Legion III. NASSELLARIA, (continued 13)

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Stations 263, depth 2650 fathoms.

2. Hexalatractus fusiformis, n. sp. (Pl. 68, fig. 13).

Shell rough, nearly spindle-shaped, with sharp collar and slight lumbar stricture. Length of the three joints = 2 : 5 : 12, breadth = 3 : 8 : 7. Cephalis hemispherical, with a conical horn of the same length. Thorax hemispherical with regular, circular, hexagonally-framed pores. Abdomen inversely conical, with irregular, roundish pores. From the upper half of the abdomen arise, with broad triangular base, six divergent wings, which are nearly straight, and slightly fenestrated at the base; their conical distal ends do not reach the horizontal plane, in which the basal apex of the abdomen lies.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.03, b 0.08, c 0.07.

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

Genus 610. Theophæna,^[227] Haeckel, 1881, Prodromus, p. 437.

Definition.—Theophænida (vel Tricyrtida multiradiata clausa) with nine lateral wings on the abdomen.

The genus Theophæna differs from the preceding six-radiate Hexalatractus in the possession of nine lateral wings, and may be derived from the triradiate Rhopalocanium by interpolation of six secondary wings between the three primary apophyses.

1. Theophæna corona, n. sp. (Pl. 70, fig. 12).

Shell rough, nearly spindle-shaped, with two sharp strictures. Length of the three joints = 4 : 9 : 16, breadth = 5 : 12 : 10. Cephalis hemispherical, very thick-walled, with a conical horn of the same length; both covered with numerous small dimples and spinules. Thorax campanulate; abdomen inversely conical; both with regular, circular pores. Thorax with nine thin curved ribs, which in the upper half of the abdomen arise as nine large feet, which are strongly compressed and curved (with the convexity outwards); their distal ends form nine ovate spinulate cones, and lie in the same horizontal plane as the basal apex of the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.09, c 0.16; breadth, a 0.05, b 0.12, c 0.1.

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

2. Theophæna nonaria, n. sp.

Shell thorny, ovate, with two slight strictures. Length of the three joints = 1 : 4 : 5, breadth = 1 : 5 : 4. Cephalis subspherical, with a conical horn of half the length. Thorax subspherical, with regular, circular pores and conical spines. Abdomen ovate, smooth, with irregular, roundish pores. In the upper half of the thorax descend nine straight, little divergent ribs, which in the lower half become free, and represent nine slender, conical wings; their distal ends do not reach the horizontal plane in which the basal end of the abdomen lies.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.15; breadth, a 0.03, b 0.14, c 0.12.

Habitat.—South of Australia, Station 160, surface.

Family LXVII. Theocyrtida, n. fam.

Definition.—Tricyrtida eradiata. Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, without radial apophyses.

The family Theocyrtida, composed of the Theocorida and Theocapsida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed, and bears no external radial apophyses. The two subfamilies differ in the shape of the terminal mouth, which in the Theocorida is a simple wide opening, in the Theocapsida closed by a lattice-plate. The phylogenetic origin of the Theocyrtida may be found either in the Podocyrtida or in the Sethocyrtida; they may have been derived from the former by reduction and loss of the three primary apophyses, or from the latter by development of an abdomen.

The number of species in this group is very large, and many belong to the most common and widely distributed Cyrtoidea. A great number of living and fossil species have already been described by Ehrenberg, the majority being disposed in his genera Lithocampe and Eucyrtidium.

The number of genera, however, is comparatively small, and their distinction difficult, since the form of the shell presents no striking differences.

It exhibits all possible passages, from a flatly expanded or nearly discoidal form with a wide open mouth, to a conical or cylindrical, and by constriction of the terminal mouth to an ovate or spindle-shaped form. By complete closure of the mouth the Theocapsida arise. In some genera remarkable traces of the original triradial structure are preserved. The most interesting of these forms is Axocorys, with an internal axial columella, which bears a number of verticils, each with three radial branches.

Synopsis of the Genera of Theocyrtida.

I. Subfamily Theocorida. Terminal mouth of the abdomen a simple wide opening. Abdomen gradually dilated towards the wide open mouth. Abdomen flatly expanded, discoidal. With horn, 611. Theocalyptra.

No horn, 612. Cecryphalium.

Abdomen conical. One horn, 613. Theoconus.

Two or more horns, 614. Lophoconus.

Abdomen cylindrical, of nearly equal breadth throughout its whole length. Mouth truncate. A single apical horn on the cephalis. Thorax and abdomen of equal breadth, 615. Theocyrtis.

Thorax much broader than the tubular abdomen, 616. Theosyringium.

Two horns or a bunch of horns on the cephalis, 617. Lophocyrtis.

No horn on the cephalis, 618. Tricolocampe.

Abdomen ovate or inversely conical. Mouth more or less constricted. A single apical horn on the cephalis. Shell-cavity without an internal columella, 619. Theocorys.

Shell-cavity with an axial columella, 620. Axocorys.

Two horns or a bunch of horns on the cephalis, 621. Lophocorys.

No horn on the cephalis, 622. Theocampe.

II. Subfamily Theocapsida. Terminal mouth closed by a lattice-plate. No latticed septum between thorax and abdomen. An apical horn, 623. Theocapsa.

No horn on the cephalis, 624. Tricolocapsa.

A complete latticed septum between thorax and abdomen, 625. Phrenocodon.

I. Subfamily Theocorida. Terminal mouth of the abdomen a simple wide opening.

Abdomen gradually dilated towards the wide open mouth.

Abdomen flatly expanded, discoidal.

With horn,

611. Theocalyptra.

No horn,

612. Cecryphalium.

Abdomen conical.

One horn,

613. Theoconus.

Two or more horns,

614. Lophoconus.

Abdomen cylindrical, of nearly equal breadth throughout its whole length. Mouth truncate.

A single apical horn on the cephalis.

Thorax and abdomen of equal breadth,

615. Theocyrtis.

Thorax much broader than the tubular abdomen,

616. Theosyringium.

Two horns or a bunch of horns on the cephalis,

617. Lophocyrtis.

No horn on the cephalis,

618. Tricolocampe.

Abdomen ovate or inversely conical. Mouth more or less constricted.

A single apical horn on the cephalis.

Shell-cavity without an internal columella,

619. Theocorys.

Shell-cavity with an axial columella,

620. Axocorys.

Two horns or a bunch of horns on the cephalis,

621. Lophocorys.

No horn on the cephalis,

622. Theocampe.

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

No latticed septum between thorax and abdomen.

An apical horn,

623. Theocapsa.

No horn on the cephalis,

624. Tricolocapsa.

A complete latticed septum between thorax and abdomen,

625. Phrenocodon.

Subfamily 1. Theocorida, Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocyrtida with the basal mouth of the shell open (vel Tricyrtida eradiata aperta).

Genus 611. Theocalyptra,^[228] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with discoidal or flatly expanded abdomen. Cephalis with a single apical horn, or with two divergent horns.

The genus Theocalyptra, and the following closely allied genus Cecryphalium, differ from all the other Theocorida in the flattened form of the cap-shaped or nearly discoidal shell. The abdomen specially is quite flat, often horizontally expanded, and like the marginal brim of a flat hat. They may be derived from the Dicyrtida Sethocephalus by the development of an abdomen, or from Corocalyptra by loss of the collar wings. The network is usually very delicate, as in the latter. The cephalis of Theocalyptra bears one or two horns.

1. Theocalyptra veneris, n. sp.

Shell flatly campanulate, very delicate and fragile, very similar to Eucecryphalus agnesæ (Pl. 59, fig. 3), but without collar spines. Length of the three joints = 1 : 4 : 2, breadth = 1 : 7 : 9. Cephalis hemispherical, with a single bristle-shaped horn of twice the length. Thorax subconical, separated from the flatter abdomen by a deep stricture, with thin bars, and large, subregular, hexagonal meshes, increasing in size towards the smooth mouth-edge.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.04; breadth, a 0.025, b 0.15, c 0.1.

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

2. Theocalyptra orci, Haeckel.

Halicalyptra orci, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. x. figs. 9, 10.

Shell flatly campanulate, very similar to the preceding species in general form and fenestration, but flatter and smaller, with different proportions. Length of the three joints = 7 : 2 : 1, breadth = 1 : 6 : 8. Cephalis hemispherical, very small, with two divergent, bristle-shaped horns of the same length. Abdomen nearly horizontally expanded.

Dimensions.—Length of the three joints, a 0.015, b 0.04, c 0.01; breadth, a 0.02, b 0.12, c 0.16.

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

3. Theocalyptra discoides, Haeckel.

Cycladophora discoides, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 4.

Shell flatly campanulate, similar to the two preceding species, but not so delicate, with thicker bars, and roundish, not hexagonal meshes. Length of the three joints = 1 : 2 : 2, breadth = 3 : 6 : 9. Cephalis large, trilobed, with a short, oblique horn of half the length. Thorax campanulate, conical, separated from the abdomen by a circle of smaller pores and a deep stricture. Abdomen flat, discoidal, with three circles of larger pores.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.06, b 0.12, c 0.18.

Habitat.—Fossil in Barbados.

4. Theocalyptra cornuta, Haeckel.

Carpocanium cornutum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ii. fig. 9.

Halicalyptra cornuta, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 5, pl. i. figs. 13, 14.

Lophophæna cornuta, Haeckel, 1862, Monogr. d. Radiol., p. 299.

Shell campanulate-conical, with two sharp strictures. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 5. Cephalis subspherical, with two stout, pyramidal, divergent horns of twice the length. Thorax campanulate, with eight to ten transverse rows of roundish or nearly square pores, increasing in size towards the abdomen, which is flatly expanded, nearly discoidal, separated by a circle of smaller pores; the last circle of pores (on the margin) is larger.

Dimensions.—Length of the three joints, a 0.025, b 0.09, c 0.03; breadth, a 0.03, b 0.12, c 0.16.

Habitat.—Arctic Ocean, Kamtschatka (Bailey), Greenland (Ehrenberg).

Genus 612. Cecryphalium,^[229] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with discoidal or flatly expanded abdomen. Cephalis without horn.

The genus Cecryphalium has the same flat, conical, or nearly discoidal shell as the preceding Theocalyptra, its ancestral genus, but differs from it in the complete absence of horns on the cephalis.

