Legion III. NASSELLARIA, (continued 11)

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

Habitat.—North Pacific, Station 237, surface.

5. Pterocorys falcifera, Haeckel.

Pterocanium falciferum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 107, Taf. iv. fig. 15.

? Pterocanium bibrachiatum, Stöhr, 1880, Palæontogr., vol xxvi. p. 106, Taf. iv. fig. 14.

Shell subovate, with two distinct strictures. Length of the three joints = 2 : 6 : 5, breadth = 3 : 9 : 10. Cephalis subspherical, with a conical horn of the same length. Thorax hemispherical, thick-walled, rough, with three stout triangular wings, which are about as long as the shell, and curved downwards, with upper convexity. Abdomen ovate, cylindrical, with wide, truncate mouth. Pores irregular, roundish, large and small intermingled; at the base of the abdomen (below the lumbar girdle) a circle of somewhat oblong, quadrangular pores.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.05; breadth, a 0.03, b 0.09, c 0.1.

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

6. Pterocorys aquila, n. sp. (Pl. 71, fig. 5).

Shell ovate, with two deep strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 8 : 6. Cephalis hemispherical, with a slender curved horn of three times the length. Thorax hemispherical, campanulate, spiny, prolonged above the lumbar girdle into three stout, three-sided prismatic wings, which are longer than the shell, fenestrated at the base, and S-shaped, curved. Abdomen barrel-shaped, with wide, truncate mouth. Pores irregular, roundish, of very different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.03, b 0.16, c 0.12.

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

7. Pterocorys hirundo, n. sp. (Pl. 71, fig. 4).

Shell slender, ovate, with two deep strictures. Length of the three joints = 1 : 4 : 4, breadth = 2 : 5 : 5. Cephalis hemispherical, with a large pyramidal horn longer than the half shell. Thorax conical, spiny, prolonged above the lumbar girdle into three slender, triangular, prismatic wings, which are about as long as the shell, and slightly curved downwards, with lower convexity. Abdomen inflated, with wide, truncate mouth. Pores irregular, roundish, of very different sizes.

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

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

8. Pterocorys barbadensis, Haeckel.

Pterocanium barbadense, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 6.

Pterocyrtidium barbadense, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi., Taf. xxxiii. fig. 29, a, b.

Shell slender, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 4, breadth = 2 : 4 : 4. Cephalis hemispherical, with a stout pyramidal horn of twice the length. Thorax campanulate-conical, in the lower half with three divergent, angular wings, which are slightly curved downwards, and as long as the thorax. Abdomen cylindrical, with wide, truncate mouth. Pores small, subregular, circular.

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

Habitat.—Fossil in Barbados.

9. Pterocorys apis, Haeckel.

Pterocodon apis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 3.

Shell slender, smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 3 : 4. Cephalis hemispherical, with a curved, conical horn of three times the length. Thorax very small, with three nearly horizontal, conical wings, which are slightly curved downwards, and twice as long as the thorax. Abdomen cylindrical, three times as long as the thorax, with wide, truncate mouth. Pores small, subregular, circular. Differs from all other species in the very small size of the thorax; the abdomen is broken off in Ehrenberg's figure.

Dimensions.—Length of the three joints, a 0.15, b 0.02, c 0.06; breadth, a 0.02, b 0.03, c 0.04.

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

10. Pterocorys melitta, Haeckel.

Rhopalocanium ornatum, Bury, 1862, Polycystins of Barbados, Taf. vi. fig. 4.

Shell slender, smooth, with two deep strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 2. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax broad and short, loaf-shaped, with three conical wings, which are horizontally expanded, and half as long as the shell. Abdomen cylindrical, with wide, truncate mouth. Pores small, subregular, circular.

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

Habitat.—Fossil in Barbados.

11. Pterocorys turgida, Haeckel.

Lychnocanium turgidum, Ehrenberg, 1885, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 6.

Shell thick-walled, pear-shaped, smooth, with sharp collar stricture. The lumbar stricture is not distinct externally, but is represented by a broad, internal, annular septum. Length of the three joints = 1 : 6 : 3, breadth = 2 : 7 : 6. Cephalis hemispherical, with a stout pyramidal horn of the same length. Thorax and abdomen together pear-shaped, inflated. Immediately above the lumbar stricture three stout, conical, lateral wings, as long as the cephalis, arise. Mouth very small, about as broad as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.06; breadth, a 0.03, b 0.13, c 0.12.

Habitat.—Fossil in Barbados.

Subgenus 2. Pterosyringium, Haeckel.

Definition.—Horn of the cephalis simple. Abdomen prolonged into a narrow cylindrical tube.

12. Pterocorys tubulosa, n. sp. (Pl. 68, fig. 6).

Pterosyringium tubulosum, Haeckel, 1879, Atlas, loc. cit.

Shell thick-walled, rough, with two slight strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 3 : 1. Cephalis hemispherical, with a conical horn of the same length. Thorax ovate, in the upper half with three ribs, arising into short, triangular, slightly prominent wings. Abdomen prolonged into a cylindrical, narrow tube of the same length as the thorax. Terminal mouth very narrow. Pores subregular, circular.

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

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

13. Pterocorys pipetta, n. sp.

Shell thin-walled, smooth, with two slight strictures. Length of the three joints = 1 : 6 : 3, breadth = 1 : 3 : 1. Cephalis ovate, with a conical horn of twice the length. Thorax ovate, in the middle zone with three conical wings of the same length, curved slightly downwards (like those of Pterocorys columba, Pl. 71, fig. 2). Abdomen constricted into a cylindrical tube half as long as the thorax, with narrow mouth. Pores subregular, circular.

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

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

Subgenus 3. Pterocorythium, Haeckel.

Definition.—Horn of the cephalis double or multiple. Abdomen not prolonged into a narrow tube.

14. Pterocorys rhinoceros, n. sp. (Pl. 71, fig. 1).

Shell very delicate and thin-walled, with two sharp strictures. Length of the three joints = 2 : 10 : 3, breadth, 3 : 11 : 9. Cephalis obtuse, conical, with two divergent, conical horns of equal length. Thorax triangular, pyramidal; from its three edges there arise on the middle joint three conical descending wings (little larger than the horns), and from the base of each wing descend two divergent crests, forming at the sides of the pyramid three rounded lobes. Abdomen short, cylindrical, with wide, truncate mouth. Network of the whole shell very delicate, with very small and numerous, regular, circular, hexagonally-framed pores.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.03; breadth, a 0.03, b 0.11, c 0.09.

Habitat.—Central Pacific, Stations 270 to 274, surface, and in various depths.

15. Pterocorys prismatica, n. sp.

Shell very delicate and thin-walled throughout, with fine fenestration similar to that of the preceding species, but differing from it in the form of the abdomen, which is much larger, three-sided and prismatic; three edges of the prism decurrent from the bases of the three short wings. Length of the three joints = 1 : 4 : 5, breadth = 2 : 6 : 6. No lobes at the thorax. Mouth wide open, truncate, triangular.

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

Habitat.—South Pacific, Station 288, surface.

16. Pterocorys tricornis, n. sp.

Shell spiny, with two deep strictures. Length of the three joints = 1 : 5 : 3, breadth = 1 : 7 : 5. Cephalis subspherical, with three stout, pyramidal, divergent horns, which are three times as long, and bear three serrated edges. Thorax three-sided pyramidal, spiny; its three edges prolonged at the girdle into three stout, triangular, prismatic wings of the same length, little curved. Abdomen short, cylindrical, with wide open, truncate mouth. Pores irregular, polygonal, roundish.

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

Habitat.—North Pacific, Station 244, surface.

17. Pterocorys zittelii, Haeckel.

Pterocyrtidium zittelii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 531, 540, Taf. xxxiii. figs. 28, a, b.

Shell thin-walled, rough, with two slight strictures. Length of the three joints = 2 : 5 : 7, breadth = 3 : 5 : 5. Cephalis hemispherical, armed with a very large, prismatic, vertical horn, which is half as long as the shell, and at its base surrounded by several (three to five) shorter, upwardly diverging horns. Thorax campanulate, in the upper half with three short, downwardly diverging, conical wings. Abdomen subcylindrical, with wide, truncate mouth. Pores small, subregular, circular.

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

Habitat.—Fossil in Barbados.

18. Pterocorys macroptera, n. sp.

Shell thin-walled, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 3. Cephalis hemispherical, armed with two larger and six to eight smaller, conical, divergent horns of different lengths. Thorax three-sided pyramidal; its three edges prolonged into three very large diverging wings, which are slender, three-sided, prismatic, and nearly twice as long as the shell. Abdomen short, cylindrical, with wide, truncate mouth. Pores irregular, roundish, in the middle part of the shell (on both sides of the girdle) much larger than in the upper and lower part.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.06; breadth, a 0.04, b 0.12. c 0.1.

Habitat.—South Atlantic, Station 335, surface.

Genus 583. Theopilium,^[200] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three lateral ribs enclosed in the wall of the thorax, without free lateral or terminal appendages.

The genus Theopilium differs from all the other Theopilida in the absence of free external appendages; it has neither lateral wings nor terminal feet, but three divergent ribs are enclosed in the wall of the thorax. It agrees in this character with the Dicyrtid Lamprodiscus, and may be derived directly from this by development of an abdomen.

1. Theopilium tricostatum, n. sp. (Pl. 70, fig. 6).

Shell flatly conical, smooth. Length of the three joints = 1 : 4 : 2, breadth = 2 : 6 : 10. Cephalis subspherical, with a thin oblique horn of the same length. Thorax with three stout ribs in its wall, and with subregular, hexagonal pores increasing in size towards the girdle. Abdomen flatter than the thorax, without ribs, nearly horizontal, with subregular, square pores, disposed in four to six concentric, subcircular series of different sizes; decreasing in size towards the wide open mouth. Seen from the side, this species resembles Corocalyptra agnesæ, (Pl. 59, fig. 3).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.12, c 0.2.

