Legion III. NASSELLARIA, (continued 8)

Dimensions.—Shell 0.09 long, 0.06 broad; mouth 0.035 broad.

Habitat.—Fossil in tertiary rocks of Sicily (Grotte).

5. Cyrtocalpis sethopora, n. sp. (Pl. 52, fig. 4).

Shell smooth, urceolate, very thin-walled, with large irregular roundish meshes, each of which is closed by a thin porous sieve-plate. Mouth two-thirds as broad as the shell, with a broad, emarginate, longitudinally striped peristome. (Perhaps the shell of a Tintinnoid Infusorium?)

Dimensions.—Shell 0.08 long, 0.05 broad; mouth 0.03 broad.

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

6. Cyrtocalpis compacta, n. sp. (Pl. 52, figs. 7, 8).

Shell smooth, ovate, very thick-walled, with small, subregular, circular pores of equal size, perpendicularly perforating the wall, about half as broad as the bars. Mouth small, only one-third as broad as the compact shell. (Perhaps a reduced Lithocampe or Lithomitra?)

Dimensions.—Shell 0.08 long, 0.04 broad; mouth 0.015 broad.

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

7. Cyrtocalpis lithomitra, n. sp. (Pl. 52, figs. 5, 6).

Shell smooth, slender, ovate, nearly cylindrical, with small subregular, circular pores, which are disposed in nine to twelve transverse rows, and obliquely ascending perforate the wall. Mouth wide, without peristome, about two-thirds as broad as the shell. (Compare Lithomitra, Pl. 79.)

Dimensions.—Shell 0.09 long, 0.045 broad; mouth 0.03 broad.

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

8. Cyrtocalpis ovulum, n. sp.

Cyrtocalpis obliqua, var. ovulum, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v. fig. 3.

Shell smooth, broad, ovate, with very numerous and small regular circular pores, quincuncially disposed, twice as broad as the bars. Mouth without peristome, about half as broad as the shell.

Dimensions.—Shell 0.09 long, 0.047 broad; mouth 0.04 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

9. Cyrtocalpis obliqua, Haeckel.

Cyrtocalpis obliqua, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v. figs. 4-11.

Shell smooth, irregularly ovate, more or less oblique, variable in size and form, sometimes nearly spherical, at other times subcylindrical. Pores subregular, circular, once or twice the breadth of the bars. Mouth simple without peristome, about half as broad as the shell.

Dimensions.—Shell 0.07 to 0.1 long, 0.05 to 0.08 broad; mouth 0.03 to 0.04 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

10. Cyrtocalpis gromia, n. sp. (Pl. 51, fig. 11).

Shell rough, ovate, very thick-walled, with subregular, circular pores of somewhat variable size. The diameter of the internal, simple, subspherical cavity is five to six times as great as the thickness of the wall. Mouth tubular, cylindrical, very narrow, only one-sixth as broad as the shell.

Dimensions.—Shell 0.16 long, 0.11 broad; mouth 0.02 broad.

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

Genus 530. Mitrocalpis,^[147] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archicorida with a double ovate or ellipsoidal shell, composed of two parallel lattice-plates, which are connected by numerous beams. Apex without horn.

The genus Mitrocalpis and the following closely allied Spongocyrtis differ from the four preceding genera of Archicorida in the complicated structure of the shell-wall, which in the former is double, in the latter spongy. The mouth is in both genera constricted, narrow, and the apex without a horn. Mitrocalpis has been derived probably from Cyrtocalpis in the same way as Peripyramis from Bathropyramis, by development of spines on the surface of the shell, which at equal distances from the latter become connected by branches, thus forming an outer envelope.

1. Mitrocalpis palliata, n. sp.

Shell ellipsoidal, large, one and a third times as long as broad. Inner shell very thin-walled, with irregular, polygonal pores of very variable size and form. From its nodal points there arise numerous bristle-shaped radial beams, about as long as the diameter of the mouth, which are connected at equal distances from the surface by delicate threads, forming the outer enveloping shell. The surface of the latter is smooth. The thin bars of the inner shell are twice to four times as broad as those of the outer. Mouth about one-seventh as broad as the shell, with a short tubular peristome.

Dimensions.—Shell 0.35 long, 0.27 broad; mouth 0.04, distance of both shells 0.037.

Habitat.—Central Pacific, Station 271, surface.

Genus 531. Spongocyrtis,^[148] Dunikowski.

Spongocyrtis, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, vol. xlv. p. 31.

Definition.—Archicorida with a spongy ovate shell, the wall of which is composed of irregular spongy wickerwork. Apex without horn.

The genus Spongocyrtis differs from most other Monocyrtida in the spongy structure of the shell, which is found in only very few other genera of Cyrtoidea, e.g., in Spongopyramis and Spongomelissa. It has been derived either from the similar Cyrtocalpis by development of irregular spongy wickerwork on the surface of the simple lattice-shell; or from Arachnocalpis (Pl. 98, fig. 13) by loss of the peristome.

1. Spongocyrtis montis ovis, Dunikowski.

Spongocyrtis montis ovis, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, vol. xlv. p. 31, Taf. vi. figs. 67, 68.

Shell broad, ovate, rough, spongy, thick-walled; length to the breadth = 4 : 3. Spongy framework very dense and dark, with very small roundish pores. Mouth constricted, with a short tubular peristome, about one-third as broad as the shell.

Dimensions.—Shell 0.35 long, 0.26 broad; mouth 0.08 broad.

Habitat.—Fossil in the Alpine Lias (Schafberg bei Salzburg, Dunikowski).

2. Spongocyrtis arachnoides, n. sp.

Shell ellipsoidal, spiny, spongy, thin-walled; length to the breadth = 3 : 2. Spongy framework loose and delicate, with irregular polygonal meshes and arachnoidal thread-like bars. Mouth constricted, without peristome, about one-fifth as broad as the shell. (Very similar to Arachnocalpis ellipsoides, Pl. 98, fig. 13, but without corona around the mouth.)

Dimensions.—Shell 0.32 long, 0.21 broad; mouth 0.04 broad.

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

Subfamily 2. Archicapsida, Haeckel, 1881, Prodromus, p. 428.

Definition.—Cyrtocalpida, with the basal mouth of the shell fenestrated (vel Monocyrtida eradiata clausa).

Genus 532. Halicapsa,^[149] Haeckel, 1881 Prodromus, p. 429.

Definition.—Archicapsida with an apical horn.

The genus Halicapsa, and the following closely allied Archicapsa, represent together the small subfamily of Archicapsida, or of those Cyrtocalpida, in which the basal mouth of the simple shell is closed by a lattice plate. This may be the original state of this family, if it is derived from the Circospyrida (Circospyris, Dictyospyris) by loss of the sagittal constriction and the primary ring. But it is also possible that the Archicapsida have been partly derived from the Archicorida by secondary fenestration of the open mouth. The genus Halicapsa may be easily confounded with the similar Ellipsid Lithapium (compare p. 303, Pl. 14, figs. 8-10). The skeleton of both genera may be perfectly similar, the only distinction being the structure of the central capsule, which in Halicapsa is that of the Monopylea, in Lithapium that of the Peripylea.

Subgenus 1. Calpocapsa, Haeckel.

Definition.—Surface of the shell smooth or rough, but not spiny.

1. Halicapsa lithapium, n. sp. (Pl. 97, fig. 6).

Shell pear-shaped, rough, one and a half times as long as broad. Pores subregular, circular, twice as broad as the bars. Basal plate with four larger ovate cortinar pores (two larger cardinal and two smaller jugular), and with six smaller peripheral pores (fig. 6). Horn of the apex three-sided pyramidal, stout, half as long as the shell.

Dimensions.—Shell 0.16 long, 0.1 broad; horn 0.08 long.

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

2. Halicapsa triglochin, n. sp. (Pl. 53, figs. 3, 4).

Shell ovate, rough, a little longer than broad. Pores regular, circular, hexagonally framed, of the same breadth as the bars. Basal plate (fig. 4) without larger pores. Horn pyramidal, stout, about half as long as the shell, with three short, horizontally divergent secondary spines at the base (possibly remnants of three original cortinar feet?)

Dimensions.—Shell 0.11 long, 0.09 broad; horn 0.06 long.

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

3. Halicapsa prunoides, n. sp.

Shell pear-shaped, tuberculate, a little longer than broad. Pores irregular, roundish, of different sizes. Basal plate with four larger and six smaller pores. Horn pyramidal, stout, about one-third as long as the shell. (May belong perhaps to the similar Prunoidea Lithapium, compare p. 303 and Pl. 14, figs. 8-10.)

Dimensions.—Shell 0.14 long, 0.12 broad; horn 0.05 long.

Habitat.—Fossil in Barbados.

Subgenus 2. Echinocapsa, Haeckel, 1881, Prodromus, p. 429.

Definition.—Surface of the shell spiny, covered with thorns, papillæ or larger spines.

4. Halicapsa papillata, n. sp.

Shell bottle-shaped, papillate, one and a half times as long as broad. Pores circular, much larger in the middle part than towards the poles. The elevated frames between them bear on the nodal points large blunt conical papillæ. Basal plate without larger pores. Horn three-sided pyramidal, one-third as long as the shell, gradually passing into the slender neck of the bottle.

Dimensions.—Shell 0.22 long, 0.15 broad; horn 0.07 long.

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

5. Halicapsa pyriformis, Haeckel.

? Haliomma pyriforme, Bailey, 1856, Amer. Journ. Sci. and Arts, vol xxii. p. 1, pl. i. fig. 29.

Shell pear-shaped, a little longer than broad, covered with numerous short conical spines. Pores subregular, circular, of nearly equal size, twice as broad as the bars. Basal plate with four crossed larger ovate pores (two larger cardinal and two smaller jugular pores). Horn stout pyramidal, scarcely one-fourth as long as the shell.

Dimensions.—Shell 0.16 long, 0.14 broad; horn 0.04 long.

Habitat.—Fossil in Barbados, living in the North Pacific (Kamtschatka)?

6. Halicapsa hystrix, n. sp. (Pl. 53, figs. 5, 6).

Shell pear-shaped, subspherical, a little longer than broad, with scattered stout pyramidal spines about as long as the radius of the shell. Pores subregular, circular, three times as broad as the bars. Basal plate (fig. 6) without larger pores. Horn very large, pyramidal, longer than the shell.

Dimensions.—Shell 0.1 long, 0.09 broad; horn 0.13 long.

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

Genus 533. Archicapsa,^[150] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archicapsida without apical horn.

The genus Archicapsa differs from the preceding Halicapsa in the absence of the apical horn, and represents the simplest form among the Monocyrtida clausa, a simple, ovate, or pear-shaped shell without any appendages. The characteristic structure of the basal lattice-plate (with three or four large cortinar pores) makes it probable that Archicapsa has been derived either from Halicapsa, by loss of the horn, or directly from Dictyospyris, by reduction of the sagittal ring and constriction.

