : 8. Cephalis ovate, with a pyramidal horn of half the length. Thorax campanulate, with regular, circular pores, twice as broad as those of the cephalis. Mouth constricted, scarcely half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 3000 fathoms.

2. Sethocyrtis cancrina, Haeckel.

Eucyrtidium cancrinum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 4.

Shell smooth, bottle-shaped, with obliterated collar stricture. Length of the two joints = 4 : 9, breadth = 2 : 7. Cephalis subcylindrical, with a stout conical horn of the same length, and sometimes a smaller accessory horn at its base. Thorax ovate, truncate, with regular, circular, quincuncial pores, twice as broad as those of the cephalis. Mouth little constricted, flat, nearly as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.02 broad; thorax 0.09 long, 0.07 broad.

Habitat.—Fossil in Barbados.

3. Sethocyrtis diomedis, n. sp.

Shell thorny, pear-shaped, with slight collar stricture. Length of the two joints = 3 : 16, breadth = 4 : 20. Cephalis hemispherical, with a conical horn of twice the length. Thorax inflate, ovate, truncate at both poles, with regular, circular pores, twice as broad as those of the thorax. Mouth constricted, flat, half as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.12 to 0.16 long, 0.16 to 0.2 broad.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

4. Sethocyrtis menelai, n. sp.

Shell spiny, pear-shaped, with sharp collar stricture. Length of the two joints = 3 : 15, breadth = 4 : 18. Cephalis subspherical, with a large, cylindro-conical horn, about as long as the whole shell. Thorax inflate, subspherical, truncate, with large, irregular, roundish pores, four to six times as large as those of the cephalis. Mouth constricted, flat, one-third as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.15 long, 0.18 broad.

Habitat.—Fossil in Barbados.

5. Sethocyrtis subacuta, Haeckel.

Eucyrtidium subacutum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 18.

Shell smooth, pear-shaped, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, with small, irregular pores and a rudimentary horn of half the length. Thorax ovate, with large, subregular, hexagonal pores and thin bars between them. Mouth constricted, flat, half as broad as the thorax, without prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Philippine Sea, depth 3300 fathoms (Ehrenberg).

6. Sethocyrtis pleuracantha, Haeckel.

Eucyrtidium pleuracanthum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 21.

Shell smooth, bottle-shaped, with distinct collar stricture. Length of the two joints = 2 : 4, breadth = 1 : 3. Cephalis slenderly ovate, with an excentric pyramidal horn of the same length. Thorax inflate, ovate, with irregular, roundish pores and thin bars between them. Mouth constricted, flat, half as broad as the thorax, without prominent peristome.

Dimensions.—Cephalis 0.04 long, 0.02 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Tropical Pacific, Stations 200, 225, 266, 274, &c., at various depths.

7. Sethocyrtis agamemnonis, n. sp. (Pl. 62, figs. 11, a, b).

Shell pear-shaped, rough, with sharp collar stricture. Length of the two joints = 2 : 10, breadth = 3 : 8. Cephalis subspherical, with very small pores and a small, pyramidal horn of half the length. Thorax inflate, ovate; in the uppermost part (beyond the collar stricture) with a ring of six to nine very large roundish pores, which are twice to four times as broad as the other irregular, roundish pores. (The shell is seen in fig. 11 from the apical pole, in fig. 11a with the cephalis, in fig. 11b without it, exhibiting the four central collar pores of the cortinar septum.) Mouth truncate, without prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.1 long, 0.08 broad.

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

8. Sethocyrtis cassis, Haeckel.

Cornutella cassis, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 38.

Cyrtocalpis cassis, Haeckel, 1862, Monogr. d. Radiol., p. 287.

Shell pear-shaped, smooth, with obliterated collar stricture. Length of the two joints = 4 : 13, breadth = 3 : 12. Cephalis ovate, with a conical horn of half the length. Thorax inflate, ovate, with subregular, circular, quincuncial pores, twice to three times as broad as the bars. Mouth constricted, truncate, two-thirds as broad as the thorax, without prominent peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.13 long, 0.12 broad.

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

Genus 576. Sethocorys,^[193] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or sub-cylindrical thorax, the mouth of which is constricted and prolonged into a ring-like peristome. Cephalis with an apical horn.

The genus Sethocorys differs from the preceding Sethocyrtis, its ancestral form, in the form of the constricted mouth, which is prolonged into a prominent, hyaline, tubular, or annular peristome.

