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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.