1. Archicapsa triforis, n. sp. (Pl. 53, figs. 1, 2).

Shell pear-shaped, smooth, one and a half times as long as broad. Pores subregular, circular, of about the same breadth as the bars. Basal plate (fig. 2) with three very large pores, three times as broad as the others (one odd sternal pore and two paired cardinal pores).

Dimensions.—Shell 0.09 long, 0.06 broad.

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

2. Archicapsa quadriforis, n. sp.

Shell ovate, rough, a little longer than broad. Pores subregular, circular, twice as broad as the bars. Basal plate with four larger ovate cortinar pores (two smaller jugular and two larger cardinal pores).

Dimensions.—Shell 0.12 to 0.15 long, 0.1 to 0.12 broad.

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

3. Archicapsa nonaforis, n. sp.

Shell pear-shaped, thorny, one and a half times as long as broad. Pores regular, circular, small, hexagonally framed, twice as broad as the bars. Basal plate with nine cortinar pores (three larger alternating with three pairs of smaller pores, as in Pl. 87, fig. 2).

Dimensions.—Shell 0.14 long, 0.09 broad.

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

Section II. DICYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 296.

Definition.—Cyrtoidea dithalamia, with two-jointed shell, being divided by a transverse collar stricture into an apical joint (or cephalis) and a basal joint (or thorax).

Synopsis of the three Families and six Subfamilies of Dicyrtida.

Family LXII. Tripocyrtida. Three radial apophyses. Mouth open, 1. Sethopilida.

Mouth closed, 2. Sethoperida.

Family LXIII. Anthocyrtida. Numerous radial apophyses. Mouth open, 3. Sethophormida.

Mouth closed, 4. Sethophænida.

Family LXIV. Sethocyrtida. No radial apophyses. Mouth open, 5. Sethocorida.

Mouth closed, 6. Sethocapsida.

Family LXII. Tripocyrtida. Three radial apophyses.

Mouth open,

1. Sethopilida.

Mouth closed,

2. Sethoperida.

Family LXIII. Anthocyrtida. Numerous radial apophyses.

Mouth open,

3. Sethophormida.

Mouth closed,

4. Sethophænida.

Family LXIV. Sethocyrtida. No radial apophyses.

Mouth open,

5. Sethocorida.

Mouth closed,

6. Sethocapsida.

Family LXII. Tripocyrtida, n. fam.

Definition.—Dicyrtida triradiata. (Cyrtoidea with a two-jointed shell, divided by a transverse constriction into cephalis and thorax, and bearing three radial apophyses.)

The family Tripocyrtida, composed of the Sethopilida and Sethoperida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is two-jointed and bears three radial apophyses. The two subfamilies differ in the shape of the mouth, which in the Sethopilida is a simple wide opening, but in the Sethoperida is closed by a lattice-plate; the former are here divided into sixteen, the latter into eight different genera. Though probably the two shell-joints are not truly homologous in all Tripocyrtida, we call the first joint here, as in all Dicyrtida, the cephalis, and the second joint the thorax.

Numerous Tripocyrtida, living as well as fossil forms, were formerly described by Ehrenberg. His genera Dictyophimus, Clathrocanium, Lithomelissa, and Lychnocanium belong to the Sethopilida, and have the mouth open; his genera Lithopera and Lithochytris (partly) belong to the Sethoperida, and have the basal mouth closed by a lattice-plate. Many of these Tripocyrtida belong probably to the oldest forms of Dicyrtida, are nearly related to the Phormospyrida, and therefore of special phylogenetic interest, as was demonstrated by Bütschli (1882, loc. cit., pp. 514-519). This near relation to certain Spyroidea (Tripospyris, Acrospyris, &c.) is particularly striking in some forms of Clathrocanium, Lithomelissa, &c. Some other Tripocyrtida seem to possess a closer relation to certain Plectoidea (Plagoniscus, Plectaniscus), so mainly some forms of Tripocyrtis and Dictyophimus.

The cephalis, or the first joint of the shell, corresponds usually to the whole shell of the Zygospyrida and of numerous Monocyrtida, and exhibits various modifications of shape, which have been already described in these latter families. It is usually subspherical or hemispherical and armed with an apical horn. In a small number of genera the horn is lost, in some other genera multiplied. The cephalis is separated from the thorax not only externally by the collar constriction, but commonly also internally by a transverse horizontal fenestrated septum, which usually exhibits three or four characteristic cortinar pores. The central capsule, originally enclosed in the cephalis, develops usually three or four large pear-shaped cæcal sacs which pass through the cortinar pores and depend into the thorax (Pl. 55, figs. 2-11; Pl. 60, figs. 3-7, &c.).

The thorax in this family exhibits a great variety of interesting modifications, mainly in the development of the three radial apophyses arising from it. These may be either enclosed in the wall of the thorax as ribs, or arise as free wings, very often prolonged over the mouth as three terminal feet. Finally the three terminal feet only remain, whilst the original ribs are lost. The special ornamentation of these three apophyses exhibits an extraordinary variety and elegancy of structure, and many Tripocyrtida belong, no doubt, to the most graceful and admirable forms of Nassellaria.

Synopsis of the Genera of Tripocyrtida.

I. Subfamily Sethopilida. Terminal mouth of the thorax a simple wide opening. A. Three radial ribs (or cortinar rods) partly or completely enclosed in the wall of the thorax. No latticed vertical cephalic wings. a. Three thoracic ribs prolonged into three terminal feet. Cephalis with a horn. Feet solid, 534. Dictyophimus.

Feet latticed, 535. Tripocyrtis.

No horn, feet solid, 536. Sethopilium.

b. Three thoracic ribs prolonged into three lateral wings. Thorax perfectly latticed. With horn, 537. Lithomelissa.

No horn, 538. Psilomelissa.

Thorax with spongy framework, 539. Spongomelissa.

Thorax with three large lateral holes between the three ribs, 540. Clathrocanium.

c. Three thoracic ribs completely enclosed in the wall of the flat thorax Peristome simple, smooth, 541. Lamprodiscus.

Peristome with a corona of spines, 542. Lampromitra.

B. Three radial ribs enclosed in the wall of the thorax and connected with the cephalic horn by three latticed vertical wings. a. Thorax completely latticed No frontal horn (four spines), 543. Callimitra.

With frontal horn (five spines), 544. Clathromitra.

b. Thorax with three large lateral holes between the three ribs. No frontal horn, 545. Clathrocorys.

C. Three radial beams (or cortinar rods) perfectly free, not enclosed in the wall of the thorax. Three beams outside the thorax, arising freely from the collar stricture (no cephalic hole), 546. Eucecryphalus.

Three beams inside the thorax. Cephalis with a large apical hole, 547. Amphiplecta.

D. Three radial terminal feet on the peristome (the three original lateral ribs are lost). Feet solid, 548. Lychnocanium.

Feet latticed, 549. Lychnodictyum.

II. Subfamily Sethoperida. Terminal mouth of the thorax closed by a lattice-plate. Three divergent ribs (or cortinar rods) enclosed either in the wall or in the cavity of the thorax. Three ribs enclosed in the lattice-wall of the thorax, 550. Sethopera.

Three internal rods in the cavity of the thorax, 551. Lithopera.

Three divergent free lateral wings (as prolongation of the three ribs) on the sides of the thorax. Three solid lateral spines. Cephalis with horn, 552. Micromelissa.

No horn, 553. Peromelissa.

Three latticed lateral wings. With horn, 554. Sethomelissa.

Three free terminal feet (on the base of the thorax). Three feet solid, 555. Tetrahedrina.

Three feet latticed. Shell without external mantle, 556. Sethochytris.

Shell with an arachnoidal mantle, 557. Clathrolychnus.

I. Subfamily Sethopilida. Terminal mouth of the thorax a simple wide opening.

A. Three radial ribs (or cortinar rods) partly or completely enclosed in the wall of the thorax. No latticed vertical cephalic wings.

a. Three thoracic ribs prolonged into three terminal feet.

Cephalis with a horn.

Feet solid,

534. Dictyophimus.

Feet latticed,

535. Tripocyrtis.

No horn, feet solid,

536. Sethopilium.

b. Three thoracic ribs prolonged into three lateral wings.

Thorax perfectly latticed.

With horn,

537. Lithomelissa.

No horn,

538. Psilomelissa.

Thorax with spongy framework,

539. Spongomelissa.

Thorax with three large lateral holes between the three ribs,

540. Clathrocanium.

c. Three thoracic ribs completely enclosed in the wall of the flat thorax

Peristome simple, smooth,

541. Lamprodiscus.

Peristome with a corona of spines,

542. Lampromitra.

B. Three radial ribs enclosed in the wall of the thorax and connected with the cephalic horn by three latticed vertical wings.

a. Thorax completely latticed

No frontal horn (four spines),

543. Callimitra.

With frontal horn (five spines),

544. Clathromitra.

b. Thorax with three large lateral holes between the three ribs. No frontal horn,

545. Clathrocorys.

C. Three radial beams (or cortinar rods) perfectly free, not enclosed in the wall of the thorax.

Three beams outside the thorax, arising freely from the collar stricture (no cephalic hole),

546. Eucecryphalus.

Three beams inside the thorax. Cephalis with a large apical hole,

547. Amphiplecta.

D. Three radial terminal feet on the peristome (the three original lateral ribs are lost).

Feet solid,

548. Lychnocanium.

Feet latticed,

549. Lychnodictyum.

II. Subfamily Sethoperida. Terminal mouth of the thorax closed by a lattice-plate.

Three divergent ribs (or cortinar rods) enclosed either in the wall or in the cavity of the thorax.

Three ribs enclosed in the lattice-wall of the thorax,

550. Sethopera.

Three internal rods in the cavity of the thorax,

551. Lithopera.

Three divergent free lateral wings (as prolongation of the three ribs) on the sides of the thorax.

Three solid lateral spines.

Cephalis with horn,

552. Micromelissa.

No horn,

553. Peromelissa.

Three latticed lateral wings. With horn,

554. Sethomelissa.

Three free terminal feet (on the base of the thorax).

Three feet solid,

555. Tetrahedrina.

Three feet latticed.

Shell without external mantle,

556. Sethochytris.

Shell with an arachnoidal mantle,

557. Clathrolychnus.

Subfamily 1. Sethopilida, Haeckel, 1881, Prodromus, p. 431.

Definition.—Tripocyrtida, with the basal mouth of the shell open (vel Dicyrtida triradiata aperta).

Genus 534. Dictyophimus,^[151] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 53.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three complete thoracic ribs, prolonged into three solid divergent feet on the peristome. Cephalis with an apical horn.

The genus Dictyophimus, comprising many common species, may be regarded as the common ancestral form of all sethopilida, and therefore also of the whole family of Dicyrtida. The cephalis bears an apical horn, and the thorax three ribs, which are prolonged over the open mouth into three solid feet. Dictyophimus may be derived either from Euscenium or Peridium (Archiperida), or from Tripospyris (Zygospyrida), or from Plectaniscus (Plectanida), by development of lattice-work between the three terminal feet, which therefore become thoracic ribs.