1. Sethocorys achillis, n. sp. (Pl. 62, fig. 8).

Shell rough, pear-shaped, with distinct collar stricture. Length of the two joints = 4 : 8, breadth = 3 : 8. Cephalis ovate, with a stout pyramidal horn of half the length. Thorax nearly spherical, with regular, circular, quincuncial pores of the same breadth as the cephalic pores. Mouth constricted, half as broad as the thorax, with a broad, smooth, striated peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Cosmopolitan; Mediterranean (Corfu), Atlantic, Indian, Pacific; many stations, at various depths.

2. Sethocorys patrocli, n. sp.

Shell thorny, pear-shaped, with slight collar stricture. Length of the two joints = 4 : 12, breadth = 3 : 10. Cephalis ovate, with a pyramidal horn of twice the length. Thorax ovate, truncate at both poles, with regular, circular pores, twice as broad as the cephalic pores. Mouth constricted, half as broad as the thorax, with a broad, smooth, prominent peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.12 long, 0.1 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 3000 fathoms.

3. Sethocorys armadillo, Haeckel.

Eucyrtidium armadillo, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf ix. fig. 10.

Shell slenderly ovate, smooth, with deep collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 6. Cephalis ovate, at the apex thorny, with a conical horn of the same length. Thorax smooth, ovate, truncate, with small, regular, circular pores, disposed in from twelve to fifteen transverse rows of the same breadth as the cephalic pores. Mouth constricted, half as broad as the thorax, with a broad, hyaline, prominent peristome.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.06 broad.

Habitat.—Fossil in Barbados.

4. Sethocorys odysseus, n. sp. (Pl. 62, fig. 10).

Shell ovate, smooth, with obliterated collar stricture. Length of the two joints = 2 : 9, breadth = 4 : 8. Cephalis hemispherical, with a slender, conical horn of the same length. Thorax nearly spherical, with regular, circular pores, of the same breadth as the cephalic pores, quincuncially disposed. Mouth constricted, only one-third as broad as the thorax, with a broad, hyaline, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.08 broad.

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

5. Sethocorys amphora, Haeckel.

Lophophæna amphora, Stöhr, 1880, Palæontogr., vol. xxvi. p. 99, Taf. iii. fig. 11.

Shell ovate, mouth with distinct collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 4. Cephalis hemispherical, with a short conical horn of half the length. Thorax ovate, truncate, with small, regular, circular, quincuncial pores. Mouth constricted, half as broad as the thorax, with a narrow, prominent, hyaline peristome.

Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.07 long, 0.06 broad.

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

6. Sethocorys ajacis, n. sp.

Shell slenderly ovate, smooth, without external collar stricture, but with an internal septum. Length of the two joints = 1 : 3, breadth = 1 : 2. Cephalis conical, with a large pyramidal horn of twice the length, and sometimes with a smaller accessory horn at its base; its pores scarce, irregular. Thorax ovate, truncate, hyaline, in the greater part without pores, in the smaller part with from two to four transverse rows of small, circular pores only. Mouth constricted, with a large cylindrical, tubular, hyaline peristome, half as long as the shell.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.07 broad.

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

Genus 577. Lophophæna,^[194] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or subcylindrical thorax, the mouth of which is either truncate or constricted. Cephalis armed with several large horns.

The genus Lophophæna differs from the nearly allied Sethocorys and Dictyocephalus only in the armature of the large cephalis, which bears a group of large horns, often arranged in a corona of radial spines. Sometimes these spines are connected by anastomosing branches (like Arachnocorys).

Subgenus 1. Lophophænula, Haeckel.

Definition.—Horns of the cephalis simple, free, radial spines, neither branched nor connected.

1. Lophophæna galea, Ehrenberg.

Lophophæna galea orci, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin p. 245.

Lophophæna apiculata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 11.

? Cornutella spiniceps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 6.

Shell with slight collar stricture. Length of the two joints = 5 : 4, breadth = 5 : 6. Cephalis subglobular, with numerous bristle-shaped, radial spines, about as long as its radius. Thorax about the same size, truncate, conical, smooth, with wide open mouth. Pores in both joints of equal size, small, regular, circular.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.04 long, 0.06 broad.

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

3. Lophophæna radians, Ehrenberg.

Lophophæna radians, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 9.

? Lophophæna lynx, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 13.

Shell with slight collar stricture. Length of the two joints = 4 : 6, breadth = 4 : 5. Cephalis subglobular, with numerous, stout, conical, radial spines, about as long as its diameter. Thorax of about the same size, subcylindrical, smooth, truncate, with wide open mouth. Pores in both joints of equal size, small, regular, circular.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.05 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; also fossil in Barbados.