Habitat.—Central Pacific, Stations 260 to 274, surface.

2. Theopilium triradiatum, n. sp.

Shell flatly conical, smooth, in general of the same form as, and with similar fenestration to, the preceding species, but different in the proportions. Length of the three joints = 1 : 4 : 2, breadth = 2 : 4 : 6. Cephalis hemispherical, with two divergent, thin horns of the same length. Thorax more elevated, about as high as broad. The three divergent ribs are not limited to the thorax, but prolonged through the whole abdomen, the outline of which is a prolongation of that of the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.1, c 0.05; breadth, a 0.05, b 0.1, c 0.15.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Theopilium cranoides, Haeckel.

Eucyrtidium cranoides, Haeckel, 1862, Monogr. d. Radiol., p. 320, Taf. vii. figs. 1-3.

Shell campanulate-conical, smooth. Length of the three joints = 2 : 5 : 4, breadth = 3 : 9 : 10. Cephalis ovate, with a straight, excentric, prismatic horn of the same length. The campanulate thorax is separated from it by no external collar stricture, but by an internal septum. From the base of the horn arise three divergent radial ribs, running in the wall of the two first joints to the lumbar stricture (loc. cit., Taf. vii. fig. 3). Abdomen short and wide, without ribs. Pores rather large, regular, circular, quincuncial, in the cephalis smaller. Central capsule four-lobed.

Dimensions.—Length of the three joints, a 0.027, b 0.054, c 0.047; breadth, a 0.03, b 0.09, c 0.1.

Habitat.—Mediterranean (Messina), surface.

Genus 584. Corocalyptra,^[201] n. gen.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, free, lateral wings, arising from the collar stricture between cephalis and thorax.

The genus Corocalyptra comprises a small number of very elegant hat-shaped Tricyrtida, which resemble greatly Eucecryphalus among the Dicyrtida. As in the latter, three free, radial spines, or simple wings, corresponding to the three basal feet of Cortina, arise from the collar stricture between the small hemispherical cephalis and the large, flatly conical thorax. Corocalyptra differs from Eucecryphalus, its ancestral form, in the development of a flat and broad abdomen, which is a prolongation of the thorax, and may be compared to the brim of a hat.

1. Corocalyptra agnesæ, n. sp. (Pl. 59, fig. 3).

Shell flatly conical or hat-shaped. Length of the three joints = 1 : 4 : 2, breadth = 2 : 8 : 12. Cephalis hemispherical, with an oblique, small, conical horn of the same length. From the slight collar stricture arise three slender, conical feet of equal length, twice as long as the apical horn, nearly horizontally divergent. Lateral outline of the conical thorax straight, of the flatter abdomen convex; the smooth margin of the abdomen turned inwards. Network delicate, with subregular, hexagonal pores.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.15, c 0.24.

Habitat.—Central Pacific, Station 270, surface.

2. Corocalyptra elisabethæ, n. sp. (Pl. 59, fig. 10).

Shell flatly conical, hat-shaped, very similar to the preceding species, but with different proportions. Length of the three joints = 1 : 4 : 2; breadth = 1 : 7 : 10. Cephalis very small, with an oblique horn of the same length. The three feet are of different sizes, the caudal odd foot being twice as long as the two lateral, which are equal to the horn. Lateral outline of the campanulate thorax convex, of the flatter abdomen less convex. Margin of the mouth flat.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.03; breadth a 0.02, b 0.14, c 0.2.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Corocalyptra emmæ, n. sp. (Pl. 59, fig. 4).

Shell nearly conical, hat-shaped. Length of the three joints = 1 : 3 : 1, breadth = 1 : 5 : 7. Cephalis hemispherical, with a straight horn of the same length. Feet of the collar larger than in the preceding species, the two lateral smaller being directed upwards, the larger odd caudal downwards. Thorax slightly campanulate; its hexagonal meshes two to four times as large as those of the short, convex abdomen, which is turned inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.09, c 0.03; breadth, a 0.025, b 0.13, c 0.17.

Habitat.—Central Pacific, Station 273, surface.

4. Corocalyptra margarethæ, n. sp.

Shell nearly conical, hat-shaped, very similar to the preceding species, but with much more delicate hexagonal network, with thread-like bars. Length of the three joints = 1 : 7 : 2, breadth = 1 : 10 : 12. Cephalis hemispherical, with six bristle-shaped spines of half the length of the shell; three horns divergent upwards, and three alternating feet divergent downwards. Thorax nearly conical. Abdomen flatter.

Dimensions.—Length of the three joints, a 0.015, b 0.1, c 0.03; breadth, a 0.02, b 0.15, c 0.18.

Habitat.—North Pacific, Station 236, surface.

5. Corocalyptra ludovicæ, n. sp.

Shell flatly campanulate or hat-shaped. Length of the three joints = 1 : 4 : 3, breadth = 2 : 7 : 10. Cephalis hemispherical, with six bristle-shaped spines, about one-fourth to one-third as long as the shell; three horns diverging upwards, and three alternate feet diverging downwards. Thorax nearly conical. Abdomen much larger than in all preceding species, inflated, with convex, lateral outline; its mouth-edge curved inwards. The network is much finer than in the similar Corocalyptra emmæ (Pl. 59, fig. 4), and the abdomen is relatively twice as long and broad.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.04, b 0.14, c 0.2.

Habitat.—Central Pacific, Station 271, surface.

Genus 585. Dictyoceras,^[202] Haeckel, 1862, Monogr. d. Radiol., p. 333.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the sides of the thorax, which are not prolonged into the cephalis.

The genus Dictyoceras and the following Pteropilium agree with the two preceding genera in the possession of three lateral wings on the sides of the thorax; but whilst these in the latter are simple solid spines, they are in the former vertical fenestrated plates. Dictyoceras may be derived from Pterocorys by development of a vertical lattice-plate between the thorax and the three free lateral spines arising from it.

1. Dictyoceras insectum, n. sp. (Pl. 71, figs. 6, 7).

Shell with two distinct strictures. Length of the three joints = 1 : 3 : 2, breadth = 2 : 4 : 3. Cephalis hemispherical, with a slender pyramidal horn of twice the length. Thorax subspherical, in the upper half with three divergent lattice-wings of the same length, each of which represents a slender, fenestrated, three-sided pyramid. Abdomen subovate, with wide, truncate mouth (in the figured specimen broken off). Pores circular, small, of different sizes.

Dimensions.—Length of the three joints, a 0.025, b 0.055, c 0.04; breadth, a 0.035, b 0.08, c 0.06.

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

2. Dictyoceras formica, n. sp. (Pl. 71, fig. 8).

Shell with obliterate collar, but deep lumbar stricture. Length of the three joints = 1 : 2 : 3, breadth = 2 : 5 : 4. Cephalis conical, with an oblique curved horn of the same length. Thorax with three vaulted swellings between the three prominent, diverging lattice-wings, the apex of which is prolonged downwards into a solid curved spine, half as long as the inflated abdomen. Mouth little constricted. Pores irregular, roundish, of different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.03, b 0.1, c 0.09.

Habitat.—North Atlantic, Station 353, surface.

3. Dictyoceras melitta, n. sp. (Pl. 71, fig. 9).

Shell with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 6 : 5. Cephalis subspherical, with two conical divergent horns of the same length. Thorax three-sided pyramidal, the three edges prolonged into three lattice-wings of the same form, with short, terminal spines. Abdomen inflated, subovate, with constricted mouth. Pores small, regular, circular, of equal size, with very thin bars.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.04, b 0.18, c 0.15.

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

4. Dictyoceras bombus, n. sp. (Pl. 71, fig. 10).

Shell with deep collar, but evanescent lumbar stricture. Length of the three joints = 1 : 5 : 3, breadth = 1 : 6 : 7. Cephalis subspherical, with a conical horn of the same length. Thorax campanulate, with three short and broad, triangular lattice-wings, the upper edge of which is nearly horizontal, the lower nearly vertical and decurrent from the height of the collar to the lumbar stricture. Abdomen inflated, with constricted mouth of half the breadth. Pores small, subregular, circular, of nearly equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.06; breadth, a 0.025, b 0.12, c 0.14.

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

5. Dictyoceras virchowii, Haeckel.

Dictyoceras virchowii, Haeckel, 1862, Monogr. d. Radiol., p. 333, Taf. viii. figs. 1-5.

Lithornithium dictyoceras, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1860, p. 840.

Shell with two distinct strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 5 : 6. Cephalis subspherical, with an oblique curved horn of the same length. Thorax conical, with three broad, triangular lattice-wings different in size and direction, two of which are directed outwards, the third downwards—each terminated by a strong spine. Abdomen oblique, inflated, with wide open, truncate mouth. On the shell surface some few conical spines are scattered. Pores irregular, roundish, of different sizes. On the peculiar symmetry of this remarkable form, compare the detailed description in my Monograph.

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

Habitat.—Mediterranean, Messina, surface.

Genus 586. Pteropilium,^[203] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the sides of the thorax, prolonged into the horn of the cephalis in the form of three vertical, free cephalic wings.

The genus Pteropilium differs from the preceding closely allied Dictyoceras in the development of three free, vertical, latticed cephalic wings, expanded between the apical horn of the cephalis and the three wings of the thorax; they may be direct prolongations of the latter. Pteropilium, however, may also be derived directly from the Dicyrtida Callimitra or Clathrocorys by development of an abdomen. All these interesting forms are closely allied to the Plectoidea.

Subgenus 1. Clathropilium, Haeckel, 1881, Prodromus, p. 435.

Definition.—Thorax completely latticed, without three larger lateral holes between the three wings.