1. Cecryphalium lamprodiscus, n. sp. (Pl. 58, fig. 2).

Shell flatly conical, with two slight strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 7 : 11. Cephalis roundish, very small. Thorax conical, with straight lateral outline; its pores irregular, polygonal, increasing in size towards the girdle. Abdomen little flatter than the thorax, forming its direct prolongation, with five to six circular, concentric rows of pores; the first row formed by sixty to eighty very large, oblongish, quadrangular pores, the second row by very small, the third again by larger pores; the outmost rows by very small and numerous pores.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.02, b 0.14, c 0.22.

Habitat.—Central Pacific, Station 272, surface.

2. Cecryphalium sestrodiscus, n. sp. (Pl. 58, fig. 1).

Shell very flat, subconical, nearly discoidal, with two distinct strictures. Length of the three joints = 1 : 2 : 1, breadth = 1 : 8 : 10. Cephalis kidney-shaped, very small. Thorax flat, campanulate, with curved lateral outline; its pores irregular, polygonal, increasing in size towards the girdle. Abdomen horizontally expanded, like the brim of a hat, with five to six concentric, circular rows of pores, the pores of the inner rows twice to three times as large as those of the outer rows. (The inner circle of large, oblongish, quadrangular pores, characteristic of the preceding species, is here divided into three concentric rings by two circular hoops.)

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.02, b 0.15, c 0.2.

Habitat.—Central Pacific, Station 274, surface.

Genus 613. Theoconus,^[230] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with conical abdomen, gradually dilated towards the wide open mouth. Cephalis with a single horn.

The genus Theoconus, and the following closely allied Lophoconus, differ from the other Theocorida in the conical or campanulate form of the shell; the abdomen is a truncated cone, gradually dilated towards the terminal mouth. The latter is usually truncated, widely open, sometimes with a slightly constricted peristome. The cephalis of Theoconus bears a single apical horn.

Subgenus 1. Theocorax, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Theoconus zancleus, Haeckel.

Eucyrtidium zancleum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 41, Taf. vi. figs. 1-3.

Eucyrtidium zancleum, Haeckel, 1862, Monogr. d. Radiol., p. 321.

Shell bell-shaped, nearly conical, smooth. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 6. Cephalis nearly spherical, with a stout, straight, pyramidal horn of the same length. Thorax hemispherical. Abdomen gradually increasing in breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, circular, regular, four times as broad as the thin bars.

Dimensions.—Length of the three joints, a 0.027, b 0.08, c 0.1; breadth, a 0.03, b 0.12, c 0.18.

Habitat.—Mediterranean (Messina, Naples, Nice, &c.).

2. Theoconus ægæus, Haeckel.

Eucyrtidium ægæum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 31; Mikrogeol., 1854, Taf. xxxv. a, xix. a, fig. 5.

Eucyrtidium ægæum, Haeckel, 1862, Monogr. d. Radiol., p. 329.

Shell flatly bell-shaped, nearly conical. Length of the three joints = 2 : 5 : 3; breadth = 1 : 7 : 8. Cephalis ovate, with a stout, straight, pyramidal horn of the same length. Thorax flat, bell-shaped. Abdomen with increasing breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, regular, circular, three times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.03; breadth, a 0.016, b 0.07, c 0.08.

Habitat.—Mediterranean (Coast of Greece and Sicily), surface.

3. Theoconus zanguebaricus, Haeckel.

Eucyrtidium zanguebaricum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. ix. fig. 22.

Shell bell-shaped. Length of the three joints = 1 : 2 : 1, breadth = 1 : 3 : 4. Cephalis ovate, with a straight, pyramidal horn of half the length. Thorax hemispherical, without collar stricture, but with evident girdle stricture. Abdomen dilated towards the wide truncated mouth. Pores regular, hexagonal, of nearly equal size and form, four to six times as broad as the thin bars.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.03; breadth, a 0.024, b 0.09, c 0.11.

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

4. Theoconus campanulatus, Haeckel.

? Eucyrtidium campanulatum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 241.

Eucyrtidium campanulatum, Haeckel, 1862, Monogr. d. Radiol., p. 329.

Shell bell-shaped, smooth. Length of the three joints = 2 : 3 : 7, breadth = 3 : 7 : 10. Cephalis small, spherical, with a short, conical, oblique horn of the same length. Thorax hemispherical, with an external girdle stricture, prolonged into the truncated, barrel-shaped abdomen, which is a little constricted at the very wide mouth. Pores small and very numerous, regular, circular, twice to three times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.07; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—North Atlantic, Station 352, surface.

5. Theoconus orthoconus, n. sp.

Shell perfectly conical, smooth. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 4. Cephalis hemispherical, with a strong, straight, conical horn of the same length. Thorax conical, without external girdle stricture, prolonged into the truncated, conical abdomen, which is gradually dilated into a very wide mouth. Pores small, of nearly equal size and similar form, of the same breadth as the bars.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.06, c 0.12.

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

Subgenus 2. Theocorbis, Haeckel.

Definition.—Pores of the thorax and of the abdomen of different sizes or dissimilar forms.

6. Theoconus jovis, n. sp. (Pl. 69, fig. 4).

Shell bell-shaped, nearly conical. Length of the three joints = 5 : 6 : 7, breadth = 4 : 10 : 14. Cephalis nearly cylindrical, large, little curved, with a very large, oblique, pyramidal horn, as long as the two first joints together. Thorax and the broader abdomen irregularly bell-shaped, dilated towards the wide mouth. Pores circular, somewhat irregularly disposed, gradually increasing in size towards the mouth.

Dimensions.—Length of the three joints, a 0.05, b 0.06, c 0.07; breadth, a 0.04, b 0.1, c 0.14.

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

7. Theoconus junonis, n. sp. (Pl. 69, fig. 7).

Shell nearly conical. Length of the three joints = 4 : 5 : 8, breadth = 3 : 8 : 11. Cephalis ovate, with a large apical opening at the base of the vertical compressed horn, which has about the same length. Thorax and the broader abdomen together conical, gradually dilated towards the wide mouth. Thorax with a bosom-like protuberance on one side. Pores circular, gradually increasing in size.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.08; breadth, a 0.03, b 0.08, c 0.11.

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

8. Theoconus longicornis, n. sp.

Shell conical, thorny. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis nearly spherical, with a very large, cylindrical, perpendicular, straight horn, once and a half to twice as long as the whole shell. Thorax conical. Abdomen nearly hemispherical, with wide open mouth. Pores circular, four to six times as broad in the thick-walled spiny abdomen as in the thin-walled rough thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.09, c 0.18.

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

9. Theoconus ampullaceus, Haeckel.

Lithocampe ampullacea, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iv. fig. 1.

Theocorys ampullacea, Haeckel, 1881, Prodromus, p. 434.

Shell bell-shaped, nearly conical, thorny. Length of the three joints = 3 : 4 : 10; breadth = 4 : 8 : 15. Cephalis subspherical, with a stout lateral horn of the same length. Thorax hemispherical, rough. Abdomen subspherical, widely truncated at both poles, spiny. Pores regular, circular, three to four times as broad in the thick-walled abdomen as in the thin-walled thorax. (Differs from the similar preceding species in the smaller horn and the two deeper strictures of the shell.)

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.08, c 0.15.

Habitat.—Fossil in Barbados.

10. Theoconus amplus, Haeckel.

? Podocyrtis ampla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 7.

? Podocyrtis ampla, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxiii. fig. 16.

? Eucyrtidium amplum, Ehrenberg, 1873, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 248.

Shell conical, smooth, with two broad internal annular septa. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a very large, straight, conical horn of the same breadth, which is as long as the conical thorax. Pores regular, circular, twice as broad in the truncate, gradually dilated abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.03, b 0.12, c 0.15.

Habitat.—Fossil in Barbados.

11. Theoconus ariadnes, n. sp.

Shell conical, nearly bell-shaped, smooth. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis subspherical, with a conical spine of about the same length. Thorax hemispherical, thin-walled. Abdomen conical, slightly constricted at the wide open mouth. Pores regular, circular, twice as large in the thick-walled abdomen as in the thin-walled thorax.

Dimensions.—Length of the three joints, a 0.018 to 0.022, b 0.03 to 0.035, c 0.06 to 0.07; breadth, a 0.015 to 0.02, b 0.04 to 0.06, c 0.07 to 0.09.

Habitat.—Cosmopolitan; Atlantic, Indian, and Pacific Oceans, common, surface.

12. Theoconus dionysius, Haeckel.

Thyrsocyrtis dionysia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 5.

Thyrsocyrtis jacchia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 7.

Shell bell-shaped, smooth. Length of the three joints = 1 : 3 : 5, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical, irregularly denticulate horn of twice or thrice the length. Thorax inflated, nearly spherical, truncate at both poles, separated by a deep stricture from the cephalis, as well as from the conical abdomen, which is dilated gradually towards the wide mouth. Pores in the thorax subregular, circular, in the abdomen twice to four times larger, and irregular.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth, a 0.02, b 0.08, c 0.1.

Habitat.—Fossil in Barbados.

13. Theoconus laterna, n. sp.

Shell conical, smooth. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 4. Cephalis small, ovate, with a strong, pyramidal, vertical horn three times the length. Thorax hemispherical, with subregular, circular, hexagonally-framed pores. Abdomen truncate, conical, with only fifteen to twenty very large, irregular, polygonal pores, which are separated by very thick bars of the same breadth as the horn.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.07, c 0.12.

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

14. Theoconus ficus, Haeckel.

Eucyrtidium ficus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 19.

Theocorys ficus, Haeckel, 1881, Prodromus, p. 434.

Shell conical, pear-shaped, smooth. Length of the three joints = 1 : 5 : 20, breadth = 2 : 10 : 25. Cephalis very small, ovate, with a conical, straight horn three times the length. Thorax quite conical, with solid wall, without pores. Abdomen very large, nearly spherical, truncate at both poles, little constricted at the very wide mouth; its pores subregular, circular, about three times as broad as the bars. (This species is intermediate between the genera Theoconus and Theocorys.)

Dimensions.—Length of the three joints, a 0.01, b 0.05, c 0.2; breadth, a 0.02, b 0.1, c 0.25.