3. Lophophæna liothorax, n. sp.

Shell with distinct collar stricture. Length of the two joints = 4 : 10, breadth = 4 : 8. Cephalis subglobular, with large, circular, hexagonally-framed pores, and with numerous stout, conical, radial spines, about as long as its diameter. Thorax twice as long, ovate, smooth, truncate, with little constricted mouth, and with irregular, roundish pores, of very different sizes.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.1 long, 0.08 broad.

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

4. Lophophæna echinocephala, n. sp.

Shell with deep collar stricture. Length of the two joints = 4 : 8, breadth = 4 : 9. Cephalis subglobular, of the same shape as in the preceding species. Thorax thorny, inflate, nearly spherical, with a constricted mouth of half the breadth, and with irregular, roundish, double-contoured pores.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.09 broad.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Lophophænoma, Haeckel.

Definition.—Horns of the cephalis connected by anastomosing branches.

5. Lophophæna circumtexta, Haeckel.

Lophophæna radians, var., Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. figs. 7, 8.

Shell with slight collar stricture. Length of the two joints = 4 : 5, breadth = 4 : 5. Cephalis subglobular, with numerous conical, radial spines, about as long as its diameter, and at equal distances from the surface, connected by anastomosing branches. Thorax nearly cylindrical, smooth, little dilated towards the truncate, wide open mouth. Pores subregular, circular.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.05 long, 0.05 broad.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

Genus 578. Dictyocephalus,^[195] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or subcylindrical thorax, the mouth of which is more or less constricted, either truncate or with a ring-like peristome. Cephalis rounded, without horn.

The genus Dictyocephalus has originated probably from Sethocorys by reduction and loss of the apical horn. The mouth is more or less constricted, either simple, truncate (Dictyocryphalus), or provided with a prominent, broad, hyaline, annular peristome (Dictyoprora).

Subgenus 1. Dictyoprora, Haeckel, 1881, Prodromus, p. 430.

Definition.—Mouth of the thorax constricted, with a prominent, ring-like or tubular, hyaline peristome.

1. Dictyocephalus amphora, n. sp. (Pl. 62, fig. 4).

Shell smooth, thick-walled, subovate, with slight collar stricture. Length of the two joints = 5 : 9, breadth = 6 : 8. Cephalis large, obtusely conical, with numerous oblique pore-canals. Thorax inflate, with six to eight transverse rows of roundish pores, increasing in size towards the base. Mouth constricted, one-third as broad as the thorax, with an internal diaphragm and a narrow hyaline peristome.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Stations 265 to 272, depth 2425 to 2925 fathoms.

2. Dictyocephalus urceolus, n. sp.

? Eucyrtidium Mongolfieri, Bury, 1862, Polycystins of Barbados, pl. v. fig. 2.

Shell smooth, thick-walled, urceolate, with obliterated collar stricture. Length of the two joints = 5 : 12, breadth = 4 : 10. Cephalis campanulate, with numerous oblique pore-canals. Thorax inflate, with five or six transverse rows of roundish pores of equal size. Mouth constricted, nearly half as broad as the thorax, with a broad hyaline peristome.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.1 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

3. Dictyocephalus excellens, Haeckel.

Eucyrtidium excellens, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 2.

Shell annulate, thick-walled, urceolate, with slight collar stricture. Length of the two joints = 5 : 10, breadth = 4 : 7. Cephalis large, ovate-conical, with numerous oblique pore-canals. Thorax ovate, with ten to twelve transverse rows of regular, roundish pores, which are separated by prominent annular ribs. Mouth constricted, about half as broad as the thorax, with a broad hyaline peristome.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.1 long, 0.07 broad.

Habitat.—Fossil in Barbados.

4. Dictyocephalus ocellatus, Haeckel.

Dictyocephalus ocellatus, Haeckel, 1862, Monogr. d. Radiol., p. 297.

? Eucyrtidium ocellatum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 299.

Shell smooth, thick-walled, with deep collar stricture. Length of the two joints = 3 : 9, breadth = 4 : 7. Cephalis subspherical, with numerous oblique pore-canals. Thorax inflate, campanulate, hyaline, only with three or four remote transverse rows of circular, double-contoured pores of equal size. Mouth constricted, one-third as broad as the thorax, with a narrow hyaline annular peristome.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.07 broad.

Habitat.—North Atlantic, Greenland; Færöe Channel (Gulf Stream), John Murray.

5. Dictyocephalus crassiceps, Haeckel.

Eucyrtidium crassiceps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 4.

Shell smooth, thick-walled, with sharp collar stricture. Length of the two joints = 4 : 6, breadth = 3 : 4. Cephalis ovate, in the upper part with scattered pores, in the lower part with one transverse row of pores. Thorax hyaline, subcylindrical, only with four or five remote transverse rows of small, circular pores. Mouth constricted, half as broad as the thorax, with a short hyaline peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.06 long, 0.04 broad.

