Chapter XIII: Section I: MONOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 281 (2)

The genus _Bathropyramis_ and the following four nearly allied genera form together a peculiar group of Archiphormida, the Litharachnida, possessing near relations to _Sethopyramis_ and the allied Sethophormida, from which they are probably derived by reduction and loss of the small cephalis. The shell in all these forms is distinctly pyramidal, composed of numerous divergent radial beams (commonly six to nine), which form the edges of the pyramid, and are connected by parallel horizontal rings. The quadrangular meshes so produced are quite simple in _Bathropyramis_. This genus cannot be sharply separated from _Sethopyramis_, its ancestral form.

Subgenus 1. _Acropyramis_, Haeckel, 1881, Prodromus, p. 428.

_Definition_.--Shell smooth, without spines on the surface.

1. _Bathropyramis acephala_, n. sp.

Shell smooth, slenderly pyramidal, with three cortinar pores at the apex and with six stout radial beams or longitudinal ribs, connected by twelve to sixteen complete hexagonal horizontal rings. Meshes nearly square, increasing gradually in size towards the mouth.

_Dimensions._--Shell 0.25 long, 0.15 broad.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.

2. _Bathropyramis quadrata_, n. sp. (Pl. 54, fig. 1).

Shell smooth, slenderly pyramidal, with three cortinar pores at the apex and nine stout radial beams, connected by eight to twelve complete circular horizontal rings. Meshes subregular, square, increasing in size gradually towards the circular mouth.

_Dimensions._--Shell 0.2 to 0.3 long, 0.12 to 0.2 broad.

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

{1160}3. _Bathropyramis trapezoides_, n. sp. (Pl. 54, fig. 3).

Shell smooth, broadly pyramidal, with four cortinar pores at the apex and eight (or sometimes nine) stout radial beams, connected by twelve to sixteen complete octagonal horizontal rings. Meshes trapezoidal, of nearly equal length, but gradually increasing in breadth.

_Dimensions._--Shell 0.3 long, 0.3 broad.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.

4. _Bathropyramis interrupta_, n. sp. (Pl. 55, fig. 7).

Shell smooth, flatly pyramidal, nearly discoidal, with four cortinar pores at the apex and nine to ten stout radial beams, connected by eight to sixteen interrupted rings; the rings are complete only in the apical part, in the distal part more or less irregularly interrupted.

_Dimensions._--Shell 0.12 long, 0.36 broad.

_Habitat._--North Atlantic, Station 354, surface.

5. _Bathropyramis medusa_, n. sp.

Shell smooth, flatly pyramidal, nearly discoidal, with four cortinar pores and numerous radial beams (thirty to fifty); the four perradial of these are prolongations of the four cortinar beams, and alternate with four interradial of the same size. Between these are intercalated eight adradial beams arising from the third ring; and between the former and the latter, sixteen to twenty-four peripheral radial beams, arising from the fourth to the sixth ring. The inner four to six rings are complete, the outer ten to fifteen irregularly interrupted.

_Dimensions._--Shell 0.08 long, 0.3 to 0.4 broad.

_Habitat._--South Atlantic, Station 338, surface.

Subgenus 2. _Cladopyramis_, Haeckel, 1881, Prodromus, p. 428.

_Definition_.--Shell spiny, with prominent simple or branched spines on the surface.

6. _Bathropyramis spinosa_, n. sp.

Shell spiny, slenderly pyramidal, with three cortinar pores at the apex and with nine strong radial beams, connected by fifteen to twenty complete parallel rings. Meshes subregular square, increasing gradually in size. Surface covered with simple, strong conical spines, arising from the nodal points.

_Dimensions._--Shell 0.24 long, 0.16 broad.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

{1161}7. _Bathropyramis ramosa_, n. sp. (Pl. 54, fig. 4).