Subgenus 1. Dictyophimium, Haeckel.

Definition.—Shell smooth or rough, without prominent spines on the edges of the three thoracic ribs. (Commonly one single horn on the cephalis.)

1. Dictyophimus sphærocephalus, n. sp. (Pl. 57, fig. 10).

Shell smooth, with a deep collar stricture, separating two joints of nearly equal size. Cephalis subglobular, rough, with a stout pyramidal horn of half the length, and regular, circular, hexagonally framed pores. Thorax nearly three-sided prismatic, smooth, with three stout, little divergent or nearly parallel ribs, which are prolonged into conical subvertical feet half as long. Thoracic pores irregular, roundish.

Dimensions.—Cephalis 0.08 long, 0.08 broad; thorax 0.08 long, 0.08 broad.

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

2. Dictyophimus tripus, Haeckel.

Dictyophimus tripus, Haeckel, 1862, Monogr. d. Radiol., p. 306, Taf. vi. fig. 1.

Shell with a slight collar stricture, separating two joints of slightly different size. Cephalis nearly ellipsoidal, large, with a slender conical horn of the same length. Thorax truncate three-sided pyramidal, with three strongly divergent ribs, which are prolonged into three slender conical feet of about the same length. Pores irregular, roundish, of variable size.

Dimensions.—Cephalis 0.032 long, 0.028 broad; thorax 0.34 long, 0.064 broad.

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

3. Dictyophimus plectaniscus, n. sp. (Pl. 61, figs. 8, 9).

Shell flat, pyramidal, smooth, with distinct collar stricture. Cephalis hemispherical, with a conical horn of the same length and numerous small regular pores. Thorax flat, triangular, pyramidal, with three widely divergent ribs, which are prolonged into three cylindrical feet of the same length. Thoracic pores fifteen, very large, subregular, roundish, disposed in two transverse girdles, the inner with six, the outer with nine pores; five pores between every two ribs.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.08 long, 0.18 broad.

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

4. Dictyophimus craticula, Ehrenberg.

Dictyophimus craticula, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. figs. 4, 5.

Dictyophimus craticula, Bütschli, 1882, Zeitschr. f. Wiss. Zool., vol. xxxvi. p. 515, Taf. xxxiii. fig. 35.

Shell flat, pyramidal, very similar to the preceding species, but differing in the rudimentary horn, which is smaller than half the cephalis, and in the length of the three cylindrical feet, which are twice to three times as long as the shell. The nine inferior large pores of the thorax are twice to three times as large as the six superior pores. The basal peristome is commonly thorny.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.1 long, 0.2 broad.

Habitat.—Fossil in Barbados.

5. Dictyophimus pyramis, n. sp. (Pl. 61, fig. 16).

Shell regular, pyramidal, with flat collar stricture. Relative length of the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a stout pyramidal horn of the same length. Thorax triangular pyramidal, with three prominent ribs, which are prolonged into three slender pyramidal feet, half as long. Pores small and very numerous, subregular, circular.

Dimensions.—Cephalis 0.03 long, 0.05 broad; thorax 0.1 long, 0.15 broad.

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

6. Dictyophimus challengeri, Haeckel.

Dictyophimus challengeri, Haeckel, 1878, Protistenreich, p. 47, fig. 35.

Shell campanulate, with sharp collar stricture. Relative length of the joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a stout pyramidal horn of twice the length, and numerous very small pores. Thorax nearly hemispherical, with three vaulted bosoms between the three decurrent ribs, which are prolonged into three nearly parallel and vertical feet of about the same length. Pores subregular, circular, of medium size. This species is very similar to Lychnodictyum challengeri, Haeckel, but differs in the smaller straight horn and the longer solid feet, which are not fenestrated.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.13 broad.

Habitat.—Tropical Atlantic, Station 347, surface.

7. Dictyophimus lasanum, n. sp. (Pl. 61, fig. 5).

Shell nearly pear-shaped, with distinct collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis hemispherical, with a conical horn of the same length. Thorax nearly spherical, on both poles truncate and constricted, with three decurrent curved ribs and small regular circular pores. The prolongations of the ribs form three divergent pyramidal straight feet, nearly as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.09 broad.

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

8. Dictyophimus longipes, n. sp. (Pl. 61, fig. 3).

Shell three-sided pyramidal, with distinct collar stricture. Relative length of the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a rudimentary pyramidal horn, scarcely one-fourth as long; and with small circular regular pores. Thorax with larger irregular pores, and three vaulted bosoms between the three decurrent ribs, which are prolonged into three very long and slender prismatic feet, S-shaped, curved, and twice to three times as long as the shell.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.13 broad.

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

9. Dictyophimus gracilipes, Bailey.

Dictyophimus gracilipes, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 4, pl. i. fig. 8.

Shell three-sided pyramidal, with a deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis hemispherical, with a thin horn of the same length. Thorax with three curved ribs, which are prolonged into three divergent angular feet of the same length. Pores irregular roundish.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.05 long, 0.08 broad.

Habitat.—North Pacific, Station 240, surface, Kamtschatka (Bailey).

10. Dictyophimus cortina, n. sp. (Pl. 61, fig. 1).

Shell three-sided pyramidal, with distinct collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a pyramidal horn of half the length. Thorax with much larger irregular roundish pores and three prominent ribs, which are prolonged into three stout, club-shaped, strongly divergent feet of the same length. Mouth widely open, elegantly coronate, with a circle of numerous small cilia.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08 broad.

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

11. Dictyophimus arabicus, Haeckel.

Lychnocanium arabicum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 296, Taf. x. fig. 3.

Shell smooth, three-sided pyramidal, with deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a slender horn of the same length. Thorax with much larger, irregular roundish pores, and three widely divergent ribs, which are prolonged into three slender, somewhat recurved feet of about the same length.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.07 long, 0.09 broad.

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

12. Dictyophimus platycephalus, n. sp. (Pl. 60, figs. 4, 5).

Shell smooth, flat, three-sided pyramidal, with distinct collar stricture. Relative length of the two joints = 1 : 3, breadth = 3 : 9. Cephalis flat, cap-shaped, three times as broad as long, with a slender conical horn of the same length. Thorax flatly vaulted, with much larger, irregular roundish, double-edged pores, and three widely divergent ribs, which are prolonged into three slender conical feet of the same length. Central capsule in the cephalis flat, discoidal, with a discoidal nucleus of half the size, and with four large pear-shaped cæcal sacs depending into the thorax, each of which contains a large oil globule (fig. 4).

Dimensions.—Cephalis 0.02 long, 0.07 broad; thorax 0.06 long, 0.18 broad.

Habitat.—North Atlantic, Canary Islands (Lanzerote), Haeckel, surface.

13. Dictyophimus brandtii, n. sp. (Pl. 60, fig. 6).

Shell smooth, flat, three-sided pyramidal, with deep collar stricture, very similar to the preceding species. Relative length of the two joints = 1 : 3, breadth = 2 : 7. Cephalis hemispherical, with a slender conical horn of twice the length. Thorax flatly vaulted, with irregular polygonal pores and thin bars; and with three widely divergent ribs, which are prolonged into three slender prismatic feet of thrice the length. In fig. 6 the shell is seen from the base and exhibits very distinctly the collar septum with its four large meshes, two minor jugular and two major cardinal pores.

Dimensions.—Cephalis 0.03 long, 0.07 broad; thorax 0.08 long, 0.2 broad.

Habitat.—North Pacific, Station 236, surface.

14. Dictyophimus lucerna, Haeckel.

Lychnocanium lucerna, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 6; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. viii. fig. 3.

Lychnocanium lucerna, Haeckel, 1862, Monogr. d. Radiol., p. 311.

Shell smooth, three-sided pyramidal, with slight collar stricture. Relative length of the two joints = 1 : 4, breadth = 1 : 4. Cephalis hemispherical, with a thick conical horn of twice the length. Thorax with small regular, circular pores and three flat sides; between these arise three rounded ribs, which are prolonged into three short, conical, divergent feet, one-third as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.025 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Fossil in Barbados.

15. Dictyophimus hamosus, Haeckel.

Lychnocanium hamosum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. vii. fig. 9.

Shell pear-shaped, rough, with deep collar stricture. Relative length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis subglobular, with a conical horn of twice the length. Thorax with small, regular, circular pores, and with three prominent ribs, prolonged into three vertical prismatic feet, which are about as long as the shell, parallel or a little convergent towards the distal end, with recurved teeth or hooks at the lateral edges.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Fossil in Barbados.

16. Dictyophimus tridentatus, Haeckel.

Lychnocanium tridentatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 4.

Shell smooth, three-sided pyramidal, with deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a conical horn of the same length, and some small accessory thorns. Thorax tetrahedral, with three smooth hyaline walls, bearing only a single series of small pores on each side of the three prominent ribs, which are prolonged into three strong prismatic curved feet of twice the length, with the convexity external. A group of small pores and a strong triangular tooth at the base of each foot.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Fossil in Barbados.

Subgenus 2. Lamprotripus, Haeckel, 1881, Prodromus, p. 432.

Definition.—Shell spiny or thorny, with prominent spines on the edges of the three thoracic ribs. (Commonly one larger and a few smaller horns or spines on the cephalis.)

17. Dictyophimus triserratus, n. sp. (Pl. 61, fig. 17).

Shell three-sided pyramidal, with slight collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis small, subspherical, with a large pyramidal horn three times as long. Thorax with much larger, irregular roundish, double-edged pores, and three prominent, serrate ribs, which are prolonged into three pyramidal strongly divergent feet of the same length.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.09 broad.

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

18. Dictyophimus bicornis, n. sp.

Shell thorny, with deep collar stricture. Relative length of the two joints = 2 : 3, breadth = 2 : 3. Cephalis nearly as large as the thorax, subglobular, with numerous small, circular pores, and two divergent pyramidal horns of half the length (a major occipital and a minor frontal horn). Thorax three-sided pyramidal, with larger irregular pores and three serrate ribs, which are prolonged into three prismatic spiny feet of half the length. (Differs from the similar Dictyophimus sphærocephalus, Pl. 57, fig. 10, mainly in the double horn and the spinulate feet.)

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.08 long, 0.07 broad.

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

19. Dictyophimus pocillum, Ehrenberg.

Dictyophimus pocillum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. fig. 6.

Shell thorny, with distinct collar stricture. Relative length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis nearly spherical, with numerous small conical spines. Thorax flat, three-sided pyramidal with large, irregular, roundish pores, and three strong, widely divergent, spinulate ribs, which are prolonged into three prismatic spinulate feet of the same length.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.15 long, 0.15 broad.

Habitat.—Fossil in Barbados.

20. Dictyophimus cienkowskii, n. sp. (Pl. 60, fig. 1).

Lamprotripus squarrosus, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal, with slight collar stricture. Relative length of the two joints = 1 : 3, breadth = 2 : 6. Cephalis flat, cap-shaped, three times as long as broad, with numerous bristle-shaped spines three times as long. Thorax also spiny, with irregular, very large, polygonal meshes and thin bars; its three ribs prolonged into three very long and thin, widely divergent, prismatic feet, bearing numerous long spines on the three edges.