Habitat.—Fossil in Barbados.

Genus 614. Lophoconus,^[231] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with conical abdomen gradually dilated towards the wide open mouth. Cephalis with two or more horns or a corona of horns.

The genus Lophoconus has the same conical shell with truncate mouth as Theoconus, and differs from it only in the armature of the cephalis, bearing either two large divergent horns (usually a larger occipital and a smaller frontal horns), or a bunch or corona of numerous divergent horns.

1. Lophoconus antilope, Haeckel.

Eucyrtidium antilope, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 18.

Shell conical, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 8, breadth = 2 : 4 : 8. Cephalis hemispherical, with two divergent, pyramidal horns of twice the length. Thorax campanulate. Abdomen gradually dilated towards the wide open mouth. Pores very small and numerous, regular, hexagonal.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.12; breadth, a 0.025, b 0.07, c 0.12.

Habitat.—Indian Ocean; between Aden and Socotra (Haeckel); Zanzibar (Pullen).

2. Lophoconus hexagonalis, n. sp.

Shell campanulate, conical, spiny, with two sharp strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis hemispherical, with numerous conical spines of different sizes, the largest of twice the length. Thorax campanulate, with smaller spines. Abdomen inflated, dilated towards the wide mouth. Pores large, three or four times as broad as the bars, subregular, hexagonal.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.07, c 0.12.

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

3. Lophoconus cornutella, n. sp.

Shell slender, conical, smooth, without external strictures, but with two internal, annular septa. Length of the three joints = 1 : 2 : 6, breadth = 1 : 2 : 4. Cephalis ovate, with two stout, divergent, conical horns of three times the length. Thorax and abdomen together conical, gradually dilated towards the wide truncate mouth. Pores regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.02, b 0.04, c 0.08.

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

4. Lophoconus apiculatus, Haeckel.

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

Shell campanulate, conical, thorny, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis subspherical, with a bunch of eight to twelve divergent, conical horns, the largest of which are longer than the cephalis. The regular, circular pores are in the campanulate thorax scarcely half as broad as in the truncate, gradually dilated abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.025, b 0.06, c 0.08.

Habitat.—Fossil in Barbados.

5. Lophoconus cervus, Haeckel

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

Shell conical, smooth, without external stricture, but with two internal annular septa. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis campanulate, with two to six divergent, partly ramified horns. Pores in the thorax regular, circular, in the abdomen three to four times as large, regular, hexagonal.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.12.

Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface (? Zanzibar, 2200 fathoms, Pullen).

6. Lophoconus rhinoceros, n. sp. (Pl. 69, fig. 2).

Shell campanulate, conical, rough, with two sharp strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with numerous very small pores, and two stout, divergent, pyramidal horns, the major of which is longer, the minor shorter, than the cephalis. Thorax campanulate, with small, regular, circular pores. Abdomen inflated, with thickened margin at the wide open mouth, and with irregular, roundish pores, twice to four times as broad as those of the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.09; breadth, a 0.04, b 0.09, c 0.12.

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

Genus 615. Theocyrtis,^[232] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, and wide open truncate mouth. Cephalis with a single horn.

The genus Theocyrtis and the three following closely allied genera differ from the other Theocorida in the cylindrical form of the slender abdomen, which is of equal breadth nearly throughout its whole length. The terminal mouth is wide open, usually truncate, and of the same breadth; sometimes slightly constricted. The cephalis of Theocyrtis bears a single horn.

Subgenus 1. Theocorypha, Haeckel.

Definition.—Pores of the thorax and abdomen of nearly equal size and similar form.

1. Theocyrtis trachelius, Haeckel.

Eucyrtidium trachelius, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 8.

Shell thin-walled and very fragile, smooth. Length of the three joints = 2 : 8 : 7, breadth = 2 : 9 : 8. Cephalis subspherical, with a straight, conical horn of the same length, separated by a slender neck from the inflated, subspherical thorax. Abdomen cylindrical, with a wide open, truncate mouth. Pores subregular, hexagonal, of equal size, four to six times as broad as the thin, thread-like bars.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.07; breadth, a 0.02, b 0.09, c 0.08.

Habitat.—Tropical Pacific, many Stations (200, 224, 271, &c.), surface, and in various depths.

2. Theocyrtis barbadensis, Haeckel.

Eucyrtidium barbadense, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 7.

Shell thin-walled, smooth. Length of the three joints = 2 : 4 : 5, breadth, 2 : 5 : 4. Cephalis ovate or conical, with a strong, conical horn, without external stricture, dilated into the campanulate thorax. Abdomen cylindrical, with a wide open, truncate mouth. Pores subregular, circular, quincuncially disposed, of about the same breadth as the bars.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.1, c 0.08.

Habitat.—Fossil in the Tertiary rocks of Barbados.

3. Theocyrtis cylindrica, Haeckel.

Eucyrtidium cylindricum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 1.

Shell elongate, cylindrical, straight, smooth. Length of the three joints = 1 : 2 : 6, breadth = 1 : 3 : 3. Cephalis hemispherical, with a thick, pyramidal horn of the same length (the edges of the horn giving to it the appearance of being composed of two converging spines). Thorax truncated, conical. Abdomen perfectly cylindrical, much elongated. Pores subregular, circular, twice as broad as the bars, quincuncially disposed. Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Tropical Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

4. Theocyrtis elegans, Haeckel.

Eucyrtidium elegans, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 12.

? Eucyrtidium pusillum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 6

Shell slender, cylindrical, straight, smooth. Length of the three joints = 1 : 2 : 7, breadth = 1 : 3 : 3. Cephalis subconical, with a small conical horn. Thorax campanulate, conical. Abdomen cylindrical, very slender. Pores subregular, circular, small, disposed in transverse rows, three in the thorax, six to eight in the abdomen. Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.01, b 0.02, c 0.07; breadth, a 0.015, b 0.03, c 0.03.

Habitat.—Fossil in Barbados and Sicily.

5. Theocyrtis paupera, Haeckel.

Eucyrtidium pauperum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 13.

Shell slender, cylindrical, smooth. Length of the three joints = 1 : 2 : 6, breadth = 1 : 3 : 3. Cephalis hemispherical, with a stout conical horn of twice the length. Thorax truncate, conical. Abdomen cylindrical. Pores very small, regular, circular, disposed in transverse rows, one or two in the thorax, three to five in the abdomen. (Distance between the rows twice as great as in the preceding nearly related species.) Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.01, b 0.02, c 0.06; breadth, a 0.015, b 0.03, c 0.03.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados and Sicily.

6. Theocyrtis microtheca, Haeckel.

Eucyrtidium microtheca, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 10.

Eucyrtidium hillaby, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 8.

Shell cylindrical, a little rough. Length of the three joints = 1 : 3 : 4, breadth = 1 : 3 : 3. Cephalis subspherical, with a small conical horn. Thorax hemispherical or campanulate. Abdomen cylindrical, with wide open truncate mouth. Pores subregular, circular, quincuncially disposed, of medium size, rudimentary or wanting in the cephalis.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.03 to 0.05, c 0.05 to 0.08; breadth, a 0.02 to 0.025, b 0.05 to 0.06, c 0.05 to 0.06.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms; also fossil in Barbados.

Subgenus 2. Theocorusca, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or forms.

7. Theocyrtis macroceros, n. sp. (Pl. 69, fig. 13).

Shell almost cylindrical, smooth. Length of the three joints = 1 : 2 : 5, breadth = 2 : 3 : 4. Cephalis hemispherical, with a very large cylindrical horn, once or twice as long as the shell. Thorax truncate, hemispherical. Abdomen cylindrical, only slightly contracted towards both ends. Two girdle strictures deep. Pores small, subregular, circular, more irregular and twice to three times as large in the abdomen as in the thorax, disposed in transverse rows, five to six in the thorax, eight to ten in the abdomen.

Dimensions.—Length of the three joints, a 0.02 to 0.03, b 0.04 to 0.05, c 0.1 to 0.12; breadth, a, 0.04, b 0.07, c 0.08.

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

8. Theocyrtis ptychodes, n. sp. (Pl. 69, fig. 8).

Shell almost cylindrical, smooth. Length of the three joints = 1 : 3 : 3, breadth = 2 : 4 : 4. Cephalis hemispherical, with a large, conical, curved horn of twice the length. Thorax very large, inflated, campanulate, thick-walled. Abdomen cylindrical, with a thin folded wall (like a petticoat), the thickness of which decreases gradually towards the wide truncate mouth. Pores subregular, circular, and quincuncially disposed in the two first joints, irregular and larger in the abdomen, forming longitudinal series between the folds.

Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.11; breadth, a 0.05, b 0.12, c 0.12.

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

9. Theocyrtis aspera, Haeckel.

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

Shell almost cylindrical, with rough or thorny surface. Length of the three joints = 1 : 3 : 5, breadth = 1 : 5 : 5. Cephalis subspherical, small, with a short conical horn. Thorax hemispherical, inflated. Abdomen cylindrical, with wide truncate mouth. Pores in the thorax subregular, circular, quincuncially disposed, in the abdomen irregular roundish, two to four times as large.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.06 to 0.07, c 0.08 to 0.1; breadth, a 0.02, b 0.1, c 0.1.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; fossil in Barbados.

10. Theocyrtis proserpinæ, n. sp.

Shell almost cylindrical, smooth. Length of the three joints = 3 : 6 : 9, breadth = 2 : 8 : 7. Cephalis subspherical, with a stout conical horn. Thorax campanulate. Abdomen cylindrical. Pores regular, circular, quincuncially disposed, double-edged in the thorax, and three to four times as large as in the cephalis and the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.02, b 0.08, c 0.07.

Habitat.—North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.

11. Theocyrtis oenophila, Haeckel.

Thyrsocyrtis oenophila, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 8.

Shell in the apical half conical, in the lower cylindrical. Length of the three joints = 2 : 5 : 6, breadth = 3 : 8 : 7. Cephalis subspherical, with a large prismatic horn, which is bulbous at the base, and armed with three teeth at the distal apex. Thorax conical, constricted at the base, with subregular, circular, quincuncial pores. Abdomen cylindrical, with a coronal of nine large roundish pores beyond the lumbar stricture, and two to four succeeding transverse rows of irregular, roundish, smaller pores. Mouth widely open, truncated.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Fossil in Barbados.