Shell spiny, slenderly pyramidal, with three cortinar pores at the apex, and with nine (or sometimes eight or ten) strong radial beams, connected by fifteen to eighteen complete parallel rings. Meshes subregular, square, increasing gradually in size. Surface covered with forked or irregularly branched spines, arising from the nodal points.

_Dimensions._--Shell 0.3 long, 0.17 broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 512. _Cinclopyramis_,[129] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with simple, slender, pyramidal shell, and numerous radial beams (six to nine or more). Network double, with a delicate arachnoidal fenestration, filling up the large quadrangular meshes.

The genus _Cinclopyramis_ differs from the preceding _Bathropyramis_ in the development of a very delicate secondary network, filling up the large quadrangular meshes, which are produced by the crossing of the radial beams and the parallel horizontal rings. It therefore bears the same relation to the preceding genus that _Plectopyramis_ does to _Sethopyramis_; it is perhaps derived directly from the former by loss of the small cephalis.

1. _Cinclopyramis cribellum_, n. sp.

_Cinclopyramis cribellum_ = "Ladder of lattice-shape," Bury, 1862,
Polycystins of Barbados, pl. xii. fig. 6.

Shell slender, pyramidal, with six strong radial ribs, which are connected by twelve to sixteen complete horizontal rings. Meshes trapezoidal, filled up by a very delicate and regular secondary network with square porules (two to four horizontal threads in each larger mesh).

_Dimensions._--Shell 0.2 to 0.3 long, 0.12 to 0.16 broad.

_Habitat._--Fossil in Barbados.

2. _Cinclopyramis infundibulum_, n. sp. (Pl. 54, fig. 7).

Shell slender, pyramidal, with nine strong radial ribs, which are connected by eighteen to twenty-four complete horizontal rings. Meshes subregular square, filled up by a very delicate and regular secondary network with square porules (ten to twelve horizontal threads in each larger mesh). Apex of the pyramid with three very small cortinar pores.

_Dimensions._--Shell 0.3 to 0.4 long, 0.2 to 0.25 broad.

_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms.

{1162}3. _Cinclopyramis lithosestrum_, n. sp.

Shell slender, pyramidal, with twelve strong radial ribs (six primary longer and six secondary shorter) connected by twelve to fifteen interrupted irregular rings. Meshes irregular square or trapezoidal, filled up by a delicate secondary network with irregular polygonal porules.

_Dimensions._--Shell 0.4 to 0.5 long, 0.2 to 0.3 broad.

_Habitat._--Fossil in Barbados.

Genus 513. _Peripyramis_,[130] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with double, slenderly pyramidal shell, and numerous radial beams (six to nine or more). Network double, with an external arachnoidal or spongy envelope around the primary lattice-shell.

The genus _Peripyramis_ differs from its probable ancestral form, _Bathropyramis_, by development of a delicate external envelope around the primary shell, and therefore bears to it the same relation that _Spongopyramis_ among the Dicyrtida does to _Sethopyramis_. It may also be derived directly from the former by loss of the cephalis.

1. _Peripyramis circumtexta_, n. sp. (Pl. 54, fig. 5).

Shell slender, pyramidal, with nine strong radial beams, connected by fifteen to twenty transverse horizontal rings, which are partly complete, partly interrupted. Meshes subregular, square. From the nodal points of the surface there arise branched spines, which at equal distances from it are connected by thin threads, forming a delicate outer arachnoidal shell with large irregular polygonal meshes.

_Dimensions._--Shell 0.32 long, 0.16 broad.

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

2. _Peripyramis spongiosa_, n. sp.

Shell slender, pyramidal, with nine strong radial beams, connected by twelve to eighteen irregular interrupted rings. Meshes irregular, square or polygonal. From the whole surface arise numerous branched spines, which by communication and dense ramification form an outer spongy envelope around the shell. (Similar to _Spongopyramis spongiosa_, Pl. 56, fig. 10.)

_Dimensions._--Shell 0.45 long, 0.32 broad.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.