Dimensions.—Cephalis 0.025 long, 0.05 broad; thorax 0.075 long, 0.15 broad.

Habitat.—North Pacific, Station 250, surface.

21. Dictyophimus bütschlii, n. sp. (Pl. 60, fig. 2).

Lamprotripus horridus, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal, with deep collar stricture. Relative length at the two joints = 1 : 2, breadth = 1 : 5. Cephalis subspherical, with numerous long, bristle-shaped spines and a larger ramified horn. Thorax also spiny, flatly vaulted, with large, subregular, hexagonal meshes and thin bars; its three spiny ribs prolonged into three very long and thin, prismatic, widely divergent feet, twice to four times as long as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—South Pacific, Station 284, surface.

22. Dictyophimus hertwigii, n. sp. (Pl. 60, fig. 3).

Lamprotripus spinosus, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal with sharp collar stricture. Relative length of the two joints = 1 : 2, breath = 1 : 5. Cephalis subspherical, with irregular roundish pores, numerous small spines and a large, oblique, prismatic horn of the same length, bearing on its distal end a bunch of small divergent spines. Thorax pyramidal, with larger irregular polygonal pores and thin bars; its three strong, widely divergent ribs spiny, straight, and prolonged into three prismatic slender feet of the same length. Central capsule with three lobes depending into the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Stations 270 to 274, surface.

Genus 535. Tripocyrtis,^[152] n. gen.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three complete thoracic ribs, prolonged into three latticed divergent feet on the peristome. Cephalis with an apical horn.

The genus Tripocyrtis has been derived from the preceding Dictyophimus by complete fenestration of the three basal feet, which throughout their whole length become united by complete lattice-work. This genus is closely allied to Plectaniscus.

1. Tripocyrtis plagoniscus, n. sp. (Pl. 60, fig. 10).

Cephalis subspherical, with large, roundish meshes and a stout, three-sided pyramidal, irregularly branched horn of twice the length. Thorax with a small number of large, irregular, polygonal meshes and three stout curved ribs about as long as the cephalic horn.

Dimensions.—Cephalis 0.06 long, 0.07 broad; thorax 0.11 long, 0.16 broad.

Habitat.—Central Pacific, Station 266, surface.

2. Tripocyrtis tripodiscus, n. sp.

Cephalis subspherical, with small, polygonal pores and a large, arborescent, vertical horn of thrice the length, bearing numerous ramified branches. Thorax with three straight, widely divergent ribs, of the same length as the horn, connected by a delicate, arachnoidal framework with irregular, polygonal meshes.

Dimensions.—Cephalis 0.04 long, 05 broad; thorax 0.12 long, 0.18 broad.

Habitat.—Central Pacific, Station 269, surface.

3. Tripocyrtis plectaniscus, n. sp. (Pl. 60, fig. 9).

Cephalis subspherical, with small roundish pores, and a stout, three-sided pyramidal, denticulate horn of the same length. Thorax with three little divergent and curved ribs, twice as long as the horn, in the upper half with smaller, in the lower half with larger, polygonal, irregular meshes.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Central Pacific, Station 264, surface.

Genus 536. Sethopilium,^[153] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three complete thoracic ribs, which are prolonged into three solid divergent feet on the peristome. Cephalis smooth, without a horn.

The genus Sethopilium differs from its probable ancestral form Dictyophimus by the complete loss of the cephalic horn, and of the collar septum between both joints, which are only separated by the slight external collar stricture.

1. Sethopilium orthopus, n. sp. (Pl. 97, fig. 8).

Shell smooth, with sharp collar stricture, Relative length of the two joints = 5 : 4, breadth = 7 : 6. Cephalis large, subspherical, with numerous regular circular pores, twice as broad as the bars. Thorax with three stout, straight, widely divergent ribs, prolonged into three straight pointed feet of the same length. Between every two ribs, in the centre of the collar stricture, a single large triangular mesh, and beyond this three to six rows of smaller irregular meshes.

Dimensions.—Cephalis 0.05 long, 0.07 broad; thorax 0.04 long, 0.06 broad.

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

2. Sethopilium cyrtopus, n. sp.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 4 : 6, breadth = 7 : 11. Cephalis hemispherical, with large irregular roundish pores, four times as broad as the bars. Thorax with three stout, curved, widely divergent ribs, prolonged into three cylindro-conical, curved feet of twice the length, which are convex in the proximal half, concave in the distal half. Between every two ribs, beyond the collar stricture, two large ovate meshes, and beyond this two rows of smaller irregular meshes.

Dimensions.—Cephalis 0.04 long, 0.07 broad; thorax 0.05 long, 0.11 broad.

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

3. Sethopilium macropus, n. sp. (Pl. 97, fig. 9).

Shell smooth, with slight collar stricture. Relative length of the two joints = 4 : 7, breadth = 6 : 13. Cephalis hemispherical, with irregular double-contoured pores, about as broad as the bars. Thorax with three very stout, carved, widely divergent ribs, prolonged into three curved, cylindrical, very long feet, which are three to four times as long as the shell, and convex on the outside. Between every two ribs, beyond the collar stricture, two large broad meshes, and beyond this two or three rows of smaller meshes.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.07 long, 0.13 broad.

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

Genus 537. Lithomelissa,^[154] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free lateral wings, or solid spines arising from the sides of the thorax. No terminal feet. Cephalis with one or more horns.

The genus Lithomelissa, containing numerous and widely distributed forms, may like Dictyophimus be regarded as one of the most primitive and ancient forms of Dicyrtida. It differs from the latter by the lateral (not terminal) position of the three thoracic feet, and may be derived either from Dictyophimus (by secondary development of intrapedal network towards the mouth, on the inside of the three feet) or directly from Tripospyris by similar formation of thoracic network beyond the collar stricture, outside the base of the three divergent feet and pierced by the latter. As the species of this genus are numerous, it may perhaps be better to divide it into two or three genera: Acromelissa, with a single horn, Micromelissa, with two horns, and Sethomelissa, with three or more horns.

Subgenus 1. Acromelissa, Haeckel, 1881, Prodromus, p. 431.

Definition.—Cephalis with a single occipital horn.

1. Lithomelissa macroptera, Ehrenberg.

Lithomelissa macroptera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. figs. 9, 10.

Shell smooth, with distinct collar stricture. Relative length of the two joints = 4 : 5, breadth = 3 : 4. Cephalis ovate, with a stout, excentric, vertical, pyramidal horn of the same length. Thorax little larger, ovate, truncate. Both joints with very small and scattered pores. Three divergent ribs arise from the base of the cephalic horn, and are prolonged over the major part of the thorax; their under free part arises from the middle part of the thorax and is as long as the horn, straight, pyramidal. Mouth truncate, little constricted.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.05 long, 0.04 broad.

Habitat.—Fossil in Barbados.

2. Lithomelissa ehrenbergii, Bütschli.

Lithomelissa ehrenbergii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 517, Taf. xxxiii. fig. 21a, b.

Lithomelissa macroptera, var., Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 8.

(?) Lophophæna capito, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 6.

(?) Lophophæna galeata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 12.

Shell rough, with distinct collar stricture. Relative length of the two joints = 4 : 2, breadth = 3 : 4. Cephalis ovate, with a stout excentric, oblique, pyramidal horn of half the length. Thorax little shorter, truncate, conical. Both joints with regular circular pores, of the same breadth as the bars. Three divergent conical feet, as long as the cephalis, arise below the collar stricture. Mouth truncate, not constricted.

Dimensions.—Cephalis 0.08 long, 0.06 broad; thorax 0.04 long, 0.08 broad.

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

3. Lithomelissa macroceras, n. sp.

Shell spiny, with sharp collar stricture. Relative length of the two joints = 5 : 7, breadth = 5 : 6. Cephalis spherical, with a large pyramidal horn of twice the length. Thorax little longer, ovate, truncate. Both joints with regular circular pores, three times as broad as the bars. Three divergent pyramidal feet, twice as long as the cephalis, arise from the middle part of the thorax. Mouth constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.07 long, 0.06 broad.

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

4. Lithomelissa mitra, Bütschli.

Lithomelissa mitra, Bütschli, 1881, Zeitschr. f. wiss. Zool., p. 518, Taf. xxxiii. fig. 24.

Shell smooth, with distinct collar stricture. Relative length of the two joints = 5 : 4, breadth = 4 : 5. Cephalis ovate, with a slender, straight, vertical, pyramidal horn of the same length. Thorax ovate, truncate, of about the same size. Both joints with very small and numerous pores, as broad as the bars. Three feet arising from the middle part of the thorax, very small, rudimentary, pyramidal, about as long as broad. Mouth truncate, little constricted.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.04 long, 0.05 broad.

Habitat.—Fossil in Barbados.

5. Lithomelissa pycnoptera, n. sp.

Shell rough, papillate, with slight collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis small, hemispherical, with very small pores and a slender, straight, conical horn of twice the length. Thorax subconical, with regular circular, hexagonally framed pores, as broad as the bars. From its lower half arise three divergent, very strong feet, pyramidal, as long as the thorax, and three times as long as broad.

Dimensions.—Cephalis 0.03 diameter, thorax 0.1 diameter.

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

6. Lithomelissa microstoma, n. sp.

Shell papillate, with slight collar stricture. Relative length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis small, hemispherical, with a conical horn of twice the length. Thorax subspherical, with subregular circular pores, three times as broad as the bars. From its middle part arise three divergent, stout, conical feet, of half the length, and twice as long as broad. Mouth small, strongly constricted, one-fourth to one-third as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.15 diameter.

Habitat.—Fossil in Barbados.

7. Lithomelissa amphora, Stöhr.

Lithomelissa amphora, Stöhr, 1880, Palæontograph, vol. xxvi. p. 100, Taf. iii. fig. 11.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 1 : 5, breadth = 2 : 4. Cephalis small, hemispherical, with a cervical horn of the same length. Thorax ovate, with small regular circular pores, twice as broad as the bars. From its upper half arise three divergent, slender, conical feet, only one-fourth as long. Mouth constricted, with a hyaline peristome, half as broad as the thorax.

Dimensions.—Cephalis 0.013 long, 0.026 broad; thorax 0.063 long, 0.053 broad.

Habitat.—Fossil in tertiary rocks of Sicily; Grotte (Stöhr).

Subgenus 2. Micromelissa, Haeckel, 1881, Prodromus, p. 433 (sensu emendato).

Definition.—Cephalis with two divergent horns, a superior occipital horn and an inferior frontal horn.

8. Lithomelissa thoracites, Haeckel.

Lithomelissa thoracites, Haeckel, 1862, Monogr. d. Radiol., p. 301, Taf. vi. figs. 2-8.

Lithomelissa thoracites, R. Hertwig, 1879, Organism. d. Radiol., p. 76, Taf. viii. fig. 1.