Genus 616. Theosyringium, Haeckel,^[233] 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, which is much narrower than the inflated thorax, and forms a slender, narrow tube, with truncated mouth. Cephalis with a single horn.

The genus Theosyringium differs from the closely allied Theocyrtis, its ancestral form, in the wide inflated thorax, which is much broader than the narrow tubular abdomen. The mouth of the latter is small and truncate.

1. Theosyringium tibia, n. sp. (Pl. 68, fig. 4).

Shell rough, very slender, with two distinct strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 2 : 1. Cephalis ovate, with a conical horn of the same length. Thorax ellipsoidal. Abdomen cylindrical, as long as the two former joints together. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.03, b 0.06, c 0.02.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

2. Theosyringium pipetta, n. sp. (Pl. 68, fig. 5).

Shell rough, inflated, with two sharp strictures. Length of the three joints = 2 : 7 : 9, breadth = 2 : 7 : 2. Cephalis conical, with a slender horn of half the length. Thorax subglobose. Abdomen cylindrical, as long as the two former joints together. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.09; breadth, a 0.02, b 0.07, c 0.02.

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

3. Theosyringium siphonium, n. sp.

Shell rough, inflated, with two deep strictures. Length of the three joints = 1 : 3 : 3, breadth = 1 : 2 : 1. Cephalis subspherical, with a stout pyramidal horn of twice the length. Thorax broad ovate. Abdomen slender, inversely conical, as long as the thorax, and one-third as broad as the base. Pores subregular, circular, hexagonally framed, (Similar to Eusyringium conosiphon, Pl. 78, fig. 10, but only with two strictures and three joints.)

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.1; breadth, a 0.03, b 0.07, c 0.025.

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

4. Theosyringium tubulus, Haeckel.

Eucyrtidium tubulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 6.

Shell smooth, slenderly spindle-shaped, with two slight strictures. Length of the three joints = 2 : 10 : 8, breadth = 3 : 6 : 3. Cephalis hemispherical, hyaline, with a stout, pyramidal horn of the same length. Thorax spindle-shaped. Abdomen inversely conical, half as long as the thorax prolonged into a slender, cylindrical tube. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.08; breadth, a 0.03, b 0.06, c 0.03.

Habitat.—Fossil in Barbados.

Genus 617. Lophocyrtis,^[234] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, and wide open truncate mouth. Cephalis with two horns, or a bunch of horns.

The genus Lophocyrtis differs from its ancestral form Theocyrtis only in the armature of the cephalis, bearing instead of a single horn either two divergent horns, or a bunch, or coronal of numerous spines. The slender abdomen is in both genera cylindrical, with wide open mouth.

1. Lophocyrtis holothuria, n. sp.

Shell smooth, slender, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 3. Cephalis hemispherical, with a bunch of five divergent, conical horns, the middle of which is larger and vertical, nearly as long as the thorax. Thorax campanulate, half as long as the cylindrical abdomen. Mouth truncate. Pores regular, circular, quincuncial. (Similar to Theocyrtis cylindrica, but with different cephalis and thorax.)

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.1; breadth, a 0.04, b 0.07, c 0.06.

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

2. Lophocyrtis stephanophora, Haeckel.

Eucyrtidium stephanophorum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin p. 72, Taf. viii. fig. 14.

Shell smooth, slender, with deep collar and indistinct lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis subspherical, with very small circular pores, and a corona of three to nine short conical spines. Thorax campanulate, with regular, circular pores, which are half or one-third as broad as those of the cylindrical abdomen.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.09; breadth, a 0.025, b 0.06, c 0.06.

Habitat.—Fossil in Barbados.

3. Lophocyrtis synapta, n. sp. Pl. 68, fig. 15.

Shell spiny, with two sharp strictures. Length of the three joints = 5 : 10 : 6, breadth = 4 : 9 : 7. Cephalis large, ovate, with numerous (twenty to thirty or more) conical, radially divergent spines of different sizes, the largest about as long as the cephalis. Thorax subconical, with numerous short, conical, divergent spines, which are directed downwards. Abdomen smooth, cylindrical. The irregular, polygonal pores are separated by thin bars, and in the thorax are twice to four times as broad as in the first and last joints.

Dimensions.—Length of the three joints, a 0.05, b 0.1, c 0.06; breadth, a 0.04, b 0.09, c 0.07.

Habitat.—Indian Ocean, Maldive Islands (Haeckel), surface.

4. Lophocyrtis coronata, Haeckel.

Eucyrtidium coronatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 9.

Shell smooth, cylindrical, with two deep strictures. Length of the three joints = 4 : 3 : 4, breadth = 4 : 5 : 4. Cephalis subspherical, large, of about the same size and form as the thorax, with a coronal of four to eight short, conical spines on the apex. Pores in the two first joints irregular, roundish, twice to four times as broad as the small, circular pores of the cylindrical abdomen, which are disposed in four to eight transverse rows.

Dimensions.—Length of the three joints, a 0.04, b 0.03, c 0.04; breadth, a 0.04, b 0.05, c 0.04.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms; fossil in Barbados.

5. Lophocyrtis biaurita, Haeckel.

Eucyrtidium biauritum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 8.

Eucyrtidium biauritum, Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 540, Taf. xxxiii. fig. 38, a-f.

Shell smooth, with two distinct strictures. Length of the three joints = 1 : 6 : 3, breadth = 2 : 5 : 4. Cephalis small, hemispherical, hyaline, with two large, divergent, curved horns of three times the length. Thorax ovate, with few small, widely scattered pores. Abdomen cylindrical, without pores.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.03; breadth, a 0.02, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

Genus 618. Tricolocampe,^[235] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with cylindrical abdomen, and wide open truncate mouth. Cephalis without horn.

The genus Tricolocampe differs from its ancestral genus, Theocyrtis, in the loss of the cephalic horn; it has the same cylindrical form of the slender abdomen, and a wide open terminal mouth of the same breadth. The whole shell is more or less cylindrical, (sometimes conical in the upper part), with two distinct external strictures, or internal annular septa.

Subgenus 1. Tricolocampium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Tricolocampe cylindrica, n. sp. (Pl. 66, fig. 21).

Shell nearly cylindrical, smooth. Length of the three joints = 2 : 3 : 15, breadth = 3 : 4 : 5. Cephalis hemispherical, with numerous very small pores. Thorax and abdomen cylindrical, of about equal breadth, with equal, circular pores, disposed regularly in transverse rows, three to four rows in the thorax, ten to twelve in the abdomen. Mouth wide open, not constricted.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.15; breadth, a 0.03, b 0.04, c 0.05.

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

2. Tricolocampe pupa, Haeckel.

Eucyrtidium pupa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 16.

Shell nearly cylindrical, smooth. Length of the three joints = 2 : 2 : 8, breadth = 2 : 3 : 3. Cephalis subspherical, with four larger pores. Thorax and abdomen cylindrical, of about equal breadth, with equal, very small pores, disposed regularly in transverse rows, two rows in the thorax, eight to ten in the abdomen. Mouth wide open, a little constricted.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.08; breadth, a 0.02, b 0.03, c 0.03.

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

3. Tricolocampe polyzona, n. sp. (Pl. 66, fig. 19).

Shell nearly cylindrical, thick-walled. Length of the three joints = 4 : 4 : 12, breadth = 8 : 9 : 9. Cephalis obtuse, conical. Thorax barrel-shaped. Abdomen in the middle part a little constricted. Pores very numerous, subregular, disposed regularly in transverse rows, six to eight in the cephalis, eight to ten in the thorax, twelve to fifteen in the abdomen. Mouth rather constricted, only half as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.12; breadth, a 0.08, b 0.09, c 0.09.

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms; also fossil in the Nicobars and in Barbados.

4. Tricolocampe stenozona, n. sp. (Pl. 66, fig. 20).

Shell nearly cylindrical, thin-walled. Length of the three joints = 5 : 4 : 9, breadth = 6 : 8 : 9. Form of the three joints and disposition of their pores nearly equal to the preceding species; but the proportion of the joints is different, the shell more delicate, and the mouth more widely open, and nearly as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.05, b 0.04, c 0.09; breadth, a 0.06, b 0.08, c 0.09.

Habitat.—North Pacific, Station 256, depth 2950 fathoms.

5. Tricolocampe amphizona, n. sp. (Pl. 66, fig. 17).

Shell mitre-shaped, very thick-walled. Length of the three joints = 2 : 1 : 1, breadth nearly uniform. Cephalis obtuse, conical, as long as the two other cylindrical joints together (probably composed of several united joints). Pores subregular, disposed in transverse rows, six to eight in the cephalis, two in the thorax, and two in the abdomen. Mouth widely open.

Dimensions.—Length of the three joints, a 0.04, b 0.02, c 0.02; breadth, a 0.04, b 0.05, c 0.05.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

6. Tricolocampe panthera, Haeckel.

Eucyrtidium panthera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 18.

Shell mitre-shaped or nearly cylindrical, thick-walled. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 2. Cephalis subspherical. Thorax campanulate. Abdomen cylindrical. Pores in all three joints irregular, roundish, of different sizes, irregularly disposed. Mouth widely open, truncated, not constricted.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.04 to 0.05, c 0.06 to 0.08; breadth about a 0.02, b and c 0.05.

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

Subgenus 2. Tricolocamptra, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or forms.

7. Tricolocampe urnula, n. sp. (Pl. 66, fig. 22).

Shell cylindrical, with obtuse conical apex, smooth. Length of the three joints = 2 : 3 : 10, breadth = 2 : 3 : 6. Cephalis subspherical. Thorax barrel-shaped. Abdomen cylindrical with slightly constricted wide mouth. Pores irregular, roundish, three to four times as broad in the abdomen as in the thorax, irregularly disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1; breadth, a 0.025, b 0.035, c 0.06.

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

8. Tricolocampe doliolum, n. sp.

Shell cylindrical, with hemispherical apex, rough. Length of the three joints = 1 : 3 : 5, breadth = 1 : 2 : 3. Cephalis spherical. Thorax and abdomen cylindrical, of nearly equal breadth. Mouth widely open, not constricted. Pores irregular, roundish, in the abdomen three to four times as large as in the thorax, disposed in oblique rows.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.16; breadth, a 0.03, b 0.05, c 0.09.