{1163}Genus 514. _Litharachnium_,[131] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 835.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with flatly conical, tent-shaped or nearly discoidal shell, and numerous, simple, radial beams in its wall.

The genus _Litharachnium_, and the closely allied genus _Cladarachnium_, differ from the preceding similar genera mainly in the flat form of the depressed shell, which is not slenderly pyramidal, but more tent-shaped or nearly discoidal. The radial ribs are generally not straight, but more or less curved. The top of the tent exhibits three or four important meshes, the original pores of the cortinar septum. _Litharachnium_ may be derived directly from _Sethophormis_ by reduction and loss of the cephalis.

Subgenus 1. _Litharachnidium_, Haeckel.

_Definition._--Apex with three cortinar pores (one odd sternal and two paired cardinal pores).

1. _Litharachnium tentorium_, Haeckel.

Litharachnium tentorium, Haeckel, 1862, Monogr. d. Radiol., p. 281, Taf.
iv. figs. 7-10.

Shell flatly conical or tent-shaped, with concave lateral outlines. Apex with three equal cortinar pores. Twenty radial ribs at nearly equal distances. Between them very numerous and thin secondary ribs, crossed by more than one hundred concentric rings. Pores square, as in all the following species. Margin truncate, circular.

_Dimensions._--Shell 0.35 long, 0.8 broad.

_Habitat._--Mediterranean (Messina).

2. _Litharachnium araneosum_ (Pl. 55, figs. 8, 10).

Shell flatly conical, nearly discoidal, with straight lateral outlines. Apex with three unequal cortinar pores (one odd smaller sternal and two paired larger cardinal pores). Twenty radial ribs at unequal distances, with numerous intercalated secondary ribs. Margin ciliate.

_Dimensions._--Shell 0.18 long, 0.32 broad.

_Habitat._--Central Pacific, Station 271, surface.

{1164}3. _Litharachnium arachnodiscus_, Haeckel.

_Litharachnium arachnodiscus_, Haeckel, 1862, Monogr. d. Radiol., p. 283.

_Carpocanium arachnodiscus_, Ehrenberg, 1861, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 296; Abhandl. d. k. Akad. d. Wiss. Berlin,
1872, Taf. ii. fig. 8.

Shell flatly campanulate, nearly discoidal, with convex (?) lateral outlines. Apex with three unequal cortinal pores. Nine stronger radial primary ribs complete; between them numerous secondary intercalated ribs (sixty to seventy). Margin ciliate.

_Dimensions._--Shell 0.03 long, 0.1 broad (?).

_Habitat._--Arctic Ocean (between Greenland and Iceland), depth 1000 fathoms (Schaffner).

4. _Litharachnium epeira_, n. sp. (Pl. 55, fig. 9).

Shell flatly conical or tent-shaped, with concave lateral outlines. Apex with three unequal cortinar pores. Twelve stronger radial primary ribs complete; between them numerous (twenty-four to thirty-six) thinner secondary, and very numerous (more than one hundred) tertiary ribs. Margin reflexed, like the curved brim of a hat.

_Dimensions._--Shell 0.12 long, 0.27 broad.

_Habitat._--Central Pacific, Station 274, surface.

Subgenus 2. _Litharachnoma_, Haeckel.

_Definition._--Apex with four cortinar pores (two anterior jugular and two posterior cardinal pores).

5. _Litharachnium discoides_, n. sp.

Shell flat, funnel-shaped, nearly discoidal, with concave outlines. Apex with four unequal cortinar pores (two smaller jugular and two larger cardinal pores). Twelve strong primary or perradial ribs alternating with twelve weaker secondary or interradial ribs; between these there are twenty-four shorter tertiary or adradial ribs, and in the outer flat, discoidal, half of the shell very numerous peripheral radial ribs (more than two hundred to three hundred). Margin flat, discoidal.

_Dimensions._--Shell about 0.2 long, 1.12 broad.