Shell smooth, with deep collar stricture. Cephalis ovate, with two divergent, slender, conical horns, of about half the length; a major oblique occipital horn on the posterior face, and a minor, nearly horizontal horn above the collar stricture, on the anterior face. Thorax about as large as the cephalis, truncate, ovate. Pores of both joints irregular, roundish, of different sizes. From the upper half of the thorax, below the collar stricture, there arise three slender, conical divergent feet, about as long as the cephalis. Mouth truncate, wide open, not constricted. On the numerous varieties of this common species compare my Monograph, on the structure of the ovate central capsule (enclosed in the cephalis), Hertwig, loc. cit.

Dimensions.—Cephalis 0.05 to 0.08 long, 0.04 broad; thorax 0.03 to 0.05 long, 0.05 to 0.07 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

9. Lithomelissa mediterranea, J. Müller.

Lithomelissa mediterranea, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 45, Taf. vi. fig. 11.

Lithomelissa mediterranea, Haeckel, 1862, Monogr. d. Radiol., p. 302.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 4 : 5, breadth = 4 : 5. Cephalis campanulate, conical, with two divergent small conical horns, a major occipital subvertical horn near the summit, and a minor sub-horizontal frontal horn near the collar stricture. Thorax truncate, ovate, little larger than the cephalis. From its lower part there arise three short conical, divergent feet, scarcely half as long as the cephalis (in Müller's figure one of them is seen shortened, opposite to the frontal horn). Pores irregular, roundish, much smaller in the cephalis than in the thorax. Mouth wide open, not constricted.

Dimensions.—Cephalis 0.04 diameter, thorax 0.05 diameter.

Habitat.—Mediterranean (French shore), J. Müller, surface.

10. Lithomelissa bicornis, Ehrenberg.

Lithomelissa bicornis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. ii. fig. 7.

Shell smooth, with deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 2. Cephalis hemispherical, with two divergent, stout and straight, pyramidal horns; a larger occipital horn sub-vertical near the summit, and a smaller oblique frontal horn near the collar stricture. Thorax subspherical, twice as large, with larger irregular, roundish pores. From its lower half there arise three divergent curved pyramidal feet of about the same length. Mouth constricted, only one-third as broad as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 diameter.

Habitat.—Atlantic, Stations 348 to 353, surface.

11. Lithomelissa haeckelii, Bütschli.

Lithomelissa haeckelii, Bütschli, 1883, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 517, Taf. xxxiii. fig. 23, a, b.

Shell rough, with sharp collar stricture. Relative length of the two joints = 6 : 5, breadth = 6 : 7. Cephalis subspherical, large, with two divergent horns, a very large, oblique pyramidal occipital horn on the summit, and a very small frontal horn on the middle of the forehead. Thorax campanulate, little larger than the cephalis, with regular circular pores of twice the breadth. From the upper part of the thorax, below the collar stricture, there arise three stout, divergent, angular, semi-lunar feet, about as long as the shell. Mouth wide open, not constricted.

Dimensions.—Cephalis 0.6 long, 0.6 broad; thorax 0.05 long, 0.07 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2260 fathoms; fossil in Barbados.

12. Lithomelissa bütschlii, n. sp. (Pl. 56, fig. 1).

Shell smooth, with slight collar stricture. Relative length of the two joints = 5 : 6, breadth = 4 : 5. Cephalis ovate, large, with two small conical horns, which are opposed nearly horizontally, in the upper part of the cephalis; an anterior frontal and a posterior occipital horn. Thorax ovate, truncate, little larger. Pores of both joints irregular, roundish, of very different sizes. From the middle part of the thorax there arise three short conical divergent feet. (In the figured specimen there were some accessory thorns; in another specimen, found afterwards, the surface was quite smooth, but the two horns and the three feet much larger, half as long as the cephalis.)

Dimensions.—Cephalis 0.05 long, 0.04 broad; 0.06 long, 0.05 broad.

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

Subgenus 3. Sethomelissa, Haeckel, 1881, Prodromus, p. 431.

Definition.—Cephalis with three, four, or more horns, a primary occipital, a secondary frontal, and one or more accessory parietal horns.

13. Lithomelissa corythium, Ehrenberg.

Lithomelissa corythium, Ehrenberg, 1875, Abhandl. d.k. Akad. d. Wiss. Berlin, p. 78, Taf. iii, fig. 12.

Shell smooth, with slight collar stricture. Relative length of the two joints = 4 : 3, breadth = 4 : 5. Cephalis campanulate, with three short conical horns on the summit. Thorax flat and wide. From its upper part below the collar stricture, there arise three divergent, pyramidal feet, fenestrated at the base, about as long as the shell. Mouth wide open. (The specimen figured by Ehrenberg was an incomplete one.)

Dimensions.—Cephalis 0.04 in diameter, thorax 0.03 long, 0.05 broad.

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

14. Lithomelissa decacantha, n. sp. (Pl. 56, fig. 2).

Sethomelissa decacantha, Haeckel, 1881, Prodromus et Atlas.

Shell smooth, with deep collar stricture, and with ten prismatic spines of nearly equal size and similar form. Relative length and breadth of the two joints about equal. Cephalis ovate, in the upper half hyaline, in the lower half with few scattered pores; in the equator with four prismatic horns of the same length, which diverge upwards; three of them are placed in the same meridional planes as the three wings and the three feet of the thorax (one occipital and two parietal); the fourth (frontal) horn is opposed to the occipital. Thorax campanulate, three-edged, with three vertical prominent feet (directed downward) and three horizontal wings, arising from their knees. Mouth wide open, not constricted.

Dimensions.—Cephalis 0.05 diameter; thorax 0.05 long, 0.06 broad.

Habitat.—Equatorial Atlantic, Station 347, surface.

Genus 538. Psilomelissa,^[155] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free lateral wings, or solid spines arising from the sides of the thorax. No terminal feet. Cephalis smooth, without a horn.

The genus Psilomelissa has the same formation of the shell as the nearly allied preceding genus Lithomelissa, and may be derived from it by reduction and loss of the cephalic horn. The cephalis is quite bare.

1. Psilomelissa galeata, Haeckel.

Dictyocephalus galeatus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. vii. fig. 25.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 5 : 3, breadth = 4 : 5. Cephalis ovate, with numerous irregular, roundish pores. Thorax truncate, conical, with a few small pores. From its upper part (below the collar stricture) there arise three thin, bristle-shaped, widely divergent wings, about as long as the cephalis. Mouth widely open.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.03 long, 0.05 broad.

Habitat.—Western Tropical Pacific, Stations 200 to 225, surface.

2. Psilomelissa phalacra, n. sp.

Shell smooth, with deep collar stricture. Relative length of the two joints = 5 : 6, breadth = 4 : 4. Cephalis ovate, hyaline, with few small pores only in the lower third. Thorax cylindrical, truncate, with small irregular, roundish pores. From its upper third there arise below the stricture three club-shaped, nearly horizontally divergent wings, as long as the thorax. The cephalis and the three feet are similar to those of Peromelissa phalacra, (Pl. 57, fig. 11); but the cylindrical thorax with irregularly scattered pores is completely different, and exhibits a truncate, wide open mouth.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.04 broad.

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

3. Psilomelissa hertwigii, Haeckel.

Lithomelissa hertwigii, Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 517, Taf xxxiii. fig. 22, a, b.

Shell rough, with obliterated collar stricture. Length of the two joints = 4 : 4, breadth = 5 : 5. Cephalis hemispherical. Thorax little larger, cylindrical. From its upper half there arise three very strong pyramidal divergent wings, about as long as the shell. Pores of both joints very small and numerous, circular. Mouth truncate, wide open.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.04 long, 0.05 broad.

Habitat.—Fossil in Barbados.

4. Psilomelissa calvata, n. sp. (Pl. 56, fig. 3).

Shell smooth, with sharp collar stricture. Length of the two joints = 7 : 5, breadth = 5 : 6. Cephalis ovate, large, with subregular, circular, double-contoured pores. Thorax smaller, ovate, with very irregular, roundish pores of different sizes. From its upper third there arise three conical, slender, widely divergent spines or wings of the same length. (In fig. 3 the cephalis with the three wings is alone represented.)

Dimensions.—Cephalis 0.07 long, 0.05 broad; thorax 0.05 long, 0.06 broad.

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

5. Psilomelissa sphærocephala, n. sp.

Shell rough, with deep collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis spherical. Thorax cap-shaped, flat and broad. From its upper half there arise three pyramidal wings, half as long, fenestrated at the base and nearly horizontally divergent. Mouth constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.03 diameter; thorax 0.06 long, 0.09 broad.

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

Genus 539. Spongomelissa,^[156] n. gen.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free lateral wings, or solid spines arising from the sides of the thorax. No terminal feet. Cephalis with one or more horns.

The genus Spongomelissa differs from its ancestral genus Lithomelissa only in the development of spongy framework in the shell-wall—a very rare production in the Cyrtoidea (compare Peripyramis, p. 1162, and Spongocyrtis, p. 1188).

1. Spongomelissa spongiosa, Haeckel.

Lithomelissa spongiosa, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 519, 539, Taf. xxxiii. fig. 25, a, b, c.

Shell of dense spongy structure, with a deep collar stricture. The subspherical cephalis and the truncate abdomen of nearly equal size, both with irregular delicate spongy framework. Mouth wide open. Cephalis with a large vertical apical and a small oblique frontal horn. Thorax with three very stout, three-sided prismatic widely divergent lateral wings, which are covered with numerous irregularly ramified branches; the spongy framework arises by communication of the delicate branches.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Fossil in Barbados.

Genus 540. Clathrocanium,^[157] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 829.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three prominent lateral ribs on the thorax, alternating with three large holes (or thoracic gates). Cephalis with a horn.

The genus Clathrocanium is nearly allied to Dictyophimus and Lithomelissa, and, together with these two genera, may be regarded as surviving representatives of the oldest and most primitive forms of Dicyrtida. It differs from the latter mainly in the incomplete fenestration of the shell, three large interradial holes remaining between the three perradial thoracic ribs. It may therefore be derived either from Euscenium or from Tripospyris by the development of a terminal lattice-band between the three feet. Clathrocanium may be divided into two different subgenera: Clathrocanidium, with simple horn and smooth mouth, and Clathrocorona, with fenestrated horn and coronated mouth.

Subgenus 1. Clathrocanidium, Haeckel.

Definition.—Horn of the cephalis simple, not fenestrated. Peristome smooth.

1. Clathrocanium squarrosum, Ehrenberg.

Clathrocanium squarrosum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vii. fig. 5.

Cephalis campanulate, with irregular roundish pores and a pyramidal horn of the same length, bearing at the apex three short branches. Length of the two joints 2 : 3, breadth = 2 : 6. Thorax with three simple, prismatic, thin ribs, which are twice as long as the cephalis, separated by large triangular holes and connected only at the distal end by a small triangular ring of delicate lattice-work. Peristome smooth, wide, as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.12 broad.