1. Pteropilium stratiotes, n. sp. (Pl. 70, figs. 9, 10).

Shell thin-walled, with two deep strictures. Length of the three joints = 1 : 5 : 4, breadth = 2 : 6 : 9. Cephalis hemispherical, with a vertical, straight, prismatic horn of three times the length. Thorax inflated, oblique, with three slender, nearly straight, widely divergent ribs, beginning from the collar stricture and united in its centre with the centripetal prolongation of the horn. The basal half of the three ribs is enclosed in the thorax wall, whilst the distal half lies outside it, and is connected with its lower half only by two divergent, reticulated wings. The upper edge of the ribs is connected with the occipital horn by a vertical, loosely reticulated, triangular wing. Abdomen half as long as the thorax, also of irregular and oblique form, with knee-shaped outline and a wide, truncate mouth. Network with irregular polygonal, for the most part quadrangular, meshes, separated by thin bars and forming irregular transverse rows. Some stronger, vein-like ribs ramify in the wall, diverging towards the mouth.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.08; breadth, a 0.04, b 0.12, c 0.18.

Habitat.—Central Pacific, Station 271, surface.

2. Pteropilium hoplites, n. sp.

Shell in the general form and in the irregular, quadrangular fenestration similar to the preceding species, but more heavy and with different proportions. Length of the three joints = 1 : 6 : 4, breadth = 2 : 6 : 8. Cephalis twice as broad as in Pteropilium stratiotes. Thorax more slender and subovate. Abdomen truncate, conical, gradually dilated, with straight, non-geniculate outline. Network coarser, with larger square meshes and thicker bars.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.08; breadth, a 0.05, b 0.12, c 0.16.

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

3. Pteropilium eques, n. sp.

Shell in the general form and in the irregular, quadrangular fenestration similar to those of the two preceding species, but more slender and with different proportions. Length of the three joints = 1 : 3 : 2, breadth = 2 : 4 : 4. Cephalis flatter. Thorax subconical, also flatter. Abdomen short, cylindrical, with straight outline. Network looser than in the two preceding species, with larger square meshes and thinner bars.

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

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

Subgenus 2. Arachnopilium, Haeckel, 1881, Prodromus, p. 435.

Definition.—Thorax with three large lateral holes between the three latticed wings.

4. Pteropilium clathrocanium, n. sp. (Pl. 64, fig. 7).

Arachnopilium clathrocanium, Haeckel, Prodromus, 1881, p. 435.

Shell very delicate, with two deep strictures. Length of the three joints = 2 : 4 : 2, breadth = 2 : 10 : 5. Cephalis subspherical, with circular, polygonally-framed pores, and a central, three-sided pyramidal, apical horn of twice the length. Thorax three-sided pyramidal, with three large, ovate holes between three prominent latticed wings. From its surface arises a very delicate, arachnoidal network with irregular, polygonal meshes, enveloping also the entire cephalis. Abdomen wide and short, as long as the cephalis, and half as broad as the distance of the wings, twice as broad as the constricted mouth.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.04; breadth, a 0.05, b 0.2, c 0.1.

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

Genus 587. Theopodium,^[204] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three divergent solid ribs, which lie in the wall of the thorax and the abdomen, and are prolonged into three solid terminal feet.

The genus Theopodium and the following closely allied Pterocanium differ from the preceding four genera in the development of the three radial rods or the primary cortinar spines, which are not free lateral wings, but longitudinal ribs enclosed in the wall of the thorax and abdomen, and prolonged over the basal mouth into three free terminal feet. These are solid in Theopodium, which, therefore, corresponds to Lychnocanium among the Dicyrtida.

1. Theopodium tricostatum, n. sp. (Pl. 97, fig. 14).

Shell three-sided pyramidal, thorny, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout conical horn of the same length. Thorax with regular, circular, hexagonally-framed pores. Abdomen with irregular, roundish pores of very different sizes. From the middle part of the thorax arise the three prominent, wing-like edges of the pyramid, which are prolonged over its wide mouth into three stout, pyramidal, divergent feet about as long as the thorax, with dentate, lamellar edges.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.06; breadth, a 0.04, b 0.09, c 0.12.

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

2. Theopodium pyramidale, n. sp.

Shell three-sided pyramidal, rough, without external strictures, but with two broad internal girdles. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 8. Cephalis with a thick horn of the same length, conical. Thorax with very small, regular, circular pores. Abdomen with irregular, roundish pores of very different sizes. From the collar stricture arise the three rectilinear edges of the pyramid, which are prolonged over its wide-open mouth into three stout, divergent, pyramidal feet, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.075, c 0.15.

Habitat.—Fossil in Barbados.

Genus 588. Pterocanium,^[205] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three divergent ribs, which run along the thorax and abdomen, and are prolonged into three latticed terminal feet.

The genus Pterocanium differs from the preceding Theopodium in the fenestration of the three terminal feet, which are basal prolongations of the three radial ribs, enclosed in the wall of the thorax and the abdomen. Often also these ribs are partly or wholly fenestrated. It corresponds to Lychnodictyum among the Dicyrtida, and may be derived from this by development of an abdomen. The latter forms sometimes three concave bays, at other times three convex lobes between the three latticed feet.

Subgenus 1. Pterocanarium, Haeckel.

Definition.—Free basal edge of the abdomen between the three feet concave, forming three shallower or deeper bays between them.

1. Pterocanium proserpinæ, Ehrenberg.

Pterocanium proserpinæ, Ehrenberg, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 299, Taf. xi. fig. 22.

Pterocanium proserpinæ, Haeckel, 1862, Monogr. d. Radiol., p. 332.

Shell campanulate, rough. Length of the three joints = 1 : 4 : 2, breadth 1 : 5 : 6. Cephalis subspherical, with a triangular-pyramidal vertical horn of thrice the length. Thorax hemispherical, without prominent swellings. Abdomen shorter, with three concave basal bays. Pores in the thorax and abdomen nearly equal, subregular, circular. Feet from the girdle (or the lumbar stricture) little divergent, nearly straight.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.3, b 0.1, c 0.12.

Habitat.—Mediterranean, Candia, Spratt, depth 1100 fathoms.

2. Pterocanium gravidum, n. sp., (Pl. 73, fig. 3).

Shell campanulate, nearly three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 3, breadth = 1 : 6 : 10. Cephalis subspherical, with a pyramidal straight horn of twice the length. Thorax hemispherical, without prominent swellings. Abdomen shorter, with three concave basal bays; its network prolonged to the ends of the feet. Pores in the thorax and abdomen of nearly equal size, irregular, roundish. Feet from the girdle strongly divergent, with convex back.

Dimensions.—Length of the three joints, a 0.015, b 0.075, c 0.06; breadth, a 0.02, b 0.12, c 0.2.

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

3. Pterocanium orcinum, n. sp. (Pl. 73, fig. 2).

Shell campanulate, nearly three-sided pyramidal, covered with conical spines. Length of the three joints = 1 : 4 : 3, breadth = 1 : 5 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax without prominent swellings, with subregular, circular pores. Abdomen shorter, with three concave basal edges and irregular, polygonal pores. Feet from the girdle strongly divergent, nearly straight.

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

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

4. Pterocanium contiguum, Ehrenberg.

Pterocanium contiguum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xvii. fig. 7.

Shell three-sided pyramidal, smooth. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 6. Cephalis small, subspherical, with a large conical horn three times the length. Thorax and abdomen with small, regular, circular pores of equal size, densely crowded together, with thin bars. Abdomen shorter, with three concave basal edges. Feet very thick, straight, from the girdle strongly divergent.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.025; breadth a 0.02, b 0.08, c 0.12.

Habitat.—Fossil in Barbados.

5. Pterocanium pyramis, n. sp. (Pl. 68, fig. 7).

Shell three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 3, breadth = 2 : 4 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax campanulate, with fifteen to twenty prominent longitudinal ribs, separating as many rows of regular, circular pores. Abdomen shorter, with three concave basal bays, and irregular, roundish pores. Feet very strong, pyramidal, straight, gradually divergent from the girdle.

Dimensions.—Length of the three joints, a 0.025, b 0.08, c 0.06; breadth, a 0.04, b 0.08, c 0.12.

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

6. Pterocanium virgineum, n. sp. (Pl. 73, fig. 6).

Shell nearly three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 8, breadth 2 : 6 : 9. Cephalis hemispherical, with a conical straight horn three times the length. Thorax campanulate, with three slight swellings between the three knee-shaped ribs, and with regular circular pores. Abdomen longer, with three concave basal bays, and with very small and numerous pores (much smaller than those of the thorax). At both sides of the three prominent abdominal crests, two rows of larger, nearly square pores occur. Feet slender, nearly straight, divergent.

Dimensions.—Length of the three joints, a 0.15, b 0.06, c 0.12; breadth, a 0.03, b 0.09, c 0.14.

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

7. Pterocanium prætextum, Haeckel.

Lychnocanium prætextum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 2.

Shell nearly three-sided prismatic, smooth. Length of the three joints = 1 : 2 : 1, breadth = 1 : 4 : 4. Cephalis subspherical, with a straight, conical horn of three times the length. Thorax campanulate with three slight swellings between the three knee-shaped ribs, and with regular, circular pores. Abdomen smaller, with three deep concave basal bays, and with irregular, roundish pores. Feet longer than the shell, slender, pyramidal, straight, parallel.

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

Habitat.—Indian Ocean, Ceylon (Haeckel); Zanzibar (Pullen).

8. Pterocanium depressum, Haeckel.

Lychnocanium depressum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 1.

Shell (including the feet) nearly three-sided prismatic, rough. Length of the three joints = 1 : 2 : 1, breadth = 1 : 6 : 6. Cephalis subspherical, with a conical horn of the same length. Thorax a very flat and broad triangular pyramid, three times as broad as long. Abdomen smaller, with three deep, parabolic, concave bays. Pores irregular, roundish. Feet longer than the shell, slender, pyramidal, straight, parallel.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.025, b 0.12, c 0.12.