_Habitat._--Equatorial Atlantic, Station 347, surface.

6. _Litharachnium pilidium_, n. sp.

Shell flat, hat-shaped, with S-shaped outlines, in the upper half convex, in the lower half concave. Apex with four equal crossed cortinar pores. Thirty primary ribs of equal size; four of them are the prolongations of the four cortinar beams, eight intercalate between these secondary, {1165}and the other eighteen tertiary. Between them very numerous peripheral beams. Margin broad horizontal, reflexed like the brim of a "Bismarck" hat.

_Dimensions._--Shell 0.17 long, 0.38 broad.

_Habitat._--South Pacific, Station 298, depth 2225 fathoms.

Genus 515. _Cladarachnium_,[132] Haeckel, 1881, Prodromus, p. 430.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with flatly conical, tent-shaped or nearly discoidal shell, and numerous branched radial beams.

The genus _Cladarachnium_ differs from the preceding _Litharachnium_ only in the ramification of the radial beams, the distal ends of which project over the margin of the shell. Only one species of the genus has been observed.

1. _Cladarachnium ramosum_, n. sp. (Pl. 55, figs. 5, 6).

Shell flatly conical or tent-shaped, with nearly straight lateral outlines; apical part somewhat higher. Apex with three cortinar pores surrounded by a few girdles of larger pores. From these there arise about twelve to fifteen strong radial beams at unequal distances; these are somewhat curved and irregularly branched. The network between them has irregular polygonal meshes and is more delicate towards the periphery. Margin with twenty-four to thirty irregular indentations or concave excisions, separated by the prominent distal ends of the branched ribs.

_Dimensions._--Shell 0.16 long, 0.4 broad.

_Habitat._--Central Pacific, Station 271, surface.

Genus 516. _Cystophormis_,[133] n. gen.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with ovate or urceolate shell and numerous radial ribs in its wall. Mouth more or less constricted, smooth, truncated. Apex without horn.

The genus _Cystophormis_, like the preceding genera, exhibits numerous prominent radial or longitudinal ribs in the wall of the urceolate shell; it differs from these in the constricted and truncated mouth, with smooth margin of the peristome.

1. _Cystophormis pila_, n. sp. (Pl. 52, fig. 1).

Shell balloon-shaped, subspherical, with twenty denticulate meridional ribs, alternating with twenty longitudinal rows of circular pores, which are twice as broad as the bars. Peristome constricted and then dilated, smooth, half as broad as the shell.

_Dimensions._--Shell 0.11 long, 0.09 broad; mouth 0.06 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.

{1166}2. _Cystophormis ærostatica_, n. sp. (Pl. 52, figs. 2, 3).

Shell balloon-shaped, subspherical, with twenty smooth meridional ribs, alternating with twenty longitudinal rows of circular pores, of the same breadth as the bars. Peristome constricted, about half as broad as the shell.

_Dimensions._--Shell 0.09 long, 0.07 broad; mouth 0.03 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.

3. _Cystophormis spiralis_, n. sp. (Pl. 51, fig. 9).

Shell ovate, one and a half times as long as broad, with twenty spirally convoluted, elegantly denticulated ribs, alternating with twenty spiral rows of small circular pores, of about the same breadth as the bars. Peristome constricted, very small, only one-seventh as broad as the shell.

_Dimensions._--Shell 0.1 long, 0.07 broad; mouth 0.01 broad.

_Habitat._--West Tropical Pacific, Station 225, depth 4475 fathoms.

4. _Cystophormis tabulata_ (Pl. 79, fig. 2).

Shell urceolate and tabulate, twice as long as broad with twenty-five to thirty denticulated longitudinal ribs crossed by twenty to twenty-four transverse rings. Pores therefore regularly disposed in longitudinal and transverse rows; each pore circular, with a square frame. Peristome constricted, scarcely half as broad as the shell.