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

2. Clathrocanium sphærocephalum, n. sp. (Pl. 64, fig. 1).

Cephalis spherical, with regular circular pores and a prismatic horn of the same length, with three serrated edges. Length of the two joints = 2 : 3, breadth 2 : 4. Thorax with three broad, triangular, latticed, divergent ribs, which are separated by three large ovate holes (about as large as the cephalis), and connected at the distal end by a broad fenestrated circular ring of regular lattice-work (about six pores in its height). Peristome smooth, constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08 broad.

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

3. Clathrocanium coarctatum, Ehrenberg.

Clathrocanium coarctatum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf vii. fig. 6.

Lychnocanium fenestratum, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 767.

Cephalis spherical, thorny, with regular circular pores and a simple pyramidal horn of the same length. Length of the two joints = 2 : 3, breadth = 2 : 5. Thorax with three simple, prismatic, little prominent ribs, which are separated by three large ovate holes (twice as long as the cephalis), and connected below the prominent distal end by a narrow circular ring of delicate lattice-work. Peristome smooth, wide, little narrower than the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.06 long, 0.1 broad.

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

4. Clathrocanium triomma, n. sp. (Pl. 64, fig. 3).

Cephalis spherical, thorny, with regular circular pores, and a slender prismatic horn of twice the length, bearing at its apex three short recurved branches. Length of the two joints = 2 : 4, breadth = 2 : 5. Thorax with three broad prismatic, fenestrated ribs, which are separated by three large subcircular holes, and below the prominent distal end by a broad, triangular, roundish ring of subregular lattice-work (with square pores). Peristome smooth, about half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.1 broad.

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

Subgenus 2. Clathrocorona, Haeckel, 1881, Prodromus, p. 431.

Definition.—Horn of the cephalis fenestrated. Peristome on the margin of the basal mouth with a corona of spines.

5. Clathrocanium diadema, n. sp. (Pl. 64, fig. 2).

Clathrocorona diadema, Haeckel, 1881, Prodromus, p. 431.

Cephalis hemispherical, thorny, with irregular roundish pores, and a large prismatic horn of twice the length, the three edges of which are denticulate and fenestrated, each with a series of square pores. Length of the two joints = 1 : 3, breadth = 2 : 4. Thorax thorny, with three broad fenestrated divergent ribs, which are separated by three large ovate holes (twice as long as the cephalis) and have their prominent distal ends connected below by a broad circular ring of lattice-work (with irregular polygonal small meshes). Peristome wide, two-thirds as broad as the thorax, with a circular corona of small square pores and alternating prominent small teeth.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09 broad.

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

6. Clathrocanium reginæ, n. sp. (Pl. 64, fig. 4).

Clathrocorona reginæ, Haeckel, 1881, Prodromus, p. 431.

Cephalis hemispherical, with irregular roundish pores and a prismatic club-shaped horn of twice the length, the three edges of which are denticulate and fenestrated. Length of the two joints = 1 : 3, breadth = 1 : 4. Thorax thorny, with three broad triangular, fenestrated and nodulated ribs, which are separated by three large ovate holes (twice as long as the cephalis) and have their prominent distal ends connected below by a circular ring of lattice-work. Peristome constricted, as broad as the thorax, with a corona of short spines.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.08 long, 0.12 broad.

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

Genus 541. Lamprodiscus,^[158] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 831.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three divergent lateral ribs in the wall of the flat, conical, discoidal, or pyramidal thorax. Cephalis with a horn. Peristome smooth, without corona of spines.

The genus Lamprodiscus, and the following nearly allied Lampromitra, differ from all preceding Sethopilida in the complete connection of the three thoracic feet by lattice-work, so that they are imbedded in the thorax-wall as prominent ribs and are not prolonged beyond the margin as free feet. The shell is commonly very flat, conical or pyramidal, sometimes nearly discoidal. The margin of Lamprodiscus is simple, smooth.

1. Lamprodiscus monoceros, Ehrenberg.

Lamprodiscus monoceros, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. vii. fig. 2.

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 8. Cephalis spherical, hyaline, without pores, with an oblique conical horn of the same length. Thorax flat, campanulate, nearly hemispherical, with convex lateral outlines, and regular hexagonal meshes, increasing gradually in size towards the mouth. Bars very thin. Peristome smooth.

Dimensions.—Cephalis 0.02 diameter; thorax 0.1 long, 0.16 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), Station 200, surface.

2. Lamprodiscus coscinodiscus, Ehrenberg.

Lamprodiscus coscinodiscus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. vii. fig. 3.

Shell smooth, with sharp collar stricture. Thorax of the same form and structure as in the preceding species, differing from it mainly in the structure of the smooth circular margin, which is composed of a ring of very small square pores. Length of the two joints = 1 : 4, breadth = 1 : 8. Cephalis with small hexagonal pores, without horn or with a short rudimentary horn. Lateral outlines of the campanulate thorax in the upper part concave, in the lower convex.

Dimensions.—Cephalis 0.02 diameter; thorax 0.08 long, 0.16 broad.

Habitat.—Tropical Pacific, Stations 206, 224, 266, &c., surface.

3. Lamprodiscus tricostatus, n. sp.

Shell smooth with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 7. Cephalis spherical, with an oblique conical horn of twice the length and small circular pores. Thorax flatly conical, twice as broad as high, with straight lateral outline, and regular hexagonal meshes, increasing gradually in size towards the mouth; bars very thin. Peristome or margin of the basal mouth circular, smooth. Very similar to Theopilium tricostatum (Pl. 70, fig. 6), but without abdomen. Differs from the two preceding species mainly in the conical form of the thorax and the less delicate network.

Dimensions.—Cephalis 0.03 diameter; thorax 0.1 long, 0.2 broad.

Habitat.—Cosmopolitan, Mediterranean, Atlantic, Indian, Pacific; surface.

4. Lamprodiscus lævis, Haeckel.

Eucecryphalus lævis, R. Hertwig, 1879, Organism. d. Radiol., p. 77, Taf. viii. figs. 6, 6a, 6b.

Shell smooth, with distinct collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with small circular pores and an oblique conical horn of twice the length. Thorax flat, pyramidal, twice as broad as long, with three strong, straight divergent edges and subregular roundish pores. Peristome smooth.

Dimensions.—Cephalis 0.025 diameter; thorax 0.08 long, 0.16 broad.

Habitat.—Mediterranean (Messina), R. Hertwig, surface.

Genus 542. Lampromitra, Haeckel,^[159] 1881, Prodromus, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three divergent lateral ribs in the wall of the flat conical or pyramidal thorax. Cephalis commonly with a horn. Peristome with a corona of spines.

The genus Lampromitra differs from the preceding and nearly allied Lamprodiscus only in the development of a dentated peristome, or an elegant corona of teeth around the wide open mouth. It bears therefore to the latter the same relation that Clathrocorona does to Clathrocanium.

1. Lampromitra coronata, n. sp. (Pl. 60, fig. 7, 7a).

Shell flat, conical, with slight collar stricture. Length of the two joints = 1 : 2, breadth = 2 : 7. Cephalis hemispherical, with a conical oblique horn of twice the length, and small subregular hexagonal pores. Thorax with larger, subregular, hexagonal meshes, six to eight times as broad as the bars. Peristome or basal margin of the thorax circular, with a marginal ring of smaller polygonal meshes and a triple coronal of short spines; two external rings of short conical centrifugal spines, and an internal ring of thin centripetal rods (fig. 7a). In fig. 7 the shell is seen from below and exhibits very distinctly the internal cross of the collar septum, composed of the four divergent cortinar bars; between the latter descend the four pear-shaped lobes of the central capsule (each containing an oil globule), whilst the apical part of the capsule (with the nucleus) is hidden in the large cap-shaped cephalis.

Dimensions.—Cephalis 0.03 long, 0.07 broad; thorax 0.06 long, 0.2 broad.

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

2. Lampromitra quadricuspis (Pl. 58, fig. 7).

Shell flat, conical, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 2 : 10. Cephalis hemispherical, with subregular circular pores and an oblique, conical, occipital horn of twice the length, bearing three divergent lateral branches, which are directed upwards, and correspond to the three thoracic ribs. Further down, near the collar stricture, a short divergent frontal horn arises. Thorax with irregular roundish pores of different sizes, three to six times as broad as the bars. Peristome with a simple coronal of short, conical, divergent spines, about as long as the diameter of the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.2 broad.

Habitat.—North Atlantic, Canary Islands, surface.

3. Lampromitra furcata, n. sp. (Pl. 58, fig. 8).

Shell flat, conical, with deep collar stricture, very similar in form and structure to the preceding species; differs from it in the shape of the peristome and the armature of the cephalis, which bears a conical, forked, occipital horn of the same length, and a small rudimentary divergent frontal horn. Length of the two joints = 1 : 2, breadth = 1 : 6. The four pores of the collar septum (two larger cardinal and two smaller jugular) exhibit in this species a peculiar asymmetry (fig. 8). The peristome bears a simple coronal of spines as long as the diameter of the cephalis. The major part of them is forked, some irregularly branched.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.18 broad.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

4. Lampromitra pyramidalis, n. sp.

Shell flat, pyramidal, smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 9. Cephalis subspherical, with an oblique pyramidal horn of twice the length, and small circular pores. Thorax with three strong, divergent, straight ribs and three flat triangular sides between them, with subregular hexagonal pores, increasing in size towards the mouth. Peristome with a simple coronal of large and numerous divergent, conical spines, half as long as the shell.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.18 broad.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms.

5. Lampromitra huxleyi, Haeckel (Pl. 59, fig. 1).

Eucecryphalus huxleyi, Haeckel, 1879, Natürl. Schöpfungsgesch., Edit. vii. Taf. xvi. fig. 9.

Shell flat, conical, spiny, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a short conical horn of the same length. Thorax with irregular polygonal pores. Peristome with three coronals of divergent bristle-shaped spines; the first directed obliquely upwards, the second outwards, and the third nearly vertically, downwards; the bristles of the latter are much longer, about as long as the height of the shell.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.16 broad.

Habitat.—Australia (east coast), Station 169, surface.

6. Lampromitra schultzei, Haeckel.

Eucecryphalus schultzei, Haeckel, 1862, Monogr. d. Radiol., p. 309, Taf. v. figs. 16-19.

Shell flat, conical, smooth, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a small conical horn of half the length, and very small roundish pores. Thorax with three strong, straight ribs and irregular polygonal pores, which are much larger in the middle part than in the upper or lower part. Peristome with a double coronal of short, conical, divergent spines; the superior obliquely ascending, the inferior vertically descending. (Named in honour of the late Professor Max Schultze, the illustrious histologist.)

Dimensions.—Cephalis 0.025 diameter; thorax 0.07 long, 0.2 broad.

Habitat.—Mediterranean, Messina, surface.