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

9. Pterocanium campanella, Haeckel.

Lychnocanium campanella, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 12

Podocyrtis campanella, Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 769.

Shell campanulate, smooth, with three high fenestrated crests and deep collar stricture. Length of the three joints = 1 : 3;1, breadth = 1 : 4 : 3. Cephalis subspherical, with a slender horn of the same length. Thorax inflated, campanulate, with three vaulted swellings between the three curved ribs. Abdomen short, with three semicircular bays between the three feet. Pores of the whole shell regular, circular, small, and numerous. Feet broad, triangular, shorter than the thorax, with convex back and convergent ends.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.2; breadth a 0.02, b 0.08, c 0.07.

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

10. Pterocanium tricolpum, n. sp. (Pl. 73, fig. 1).

Shell nearly three-sided prismatic, smooth, with three high fenestrated crests and two deep strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 5 : 5. Cephalis subspherical, with an oblique, conical horn of the same length. Thorax inflated, with three highly vaulted bosoms between the three high crests, and with subregular, circular pores. Abdomen shorter, with three concave (or nearly rectangular, square) basal bays between the three feet, and with irregular, roundish pores, three to four pairs of larger pores occurring at the sides of the base of the feet. Feet nearly as long as the shell, with fenestrated bases, nearly straight and parallel; somewhat convergent, with convex back. (Often the concave bays between the three feet are not square, as in the specimen figured, but semicircular.) The ends of the feet are sometimes strongly convergent. The vaultings of the three swellings and the reticulation are also variable; the whole form is often irregular.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.025, b 0.1, c 0.1.

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

Subgenus 2. Pterocanidium, Haeckel.

Definition.—Free basal edge of the abdomen between the three feet convex, forming three rounded or semicircular prominent lobes between them.

11. Pterocanium eucolpum, n. sp. (Pl. 73, fig. 4).

Dictyopodium eucolpum, Haeckel, 1881, Prodromus et Atlas.

Shell about triangular-prismatic, with two deep strictures, smooth. Length of the three joints = 1 : 3 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with a conical, oblique horn of the same length. Thorax inflated, with three hemispherical swellings between the three crests, and with subregular, hexagonal pores. Abdomen longer, with much smaller, irregular, roundish pores, forming three broad, convex lobes between the three feet. (In the figured specimen the lobes were not fully developed, and extremely thin below the line parallel to the edge. In another specimen, found afterwards in the same locality, the three lobes were much larger, semicircular, and reached almost to the basal plane of the ends of the feet by reason of their convexity.) Feet strong, with slightly convex back, divergent.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.1; breadth, a 0.03, b 0.09, c 0.12.

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

12. Pterocanium bicorne, n. sp. (Pl. 73, fig. 5).

Dictyopodium bicorne, Haeckel, 1881, Prodromus et Atlas.

Shell nearly three-sided pyramidal, slender, smooth. Length of the three joints = 1 : 2 : 2, breadth = 1 : 4 : 4. Cephalis hemispherical, with two oblique, conical horns of nearly equal length. Thorax nearly hemispherical, with slightly prominent crests, and with subregular, hexagonal pores. Abdomen of about the same length, with much smaller, irregular, roundish pores, forming three convex, nearly circular lobes between the three large divergent feet. These are slender, three-sided pyramidal, longer than the shell, fenestrated at the thickened base, with some rows of larger pores; their back is slightly concave.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.02, b 0.08, c 0.09.

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

13. Pterocanium trilobum, Haeckel.

Dictyopodium trilobum, Haeckel, 1882, Monogr. d. Radiol., p. 340, Taf. viii. figs. 6-10.

Shell three-sided pyramidal, nearly tetrahedral, covered with conical spines. Length of the three joints = 1 : 4 : 2, breadth = 1 : 6 : 10. Cephalis hemispherical, with a large conical horn (as long as the thorax). Thorax tetrahedral, with little prominent crests. Abdomen forming three semicircular, convex lobes between the three feet, half as long as the thorax, with the same irregular, roundish pores. Feet slender, about as long as the shell, triangular, with convex back, strongly divergent, fenestrated at the inflated and thickened base. (Compare the special description of the living form and its soft body in my Monograph.)

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.12, c 0.2.

Habitat.—Mediterranean, Messina, surface.

Genus 589 Pterocodon,^[206] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three solid free lateral wings on the thorax, and numerous solid terminal feet around the mouth of the abdomen.

The genus Pterocodon differs from the closely allied Pterocorys, its ancestral form, in the development of numerous solid feet around the terminal mouth, similar to the terminal corona of Calocyclas.

1. Pterocodon campana, Ehrenberg.

Pterocodon campana, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 10.

Pterocodon campana, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 1.

Shell slender, campanulate, subconical, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 3 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax hemispherical, in the upper part with three divergent, conical horns, as long as the cephalis, and curved downwards. Abdomen with four transverse rows of large circular pores, increasing in size towards the mouth; the largest (undermost), five times as broad as the circular thoracic pores. Mouth not constricted, with a corona of twelve to fifteen divergent, conical feet.

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

Habitat.—Fossil in Barbados.

2. Pterocodon ornatus, n. sp. (Pl. 70, fig. 11).

Shell nearly ovate, with two deep strictures. Length of the three joints = 1 : 3 : 5, breadth = 1 : 5 : 7. Cephalis hemispherical, with a large oblique horn reaching half the length of the shell; three edges of the horn wing-shaped and dentated. Thorax hemispherical, in the middle zone with three conical wings, which are half as long as the thorax, and curved downwards. Pores hexagonal, roundish, twice as broad in the inflated abdomen as in the thorax. Mouth constricted, with a corona of from fifteen to eighteen conical, divergent, curved feet, similar to the thoracic wings.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth, a 0.025, b 0.1, c 0.14.

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

3. Pterocodon favosus, n. sp.

Shell ovate, with two slight strictures. Length of the three joints = 1 : 2 : 2, breadth = 2 : 4 : 4. Cephalis hemispherical, with a conical horn of twice the length. Three wings of the thorax equal to those of the preceding species. Pores regular, circular, hexagonally framed, of equal size in the thorax and abdomen. Mouth constricted, with a corona of nine straight, conical, nearly vertical feet.

Dimensions.—Length of the three joints, a 0.0025, b 0.05, c 0.05; breadth, a 0.05, b 0.09, c 0.1.

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

Genus 590. Dictyocodon,^[207] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the thorax, and numerous latticed terminal feet around the mouth of the abdomen.

The genus Dictyocodon, one of the most elegant among the Nassellaria, differs from the preceding Pterocodon in the fenestration of the three lateral wings of the thorax, and the numerous terminal feet of the abdomen. It may be derived from Dictyoceras by development of regular lattice-feet around the terminal mouth.

Subgenus 1. Dictyocodella, Haeckel.

Definition.—The three lateral lattice-wings arise from the thorax alone.

1. Dictyocodon annasethe, n. sp. (Pl. 71, fig. 11).

Shell with two deep strictures. Length of the three joints = 2 : 5 : 4, breadth = 1 : 5 : 6. Cephalis subspherical, with a very large, three-sided prismatic horn of three times the length, bearing at the base some smaller accessory spines. Thorax nearly conical, with three large, inflated, triangular lattice-wings, the upper edge of which (the cortinar rod) descends obliquely, and is larger than the thorax, ending in a spine. Abdomen inflated, subcylindrical, divided at the wide open mouth by nine deep incisions into nine large triangular feet. Network in the thorax and wings composed of small, regular, hexagonal pores, in the abdomen of three transverse rows of irregular, very large pores, which are surrounded and separated by bands of very small pores; in each foot one large pore and a marginal series of very small pores occur. I dedicate this wonderful species to the memory of my dear wife, Anna Sethe.

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

Habitat.—Indian Ocean; Cocos Islands (Rabbe), surface.

2. Dictyocodon carolotæ, n. sp. (Pl. 71, fig. 14).

Shell with two deep strictures. Length of the three joints = 1 : 3 : 7, breadth = 2 : 5 : 6. Cephalis hemispherical, with an oblique pyramidal horn of twice the length. Thorax subconical, in the upper half with three divergent, triangular wings of half the length, the upper edge of which is nearly horizontal, little curved. Abdomen nearly cylindrical; divided at the wide open mouth by nine deep incisions into nine triangular, vertical feet, about as large as the wings. Network very delicate, with regular, small, circular pores of equal size and very thin bars. I dedicate this elegant species to my dear mother, Charlotte Sethe.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.14; breadth, a 0.04, b 0.1, c 0.12.

Habitat.—Cape of Good Hope (Bleek), surface.

Subgenus 2. Dictyocodoma, Haeckel.

Definition.—The three lateral wings are prolonged from the thorax to the abdomen.

3. Dictyocodon palladius, n. sp. (Pl. 71, figs. 12, 13).

Shell with distinct collar, but evanescent lumbar stricture. Length of the three joints = 1 : 2 : 7, breadth = 1 : 3 : 8. Cephalis very small, with a large pyramidal horn of twice the length, bearing at its base some small, often branched, accessory spines. Thorax three-sided pyramidal, without external boundary prolonged into the large, inflated, gradually dilated abdomen. The internal boundary between the two is marked by a fenestrated, horizontal ring (not indicated in the figure). Three prominent, triangular, fenestrated wings arise from the base of the cephalic horn, and are prolonged nearly through the whole shell almost to the edge of the mouth; in its lower half they form three elevated fenestrated apophyses, the upper edge of which is nearly horizontal. Mouth divided by about twenty incisions into as many triangular, vertical, fenestrated feet. The network of the whole shell is very delicate, like fine gauze, composed of very small, regular, hexagonal pores.