Habitat.—Fossil in Barbados.

9. Tricolocampe cingulata, n. sp.

Shell subcylindrical, with obtuse conical apex, thick-walled. Length of the three joints = 2 : 3 : 11, breadth = 3 : 7 : 8. Cephalis hemispherical, not separated externally from the short conical thorax, but with internal collar septum. Abdomen cylindrical, with wide open, non-constricted mouth. Pores in the thorax narrow, obliquely ascending, in the abdomen twice as large, circular, arranged in ten to twelve regular transverse rows, separated by slight strictures. Lumbar septum nearly complete.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1 to 0.12; breadth, a 0.03, b 0.07, c 0.08.

Habitat.—Fossil in Barbados, and in Tertiary rocks of Sicily; living in the depths of the Atlantic and Central Pacific, Station 348, depth 2450 fathoms; Station 268, depth 2900 fathoms.

10. Tricolocampe arcta, Haeckel.

? Eucyrtidium arctum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 33.

? Lithocampe arcta, Haeckel, 1862, Monogr. d. Radiol., p. 317.

Shell subcylindrical, with obtuse conical apex. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 2. Cephalis subspherical. Thorax campanulate, separated by a deep collar, but a slight lumbar stricture. Abdomen cylindrical, with wide truncate mouth. Pores in the thorax narrow, obliquely ascending, in the abdomen half as large, very small, and densely disposed in six to eight regular transverse rows.

Dimensions.—Length of the three joints, a 0.022, b 0.045, c 0.09; breadth, a 0.026, b 0.05, c 0.05.

Habitat.—Central Pacific, Station 266 to 274, depth 2350 to 2925 fathoms.

Genus 619. Theocorys,^[236] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with ovate abdomen, broader than the constricted mouth. Cephalis with a single horn.

The genus Theocorys and the two following closely allied genera, united formerly with Eucyrtidium, differ from the preceding Theocorida in the constriction of the peristome, so that the inflated abdomen is broader than the terminal mouth. They represent, therefore, the transition to the Theocapsida, with closed mouth. The abdomen is commonly more or less ovate or barrel-shaped, sometimes inversely conical. The cephalis of Theocorys bears a single apical horn.

Subgenus 1. Theocoronium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Theocorys turgidula, Haeckel.

Eucyrtidium turgidulum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 13.

Shell slender, ovate, with two deep strictures, very fragile and thin-walled. Length of the three joints = 2 : 5 : 7, breadth = 2 : 6 : 6. Cephalis subspherical, with a pyramidal horn of the same length. Thorax nearly spherical. Abdomen ovate, twice as broad as the constricted mouth. Pores very numerous, regular hexagonal, three to four times as broad as the bars.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.07; breadth, a 0.02, b 0.06, c 0.06.

Habitat.—Tropical Pacific (Philippine Sea), Stations 206 and 224, surface.

2. Theocorys veneris, n. sp. (Pl. 69, fig. 5).

Shell inversely ovate, with two deep strictures, smooth. Length of the three joints = 2 : 5 : 6, breadth = 3 : 7 : 6. Cephalis hemispherical, with a slender conical horn of twice the length. Thorax nearly spherical. Abdomen ovate, twice as broad as the constricted mouth. Pores regular, circular, twice as broad as the bars, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.07, c 0.06.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; many Stations, surface.

3. Theocorys cretica, Haeckel.

Eucyrtidium creticum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. xi. fig. 23.

Shell ovate, thin-walled, smooth, with two deep strictures. Length of the three joints = 2 : 4 : 4, breadth = 3 : 6 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax and abdomen nearly hemispherical, inflated, united by the opposite bases of the hemispheres. Constricted mouth only one-third as broad as the abdomen. Pores very small and numerous, regular, circular, of the same breadth as the bars, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Mediterranean, Crete, Corfu, surface.

4. Theocorys ovata, n. sp. (Pl. 69, fig. 16).

Shell quite ovate, thick-walled, smooth, without external strictures. Length of the three joints = 2 : 2 : 9. breadth = 3 : 5 : 7. Cephalis conical, with a thick conical horn of the same length. Thorax and abdomen gradually dilated towards the base, and then hemispherical, constricted. Mouth scarcely one-third as broad as the abdomen, prolonged into a short tube. Pores regular, circular, disposed in transverse rows, two to three in the cephalis, two to three in the thorax, eight to ten in the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.09; breadth, a 0.03, b 0.05, c 0.07.

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

5. Theocorys plutonis, n. sp. (Pl. 69, fig. 1).

Shell ovate, thick-walled, smooth, with two slight strictures. Length of the three joints = 2 : 5 : 4, breadth = 4 : 7 : 6. Cephalis hemispherical, with a conical, oblique horn of the same length. Thorax and abdomen only slightly inflated, gradually decreasing towards the wide, little constricted mouth. Pores subregular, circular, much larger in the abdomen and the lower half of the thorax than in the upper half and the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.04; breadth, a 0.04, b 0.07, c 0.06.

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

6. Theocorys scolopax, Haeckel.

Eucyrtidium scolopax, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 5.

Shell slender, inversely ovate, smooth. Length of the three joints = 1 : 3 : 3, breadth = 1 : 4 : 4. Cephalis subspherical, with a long, slightly curved horn, half as long as the whole shell. Thorax campanulate. Abdomen inversely ovate, twice as broad as the constricted mouth (incomplete in Ehrenberg's figure).

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

Habitat.—Fossil in Barbados.

Subgenus 2. Theocorythium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of different sizes or dissimilar forms.

7. Theocorys dianæ, n. sp. (Pl. 69, fig. 11).

Shell almost ovate, with two deep strictures. Length of the three joints = 3 : 6 : 8, breadth = 3 : 9 : 8. Cephalis subspherical, with a slender, pyramidal horn of three times the length. Thorax conical, constricted at the base. Abdomen bottle-shaped. Pores in the thorax irregular, polygonal, in the abdomen subregular, circular, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.08; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—North Pacific, Station 253, surface.

8. Theocorys hyalothorax, n. sp.

Shell slender, ovate, with two deep strictures. Length of the three joints = 6 : 9 : 8, breadth = 7 : 12 : 11. Cephalis subspherical, with numerous densely-placed circular pores, and with a pyramidal, slender horn of the same length. Thorax hemispherical, hyaline, without any pores. Abdomen ovate, twice as broad as the constricted mouth, with two to four widely distant, transverse rows of small, circular pores.

Dimensions.—Length of the three joints, a 0.024, b 0.036, c 0.032; breadth, a 0.028, b 0.048, c 0.044.

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

9. Theocorys bachabunda, Haeckel.

Thyrsocyrtis bachabunda, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 4.

Shell inversely ovate, with two distinct strictures. Length of the three joints = 2 : 5 : 9, breadth = 3 : 9 : 8. Cephalis subspherical, small, with a large cylindrical horn, which is half as long as the whole shell, and armed with spines at the conical apex. Thorax conical, inflated, with small, subregular, circular, quincuncial pores. Abdomen inversely ovate, with irregular, roundish, pores of larger and smaller sizes mixed, gradually lessening towards the constricted mouth.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—Fossil in Barbados.

10. Theocorys attenuata, Haeckel.

Eucyrtidium attenuatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 16.

Shell inversely ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 2 : 5 : 5, breadth = 2 : 7 : 6. Cephalis hemispherical, with a short, oblique, conical horn. Thorax inflated, campanulate, with small, regular, circular, quincuncial pores. Abdomen inversely conical, with irregular pores of larger and smaller sizes mixed, gradually lessening towards the truncated mouth.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.05; breadth, a 0.025, b 0.07, c 0.06.

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

11. Theocorys obliqua, n. sp. (Pl. 69, fig. 10).

Shell inversely ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 3 : 7 : 4, breadth = 4 : 9 : 8. Cephalis hemispherical, with a stout, pyramidal, oblique horn of the same length. Thorax and abdomen together ovate, gradually lessening towards the constricted mouth, which is only half as broad. Pores irregular, roundish, in the thorax twice to four times as broad as in the abdomen. Both joints are separated by an oblique, internal, lumbar septum, which in some specimens observed was more oblique than in that figured; some specimens had a very irregular form.

Dimensions.—Length of the three joints, a 0.025 to 0.03, b 0.06 to 0.07, c 0.03 to 0.04; breadth, a 0.04, b 0.09, c 0.08.

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

12. Theocorys alauda, Haeckel.

Eucyrtidium alauda, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 4.

Shell nearly spindle-shaped, decreasing from the thicker middle towards both ends. Length of the three joints = 1 : 3 : 8, breadth = 1 : 4 : 5. Cephalis subspherical, with a strong, conical horn of three times the length. Thorax campanulate, with numerous regular, circular, quincuncial pores. Abdomen inversely ovate, slender, twice as broad as the truncated mouth, with irregular, roundish pores, three to four times as large as those of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.16; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Fossil in Barbados and in Tertiary rocks of Sicily.

13. Theocorys apollinis, n. sp. (Pl. 69, fig. 3).

Shell ovate, with two deep strictures. Length of the three joints = 2 : 3 : 5, breadth = 2 : 5 : 7. Cephalis subspherical, with a large, straight, cylindrical horn, about as long as the whole shell (in the specimen figured this is broken off). Thorax truncate, conical. Abdomen subglobose, truncate on both poles, twice as broad as the constricted mouth. Pores quincuncial, subregular, circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.05; breadth, a 0.02, b 0.05, c 0.07.

Habitat.—South Atlantic, Station 332, surface.

14. Theocorys sphærophila, Haeckel.

Eucyrtidium sphærophilum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. viii. fig. 16.

Shell almost ovate, rough, with two slight strictures. Length of the three joints = 2 : 7 : 10, breadth = 3 : 8 : 12. Cephalis subspherical, with a strong, conical horn of the same length. Thorax nearly spherical, with subregular, circular pores of different sizes. Abdomen ovate, truncate at both poles, nearly twice as broad as the constricted mouth, with very large, subregular, hexagonal pores, four to six times as broad as the bars, in three to four transverse, and ten to twelve longitudinal rows.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

15. Theocorys tuberculata, n. sp.

Shell almost ovate, tuberculate, with deep collar, but slight lumbar stricture. Length of the three joints = 2 : 5 : 12, breadth = 3 : 8 : 11. Cephalis hemispherical, with a cylindrical horn of twice the length. Thorax hemispherical, with regular, circular, double-edged, quincuncial pores, between which conical tubercles occur. Abdomen truncate, ovate, twice as broad as the constricted mouth, with regular, circular, hexagonally-framed pores, three to four times as broad as those of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.03, b 0.08, c 0.11.