Habitat.—Fossil in Barbados.

6. Dictyocephalus australis, n. sp. (Pl. 62, fig. 1).

Shell smooth, thick-walled, with slight collar stricture. Length of the two joints = 2 : 9, breadth = 3 : 6. Cephalis hemispherical, with few small pores. Thorax subcylindrical, with large, roundish, double-contoured pores, irregularly disposed. Mouth constricted, two-thirds as broad as the thorax, with a broad, hyaline peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.06 broad.

Habitat.—East coast of Australia, Station 164, surface.

7. Dictyocephalus mediterraneus, n. sp. (Pl. 62, fig. 2).

Shell rough, thin-walled, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 8. Cephalis hemispherical, with small, circular pores. Thorax ovate, truncate, with much larger circular pores of different sizes and thin bars between them. Mouth little constricted, two-thirds as broad as the thorax, with a narrow, hyaline peristome.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.08 broad.

Habitat.—Mediterranean, Smyrna (Haeckel), surface.

8. Dictyocephalus papillosus, Haeckel.

Eucyrtidium papillosum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 10.

Shell thin-walled, papillate, with obliterated collar stricture. Length of the two joints = 2 : 7, breadth = 3 : 5. Cephalis hemispherical, with small, circular pores. Thorax slenderly ovate, with larger, subregular, circular pores, separated by oblique series of conical papillæ. Mouth with a broad, hyaline peristome (the "third articulus" of Ehrenberg), separated by a stricture from the little broader thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.05 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.

9. Dictyocephalus tabulatus, n. sp.

Shell thin-walled, papillate, with obliterated collar stricture. Length of the two joints = 2 : 10, breadth = 3 : 7. Cephalis hemispherical, with small, circular pores. Thorax slenderly ovate, truncate, with large, subregular, circular, hexagonally-framed pores. Mouth little constricted, nearly as broad as the thorax, with a broad, hyaline peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad, thorax 0.1 long, 0.07 broad.

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

10. Dictyocephalus reticulum, Haeckel.

Dictyocephalus reticulum, Haeckel, 1862, Monogr. d. Radiol., p. 297.

Eucyrtidium reticulum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 300.

Shell thin-walled, smooth, with deep collar stricture. Length of the two joints = 2 : 8, breadth = 3 : 5. Cephalis subspherical, with small, circular pores. Thorax campanulate, with transverse rows of alternating square pores. Mouth little constricted, nearly as long as the thorax, with a narrow, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.05 broad.

Habitat.—Arctic Ocean, Greenland (Schaffner); Iceland (Krabbe).

11. Dictyocephalus ampulla, n. sp.

Shell thin-walled, smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, without pores, hyaline. Thorax inflate, subspherical, with scarce and small, widely-scattered, circular pores. Mouth constricted, only one-third as broad as the thorax, with a narrow, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.07 broad.

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

Subgenus 2. Dictyocryphalus, Haeckel, 1881, Prodromus, p. 430.

Definition.—Mouth of the thorax flat or truncate, without prominent ring-like peristome.

12. Dictyocephalus obtusus, Ehrenberg.

Dictyocephalus obtusus, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830.

Lophophæna obtusa, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 40.

Cornutella obtusa, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 877.

Dictyocephalus obtusus, Haeckel, 1862, Monogr. d. Radiol., p. 296.

Shell smooth, thick-walled, with distinct collar stricture. Length of the two joints = 5 : 6, breadth = 4 : 5. Cephalis ovate, little smaller than the subcylindrical thorax. Pores subregular, circular, of little different sizes. Mouth truncate, without ring-like peristome.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.05 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta), Grotte, &c.

13. Dictyocephalus globiceps, n. sp. (Pl. 62, fig. 7).

Shell rough, thin-walled, with distinct collar stricture. Length of the two joints = 6 : 8, breadth = 6 : 7. Cephalis subspherical, large, with circular, double-contoured pores. Thorax cylindrical, with irregular, roundish pores, the size of which, like the thickness of the wall, decreases gradually towards the truncate mouth, which has no ring-like peristome.

Dimensions.—Cephalis 0.06 long, 0.06 broad; thorax 0.08 long, 0.07 broad.

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

14. Dictyocephalus cavea, n. sp.

Shell rough, thin-walled, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 5 : 7. Cephalis hemispherical, thorny, with numerous regular, circular pores. Thorax subcylindrical, with very large, circular, hexagonally-framed pores (in nine longitudinal alternating rows), three to five times as broad as the cephalic pores. Mouth truncate, wide open, without ring-like peristome.

