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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.