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

16. Theocorys martis, n. sp.

Shell slender, ovate, with two deep strictures. Length of the three joints = 3 : 6 : 18, breadth = 4 : 8 : 12. Cephalis small, hemispherical, with a very large, sword-shaped broad horn, nearly as long as the whole shell. Thorax hemispherical, honey-comb like, with regular, circular, hexagonally-framed pores. Abdomen ovate, with irregular, roundish, very large pores, four to six times as broad as the bars, and as the pores of the thorax. Constricted mouth half as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.18; breadth, a 0.04, b 0.08, c 0.12.

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

17. Theocorys mercurii, n. sp.

Shell ovate, conical, with two slight strictures. Length of the three joints = 1 : 3 : 7, breadth = 2 : 4 : 7. Cephalis hemispherical, with a broad pyramidal horn of the same length. Thorax campanulate, with longitudinal series of small, regular, circular pores, separated by divergent crests. Abdomen nearly spherical, one and a half times as broad as the constricted mouth, which is prolonged into a thin, solid, cylindrical peristome. Pores of the abdomen regular, circular, hexagonally framed, three to four times as broad as the bars, and as the pores of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.15; breadth, a 0.04, b 0.09, c 0.15.

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

18. Theocorys minervæ, n. sp. (Pl. 69, fig. 14).

Shell ovate, conical, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a large pyramidal horn as long as the thorax, and with small, circular pores. Thorax rough, with regular, quincuncial, circular pores, three to four times as large as those of the cephalis. Abdomen barrel-shaped, with irregular, roundish pores of very different sizes, six very large pores immediately beyond the lumbar stricture, and four to five rows of pores, which are twice to four times as large as those of the thorax. Mouth truncated, with thickened margin, two-thirds as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.12, c 0.16; breadth, a 0.04, b 0.16, c 0.2.

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

Genus 620. Axocorys,^[237] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with ovate abdomen, including an internal vertical axial rod, which bears three divergent radial spines or verticils of three branches, and is prolonged into an apical horn.

The genus Axocorys contains only a single but very remarkable species, and may, perhaps, represent a peculiar group, which has closer relations to the Plectoidea than to the other Tricyrtida. The pyriform three-jointed shell has neither lateral nor terminal free appendages, but possesses a very large apical horn, and an inner prolongation of this, an axial rod, which bears some triradiate verticils of branched spines. The original ancestral forms of this remarkable genus are probably Plagoniscus and Plectaniscus (pp. 912 and 924).

1. Axocorys macroceros, n. sp. (Pl. 68, figs. 1, 1a).

Shell pear-shaped, with two distinct strictures. Length of the three joints = 2 : 3 : 16, breadth = 3 : 6 : 16. Cephalis hemispherical, with few small pores. From its apex arises vertically a very long three-sided prismatic horn with denticulate edges, three to four times as long as the shell. An inner thin prolongation of the horn descends vertically nearly to the mouth, and bears on its basal end three verticils of branched spines, each verticil with three divergent forked spines (fig. 1a). Pores regular, circular, in the subspherical abdomen three times as large as in the hemispherical thorax. The constricted mouth is scarcely broader than the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.16; breadth a 0.03, b 0.06, c 0.16.

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

Genus 621. Lophocorys,^[238] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with ovate abdomen, broader than the constricted mouth. Cephalis with two divergent horns, or with a bunch of horns.

The genus Lophocorys differs from its ancestral form, Theocorys, only in the armature of the cephalis, bearing either two divergent horns, or a corona of several radial horns. In two species there are four horns on the apex, a larger vertical (occipital) horn being surrounded by three smaller, upwards divergent horns.

1. Lophocorys astrocephala, n. sp. (Pl. 69, fig. 9).

Shell smooth, inversely ovate, with deep collar and slight lumbar stricture. Length of the three joints = 3 : 7 : 6, breadth = 4 : 11 : 10. Cephalis subspherical, stellate, densely covered with numerous (ten to twenty or more) divergent, large, slenderly conical horns, the longest of which reach the length of the shell. Thorax campanulate, with small, regular, circular pores. Abdomen tapering towards the constricted mouth, in the upper half with the same pores, in the lower half with smaller, scarce pores, or nearly hyaline.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.06; breadth, a 0.04, b 0.11, c 0.1.

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

2. Lophocorys acanthocephala, Haeckel.

Eucyrtidium acanthocephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 8.

Shell rough, bottle-shaped, with two slight strictures. Length of the three joints = 5 : 11 : 7, breadth = 4 : 12 : 10. Cephalis conical, with a large pyramidal horn of the same length, and three smaller divergent accessory horns at the base of the three edges of the latter. Thorax campanulate, nearly as long as the tapering abdomen (which in the figure of Ehrenberg is broken off). Pores regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.05, b 0.11, c 0.07; breadth, a 0.04, b 0.12, c 0.1.

Habitat.—Fossil in Barbados.

3. Lophocorys bicornis, Haeckel.

Eucyrtidium bicorne, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 7.

Shell smooth, almost spindle-shaped, with two slight strictures. Length of the three joints = 2 : 8 : 3, breadth = 3 : 5 : 4. Cephalis hemispherical, with two stout, pyramidal, divergent horns of twice the length. Thorax ovate, with seven to eleven transverse rows of small, regular, circular pores (often very scarce in the upper half). Abdomen with two to four transverse rows of the same pores. Mouth constricted, half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.03; breadth, a 0.03, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

4. Lophocorys quadricornis, n. sp.

Shell rough, slenderly ovate, with two distinct strictures. Length of the three joints = 2 : 4 : 2, breadth = 2 : 4 : 3. Cephalis ovate, with four very stout, three-sided prismatic horns; the largest is as long as the thorax and vertical upon the apex, the three smaller are as long as the cephalis and diverge upwards from the base of the former. Thorax ovate, with large, irregular, roundish pores, which are three to four times as broad as the small, circular pores of the first and the third joint. Constricted mouth half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.045, b 0.085, c 0.04; breadth, a 0.035, b 0.075, c 0.06.

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

5. Lophocorys bovicornis, n. sp. (Pl. 69, fig. 12).

Shell rough, subovate, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with two divergent, curved horns of different lengths. Thorax campanulate, with small, circular pores. Abdomen subspherical, truncate at both poles, twice as broad as the constricted mouth, thorny, with very large, circular pores, four to six times as broad as those of the smaller thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.04, b 0.09, c 0.12.

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

Genus 622. Theocampe,^[239] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with ovate abdomen, broader than the constricted mouth. Cephalis without horn.

The genus Theocampe differs from the two preceding genera in the absence of horns on the cephalis, and may, therefore be derived from Theocorys by reduction of the apical horn. It bears to the latter the same relation as Tricolocampe does to Theocyrtis.

Subgenus 1. Theocampana, Haeckel.

Definition.—Pores of the thorax and the abdomen of nearly equal size and similar form.

1. Theocampe ehrenbergii, Haeckel.

Dictyomitra ehrenbergii, Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 82, Taf ii. fig. 5.

Shell ovate, smooth. Length of the three joints = 2 : 3 : 13, breadth = 4 : 7 : 12. Cephalis hemispherical. Thorax truncate, conical. Abdomen inflated, nearly spherical, twice as broad as the constricted mouth. Pores of nearly equal size and form, small, regular, circular.

Dimensions.—Length of the three joints, a 0.014, b 0.018, c 0.076; breadth, a 0.023, b 0.044, c 0.073.

Habitat.—Fossil in the chalk of Northern Germany; Brunswick (Zittel).

2. Theocampe pirum, Haeckel.

Eucyrtidium pirum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. x. fig. 14.

Eucyrtidium excellens, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 31.

Shell ovate, smooth. Length of the three joints = 3 : 5 : 15, breadth = 6 : 10 : 16. Cephalis hemispherical. Thorax truncate conical. Abdomen inflated, subspherical, three times as broad as the constricted mouth. Pores of nearly equal size, regular, circular in the thorax alternating, in the abdomen disposed in five to six transverse, widely distant rows.

Dimensions.—Length of the three joints, a 0.015, b 0.025 c 0.075; breadth, a 0.03, b 0.05, c 0.08.

Habitat.—Fossil in the Tertiary rocks of Barbados.

3. Theocampe stenostoma, n. sp. (Pl. 66, fig. 23).

Shell about ovate, smooth. Length of the three joints = 3 : 4 : 3, breadth = 6 : 8 : 9. Cephalis hemispherical, large. Thorax and abdomen short, barrel-shaped. Both strictures deep. Abdomen three times as broad as the constricted mouth. Pores of equal size, regular, circular, disposed in oblique rows.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.03; breadth, a 0.06, b 0.08, c 0.09.

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

4. Theocampe nucula, Haeckel.

Eucyrtidium nucula, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 29, Taf. vii. fig. 19.

Shell nearly ovate, rough. Length of the three joints = 3 : 5 : 3, breadth = 4 : 7 : 6. Cephalis hemispherical, large. Thorax and abdomen inflated. Both strictures deep. Thorax broader than the short abdomen, and twice as broad as the constricted mouth. Pores of equal size, regular, circular, regularly disposed in transverse rows: three in the cephalis, six in the thorax, and three in the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.03; breadth, a 0.04, b 0.07, c 0.06.

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

5. Theocampe cryptoprora, Haeckel.

Eucyrtidium cryptoprora, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 14.

Shell ovate, thin-walled, smooth, without external strictures, but with two distinct internal annular septa. Length of the three joints = 2 : 7 : 4, breadth = 3 : 7 : 6. Cephalis, large, subspherical, hyaline; its lower half hidden in the upper part of the campanulate thorax. Mouth little constricted, nearly as broad as the truncate abdomen. All pores equal, small, regular, circular.

Dimensions.—Length of the three joints, a 0.025, b 0.07, c 0.04; breadth, a 0.03, b 0.07, c 0.06.