Dimensions.—Length of the three joints, a 0.03, b 0.055, c 0.21; breadth, a 0.03, b 0.09, c 0.25.

Habitat.—Central Pacific, Station 271, surface.

4. Dictyocodon prometheus, n. sp.

Shell tower-shaped, very similar to the preceding species in form and fenestration, but more slender and different in the longer and three-sided prismatic abdomen. Length of the three joints = 1 : 1 : 8, breadth = 1 : 3 : 7. Cephalis with two large divergent horns of three times the length, which are united by interior prolongations with the basal central point, from which arise the upper edges of the three divergent wings; the ends of the latter are directed downwards. Mouth with a corona of about thirty irregular, triangular feet.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.025; breadth, a 0.03, b 0.08, c 0.2.

Habitat.—Tropical Atlantic, Station 347, surface.

Genus 591. Pleuropodium,^[208] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) without ribs in the thorax, but with three ribs enclosed in the abdomen, which are prolonged into three terminal feet.

The genus Pleuropodium, formerly confounded with Theopodium and Pterocanium, differs from these two closely allied ancestral genera in the localisation of the three lateral ribs, which have disappeared in the thorax and become limited to the abdomen. It is therefore intermediate between the former and the following Podocyrtis.

1. Pleuropodium charybdeum, Haeckel.

Pterocanium charybdeum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 43, Taf. vi. figs. 7-10.

Podocyrtis charybdea, J. Müller, 1856, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 492.

Shell campanulate, armed with scattered, bristle-shaped spines, with sharp collar and slight lumbar stricture. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 5. Cephalis cupola-shaped, with a large prismatic, somewhat curved horn, half as long as the shell. Thorax hemispherical, spiny. Abdomen short and wide, three-sided prismatic, with three stout longitudinal ribs, which are prolonged into three slender, prismatic, nearly vertical, slightly curved feet, about as long as the shell. Pores irregular, roundish, of variable size.

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

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

2. Pleuropodium cortina, n. sp.

Shell campanulate, smooth, with two distinct strictures. Length of the three joints = 1 : 4 : 2, breadth = 1 : 3 : 4. Cephalis subspherical, with a small, pyramidal, straight horn of the same length. Thorax pear-shaped, with regular, circular, hexagonally-framed pores. Abdomen three-sided pyramidal, with irregular, roundish pores and three prominent, stout, prismatic ribs, which are prolonged into three straight, divergent feet of the same length.

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

Habitat.—North Atlantic, Station 354, surface.

Genus 592. Podocyrtis,^[209] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn, which usually is simple.

The genus Podocyrtis, and the two following closely allied genera, differ from all the preceding Theopilida in the absence of lateral ribs or wings, and the possession of three free terminal feet, which arise directly from the peristome, or from the margin of the abdominal mouth. They may be derived from Pleuropodium by reduction and loss of the three piercing lateral ribs, the terminal free prolongations of which only remain. The genus Podocyrtis is one of the largest and most common among all Cyrtoidea, being rich mainly in fossil forms. Ehrenberg in his Polycystins of Barbados (1875, loc. cit., p. 80) enumerated not less than thirty-one species. Some of these are yet living, and occur in the Pacific Radiolarian ooze collected by the Challenger. Other new forms are to be added, so that the number of species described in the following pages amounts to forty-five. Many of these are cosmopolitan, or at least common and widely distributed. To facilitate study we may divide this large genus into four subgenera: in two of these the terminal feet are divergent, or nearly parallel; in the two others convergent. In each of these two groups the pores of the thorax and the abdomen are either nearly equal in size and form, or distinctly different, the abdominal pores being often much larger than the thoracic. The small cephalis bears constantly an apical horn, which is usually simple, rarely branched.

Subgenus 1. Podocyrtarium, Haeckel.

Definition.—Feet divergent (the distance between their ends being greater than that between their bases). Pores of the thorax and abdomen nearly equal in size and similar in form.

1. Podocyrtis tripodiscus, n. sp. (Pl. 72, fig. 4).

Shell nearly conical, gradually dilated from the apical to the basal part, with two slight strictures. Surface a little rough. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 6. Pores subregular, circular, quincuncially disposed, of nearly equal size in the conical thorax and the subspherical abdomen. Cephalis hemispherical, with smaller pores and a spindle-shaped spiny horn of twice the length. Feet cylindrical, as long as the abdomen, little divergent, their ends curved outwards and thickened into a papillate knob.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.08; breadth, a 0.03, b 0.07, c 0.11.

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

2. Podocyrtis attenuata, Ehrenberg.

Podocyrtis attenuata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 5.

Shell nearly conical, gradually dilated from the apical to the basal part, with two slight strictures. Surface a little rough. Length of the three joints = 2 : 3 : 4, breadth = 2 : 4 : 5. Pores subregular, circular, equal, quincuncial. Cephalis subspherical, with a conical horn of twice the length. Feet cylindrical, as long as the abdomen, little divergent (sometimes as in the specimen figured, nearly parallel).

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

Habitat.—Fossil in Barbados.

3. Podocyrtis thyrsoceras, n. sp.

Shell slender, conical, smooth, very similar to Thyrsocyrtis rhizodon, Ehrenberg (1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 1), with two slight strictures, nearly of the same form and fenestration as in the preceding smaller species. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with a large cylindrical straight horn, which reaches the length of the abdomen, and is papillate in the distal half. Feet cylindrical, divergent, nearly as long as the whole shell, broadened and spinulated at the distal end.

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

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

4. Podocyrtis conica, n. sp.

Shell conical, without external strictures, but with two internal septal rings. Surface papillate. Length of the three joints = 2 : 3 : 8, breadth = 3 : 6 : 10. Pores equal, subregular, circular, quincuncial. Cephalis hemispherical, with a thick conical horn of the same length. Feet conical, about as long as the thorax, divergent in the direction of the outline of the conical shell.

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

Habitat.—Cosmopolitan, Central Pacific, Stations 263 to 274; Tropical Atlantic, Station 348, in depths between 2350 and 2925 fathoms; also fossil in Barbados.

5. Podocyrtis corythæola, n. sp. (Pl. 72, fig. 2).

Shell ovate conical, with two deep strictures, and with rough surface. Length of the three joints = 2 : 5 : 8, breadth = 3 : 8 : 10. Cephalis hemispherical, thorny, with a strong oblique horn three times the length, which is armed with nine to twelve conical spines. Pores small, circular, of irregular size and distribution. Feet spindle-shaped, divergent, as long as the inflated abdomen.

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

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

6. Podocyrtis surena, n. sp. (Pl. 72, fig. 10).

Shell thin-walled, tower-shaped, smooth, with two deep strictures. Length of the three joints = 2 : 5 : 10, breadth = 3 : 10 : 11. Cephalis subspherical, with a bent conical horn, as long as the hemispherical thorax. Abdomen cylindrical. Pores subregular, circular, quincuncially disposed, and slightly larger in the abdomen. Feet with a thickened calf, nearly perpendicular, as long as the thorax; their distal ends little divergent, and forming a knob beset with small roundish tubercles.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.1; breadth, a 0.035, b 0.1, c 0.11.

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

7. Podocyrtis conulus, n. sp.

Shell elongate, conical, rough, without external strictures, but with two internal septal rings. Length of the three joints = 3 : 4 : 15, breadth = 5 : 7 : 12. Cephalis hemispherical, with a thick pyramidal horn of the same length. Feet also pyramidal, divergent, of the same size as the horn. Pores irregular, roundish, of variable size. Abdomen very long.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.15; breadth, a 0.05, b 0.07, c 0.12.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms; also fossil in Barbados.

8. Podocyrtis tridactyla, n. sp.

Shell conical, with two slight strictures, smooth. Length of the three joints = 2 : 6 : 5, breadth = 4 : 5 : 6. Cephalis hemispherical, with a pyramidal horn of twice the length. Pores irregular, polygonal, of variable size. Feet as long as the abdomen, constricted in the middle, trilobed at the distal end; the middle lobe twice as large as the lateral lobes.

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

Habitat.—Indian Ocean, Madagascar, Rabbe.

Subgenus 2. Podocyrtecium, Haeckel.

Definition.—Feet divergent (the distance between their ends being greater than that between their bases). Pores of the thorax and abdomen of different form or size.

9. Podocyrtis prismatica, n. sp. (Pl. 72, fig. 1).

Shell conical, rough, with two distinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 5. Cephalis subspherical, with a curved conical horn of twice the length. Thorax and abdomen together nearly hemispherical. Pores small, regular, circular, quincuncial, twice as large in the abdomen as in the thorax. Feet very large, twice as long as the whole shell, divergent, bent outwards, prismatic, with strong prominent edges.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.06; breadth, a 0.02, b 0.04, c 0.1.

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

10. Podocyrtis brevipes, Ehrenberg.

Podocyrtis brevipes, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 6.

Shell conical, smooth, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 5 : 9. Cephalis subspherical, with a conical horn of the same length. Pores regular, circular, quincuncial, three times as broad in the abdomen as in the thorax. Feet short, triangular, divergent, as long as the horn. (The specimen figured by Ehrenberg was incomplete, one foot and the horn being broken off.)

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.02, b 0.05, c 0.09.

Habitat.—Fossil in Barbados.

11. Podocyrtis divergens, n. sp. (Pl. 72, fig. 6).

Shell slender, subconical, thick-walled, with two distinct strictures. Length of the three joints = 2 : 5 : 7, breadth = 4 : 8 : 10. Cephalis hemispherical, with a large, oblique, prismatic horn three times the length, and a small divergent by-horn at its base. Thorax hemispherical, rough, with regular, circular, quincuncial pores. Abdomen cylindrical, thorny, with larger circular pores of subregular disposition, two to three times as broad as those of the thorax. Feet conical, horn-like, bent, as long as the abdomen; strongly divergent in the distal half.