Dimensions.—Cephalis 0.06 long, 0.1 broad; thorax 0.2 long, 0.14 broad.

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

15. Dictyocephalus capito, Ehrenberg.

Dictyocephalus capito, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. vii. fig. 24.

Shell smooth, thin-walled, with sharp collar stricture. Length of the two joints = 7 : 9, breadth = 6 : 8. Cephalis ovate, with numerous irregular, roundish, densely-crowded pores. Thorax ovate, with very few widely-scattered, irregular, roundish pores (broken off in Ehrenberg's figure). Mouth truncate, little constricted, without ring-like peristome.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.09 long, 0.08 broad.

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

16. Dictyocephalus hispidus, Ehrenberg.

Dictyocephalus hispidus, Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 289, Taf. v. fig. 18.

Shell rough, thin-walled, with deep collar stricture. Length of the two joints = 3 : 4, breadth = 3 : 5. Cephalis subspherical, spiny, with the same irregular, roundish pores as the funnel-shaped or nearly ovate thorax. Mouth truncate, little narrower than the thorax, without ring-like peristome.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.04 long, 0.05 broad.

Habitat.—Tropical Atlantic, Mexican Gulf (Ehrenberg); Station 338, depth 1990 fathoms.

Subfamily 2. Sethocapsida, Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethocyrtida with the basal mouth of the shell fenestrated (vel Dicyrtida eradiata clausa).

Genus 579. Sethocapsa,^[196] Haeckel, 1881, Prodromus, p. 433 (sensu emendato).

Definition.—Sethocapsida (vel Dicyrtida eradiata clausa) with a free cephalis bearing an apical horn.

The genus Sethocapsa and the two following genera represent together the small subfamily of Sethocapsida, or those Dicyrtida in which the mouth of the thorax is closed, and no radial apophyses are present. Sethocapsa may be derived either from Lithopera by loss of the three radial rods, or from Sethocyrtis by closure of the mouth.

1. Sethocapsa pyriformis, n. sp. (Pl. 57, fig. 2).

Shell rough, pear-shaped, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 3 : 8. Cephalis subspherical, with numerous small pores, and a short pyramidal or conical horn of half the length. Thorax ovate, with subregular, circular, quincuncial pores.

Dimensions.—Cephalis 0.03 diameter, thorax 0.1 long, 0.08 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 3000 fathoms.

2. Sethocapsa lagena, Haeckel.

Lithopera lagena, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 4.

Shell smooth, pear-shaped, with sharp collar stricture. Length of the two joints = 3 : 8, breadth = 3 : 6. Cephalis pear-shaped, with few scarce pores, and a small conical horn of half the length. Thorax pear-shaped, with irregular, roundish pores. This species differs from the similar Lithopera lagena almost only in the complete absence of the three internal radial collar beams inside the thorax, and may be derived from it by their retrograde metamorphosis.

Dimensions.—Cephalis 0.03 diameter, thorax 0.08 long, 0.06 broad.

Habitat.—Fossil in Barbados.

3. Sethocapsa macroceros, n. sp.

Shell smooth, pear-shaped, with slight collar stricture. Length of the two joints = 2 : 11, breadth = 2 : 9. Cephalis subspherical, with small circular pores, and a very large, straight, pyramidal horn, of about the same length as the shell. Thorax ovate, with large, irregular, roundish pores, which are surrounded by polygonal frames.

Dimensions.—Cephalis 0.02 diameter, thorax 0.11 long, 0.09 broad.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

4. Sethocapsa nidus, Haeckel.

Lithopera nidus pendulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 7.

Shell smooth, pear-shaped, with distinct collar stricture. Length of the two joints = 3 : 6, breadth = 3 : 5. Cephalis subspherical, with a large, straight, pyramidal horn of twice the length, and scarce small pores. Thorax ovate, also with very small and scarce pores.

Dimensions.—Cephalis 0.03 diameter, thorax 0.06 long, 0.05 broad.

Habitat.—Fossil in Barbados.

5. Sethocapsa bulla, n. sp.

Shell spiny, with slight collar stricture. Length of the two joints = 3 : 12, breadth = 4 : 12. Cephalis hemispherical, with small, scarce pores, and a conical horn of the same length. Thorax nearly spherical, with large, subregular, circular, quincuncial pores, twice as broad as the bars.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.12 long, 0.12 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Barbados.

6. Sethocapsa ampulla, n. sp.

Shell papillate, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis hemispherical, hyaline, without pores, with a large pyramidal horn of twice the length. Thorax nearly spherical, with large, irregular, roundish, lobulated pores.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.15 long, 0.15 broad.

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

7. Sethocapsa staurocephala, Haeckel.

? Lithopera oxystauros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 6.