Habitat.—Tropical Pacific, Stations 225 to 265, in various depths.

6. Theocampe ovulum, n. sp.

Shell perfectly ovate, thick-walled, smooth, without external strictures, but with two broad, internal septa. Length of the three joints = 2 : 3 : 10, breadth = 3 : 6 : 8. Cephalis and thorax together obtuse, conical, with obliquely ascending pores. Abdomen inflated, twice as broad as the constricted mouth, with ten to twelve transverse rows of pores. All pores equal, small, regular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1; breadth, a 0.03, b 0.06, c 0.08.

Habitat.—Fossil in Tertiary rocks of Barbados and Sicily.

7. Theocampe cassis, Haeckel.

Eucyrtidium cassis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 20.

Shell bottle-shaped, thin-walled, with slight collar, but deep lumbar stricture. Length of the three joints = 3 : 8 : 6, breadth = 2 : 7 : 7. Cephalis ovate. Thorax campanulate. Abdomen inflated, twice as broad as the constricted mouth. Pores equal, regular, circular, disposed in quincuncial rows.

Dimensions.—Length of the three joints, a 0.03, b 0.08. c 0.06; breadth, a 0.02, b 0.07, c 0.07.

Habitat.—Tropical Pacific (Philippines), Station 206, depth 2100 fathoms.

Subgenus 2. Theocamptra, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or dissimilar forms.

8. Theocampe sphærothorax, n. sp. (Pl. 66, fig. 25).

Shell almost ovate, rough. Length of the three joints = 2 : 5 : 10, breadth = 3 : 8 : 8. Cephalis hemispherical. Thorax nearly spherical, truncate. Abdomen ovate, twice as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, in the abdomen twice as broad as in the thorax, and four times as broad as in the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

9. Theocampe versipellis, Haeckel.

Eucyrtidium versipellis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 14.

Shell slenderly ovate, rough. Length of the three joints = 3 : 5 : 13, breadth = 4 : 8 : 9. Cephalis subspherical, without pores. Thorax hemispherical. Abdomen inflated, twice as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, in the abdomen three times as broad as in the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.13; breadth, a 0.04, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

10. Theocampe megalopora, Haeckel.

Eucyrtidium megaloporum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 19.

Shell almost ovate, with two distinct strictures. Length of the three joints = 2 : 6 : 3, breadth = 3 : 6 : 4. Cephalis hemispherical. Thorax ovate, inflated. Abdomen inversely ovate, two to three times as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, twice as broad in the large thorax as in the smaller abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.06, c 0.04.

Habitat.—Central Pacific, Station 267, depth 2700 fathoms.

11. Theocampe collaris, n. sp. (Pl. 66, fig. 18).

Shell almost ovate, with two distinct strictures. Length of the three joints = 3 : 3 : 6, breadth = 4 : 5 : 7. Cephalis obtuse conical, with five or six transverse rows of small pores. Thorax truncate conical, with longitudinal furrows, each of which contains a single pore. Abdomen inflated, with five or six distant, transverse rows of small, circular pores.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.06; breadth, a 0.04, b 0.05, c 0.07.

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

12. Theocampe gemmata, Haeckel.

Eucyrtidium gemmatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 6.

Shell slenderly ovate, smooth, with two internal annular septa. Length of the three joints = 1 : 1 : 4, breadth = 1 : 2 : 3. Cephalis campanulate, nearly as large as the truncate, conical thorax, both with small, irregular, obliquely descending pores. Abdomen broader, twice as broad as the constricted mouth, with numerous longitudinal ribs, alternating with single rows of small, circular pores. (This and the following allied species approach to Cycladophora, by the abdominal ribs.)

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.07; breadth, a 0.025, b 0.035, c 0.045.

Habitat.—Fossil in Barbados.

13. Theocampe costata, n. sp. (Pl. 66, fig. 24).

Shell almost ovate, with two sharp strictures. Length of the three joints = 2 : 4 : 8, breadth = 3 : 5 : 7. Cephalis hemispherical. Thorax twice as large, also hemispherical, both with regular, circular, quincuncial pores. Abdomen broader, with numerous longitudinal ribs, alternating with longitudinal rows of larger pores. Mouth constricted, half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.05, c 0.07.

Habitat.—Indian Ocean, Sunda Straits (Rabbe), surface.

14. Theocampe cryptocephala, Haeckel.

Eucyrtidium cryptocephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 11.

Shell ovate, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, its lower half hidden in the campanulate thorax. Abdomen subspherical, twice as broad as the constricted mouth. Pores subregular, circular, quincuncial, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.07; breadth, a 0.025, b 0.07, c 0.09.

Habitat.—Fossil in Barbados.

Subfamily 2. Theocapsida, Haeckel, 1881, Prodromus, p. 436.

Definition.—Theocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida eradiata clausa).

Genus 623. Theocapsa,^[240] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa), with an apical horn, and a terminal lattice-plate on the mouth.

The genus Theocapsa, and the two following genera, represent together the small subfamily of Theocapsida, or of those Tricyrtida in which the mouth is closed by a lattice-plate, and external radial appendages are wanting. Theocapsa may be derived from Theocorys by fenestration of the constricted mouth.

Subgenus 1. Theocapsetta, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or somewhat larger; pores of both nearly equal in size and similar in form.

1. Theocapsa aristotelis, n. sp. (Pl. 66, fig. 6).

Shell subovate, smooth, with two distinct strictures. Length of the three joints = 2 : 6 : 7, breadth = 3 : 8 : 8. Cephalis hemispherical, with a conical, slender horn of about the same length. Thorax and abdomen nearly equal in size, thin-walled, smooth, with small, regular, circular pores of equal size. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.07; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Mediterranean (Gibraltar), Atlantic (Canary Islands), surface.

2. Theocapsa plinii, n. sp.

Shell subovate, smooth, with two indistinct strictures. Length of the three joints = 2 : 5 : 6, breadth = 3 : 7 : 7. Cephalis hemispherical, with a pyramidal, thick horn of about the same length. Thorax and abdomen of nearly equal size, thick-walled, rough, with large, regular, circular, double-edged pores of equal size (twice as large and half as numerous as in the similar preceding species).

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.07, c 0.07.

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

3. Theocapsa democriti, n. sp. (Pl. 66, fig. 8).

Shell slender, ovate, spiny, with two distinct strictures. Length of the three joints = 3 : 5 : 6, breadth = 4 : 7 : 7. Cephalis ovate, with numerous slender horns of the same length. Thorax and abdomen with small, irregular, roundish pores of nearly equal size, armed with scattered slender spines, half as long as the cephalic horns. Basal pole hemispherical, rounded.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.06; breadth, a 0.04, b 0.07, c 0.07.

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

4. Theocapsa galeni, n. sp.

Shell broadly ovate, spiny, with two deep strictures. Length of the three joints = 2 : 7 : 6, breadth = 3 : 8 : 7. Cephalis hemispherical, with two conical, divergent horns of the same length. Thorax and abdomen with large, irregular, roundish pores of nearly equal size, armed with numerous short spines, not larger than the pores. Basal pole conical, pointed.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.06; breadth, a 0.03, b 0.08, c 0.07.

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

Subgenus 2. Theocapsilla, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or somewhat larger; pores of the two different in size or form.

5. Theocapsa wottonis, n. sp. (Pl. 66, fig. 11).

Shell subovate, rough, with two deep strictures. Length of the three joints = 3 : 7 : 5, breadth = 3 : 9 : 8. Cephalis subspherical, with regular, circular, hexagonally-framed pores, and with a stout pyramidal horn of the same length. Thorax conical, with subregular, circular, double-edged pores. Abdomen hemispherical, smaller and thinner walled, with irregular, somewhat oblong pores. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.05; breadth, a 0.03, b 0.09, c 0.08.

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

6. Theocapsa gessneri, n. sp.

Shell broadly ovate, with two deep strictures. Length of the three joints = 3 : 9 : 5, breadth = 4 : 10 : 4. Cephalis hemispherical, with a slender, conical horn of the same length. Thorax subspherical, with small, regular, circular pores. Abdomen inversely conical, with few large, somewhat oblong pores. Basal pole acute.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.05; breadth, a 0.04, b 0.1, c 0.04.

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

7. Theocapsa aldrovandi, n. sp.

Shell slender, inversely ovate, with two slight strictures. Length of the three joints = 3 : 8 : 14, breadth = 4 : 11 : 8. Cephalis subglobular, with a conical horn of the same length. Thorax also subglobular, papillate, with regular, circular, hexagonally-framed pores. Abdomen inversely conical, slender, with very small and numerous, subregular, circular pores. Basal pole ovate, pointed.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.14; breadth, a 0.04, b 0.11, c 0.08.

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

8. Theocapsa malpighii, n. sp. (Pl. 66, fig. 15).

Shell inversely ovate, with two distinct strictures. Length of the three joints = 3 : 8 : 11, breadth = 4 : 9 : 8. Cephalis hemispherical, with a conical horn of the some length Thorax hemispherical, thorny, with very small circular pores, surrounded by large, regular, hexagonal frames. Abdomen inversely campanulate, with larger circular pores, and longitudinal ribs. Basal pole blunt, conical.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.11, breadth, a 0.04, b 0.09, c 0.08.

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

Subgenus 3. Theocapsomma, Haeckel.

Definition.—Thorax much smaller than the abdomen, pores of the two nearly equal in size and similar in form.

9. Theocapsa linnæi, n. sp. (Pl. 66, fig. 13).

Shell slender, subcylindrical, rough with two slight strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 4 : 4. Cephalis hemispherical, with a pyramidal horn of twice the length (sometimes, as in the specimen figured, one or two small accessory horns occur at its base). Thorax hemispherical, thick-walled. Abdomen nearly cylindrical, twice as long as the thorax, thin-walled, with a hemispherical, rounded basal pole. The specimen figured is an abnormal one, with some deformities on the irregular abdomen; in numerous other specimens the abdomen is cylindrical, regular. Pores of the thorax and abdomen equal, very small and numerous, regular, circular, three to four times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.05 to 0.06, c 0.1 to 0.12; breadth, a 0.03, b 0.06 to 0.07, c 0.07 to 0.08.