7. Lampromitra arborescens, n. sp, (Pl. 60, fig. 8, 8a).

Shell flat, pyramidal, spiny, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 2 : 10. Cephalis cap-shaped, with an oblique, slender, conical horn of twice the length, and small circular pores. Thorax with three slight almost obliterated ribs and three vaulted sides between them, with irregular roundish pores. The three ribs are distinct in the proximal, not in the distal part. Peristome with a double coronal of smaller squarish pores and numerous divergent spines; the larger spines are irregularly branched and as long as the diameter of the cephalis.

Dimensions.—Cephalis 0.15 long, 0.03 broad; thorax 0.04 long, 0.2 broad.

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

8. Lampromitra dendrocorona, n. sp. (Pl. 58, fig. 9).

Shell flat, conical, with smooth surface and deep collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with a slender occipital horn of three times the length, and a small divergent frontal horn. Thorax with three strong prominent straight ribs and irregular polygonal meshes, increasing in size towards the mouth. Peristome with a dense coronal of numerous short conical spines and twenty-four to thirty larger arborescent spines, longer than the diameter of the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

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

Genus 543. Callimitra,^[160] Haeckel, Prodromus, 1881, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three vertical latticed wings, which stretch between the three divergent lateral ribs of the thorax and the vertical horn of the cephalis. No frontal horn.

The genus Callimitra, and the two following nearly allied genera, Clathromitra and Clathrocorys, form together a peculiar small group, the Callimitrida, living in the Central Pacific, and differing from the other Sethopilida in some remarkable points, derived perhaps directly from the Archiscenida, Archiscenium and Pteroscenium, by the development of thoracic network between the three cortinar feet. In the centre of the collar septum, where these feet are united, there arises a vertical free columella, prolonged over the top of the cephalis as a free horn, and this horn is connected with the three thoracic ribs by three vertical fenestrated wings.

1. Callimitra carolotæ, n. sp. (Pl. 63, figs. 1, 7, 8).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin bristle-shaped apical horn of the same length. Length of the two joints = 3 : 6, breadth = 2 : 6. Thorax in the upper half with irregular network, in the lower half with parallel transverse bars; in each of its three sides descend two convergent pairs of stronger, parallel, curved ribs, not confluent at the peristome. Each of the three vertical wings with eight stronger ribs, three arising from the cephalis, five from each foot. Dedicated to my dear mother Charlotte Sethe.

Dimensions.—Cephalis 0.07 long, 0.05 broad; thorax 0.15 long, 0.15 broad.

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

2. Callimitra annæ, n. sp. (Pl. 63, fig. 2).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin bristle-shaped horn of the same length. Length of the two joints = 1 : 2, breadth = 1 : 3. Thorax nearly in its whole extent with parallel transverse bars, which are crossed by two convergent systems of parallel beams; in each of its three sides descend four convergent pairs of stronger, parallel, curved ribs, not confluent at the peristome. Each of the three vertical wings with six stronger ribs, three arising from the cephalis, three from each foot. Dedicated to my dear first wife Anna Sethe.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.12 long, 0.18 broad.

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

3. Callimitra agnesæ, n. sp. (Pl. 63, fig. 5).

Cephalis pear-shaped, with irregular, square pores, and a slender bristle-shaped horn twice as long. Length of the two joints = 1 : 3, breadth = 1 : 5. Thorax in its whole extent with parallel transverse bars, which are crossed by two converging and crossed systems of parallel beams; in each of its three sides descend five convergent pairs of stronger, parallel, curved ribs, the two or three upper of which are crossed at the peristome. Each of the three vertical wings with five stronger ribs, three arising from the cephalis and the horn, two from each foot. Dedicated to my dear second wife Agnes Huschke.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.15 long, 0.22 broad.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

4. Callimitra elisabethæ, n. sp. (Pl. 63, fig. 6).

Cephalis nearly hemispherical, with irregular square pores, and a strong prismatic horn thrice the length. Length of the two joints = 2 : 7, breadth = 2 : 9. Thorax in the upper third with irregular network, in the lower two-thirds with parallel transverse bars which are crossed by two convergent systems of parallel beams; in each of its three sides descend three convergent pairs of stronger, parallel, curved ribs; the two ribs of the uppermost pair are united and confluent in a single odd rib in the lower half of the thorax. Each of the three vertical wings with seven stronger ribs, three arising from the cephalis and the horn, four from each foot. Dedicated to my dear elder daughter Elizabeth Haeckel.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.15 long, 0.2 broad.

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

5. Callimitra emmæ, n. sp. (Pl. 63, figs. 3, 4).

Cephalis campanulate, with irregular, polygonal pores, and very thin bars (of the same shape as in the thorax) and with a thin bristle-shaped horn twice the length. Length of the three joints = 3 : 6, breadth = 2 : 9. Thorax in its whole extent with an arachnoidal network similar to that in the cephalis and the three wings, composed of very numerous parallel threads, which are crossed by two crossed diagonal systems of parallel threads. In each of the three sides of the thorax descend five convergent pairs of stronger ribs, the three upper of which are crossed and form large rhomboidal meshes. Each of the three vertical wings with ten stronger ribs, four arising from the cephalis and each horn, six from each foot. Dedicated to my dear younger daughter Emma Haeckel.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.15 long, 0.22 broad.

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

Genus 544. Clathromitra,^[161] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three vertical latticed wings, which stretch between the three divergent lateral ribs of the thorax and the vertical horn of the cephalis. The front of the latter is armed with a large frontal horn.

The genus Clathromitra differs from the preceding similar Callimitra in the development of a free frontal or sternal horn, a prolongation of an internal obliquely ascending rod, opposite to the caudal foot. Therefore the shell in this genus possesses five divergent free spines, two cephalic horns, and three thoracic feet. The lattice-work of the three vertical wings is not so delicate as in Callimitra.

1. Clathromitra pterophormis, n. sp. (Pl. 57, fig. 8).

Cephalis very large, hemispherical, about as long and half as broad as the three-sided pyramidal thorax; both with irregular, polygonal meshes. Apical horn three to four times as long as the frontal horn and the three basal feet. All five spines three-sided prismatic, with nearly smooth edges. Three lateral wings half as broad as the cephalis.

Dimensions.—Cephalis 0.05 long, 0.1 broad; thorax 0.05 long, 0.15 broad.

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

2. Clathromitra pentacantha, n. sp.

Cephalis large, hemispherical, half as long as the three-sided pyramidal thorax; both with irregular, roundish meshes. Apical horn of about the same length as the frontal horn, and twice as long as the three basal feet. All five spines three-sided prismatic, with denticulated edges. Three lateral wings about as broad as the cephalis.

Dimensions.—Cephalis 0.04 long, 0.08 broad; thorax 0.1 long, 0.2 broad.

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

Genus 545. Clathrocorys,^[162] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three prominent lateral ribs on the thorax, alternating with three large holes (or thoracic gates). The three ribs are connected with the central apical horn of the cephalis by three vertical latticed wings.

The genus Clathrocorys differs from the two preceding nearly allied genera in the incomplete fenestration of the thorax, the three perradial ribs of which are separated by three large interradial holes. It has therefore the same relation to Callimitra that Clathrocanium bears to Dictyophimus.

1. Clathrocorys murrayi, n. sp. (Pl. 64, fig. 8).

Cephalis pear-shaped, with irregularly square pores. From the centre of its base there arise four strong, prismatic, radial beams of nearly equal size, the vertical, straight, cephalic horn being little longer than the three divergent, somewhat curved feet. In the three meridional planes (between the horn and each foot) a few rather thick branches arise, which by communication of the ramules form the three vertical latticed wings; each wing with two large meshes, three to five meshes of medium size, and three to four parallel arachnoidal rows of small, square, distal meshes. The three walls of the flat pyramidal thorax (between every two feet) are formed in the upper part by squarish network similar to that of the cephalis, in the middle part by a single row of arches separated by thin threads, and in the lower part by a narrow band of arachnoidal network. Dedicated to Dr. John Murray.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.04 long, 0.15 broad; apical distance of every two feet 0.15, of each foot and the horn 0.17.

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

2. Clathrocorys teuscheri, n. sp. (Pl. 64, fig. 10).

Cephalis pear-shaped, with irregular, square pores. From the centre of its base there arise seven prismatic, radial beams of equal strength, supporting the lattice-work of the wall; the single vertical beam is prolonged into the apical horn; six others lie in the three meridian planes (between the horn and each foot); three ascending end in the wall of the cephalis, three descending are prolonged into the three strong feet, which are longer than the horn. In each meridional plane there arise four thicker and several thinner bars, which by communication of their ramules form the three latticed wings; each wing with a single very large mesh, two meshes of medium size, and a narrow marginal band of small, square pores. The three walls of the flat pyramidal thorax are formed in the upper part by squarish network similar to that of the cephalis, in the lower part by a narrow band of the same; between them a large hole. Dedicated to Dr. Reinhold Teuscher.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.15 broad; apical distance of every two feet 0.2, of each foot and the horn 0.2.

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

3. Clathrocorys giltschii, n. sp. (Pl. 64, fig. 9).

Cephalis pear-shaped, with irregular, polygonal pores. From the centre of its base there arise seven prismatic, radial beams of different strength; the single vertical beam bears six lateral branches (parallel to the three ascending supporting beams), and is prolonged into the apical horn; six others lie in the three meridional planes (between the horn and each foot); three weaker ascending beams end in the wall of the cephalis, three stronger descending are prolonged into the three large diverging feet, which are twice as long as the cephalic horn. The network of the three wings and of the three-sided pyramidal thorax is about the same as in the preceding species, but much more developed; the marginal bands with the squarish network are much broader, and an arachnoidal wicker-work of very thin thread-like bars fills out the large meshes. Dedicated to Mr. Adolf Giltsch.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.12 long, 0.2 broad; apical distance of every two feet 0.24, of each foot and the horn 0.2.

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

Genus 546. Eucecryphalus,^[163] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 836.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free collar wings or solid spines arising from the collar stricture, and freely prominent between the horned cephalis and the flat conical thorax.

The genus Eucecryphalus, according to the restricted definition here given, comprises only those Sethopilida in which the three primary cortinar beams are perfectly free divergent collar wings, i.e., free spines arising outside the shell from the collar stricture, between the cephalis and thorax. The type of this genus (which I formerly united with other Sethopilida) remains Eucecryphalus gegenbauri.

Subgenus 1. Eucyrtomphalus, Haeckel, 1881, Prodromus, p. 431.

Definition.—Peristome or margin of the basal mouth of the thorax smooth, without marginal spines.

1. Eucecryphalus corocalyptra, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with an oblique conical horn twice its length. Thorax conical, twice as broad as long, with regular hexagonal meshes and straight lateral outlines. From the collar stricture there arise three slender conical spines, about as long as the thorax, divergent downwards. Similar to Corocalyptra agnesæ (Pl. 59, fig. 3), but without lumbar stricture and abdomen. Peristome or basal margin of the mouth of the thorax smooth, simple.

Dimensions.—Cephalis 0.3 diameter; thorax 0.09 long, 0.18 broad.