? Lithopera amblystauros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 5.

Shell smooth, with slight collar stricture. Length of the two joints = 3 : 4, breadth = 3 : 4. Cephalis large, ovate, with a conical horn of the same length, small scarce pores, and an internal frontal septum, composed of two crossed beams, a vertical and a horizontal. Thorax little larger than the cephalis, ovate, with irregular, small and scarce pores. (The two figures of Ehrenberg are either incomplete—in Lithopera amblystauros, the cephalic horn, and in Lithopera oxystauros, the basal part of the thorax, being broken off—or they belong to different Botryodea).

Dimensions.—Cephalis 0.03 diameter, thorax 0.04 diameter.

Habitat.—Fossil in Barbados.

Genus 580. Dicolocapsa,^[197] Haeckel, 1881, Prodromus, p. 433 (sensu emendato).

Definition.—Sethocapsida (vel Dicyrtida eradiata clausa) with a free cephalis, without apical horn.

The genus Dicolocapsa differs from the preceding Sethocapsa in the loss of the apical horn, and therefore bears to it the same relation that Dictyocephalus does to Sethocyrtis.

1. Dicolocapsa microcephala, n. sp. (Pl. 57, fig. 1).

Shell smooth, thin-walled, with distinct collar stricture. Cephalis small, subspherical, with small, crowded pores. Length of the two joints = 1 : 3, breadth = 1 : 3. Thorax also nearly spherical, three times as large as the cephalis, with small, irregularly scattered, circular pores, and much broader bars.

Dimensions.—Cephalis 0.03 diameter, thorax 0.09 diameter.

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

2. Dicolocapsa megacephala, n. sp.

Shell smooth, thin-walled, with sharp collar stricture. Cephalis large, conical, obtuse. Length of the two joints = 5 : 9, breadth = 6 : 8. Thorax ovate, truncate, with hemispherical base. Pores of both joints equal, subregular, circular, about as broad as the bars.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.09 long, 0.08 broad.

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

3. Dicolocapsa platycephala, n. sp.

Shell papillate, thick-walled, with slight collar stricture. Cephalis flat, hemispherical, hyaline, without pores (or with few small pores). Length of the two joints = 2 : 11, breadth = 4 : 9. Thorax ovate, with small, regular, circular pores, half as broad as the bars.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.11 long, 0.09 broad.

Habitat.—Fossil in Barbados.

Genus 581. Cryptocapsa,^[198] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethocapsida (vel Dicyrtida eradiata clausa) with a cephalis hidden in the thorax, without apical horn.

The genus Cryptocapsa differs from the preceding Dicolocapsa, its ancestral form, in the peculiar shape of the cephalis, which is nearly perfectly enclosed in the upper part of the inflated thorax. It has, therefore, to the latter the same relation as Carpocanium bears to Anthocyrtis.

1. Cryptocapsa bacca, n. sp.

Cephalis spherical, with small circular pores enclosed in the upper part of the thorax, which is ovate, smooth, and exhibits regular, circular pores, about as broad as the bars.

Dimensions.—Cephalis 0.03 diameter, thorax 0.15 long, 0.12 broad.

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

2. Cryptocapsa pila, n. sp.

Cephalis spherical, with few small pores, enclosed in the upper part of the thorax, which is pear-shaped, spiny, and exhibits subregular, hexagonal pores, three times as broad as the bars. From each hexagon corner a small thorn arises.

Dimensions.—Cephalis 0.04 diameter, thorax 0.25 long, 0.17 broad.

Habitat.—Central Pacific, Station 269, depth 2900 fathoms.

Section III. TRICYRTIDA, Haeckel, 1881, Prodromus, p. 426, 434.

Definition.—Cyrtoidea trithalamia, with three-jointed shell, composed of cephalis, thorax, and abdomen, with two separating transverse constrictions, an upper collar, and a lower lumbar constriction.

Synopsis of the Families and Subfamilies of Tricyrtida.

Family LXV. Podocyrtida. Three radial apophyses. Mouth open, Theopilida.

Mouth closed, Theoperida.

Family LXVI. Phormocyrtida. Numerous radial apophyses. Mouth open, Theophormida.

Mouth closed, Theophænida.

Family LXVII. Theocyrtida. No radial apophyses. Mouth open, Theocorida.

Mouth closed, Theocapsida.

Family LXV. Podocyrtida. Three radial apophyses.

Mouth open,

Theopilida.

Mouth closed,

Theoperida.

Family LXVI. Phormocyrtida. Numerous radial apophyses.

Mouth open,

Theophormida.

Mouth closed,

Theophænida.