Habitat.—Cosmopolitan; Atlantic, Indian, and Pacific Oceans; many Stations at various depths.

10. Theocapsa forskalii, n. sp. (Pl. 66, fig. 9).

Shell slender, subcylindrical, smooth, with two slight strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 2. Cephalis hemispherical, with a conical horn of half the length. Abdomen three times as long as the thorax, of the same breadth, with the same irregular, roundish pores, large and small intermingled. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.09; breadth, a 0.03, b 0.06, c 0.06.

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

11. Theocapsa wolffii, n. sp. (Pl. 66, fig. 14).

Shell slender, spindle-shaped very thick-walled, rough, without external strictures, but with two broad internal girdles. Length of the three joints = 2 : 3 : 15, breadth = 4 : 5 : 7. Cephalis with a short horn of the same length, conical. Abdomen five times as long as the thorax, with the same subregular, circular pores. Basal pole inversely conical, with some larger, elongate pores.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.15; breadth, a 0.04, b 0.05, c 0.07.

Habitat.—Mediterranean, Crete, depth 1620 fathoms (Spratt).

12. Theocapsa pallasii, n. sp.

Shell subovate, thorny, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 3. Cephalis ovate, with a pyramidal horn of the same length. Thorax and abdomen with subregular, circular pores of medium size. Basal pole hemispherical. (Differs from Theocapsa mülleri, Pl. 66, fig. 7, mainly in the larger number and smaller size of the regular, quincuncial pores.)

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

Subgenus 4. Theocapsura, Haeckel.

Definition.—Thorax much smaller than the abdomen, pores of the two different in size or form.

13. Theocapsa lamarckii, n. sp. (Pl. 66, fig. 16).

Shell slenderly ovate, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 7, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of twice the length. Thorax conical, with regular, circular pores. Abdomen three times longer, with subregular, hexagonal pores of twice the size. Basal pole hemispherical, with very large, irregular, roundish pores.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.14; breadth, a 0.03, b 0.08, c 0.1.

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

14. Theocapsa cuvieri, n. sp. (Pl. 66, fig. 10).

Shell slenderly spindle-shaped, thorny, with two slight strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 3 : 3. Cephalis subspherical, with a conical horn of the same length. Thorax conical, spiny, with regular, circular, double-edged pores. Abdomen thinner-walled, inversely conical, with irregular, roundish pores. Basal pole acute, with a bunch of larger spines.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.02, b 0.05, c 0.06.

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

15. Theocapsa baerii, n. sp.

Shell slenderly spindle-shaped, smooth with two indistinct strictures. Length of the three joints = 1 : 2 : 8, breadth = 2 : 3 : 4. Cephalis hemispherical, with a thick conical horn of the same length. Abdomen four times as long as the thorax. Pores in the thorax small and numerous, regular, circular, in the abdomen twice as large, and irregularly roundish. Basal pole inversely conical, acute. (Differs from Theocapsa wolffii, Pl. 66, fig. 14, mainly in the shape of the pores.)

Dimensions.—Length of the three joints, a 0.015, b 0.03, c 0.12; breadth, a 0.03, b 0.04, c 0.06.

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

16. Theocapsa rathkei, n. sp.

Shell slenderly conical, with two slight strictures. Length of the three joints = 1 : 2 : 10, breadth = 2 : 4 : 15. Cephalis small, with a large, conical horn of three times the length. Thorax small, thorny, with small irregular, roundish pores. Abdomen very large, as long and as broad as the thorax, with irregular polygonal or roundish, very large pores, the margin of which is finely denticulate. Basal pole truncate, rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.2; breadth, a 0.04, b 0.08, c 0.3.

Habitat.—Fossil in Barbados.

17. Theocapsa schwannii, n. sp.

Shell slenderly ovate, or pear-shaped, with two distinct strictures. Length of the three joints = 1 : 2 : 7, breadth = 2 : 4 : 7. Cephalis subspherical, small, with a stout, pyramidal horn of three times the length. Cavity of the thorax subspherical, its thick wall with small, regular, circular, hexagonally-framed pores. Abdomen very thick-walled, with crested bars, and very large, irregular, roundish pores. Basal pole rounded, truncate.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.14, breadth, a 0.04, b 0.08, c 0.14.

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

18. Theocapsa mülleri, n. sp. (Pl. 66, fig. 7).

Shell slenderly ovate, or pear-shaped, spiny, with two indistinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 3. Cephalis ovate, with a stout, pyramidal horn of the same length, and with a variable number of smaller accessory horns. Pores irregular, roundish, three to four times as broad in the inflated abdomen as in the thorax. Basal pole hemispherical, spiny.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.09; breadth, a 0.03, b 0.07, c 0.09.

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

19. Theocapsa sarsii, n. sp.

Shell pear-shaped, with two indistinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 4. Cephalis with a thick horn of the same length, conical. Abdomen subspherical, very thick-walled, its pores regular, circular, twice as broad as the bars, and three times as broad as those of the thorax. Basal pole flat, rounded.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.12; breadth, a 0.05, b 0.11, c 0.15.

Habitat.—Fossil in Barbados.

20. Theocapsa darwinii, n. sp. (Pl. 66, fig. 12).

Shell pear-shaped, with two distinct strictures. Length of three joints = 1 : 1 : 5, breadth = 1 : 2 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax campanulate, with small, regular, circular pores. Abdomen broad, ovate, with larger, regular, circular, hexagonally-framed pores. Basal pole hemispherical.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.2; breadth, a 0.04, b 0.08, c 0.2.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

Genus 624. Tricolocapsa,^[241] Haeckel.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa) without apical horn, with a terminal lattice-plate on the mouth.

The genus Tricolocapsa differs from the preceding Theocapsa in the loss of the apical horn, and exhibits therefore to it the same relation that Theocampe bears to Theocorys. In some species (Pl. 66, figs. 1, 3) a small tube begins to be developed on the cephalis, and these may perhaps be separated as a peculiar genus, Tricolopera.

Subgenus 1. Tricolocapsula, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or larger.

1. Tricolocapsa theophrasti, n. sp. (Pl. 66, fig. 1).

Shell slenderly ovate, with two slight strictures. Length of the three joints = 2 : 8 : 5, breadth = 3 : 7 : 5. Cephalis hemispherical, with a larger, tube-like, cervical pore at the collar stricture. Thorax very thick-walled, with irregular, roundish, double edged pores, smaller than the bars between them. Abdomen smaller, inversely campanulate-conical, with very irregular pores. Basal pole acute.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.05; breadth, a 0.03, b 0.07, c 0.05.

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

2. Tricolocapsa dioscoridis, n. sp. (Pl. 66, fig. 3).

Shell short and broad, with two deep strictures. Length of the three joints = 3 : 5 : 4, breadth = 4 : 7 : 5. Cephalis hemispherical, with a larger, tube-like, cervical pore above the collar stricture. Thorax very broad, with irregular, large and spare, roundish pores. Abdomen much smaller, inversely conical, with smaller pores. Basal pole obtuse.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.04; breadth, a 0.04, b 0.07, c 0.05.

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

3. Tricolocapsa linnæi, n. sp. (Pl. 66, fig. 5).

Shell short and broad, with two deep strictures. Length of the three joints = 1 : 4 : 2, breadth = 1 : 4 : 2. Cephalis hemispherical. Thorax thick-walled, inflated, with subregular, circular, double-edged pores. Abdomen much smaller, thin-walled, with irregular, polygonal pores. Basal pole hemispherical, rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.05; breadth, a 0.03, b 0.08, c 0.05.

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

4. Tricolocapsa decandollei, n. sp. (Pl. 66, fig. 4).

Shell subovate, with two sharp strictures. Length of the three joints = 2 : 2 : 2, breadth = 3 : 4 : 3.5. Cephalis campanulate. Thorax broader, ring-shaped. Abdomen inversely hemispherical. All three joints of the same length, thick-walled, with the same regular and peculiar reticulation, the small circular pores being surrounded by square, elevated frames.

Dimensions.—Length of the three joints, a 0.07, b 0.07, c 0.07; breadth, a 0.10, b 0.14, c 0.12.

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

Subgenus 2. Tricolocapsium, Haeckel.

Definition.—Thorax much smaller than the abdomen.

5. Tricolocapsa brownii, n. sp.

Shell ovate, very thick-walled, with two indistinct strictures. Length of the three joints = 2 : 4 : 7, breadth = 3 : 7 : 10. Cephalis flat, hemispherical. Thorax truncate, conical. Abdomen inflated, inversely hemispherical. Pores regular, circular, of the same breadth as the bars, hexagonally-framed, twice as large in the abdomen as in the thorax. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.07; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—Fossil in Barbados.

6. Tricolocapsa schleidenii, n. sp. (Pl. 66, fig. 2).

Shell subconical, with two deep strictures. Length of the three joints = 2 : 3 : 6, breadth = 3 : 5 : 6. Cephalis subspherical. Pores subregular, circular, arranged in transverse girdles, three in the broad thorax, six in the subglobular abdomen. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.03, b 0.05, c 0.06.

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

Genus 625. Phrenocodon,^[242] n. gen.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa) with an apical horn, and a lattice-plate between thorax and abdomen.

The genus Phrenocodon differs from the two preceding genera in the remarkable circumstance, that the basal lattice-plate closes not the terminal mouth itself, but the constricted opening between thorax and abdomen. It may therefore be regarded as a Sethocapsa, which has developed a third, open, abdominal joint. The cephalis bears an apical horn.

1. Phrenocodon clathrostomium, n. sp. (Pl. 70, figs. 7, 8).

Shell campanulate-conical, with two deep strictures. Length of the three joints = 2 : 6 : 3, breadth = 3 : 10 : 14. Cephalis hemispherical, with an oblique curved horn of the same length. Thorax subconical, with polygonal, roundish pores, increasing in size towards the girdle. A perfect fenestrated diaphragm, with irregular, roundish pores of very different sizes, separates the thorax from the abdomen. The latter is composed of three parallel, circular rings, which are connected by fifteen to twenty radial beams. As the middle ring is larger than the two others, the beams between the large quadrangular pores are divergent in the upper, convergent in the lower girdle. Short prolongations of the divergent beams form a coronal around the middle ring (compare fig. 7 profile, fig. 8 from below).

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.1, c 0.14.