Chapter XXI: Section III: TRICYRTIDA, Haeckel, 1881, Prodromus, p. 426, 434 (2)

_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.

{1336}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. {1337}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.

{1338}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.

{1339}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.

{1340}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.

{1341}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 {1342}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.

{1343}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, {1344}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 {1345}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.

{1346}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.

{1347}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, {1348}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 {1349}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.

{1350}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, {1351}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, {1352}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 {1353}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 {1354}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 {1355}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 {1356}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.

_Dimensions._--Length of the three joints, _a_ 0.04, _b_ 0.07, _c_ 0.04; breadth, _a_ 0.03, _b_ 0.07, _c_ 0.05.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.

6. _Lithornithium hirundo_, Ehrenberg.

_Lithocampe hirundo_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, p. 65.

_Lithornithium hirundo_, Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 53.

Shell nearly ovate, with two deep strictures. Length of the three joints = 2 : 6 : 4, breadth = 2 : 7 : 5. Cephalis hemispherical, with an oblique, conical horn of twice the length. Thorax hemispherical, with three long, angular, little divergent wings of twice the length, which are S-shaped, curved, and arise from its lower third, immediately above the girdle. Abdomen inversely conical. Pores irregular, roundish, of different sizes. In the figure of Ehrenberg the abdomen is broken off; in a specimen from Caltanisetta, with somewhat shorter and broader wings, I found it complete.

_Dimensions._--Length of the three joints, _a_ 0.02, _b_ 0.06, _c_ 0.04; breadth, _a_ 0.02, _b_ 0.07, _c_ 0.05.

_Habitat._--Fossil in Tertiary rocks of the Mediterranean (Ægina, Greece; Caltanisetta, Sicily).

Genus 596. _Sethornithium_,[213] Haeckel, 1881, Prodromus, p. 436.

_Definition._--#Theoperida# (vel Tricyrtida triradiata clausa) with three latticed lateral wings on the thorax.

The genus _Sethornithium_ differs from the preceding _Lithornithium_, its ancestral form, only in the fenestration of the three thoracic wings, and bears therefore to it the same relation that _Dictyoceras_ exhibits to _Pterocorys_.

1. _Sethornithium dictyopterum_, n. sp. Pl. 68, fig. 14.

Shell ovate, with two slight strictures. Length of the three joints = 2 : 4 : 3, breadth = 1 : 5 : 4. Cephalis ovate, with a pyramidal horn of twice the length. From the middle part of the thorax arise three broad, triangular, latticed wings of about the same length, the distal end of each of which is curved downwards. Abdomen inversely conical. Pores regular, circular. (Similar to _Lithornithium fringilla_, Pl. 67, fig. 2, but with much larger wings, which in the greater part are fenestrated.)

_Dimensions._--Length of the three joints, _a_ 0.04, _b_ 0.08, _c_ 0.06; breadth, _a_ 0.02, _b_ 0.1, _c_ 0.08.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

{1357}Genus 597. _Theopera_,[214] Haeckel, 1881, Prodromus, p. 436.

_Definition._--#Theoperida# (vel Tricyrtida triradiata clausa) with three lateral wings, beginning from the sides of the thorax and prolonged into the sides of the abdomen.

The genus _Theopera_ differs from the two preceding genera in the greater extension of the three lateral wings, which are prolonged from their original base, the thorax, into the inversely conical abdomen. It has therefore an intermediate position between the preceding and the following genera. It differs from the similar _Pterocanium_ and _Theopodium_ in the closure of the constricted and fenestrated mouth.

1. _Theopera prismatica_, n. sp. (Pl. 67, fig. 7).

_Rhopalocanium prismaticum_, Haeckel, 1879, Atlas, pl. lxvii. fig. 7.