Family LXVII. Theocyrtida. No radial apophyses.

Mouth open,

Theocorida.

Mouth closed,

Theocapsida.

Family LXV. Podocyrtida, n. fam. (Pl. 67, 68, 71-73).

Definition.—Tricyrtida triradiata. (Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, and bearing three radial apophyses.)

The family Podocyrtida, composed of the Theopilida and Theoperida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed and triradial, bearing three external apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Theopilida is a simple wide opening, in the Theoperida closed by a lattice-plate. The latter are derived from the former by development of this closing plate. The phylogenetic origin of the Podocyrtida may be found in the Tripocyrtida, from which they are derived by development of an abdomen. But there are also some forms, which may be derived directly from the Plectoidea, and the origin of some other forms seems to be doubtful.

The Podocyrtida represent one of the largest groups of Cyrtoidea, very rich in numerous species, which are partly very common and widely distributed. A large number of living and fossil species has already been described and figured by Ehrenberg, (1872, 1879, loc. cit.). These mainly belong to his genera Podocyrtis, Pterocanium, Rhopalocanium, Lithornithium, &c., and many of them are very characteristic and common forms, in which the triradial structure of the three-jointed shell is visible at first view. We distinguish here twenty genera and one hundred and fifty species. The majority have a shell with a simple wide open mouth (Theopilida, fourteen genera and one hundred and eighteen species), in the minority the mouth is closed by lattice-work (Theoperida, six genera and thirty-two species).

The three joints of the shell have in the majority of Podocyrtida such a proportion that the cephalis is the smallest, the abdomen the largest, and the thorax between them intermediate in size. The cephalis bears almost constantly an apical horn; this is rarely reduced or lost; sometimes two or more horns are developed. The three radial apophyses arise originally from the base of the cephalis, and may from this point run along the shell-wall embedded in the lattice-plate of the thorax and the abdomen. They leave the latter at very different points, and form either lateral wings or terminal feet, sometimes both together. They are either solid or latticed, sometimes also branched, and of very various shape. Often only the three terminal feet surrounding the mouth have remained, whilst the ribs have disappeared.

Many species of this large family are very variable and connected with other different species by numerous transitional forms; the distinction of the genera described is also often very difficult.

Synopsis of the Genera of Podocyrtida.

I. Subfamily Theopilida. (Podocyrtida aperta.) Terminal mouth of the shell a simple wide opening. A. Three free limbs or wings on the thorax (partly also on the abdomen). No free external appendages on the abdomen. Three wings of the thorax solid. Wings arising from the thorax, 582. Pterocorys.

Three ribs enclosed in the wall of the thorax, 583. Theopilium.

Wings arising free from the collar stricture, 584. Corocalyptra.

Three wings of the thorax latticed. Wings not prolonged into the cephalis, 585. Dictyoceras.

Wings prolonged into the cephalis, 586. Pteropilium.

Free appendages on the abdomen. Three ribs prolonged into three terminal feet. Ribs and feet solid, 587. Theopodium.

Ribs and feet latticed, 588. Pterocanium.

Three free wings on the thorax. Numerous terminal feet. Wings and feet solid, 589. Pterocodon.

Wings and feet latticed, 590. Dictyocodon.

B. Free appendages not on the thorax, only on the abdomen. Abdomen with three ribs and three feet, 591. Pleuropodium.

Abdomen without lateral ribs, with three terminal feet. Three feet solid, simple, 592. Podocyrtis.

Three feet solid, ramified, 593. Thyrsocyrtis.

Three feet latticed, 594. Dictyopodium.

II. Subfamily Theoperida. (Podocyrtida clausa.) Terminal mouth of the shell closed by a lattice-plate. Three lateral wings only on the thorax, Wings solid, 595. Lithornithium.

Wings latticed, 596. Sethornithium.

Three lateral wings beginning from the thorax and prolonged into the abdomen, 597. Theopera.

Three wings only on the abdomen. Spell spindle-shaped, with three lateral wings on the abdomen. No horn on the basal pole, 598. Rhopalocanium.

Basal pole of the shell with a horn, 599. Rhopalatractus.

Shell three-sided pyramidal, with three terminal-feet on the basal corners, 600. Lithochytris.

I. Subfamily Theopilida. (Podocyrtida aperta.) Terminal mouth of the shell a simple wide opening.

A. Three free limbs or wings on the thorax (partly also on the abdomen).

No free external appendages on the abdomen.

Three wings of the thorax solid.

Wings arising from the thorax,

582. Pterocorys.

Three ribs enclosed in the wall of the thorax,

583. Theopilium.

Wings arising free from the collar stricture,

584. Corocalyptra.

Three wings of the thorax latticed.