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

Habitat.—Western Tropical Pacific, Station 220, depth 1100 fathoms.

12. Podocyrtis collaris, Ehrenberg.

Podocyrtis collaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 1.

Shell conical, with slight collar and deeper lumbar stricture. Length of the three joints = 1 : 4 : 4, breadth = 1 : 4 : 8. Cephalis hemispherical, with a small oblique horn of the same length. Pores regular, circular, quincuncial, four to six times as broad in the inflated abdomen as in the conical thorax. Feet short and slightly divergent, little longer than the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.08; breadth, a 0.03, b 0.08, c 0.16.

Habitat.—Fossil in Barbados.

13. Podocyrtis ventricosa, Ehrenberg.

Podocyrtis ventricosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 3.

Shell conical, with two deep strictures, thorny. Length of the three joints = 1 : 2 : 5, breadth = 1 : 4 : 8. Cephalis subspherical, with a small conical horn of the same length. Pores regular circular, quincuncial, four to six times as broad in the inflated abdomen as in the hemispherical thorax. (Pores much larger and less numerous than in the similar preceding species.) Feet broad and stout, triangular, divergent, as long as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.025, b 0.07, c 0.16.

Habitat.—Fossil in Barbados.

14. Podocyrtis flosculata, n. sp. (Pl. 72, fig. 9).

Shell conical, rough, as broad as long, with distinct collar, but obliterated lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 7. Cephalis hemispherical, with a thick conical horn of the same length. Thorax truncate, conical, with small, circular, quincuncial pores. Abdomen inflated, with very large and remarkable regular, quincuncial pores; their inner edge circular, the outer six-lobed, the six lobes elegantly alternating with six short conical spines. Feet very coarse, equilateral triangular, half as broad as the thorax, little divergent.

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

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

15. Podocyrtis centriscus, Ehrenberg.

Podocyrtis centriscus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xiv. fig. 2.

Shell conical, rough, about as high as broad, with two obliterated strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 7. Cephalis small, hemispherical, with a stout conical horn. Pores of the inflated abdomen irregular, roundish, very large, three occurring in the course of its length, five times as broad as the small, very numerous, regular, circular pores of the conical thorax. Feet S-shaped, as long as the abdomen, with the blunt end curved outwards.

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

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

16. Podocyrtis magnifica, n. sp. (Pl. 72, fig. 5).

Shell conical, spiny, a little longer than broad, with two distinct strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 4 : 7. Cephalis hemispherical, with a large conical horn, which is as long as the abdomen, nearly scaly, and covered with short, simple, and bifid spines. Pores regular, circular, quincuncially disposed, four times as broad in the inflated abdomen as in the conical thorax. Spines of the former twice as large as those of the latter. Feet very long and slender, cylindrical, S-shaped, bent outwards at the thickened distal end, with a spindle-shaped papillate knob.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Canary Islands, Lanzerote, Haeckel, surface.

17. Podocyrtis princeps, Ehrenberg.

Podocyrtis princeps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 1.

Podocyrtis princeps, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 32.

Shell conical, with two distinct strictures. Length of three joints = 1 : 2 : 5, breadth = 1 : 4 : 7. Cephalis subspherical, with a large cylindrical, vertical horn, longer than the whole shell. Pores regular, circular, quincuncial, in the inflated spiny abdomen very large (four to five in the course of its length), five times as broad as in the smooth conical thorax. Feet about as long as the shell, slightly bent, S-shaped, cylindrical.

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

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

18. Podocyrtis euceros, Ehrenberg.

Podocyrtis euceros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 1.

Shell conical, campanulate, with two deep strictures. Length of the three joints = 1 : 3 : 6, breadth = 2 : 5 : 7. Cephalis hemispherical, with a large, cylindrical horn, nearly as long as the shell. Pores regular, circular, hexagonally framed, quincuncial, four times as broad in the papillated, inflated abdomen as in the hemispherical, smooth thorax. Feet short and broad, triangular, divergent, about as long as the thorax. (In the specimen figured by Ehrenberg, two feet were broken off).

Dimensions.—Length of the three joints, a 0.016, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, and Pacific Oceans, at many stations, and in various depths; fossil in Barbados.

19. Podocyrtis cristata, n. sp. (Pl. 72, fig. 7).

Shell conical-campanulate, thorny, with two deep strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 4 : 7. Cephalis subspherical, with a large, oblique, little bent, conical horn, as long as the abdomen. Thorax hemispherical, papillate, with small, regular, circular pores. Abdomen inflated, with very large, circular pores, (three to four in its length), six times as broad as those of the thorax, and separated by hexagonal, serrated crests. Feet cylindrical, stout, S-shaped, slightly divergent, with a spherical papillate knob at the distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.035, b 0.07, c 0.14.

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

20. Podocyrtis schomburgkii, Ehrenberg.

Podocyrtis schomburgkii, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 22; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xiv. 7.

Shell ovate-conical, with two distinct strictures. Length of the three joints = 2 : 5 : 10, breadth = 3 : 8 : 12. Cephalis hemispherical, with a large, straight, conical horn as long as the abdomen. Thorax campanulate, smooth, with small, regular, circular pores. Abdomen inflated, papillate, with very large, regular, hexagonal pores (three to four in the course of its length), five times as broad as their bars and as the pores of the thorax. Feet as long as the abdomen, nearly parallel, slightly bent outwards at the conical distal end.

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

Habitat.—Fossil in Barbados.

21. Podocyrtis hexagonalis, n. sp.

Shell nearly ovate, slender, everywhere covered with a regular network of high, hexagonal, denticulated crests, separating the circular, funnel-shaped pores, which are twice as large in the subspherical abdomen as in the hemispherical thorax, between both of which are two deep strictures. Length of the three joints = 1 : 3 : 6, breadth = 2 : 5 : 6. Cephalis hemispherical, with a long and thin cylindrical, vertical horn, as long as the abdomen. Feet of the same length and form, nearly straight, slightly divergent.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.04, b 0.11, c 0.13.

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

22. Podocyrtis ovata, n. sp.

Shell nearly ovate, papillate, without external strictures. Length of the three joints = 1 : 2 : 3, breadth = 2 : 4 : 5. Cephalis hemispherical, with a pyramidal horn half as long as the shell. Pores regular, circular, hexagonally framed, three times as broad in the inflated abdomen as in the conical thorax. Feet pyramidal, little bent, divergent, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.08; breadth, a 0.05, b 0.095, c 0.12.

Habitat.—Mediterranean, Corfu, Haeckel, surface.

23. Podocyrtis urceolata, n. sp.

? Podocyrtis mitra, Bury, 1862, Polycystins of Barbados, pl. v. fig. 3.

Shell nearly ovate, smooth, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 5. Cephalis subspherical, with a stout, conical horn of the same length. Thorax flat, hemispherical, with four to six transverse rows of small circular pores. Abdomen urceolate, with four to five transverse rows of very large, subregular, hexagonal pores. Feet short and thick, bent outwards, as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.15; breadth, a 0.05, b 0.1, c 0.13.

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

24. Podocyrtis ehrenbergii, Haeckel.

Podocyrtis amphiacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvii. fig. 3.

Shell slender, ovate, smooth, with deep collar, but evanescent lumbar stricture. Length of the three joints = 1 : 3 : 2, breadth = 1 : 3 : 3. Cephalis subspherical, with a large conical horn, as long as the campanulate thorax. Abdomen nearly cylindrical. Pores irregular, roundish, two to four times as large in the abdomen as in the thorax. Feet conical, slender, divergent, nearly as long as the shell. (In the imperfect specimen figured by Ehrenberg, two spines were broken off.)

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

Habitat.—North Pacific, Station 253, depth 3125 fathoms; fossil in Barbados.

25. Podocyrtis argulus, Ehrenberg.

Podocyrtis argulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 2.

Shell slender, ovate, or subconical, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 4. Cephalis hemispherical, with a small conical horn of the same length (broken off in the figure of Ehrenberg). Pores regular, circular, three times as broad in the inflated abdomen as in the campanulate thorax. Feet spindle-shaped, slender, divergent, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.1; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—Tropical Atlantic, Station 247, depth 2530 fathoms; also fossil in Barbados.

Subgenus 3. Podocyrtidium, Haeckel.

Definition.—Feet convergent (the distance between their ends being smaller than that between their bases). Pores of the thorax and abdomen nearly equal in size and similar in form.

26. Podocyrtis papalis, Ehrenberg.

Podocyrtis papalis, Ehrenberg, Mikrogeol., Taf. xxxvi. fig. 23; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xv. fig. 6.

Shell ovate, smooth, without external stricture. Length of the three joints = 1 : 3 : 1, breadth = 1 : 3 : 3. Cephalis ovate, with a stout pyramidal horn of twice the length. Thorax and abdomen with about thirty longitudinal, divergent ribs, separating the same number of longitudinal rows of regular, circular pores, the size of which increases gradually towards the base. Feet shovel-shaped (broad, triangular, with convex outer and concave inner side, the obtuse end being curved inwards), about as long as the short abdomen, only slightly convergent.

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

Habitat.—Fossil in Barbados.

27. Podocyrtis costata, n. sp.

Shell ovate, smooth, of the same form and structure as Podocyrtis papalis, but with two distinct strictures and different proportions. Length of the three joints = 1 : 3 : 6, breadth = 2 : 4 : 6. About thirty longitudinal ribs regularly alternating with rows of circular, regular pores. Feet as in Podocyrtis papalis.

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

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

28. Podocyrtis mitrella, Ehrenberg.

Podocyrtis mitrella, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 3.