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

2. Eucecryphalus halicalyptra, n. sp.

Shell flat, campanulate, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with two divergent conical horns, a major occipital and a minor frontal horn. Thorax with subregular hexagonal meshes and concave-convex lateral outlines, campanulate. From the collar stricture there arise three divergent bristle-shaped spines, nearly horizontal, about half as long as the thorax. Peristome smooth, with a marginal coronal of small square pores.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Stations 266 to 274, surface.

Subgenus 2. Eucecryphalium, Haeckel.

Definition.—Peristome or margin of the basal mouth of the thorax dentate, with a coronal of marginal spines.

3. Eucecryphalus cuvieri, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two joints = 1 : 8, breadth = 2 : 10. Cephalis hemispherical, with an oblique pyramidal horn twice as long. Thorax with straight outlines and regular hexagonal meshes, increasing in size towards the mouth. From the collar stricture there arise three stout conical spines, half as long as the thorax, and diverging downwards. Peristome with a ring of small square pores and alternate conical divergent spines. Differs from the similar Clathrocyclas alcmenæ (Pl. 59, fig. 6), mainly in the simple apical horn and the possession of the three collar fundamental spines.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.15 long, 0.2 broad.

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

4. Eucecryphalus mülleri, n. sp.

Shell flatly campanulate, of nearly the same structure as and similar form to that of the preceding species. Differs from it mainly in the considerable size of the cephalic horn and the three collar spines, which are bristle-shaped and longer than the shell. Length of the two joints = 1 : 4, breadth = 2 : 8. The peristome bears a double marginal ring of divergent conical spines, the upper being directed upwards, the lower downwards.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.16 broad.

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

5. Eucecryphalus gegenbauri, Haeckel.

Eucecryphalus gegenbauri, Haeckel, 1862, Monogr. d. Radiol., p. 308, Taf. v. figs. 12-15.

Eucecryphalus gegenbauri, R. Hertwig, 1879, Organism. d. Radiol., p. 76, Taf. viii. figs. 5, 5a, 5b.

Shell flatly conical, campanulate, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 8. Cephalis hemispherical, with a conical horn of the same length, and very small pores. Thorax about twice as broad as high, with large, subregular, hexagonal meshes, increasing in size downwards. In the upper half of the thorax the meshes are filled up by an extremely delicate arachnoidal network. From the collar stricture there arise three divergent bristle-shaped spines half as long as the thorax. Peristome with a double coronal of small square pores (the inner smaller and more numerous than the outer), and with a single coronal of divergent marginal spines. This cosmopolitan species is rather variable.

Dimensions.—Cephalis 0.02 to 0.03 diameter; thorax 0.1 to 0.12 long, 0.02 to 0.25 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

6. Eucecryphalus campanella, Haeckel.

Pterocodon campanella, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 2.

Shell campanulate, conical, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 2. Cephalis hemispherical, with a short conical horn half as long, and very small pores. Thorax campanulate, as broad as high, with large roundish meshes, increasing in size downwards. From the collar stricture arise three strong, divergent, somewhat curved spines, nearly as long as the thorax. Peristome with a coronal of ten to twelve strong, conical, marginal spines, which are nearly parallel, directed downwards, a little curved, and half as long as the thorax. In the complete specimen examined by me, the apical horn, the three lateral wings and twelve terminal feet were well preserved.

Dimensions.—Cephalis 0.02 to 0.03 diameter; thorax 0.06 to 0.07 long and broad.

Habitat.—Fossil in Barbados.

Genus 547. Amphiplecta,^[164] Haeckel, 1881, Prodromus, p. 424.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three internal thoracic ribs, enveloped by the network of the thorax. Cephalis with a large apical opening, surrounded by a coronal of spines.

The genus Amphiplecta (or Amphicryphalus) comprises some very peculiar forms of Sethopilida, probably widely remote from the other genera of this subfamily, and derived directly from the Plectanida (compare above, p. 921). The cortinar tripodium, composed of three feet divergent downwards, and one apical horn ascending upwards (in some species also a second frontal horn) is here enclosed in the cavity of a two-jointed shell, which exhibits two large openings, a smaller apical hole in the top of the cephalis, and a larger terminal mouth on the thorax. There is no trace of a sagittal ring.

1. Amphiplecta amphistoma, n. sp.

Cephalis subspherical, spiny, with sharp collar stricture on the base; its apical opening central, surrounded by a coronal of twelve to eighteen short spines. Length of the two joints = 7 : 8, breadth = 6 : 20. Thorax flatly conical, armed with bristle-shaped spines. Meshes of the network in both joints subregular, hexagonal, six to eight times as broad as the bars. Basal mouth bristly.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Station 274, surface.

2. Amphiplecta acrostoma, n. sp. (Pl. 97, fig. 10).

Cephalis subspherical, spiny, with distinct collar stricture on the base, its apical opening central, surrounded by a coronal of six to nine divergent denticulate spines. Length of the two joints = 5 : 6, breadth = 4 : 15. Thorax flatly conical, armed with denticulate spines. Meshes of both joints irregular, polygonal, twice to six times as broad as the bars. Basal mouth armed with longer, divergent, denticulate spines.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.15 broad.

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

3. Amphiplecta callistoma, n. sp. (Pl. 59, fig. 2).

Cephalis flat, cap-shaped, spiny, with obliterated collar stricture on the base; its apical opening excentric, oblique, surrounded by a coronal of ten to twenty bristle-shaped spines. Length of the two joints = 4 : 5, breadth = 7 : 25. Thorax flatly conical, armed with long bristle-shaped spines. Meshes of both joints irregular, hexagonal, twice to six times as broad as the bars. Basal mouth with a double irregular coronal of small square pores, and of bristle-shaped divergent spines.

Dimensions.—Cephalis 0.04 long, 0.07 broad; thorax 0.05 long, 0.25 broad.

Habitat.—Central Pacific, Station 271, surface.

Genus 548. Lychnocanium,^[165] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta), with three solid terminal feet on the peristome. No thoracic ribs. Cephalis with a horn.

The genus Lychnocanium, very rich in common living and fossil forms, comprises those Sethopilida in which the thorax bears three simple terminal feet around the mouth, but no lateral ribs in its wall. It has therefore been probably derived from Dictyophimus by reduction and loss of these three lateral ribs. The mouth is commonly more or less constricted. The three feet surrounding it are sometimes divergent, straight or curved, at other times parallel and vertical, straight, or curved and convergent. The central capsule exhibited in some living species three or four distinct lobes, filling up the upper half of the thorax.

Subgenus 1. Lychnocanella, Haeckel.

Definition.—Feet divergent, straight or scarcely curved; their terminal distance greater than their basal distance.

1. Lychnocanium lanterna, n. sp. (Pl. 61, fig. 7).

Shell conical, rough, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis with a stout pyramidal horn of the same length. Thorax pear-shaped, twice as broad as the constricted mouth, with regular, circular pores of the same breadth as the bars. Three feet pyramidal, little divergent, straight, about as long as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 2900 fathoms.

2. Lychnocanium continuum, Ehrenberg.

Lychnocanium continuum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. vii. fig. 11.

Shell smooth, with distinct collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis subspherical with a conical horn of the same length. Thorax pear-shaped, twice as broad as the constricted mouth, nearly hyaline, with a very small number of scattered minute pores. Three feet pyramidal, little divergent, straight, about as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Fossil in Barbados.

3. Lychnocanium pyriforme, n. sp. (Pl. 61, fig. 11).

Shell pear-shaped, rough, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 5. Cephalis hemispherical, with a conical horn of the same length. Thorax inflated, four times as broad as the constricted tubular mouth, with regular, circular pores. Three feet pyramidal, straight, divergent, about as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.12 long, 0.15 broad.

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

4. Lychnocanium favosum, n. sp. (Pl. 61, fig. 6).

Shell campanulate, rough, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 6. Cephalis hemispherical, with a rudimentary pyramidal horn of half the length. Thorax subglobular, three times as broad as the constricted mouth, with regular, circular pores, and an elevated hexagonal framework between them. Three feet cylindrical, slender, straight, divergent, twice to three times as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.025 broad; thorax 0.1 long, 0.12 broad.

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

5. Lychnocanium nodosum, n. sp. (Pl. 61, fig. 14).

Shell campanulate, nodose, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a rudimentary conical horn of half the length. Thorax nearly hemispherical, twice as broad as the flat mouth, with regular, circular pores, and a variable number of scattered, conical, fenestrated protuberances. Three feet very large, prismatic, straight, divergent, twice as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.12 broad.

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

6. Lychnocanium carinatum, Ehrenberg.

Lychnocanium carinatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 5.

Shell campanulate, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis subglobular, with a slender horn of the same length. Thorax conical, twice as broad as the flat mouth, with fifteen to twenty prominent, longitudinal, divergent ribs, alternating with the same number of rows of pores. Three feet slender, prismatic, straight, divergent, twice as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Fossil in Barbados.

7. Lychnocanium ventricosum, Ehrenberg.

Lychnocanium ventricosum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 12.

Shell pear-shaped, rough, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a stout conical horn twice the length. Thorax conical, three times as broad as the constricted mouth, with irregular, roundish pores of different sizes. Three feet stout, conical, divergent, half as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

8. Lychnocanium tribulus, Ehrenberg.

Lychnocanium tribulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 1.

Shell pear-shaped, nodose, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 4. Cephalis subglobular, with a conical horn twice the length. Thorax ovate, twice as broad as the constricted mouth, with irregular, roundish pores of different sizes. Three stout feet strongly divergent, pyramidal, about as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.02 broad; 0.08 long, 0.08 broad.

Habitat.—Fossil in Barbados.

Subgenus 2. Lychnocanissa, Haeckel.

Definition.—Feet divergent, more or less curved; their terminal distance greater than their basal distance.

9. Lychnocanium fortipes, n. sp. (Pl. 61, fig. 12).

Shell inflated, rough, with distinct collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 6. Cephalis small, hemispherical, with a pyramidal horn of half the length. Thorax subglobular, truncate, twice as broad as the constricted mouth, with large, regular, circular pores and very thin bars. Three feet very stout, prismatic, twice as long as the thorax, widely divergent, curved with convexity outwards, club-shaped at the distal end, with denticulate edges.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.1 long, 0.12 broad.

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

10. Lychnocanium falciferum, Ehrenberg.

Lychnocanium falciferum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 7; Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 4.

Lithomelissa falcifera, Haeckel, 1862, Monogr. d. Radiol., p. 303.

Shell inflated, rough, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis small, with a conical horn of half the length. Thorax subglobular, truncate, three times as broad as the constricted mouth, with small, regular, circular pores. Three feet widely divergent, twice as long as the thorax, curved like a crescent, with strong convexity outwards.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Fossil in Barbados.

11. Lychnocanium tuberosum, n. sp. (Pl. 61, fig. 13).

Shell conical, tuberculate, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a conical horn of the same length. Thorax inflated, twice as broad as the flat mouth, with small, irregular, roundish pores and scattered fenestrated tubercles. Three feet very large, angular, three times as long as the thorax, curved like a crescent, with strong convexity outwards.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.12 broad.

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