Wings not prolonged into the cephalis,

585. Dictyoceras.

Wings prolonged into the cephalis,

586. Pteropilium.

Free appendages on the abdomen.

Three ribs prolonged into three terminal feet.

Ribs and feet solid,

587. Theopodium.

Ribs and feet latticed,

588. Pterocanium.

Three free wings on the thorax. Numerous terminal feet.

Wings and feet solid,

589. Pterocodon.

Wings and feet latticed,

590. Dictyocodon.

B. Free appendages not on the thorax, only on the abdomen.

Abdomen with three ribs and three feet,

591. Pleuropodium.

Abdomen without lateral ribs, with three terminal feet.

Three feet solid, simple,

592. Podocyrtis.

Three feet solid, ramified,

593. Thyrsocyrtis.

Three feet latticed,

594. Dictyopodium.

II. Subfamily Theoperida. (Podocyrtida clausa.) Terminal mouth of the shell closed by a lattice-plate.

Three lateral wings only on the thorax,

Wings solid,

595. Lithornithium.

Wings latticed,

596. Sethornithium.

Three lateral wings beginning from the thorax and prolonged into the abdomen,

597. Theopera.

Three wings only on the abdomen.

Spell spindle-shaped, with three lateral wings on the abdomen.

No horn on the basal pole,

598. Rhopalocanium.

Basal pole of the shell with a horn,

599. Rhopalatractus.

Shell three-sided pyramidal, with three terminal-feet on the basal corners,

600. Lithochytris.

Subfamily 1. Theopilida, Haeckel, Prodromus, p. 435.

Definition.—Podocyrtida with the terminal mouth of the shell open (vel Tricyrtida triradiata aperta).

Genus 582. Pterocorys,^[199] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, free lateral wings arising from the sides of the thorax.

The genus Pterocorys, comprising numerous and some very common species, may be one of the oldest and most primitive Theopilida, and is perhaps the common ancestral form of all Tricyrtida. It exhibits three free lateral wings, arising from the sides of the thorax, like Lithomelissa among the Dicyrtida, and may be derived directly from this genus by development of an abdomen. The latter is commonly cylindrical or ovate, with a wide open mouth, whilst the thorax is either campanulate or three-sided and pyramidal.

Subgenus 1. Pterocyrtidium, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 531.

Definition.—Horn of the cephalis simple. Abdomen not prolonged into a narrow tube.

1. Pterocorys campanula, n. sp. (Pl. 71, fig. 3).

Shell campanulate, with two distinct strictures. Length of the three joints = 2 : 3 : 2, breadth = 2 : 4 : 6. Cephalis subovate, with a pyramidal horn of the same length. Thorax subconical, in the middle zone with three conical, horizontal wings, shorter than the cephalis, from which three thin ribs are decurrent to the mouth. Abdomen short and much dilated, with wide, truncate mouth. Pores nearly equal, small, subregular, circular.

Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.04; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Central Pacific, Stations 266 to 274, surface.

2. Pterocorys carinata, Haeckel.

Eucyrtidium carinatum, Haeckel, 1862, Monogr. d. Radiol., p. 322, Taf. vii. figs. 4-7.

Shell subovate, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis ovate, with a pyramidal horn of twice the length. Thorax campanulate, with three decurrent crests, from which in the lower part three small conical wings arise, shorter than the cephalis. Abdomen barrel-shaped, inflated, with wide, truncate mouth. Pores everywhere equal, small, regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.25, b 0.05, c 0.075; breadth, a 0.25, b 0.09, c 0.1.

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

3. Pterocorys sabæ, Haeckel.

Pterocanium sabæ, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. x. fig. 17.

Shell campanulate or subconical, with two sharp strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of the same length. Thorax subconical, in the lower third with three small, conical, little curved wings, shorter than the cephalis. Abdomen dilated towards the wide, truncate mouth. Pores subregular, circular, gradually increasing in size from the collar towards the mouth.

Dimensions.—Length of the three joints, a 0.025, b 0.06, c 0.08; breadth, a 0.02, b 0.08, c 0.09.

Habitat.—Indian Ocean, Zanzibar, 2200 fathoms (Pullen).

4. Pterocorys columba, n. sp. (Pl. 71, fig. 2).

Shell subovate, with two deep strictures. Length of the three joints = 2 : 5 : 4, breadth = 3 : 7 : 7. Cephalis hemispherical, with a curved conical horn of the same length. Thorax inflate, in the middle zone with three pyramidal downwardly divergent wings of nearly the same length. Abdomen short, inflate, little constricted towards the wide, truncate mouth. Pores all nearly equal, subregular, circular.