Shell ovate, smooth, nearly of the same form and structure as Podocyrtis papalis, but different in the proportions of the joints, in the much smaller, regular pores, and in the great breadth of the shovel-shaped, blunt, about semicircular feet. Length of the three joints = 2 : 9 : 4, breadth = 3 : 10 : 3. Cephalis subspherical, with a thick pyramidal horn of the same length. Slight collar, but no lumbar stricture.

Dimensions.—Length of the three joints, a 0.02, b 0.09, c 0.04; breadth, a 0.03, b 0.1, c 0.03.

Habitat.—Fossil in Barbados.

29. Podocyrtis mitra, Ehrenberg.

Podocyrtis mitra, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 20; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xv. fig. 4.

Shell ovate, conical, smooth, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis with the horn (of equal length) conical. Pores regular, circular, in about twenty longitudinal rows, slightly increasing in size in the middle part of the abdomen. Feet shovel-shaped, blunt, slightly divergent, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.5, c 0.7; breadth, a 0.03, b 0.075, c 0.1.

Habitat.—Cosmopolitan; Mediterranean (Gibraltar), Canary Islands, Central Pacific, Stations 265 to 274, in different depths; also fossil in Barbados.

30. Podocyrtis argus, Ehrenberg.

Podocyrtis argus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 9.

Shell ovate, with two distinct strictures, smooth. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subconical, with a conical horn of the same length. Thorax campanulate. Abdomen inflated. Pores subregular, roundish, of nearly equal breadth, quincuncial. Feet shovel-shaped, triangular, nearly vertical, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.025, b 0.08, c 0.1.

Habitat.—Tropical Atlantic, Station 347, surface; fossil in Barbados.

31. Podocyrtis eulophos, Ehrenberg.

Podocyrtis eulophos, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 6.

Shell subconical, slender, with two slight strictures, smooth. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 6. Cephalis hemispherical, with a large, spindle-shaped, angular horn of twice the length. Thorax hemispherical. Abdomen truncate, conical. Pores subregular, roundish, in about twenty longitudinal rows, their breadth gradually increasing towards the base. Feet shovel-shaped, blunt, nearly vertical, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.16; breadth, a 0.05, b 0.08, c 0.14.

Habitat.—Fossil in Barbados.

32. Podocyrtis favosa, n. sp.

Shell ovate, with two slight strictures, and with honeycomb-like surface. Length of the three joints = 1 : 5 : 2, breadth = 2 : 6 : 5. Cephalis hemispherical, with a pyramidal horn of twice the length. Thorax hemispherical. Pores regular, circular, hexagonally framed, funnel-shaped, with high, prominent crests between them. Feet shovel-shaped, little convergent, triangular, as long as the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.04; breadth, a 0.04, b 0.12, c 0.11.

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

33. Podocyrtis fusiformis, n. sp.

Shell slender, nearly spindle-shaped, diminishing gradually from the broadest middle part (immediately above the lumbar septum) towards the two poles. Length of the three joints = 1 : 5 : 8, breadth = 2 : 6 : 5. Cephalis subspherical, with a large conical horn three times the length. Thorax and abdomen with twenty-four to thirty denticulated, longitudinal ribs, separating the same number of longitudinal rows of regular, circular pores. Instead of the lumbar stricture, a broad, internal septum occurs. Feet slender, straight, as long as the abdomen, only slightly convergent.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.16; breadth, a 0.05, b 0.12, c 0.1.

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

Subgenus 4. Podocyrtonium, Haeckel.

Definition.—Feet convergent (the distance between their ends being smaller than that between their bases). Pores of the thorax and abdomen different in size or form.

34. Podocyrtis pedicellaria, n. sp. (Pl. 72, fig. 8).

Shell conical, ovate, with two very slight strictures. Length of the three joints = 2 : 3 : 8, breadth = 2 : 4 : 8. Cephalis conical, with a pyramidal horn of the same length. Pores subregular, circular, quincuncially disposed, two to three times as broad in the smooth abdomen as in the rough, spinulate thorax. Feet as long as the thorax, shovel-shaped (broad, triangular, with convex outer and concave inner side, the free ends being curved inwards), only slightly convergent.

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

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

35. Podocyrtis sinuosa, Ehrenberg.

Podocyrtis sinuosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 5.

Podocyrtis sinuosa, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 33.

Shell slender, conical, with slight collar, but without lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 4. Cephalis subspherical (in the figure of Ehrenberg broken off), with a pyramidal horn of the same length. Pores subregular, circular, four times as broad in the abdomen as in the thorax. Feet shovel-shaped, as long as the thorax.

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

Habitat.—Fossil in Barbados.

36. Podocyrtis floribunda, n. sp.

Shell ovate, conical, with two very slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 4 : 7. Between twenty-four to thirty longitudinal, denticulated ribs lie the same number of subregular pores, which are flower-like, lobed, or rosette-shaped, and two to three times as large in the abdomen as in the thorax. Feet shovel-shaped (as in the similar Podocyrtis pedicellaria (Pl. 72, fig. 8).

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms; also fossil in Barbados.

37. Podocyrtis scaphopodia, n. sp.

Shell conical, rough, with two slight strictures. Length of the three joints = 2 : 3 : 5, breadth = 2 : 4 : 8. Cephalis subspherical, with a pyramidal horn of twice the length. Pores subregular, circular, quincuncial, four times as large in the abdomen as in the thorax. Feet short and broad, triangular, shovel-shaped, with convergent ends. This species is similar to Podocyrtis brevipes, but differs in the form and size of the horn and of the feet.

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

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

38. Podocyrtis lithoconus, n. sp. (Pl. 72, fig. 3).

Shell conical, thick-walled, smooth, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 4 : 7. Cephalis hemispherical, with a spindle-shaped horn of the some length. Pores subregular, circular, two to four times as broad in the abdomen as in the thorax. Feet triangular, shovel-shaped, nearly vertical, as long as the cephalis.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

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

39. Podocyrtis ampla, Ehrenberg.

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

Shell conical, thick-walled, with distinct collar, but without lumbar stricture. Length of the three joints = 1 : 4 : 5, breadth = 1 : 6 : 7. Cephalis hemispherical, with a large conical horn, as long as the thorax. Pores regular, circular, quincuncial, three times as broad in the rough abdomen as in the smooth thorax. Feet very small, shovel-shaped, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.03, b 0.12, c 0.14.

Habitat.—North Atlantic (Florida); also fossil in Barbados.

40. Podocyrtis nana, Ehrenberg.

Podocyrtis nana, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 2.

Shell conical, thorny, with two distinct strictures. Length of the three joints = 1 : 3 : 3, breadth = 2 : 5 : 6. Cephalis hemispherical, with a large cylindrical horn, nearly as long as the shell. Pores in the abdomen irregular, roundish, two to four times as broad as the regular, circular, quincuncial pores of the thorax. Feet very small, shovel shaped, scarcely as long as the cephalis.

Dimensions.—Length of the three joints, a 0.01, b 0.03, c 0.03; breadth, a 0.02, b 0.05, c 0.06.

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

41. Podocyrtis lyæa, Haeckel.

Thyrsocyrtis lyæa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii, fig. 3.

Shell ovate, conical, with two deep strictures. Length of the three joints = 2 : 5 : 8, breadth = 3 : 8 : 9. Cephalis hemispherical, with a large conical horn, which is spinulate, scaly, and as long as the abdomen. Pores subregular, circular, two to four times as broad in the smooth abdomen as in the spiny thorax. Feet very short and broad, shovel-shaped, scarcely as long as the cephalis.

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

Habitat.—Fossil in Barbados.

42. Podocyrtis bromia, Haeckel.

Thyrsocyrtis bromia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 2.

Shell ovate, thorny, with two distinct strictures. Length of the three joints = 2 : 5 : 5, breadth = 3 : 8 : 9. Cephalis subspherical, with a large conical horn, which is half as long as the shell, and spirally dentated in the distal half. Thorax conical, spinulate, with regular, circular, quincuncial pores. Abdomen tuberculate, with a small number of very large irregular pores. Feet short, shovel-shaped, nearly vertical, as long as the cephalis.

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

Habitat.—Fossil in Barbados.

43. Podocyrtis sphærogaster, n. sp.

Shell inversely ovate, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 7. Cephalis hemispherical, with a slender, slightly bent horn, as long as the abdomen. Thorax hemispherical, spinulate. Abdomen nearly spherical, with much constricted mouth. Pores subregular, circular, hexagonally framed. Feet slender, cylindro-conical, about as long as the shell, with outer convexity, distinctly convergent.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

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

44. Podocyrtis tripus, Haeckel.

Podocyrtis bicornis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 8.

? Podocyrtis dipus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 83, Taf. xii. Fig. 11.

Shell conical, rough, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 5. Cephalis subspherical, with a large, oblique, conical horn (sometimes with a small accessory horn at its base). Thorax hemispherical, with subregular, circular, small, quincuncial pores. Abdomen campanulate, with a small number (about twenty) of very large, irregular, polygonal pores. Feet conical, small, as long as the thorax, slightly convergent or nearly vertical.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

45. Podocyrtis triacantha, Ehrenberg.

Podocyrtis triacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xiii. fig. 4.

Shell conical, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 6. Cephalis hemispherical, with a very large conical horn, nearly as long as the whole shell. Thorax campanulate, densely spinulate, with very small, regular, circular, quincuncial pores. Thorax inflated, with very large, irregular, roundish, pores (three to four in the course of its length), five to ten times as broad as those of the thorax. Feet slender and thin, subcylindrical, as long as the abdomen, divergent in the proximal half, convergent and curved inwards in the distal half.

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

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

Genus 593. Thyrsocyrtis,^[210] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three branched terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn, which usually bears lateral spines.

The genus Thyrsocyrtis differs from the preceding Podocyrtis, its ancestral form, in the ramification of the three terminal feet, which in the latter genus remain simple.

1. Thyrsocyrtis rhizodon, Ehrenberg.

Thyrsocyrtis rhizodon, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xii. fig. 1.

Shell slender, conical, smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a large cylindrical horn, reaching half the length of the shell, and papillate in the distal half. Pores nearly equal, regular, circular, quincuncially disposed, small. Feet divergent, about half as long as the shell, broadened and forked at the distal end. (The fork incision is often much deeper, as in the figure given by Ehrenberg.)

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

Habitat.—Fossil in Barbados.

2. Thyrsocyrtis arborescens, n. sp. (Pl. 68, fig. 9).

Shell nearly ovate, thorny, with a deep collar, but without lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 2 : 3 : 4. Cephalis hemispherical, with a stout scaly or branched horn, half as long as the shell. Pores irregular, roundish, small, separated by spinulated crests, of slightly different sizes. Feet divergent, cylindrical, and as long as the thorax in the proximal half, irregularly branched or arborescent in the distal half, with ten to thirty blunt, thickened or papillate, terminal branches.

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

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

3. Thyrsocyrtis furcata, n. sp.

Shell ovate, thorny, with two slight strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 3. Cephalis hemispherical, with a pyramidal smooth horn of twice the length. Pores of the thorax and abdomen nearly equal, regular, circular, quincuncial. Feet very broad, forked, about as long as the abdomen, much divergent; the outer fork-branch as long as the simple basal half of the foot, and twice as long as the inner or axial branch.

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

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

4. Thyrsocyrtis rhizopus, Haeckel.

Podocyrtis rhizodon, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 83, Taf. xv. fig. 2.

Shell pear-shaped, smooth, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 5. Cephalis ovate, with a stout, sword-shaped horn of the same length. Pores regular, circular, twice as broad in the inflated abdomen as in the truncate, conical thorax. Feet cylindrical, parallel, vertical, straight, divided at the distal end into two short fork-branches.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

5. Thyrsocyrtis rhizopodium, n. sp. (Pl. 68, fig. 8).

Shell campanulate-conical, with deep collar, but without lumbar stricture. Length of the three joints = 3 : 4 : 10, breadth = 4 : 10 : 15. Cephalis subspherical, with a small conical horn of the same length. Pores regular, circular, quincuncial, three to four times as large in the inflated abdomen as in the truncate, conical thorax. Feet cylindrical, slightly divergent, about as long as the abdomen, S-shaped, bent outwards, irregularly branched in the distal half, with tuberculate terminal branches.

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

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

6. Thyrsocyrtis radicata, Haeckel.

Podocyrtis radicata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 5.

Shell campanulate-conical, with two distinct strictures, length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 6. Cephalis subspherical, with a small conical horn of half the length. Pores regular, circular, quincuncial, four to five times as broad in the inflated, rough abdomen as in the campanulate, smooth thorax. Feet cylindrical, nearly as long as the whole shell, S-shaped, bent outwards, dilated and hand-shaped at the distal end, divided by three to five incisions in some irregular finger-like branches.

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

Habitat.—Fossil in Barbados.

7. Thyrsocyrtis trifida, n. sp.

Shell campanulate-conical, thorny, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis subspherical, with a short pyramidal horn of the same length. Pores regular, circular, hexagonally framed, twice as broad in the inflated spiny abdomen as in the rough, campanulate thorax. Feet very large, as long as the shell, cylindrical in the proximal simple half, in the distal half broadened and cleft into three large, irregularly lobed branches, two shorter lateral, and one longer abaxial branch; the latter forms the prolongation of the proximal half. The outer straight edges of the three diverging feet correspond to the edges of a three-sided pyramid.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.09, c 0.15.

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

Genus 594. Dictyopodium,^[211] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn.

The genus Dictyopodium differs from the two preceding ancestral genera in the fenestration of the three terminal feet, which in Podocyrtis are simple, in Thyrsocyrtis branched, but not latticed.

1. Dictyopodium eurylophus, Ehrenberg.

Dictyopodium eurylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 4.

Shell campanulate-conical, thorny, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout angular horn of twice the length, which at the apex is broadened and divided into some spines. Pores in the hemispherical thorax and in the truncate, conical abdomen of nearly equal size, small, subregular, circular (in the abdomen sometimes more irregular and unequal). Feet as long as the abdomen, arising from it with triangular base, diverging, fenestrated throughout the entire length.

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

Habitat.—Central Pacific, Station 263, depth 2650 fathoms; fossil in Barbados.

2. Dictyopodium oxylophus, Ehrenberg.

Dictyopodium oxylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 5.

Shell subconical, smooth, with two slight strictures. Length of the three joints = 2 : 5 : 7, breadth = 3 : 8 : 10. Cephalis subspherical, with a small, conical, smooth horn of the same length. Pores irregular, polygonal, roundish, slightly larger in the abdomen than in the thorax. Feet as long as the thorax, arising from it with triangular base, diverging, fenestrated throughout the entire length. (The figures of this and the preceding species given by Ehrenberg are incomplete, having been drawn from spoiled specimens. In perfect specimens all the three feet are present and diverge in both species in the direction of the conical outline. The main difference between the two species is connected with the pores, which in Dictyopodium oxylophus are larger and more irregular, the two strictures are here not so deep.)

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

Habitat.—Fossil in Barbados.

3. Dictyopodium scaphopodium, n. sp. (Pl. 73, fig. 8).

Shell campanulate, conical, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 1 : 4 : 8. Cephalis hemispherical, with a conical, smooth horn of twice the length. Thorax hemispherical, rough, with small, regular, circular pores. Abdomen inflated and papillate, with very large, polygonal or roundish pores (eight to ten times as broad as the thoracic pores). Feet divergent, nearly as long as the shell, S-shaped, bent outwards, solid and cylindrical in the proximal half, shovel-shaped and fenestrated in the distal half.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.025, b 0.08, c 0.16.

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

4. Dictyopodium cothurnatum, Haeckel.

Podocyrtis cothurnata, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. B. 21; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xiv. fig. 1.

Anthocyrtis cothurnata, Haeckel, 1862, Monogr. d. Radiol., p. 310.

Shell subconical, rough, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis hemispherical, with a very large cylindrical, vertical horn, about as long as the whole shell. Thorax conical, rough, with small, regular, circular pores. Abdomen inflated, with very large, roundish pores (four to five in the course of its length), six to eight times as large as the thoracic pores. Feet nearly vertical, only slightly divergent, S-shaped, bent, as long as the abdomen, cylindrical; at the distal end shovel-shaped and fenestrated (often much more than in Ehrenberg's figure).

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.1; breadth, a 0.03, b 0.09, c 0.15.

Habitat.—Fossil in Barbados.

5. Dictyopodium thyrsolophus, n. sp. (Pl. 73, fig. 7).

Shell subconical, rough, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis hemispherical, with an elegant horn, which is half as long as the shell, spindle-shaped and scaly on the distal third. Thorax hemispherical, with small, regular, circular pores. Abdomen inflated, papillate, with regular, circular pores, three times as large as the thoracic pores (five to six in the course of its length). Feet slightly divergent, cylindrical, about as long as the shell, shovel-shaped and fenestrated (with a prominent middle rib) at the distal end.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.04, b 0.1, c 0.18.

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

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

Definition.—Podocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida triradiata clausa).

Genus 595. Lithornithium,^[212] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three solid lateral wings on the thorax.

The genus Lithornithium has an ovate or spindle-shaped shell, with two distinct strictures, and tapering towards both poles. The abdomen is simple, whilst the cephalis bears an apical horn, and the thorax three free, lateral, solid, divergent wings. It may be derived from Pterocorys by development of a terminal lattice-plate closing the mouth.

1. Lithornithium ciconia, n. sp. (Pl. 67, fig. 3).

Shell nearly spindle-shaped, with two indistinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis ovate, with a large pyramidal spine of twice the length. Thorax three-sided pyramidal with three pyramidal wings of the same length, the broad triangular bases of which occupy the whole length of the thoracic edges. Abdomen inversely ovate (in the figured specimen broken off, in another specimen, found afterwards, completely closed at the distal end). Pores very small, regular, circular, of equal size.

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

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

2. Lithornithium falco, n. sp. (Pl. 67, fig. 1).

Shell nearly ovate, with two sharp strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 3. Cephalis hemispherical, with a conical spine of the same length. Thorax subspherical, with three conical wings of half the length, little curved, arising with broad triangular base from the upper half of the thorax. Abdomen inversely conical. Pores irregular, roundish, of different sizes.

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

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

3. Lithornithium trochilus, n. sp. (Pl. 67, fig. 4).

Shell nearly spindle-shaped, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 2. Cephalis hemispherical, with a thin curved horn of the same length. Cephalis subovate, with three thin curved wings of half the length, arising with broad base from its upper half. Abdomen ovate. Pores subregular, circular, of slightly different sizes.

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

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

4. Lithornithium foveolatum, Ehrenberg.

Lithornithium foveolatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 7.

Shell subovate, with two distinct strictures. Length of the three joints = 2 : 4 : 3, breadth = 3 : 5 : 4. Cephalis hemispherical, with a short conical spine of the same length. Thorax subspherical, with three broad triangular wings of half the length arising from its lower half. Abdomen subconical. Pores small, regular, circular, of nearly equal size.

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

Habitat.—Fossil in Barbados.

5. Lithornithium fringilla, n. sp. (Pl. 67, fig. 2).

Shell ovate, with two slight strictures. Length of the three joints = 4 : 7 : 4, breadth = 3 : 7 : 5. Cephalis ovate, with a pyramidal spine of the same length Thorax subconical, with three stout conical, curved wings of half the length, arising from its lower third (immediately above the girdle). Abdomen inversely campanulate. Pores subregular, circular, of equal size.