_Dimensions._--Shell 0.2 long, 0.1 broad; mouth 0.04 broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms

Genus 517. _Haliphormis_,[134] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54 (_sensu mutato_).

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with numerous radial ribs in the wall of the campanulate shell, prolonged into free terminal feet. Apex with a horn.

The genus _Haliphormis_ (with an apical horn) and the following _Archiphormis_ (without a horn) comprise those Archiphormida in which the open mouth is more or less constricted and surrounded by a coronet of radial feet, as terminal prolongations of the radial ribs of its wall. The few forms, upon which Ehrenberg originally founded the genus _Haliphormis_, are partly not recognisable, partly belong to other genera. We therefore give here a new definition of the genus, as stated in my Prodromus, 1881, p. 428.

{1167}1. _Haliphormis lagena_, n. sp. (Pl. 97, fig. 5)

Shell bottle-shaped, twice as long as broad, tapering towards both ends, with nine longitudinal curved ribs. These are connected by irregular transverse beams, and the quadrangular meshes, so produced, are filled up by irregular, delicate, arachnoidal framework. The constricted mouth is half as broad as the middle part of the shell and surrounded by nine slender convergent feet, the free distal ends of the ribs. The apex bears a small knob with an oblique horn, perhaps the rudimentary cephalis of _Sethamphora_ or _Sethopyramis_ (?).

_Dimensions._--Shell 0.6 to 0.7 long, 0.3 to 0.4 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

2. _Haliphormis costata_, n. sp.

Shell campanulate, somewhat longer than broad, with twelve prominent longitudinal ribs, alternating with twelve rows of regular circular pores. Mouth constricted half as broad as the shell, with twelve long triangular feet, formed by the free distal ends of the ribs. Apical horn short and stout, triangular pyramidal.

_Dimensions._--Shell 0.12 long, 0.1 broad; mouth 0.07 long.

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

Genus 518. _Archiphormis_,[135] Haeckel, 1881, Prodromus, p. 428.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with numerous radial ribs in the wall of the campanulate or urceolate shell, prolonged into free terminal feet. Apex without horn.

The genus _Archiphormis_ differs from the preceding _Haliphormis_, its probable ancestral form, in the absence of the apical horn. The number of the longitudinal ribs, which are prolonged into terminal feet, is from six to nine or twelve or even more.

1. _Archiphormis cancellata_, Haeckel.

(?) _Halicalyptra cancellata_, Ehrenberg, 1854, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 243.

Shell cup-shaped or campanulate, with six prominent ribs, prolonged into six terminal triangular feet, one-third as long as the shell. Ribs connected by five or six transverse horizontal rings; meshes between them rounded squarish. (As Ehrenberg has given no figure of this species, its identity with the Challenger specimen is doubtful.)

_Dimensions._--Shell 0.08 long, 0.06 broad; mouth 0.04 broad.

_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.

{1168}2. _Archiphormis campanulata_, n. sp.

Shell campanulate, with nine prominent denticulate ribs, prolonged into nine terminal feet, which are broad, lamellar, truncate, nearly vertical, one-third as long as the shell. Pores between the ribs circular, disposed in nine longitudinal and seven to eight transverse rows.

_Dimensions._--Shell 0.09 long, 0.1 broad; mouth 0.06 broad.

_Habitat._--Central Pacific, Station 270, depth 2925 fathoms.

3. _Archiphormis urceolata_, n. sp. (Pl. 98, fig. 11).

Shell urceolate, with nine smooth prominent curved ribs, prolonged into nine triangular convergent short feet, scarcely one-sixth as long as the shell. Pores between the ribs in nine regular longitudinal rows, twice or three times as broad as long, quadrangular, eight to twelve pores in each row. Mouth constricted, half as broad as the shell.

_Dimensions._--Shell 0.13 long, 0.11 broad; mouth 0.06 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.

Genus 519. _Halicalyptra_,[136] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54 (_sensu emendato_).

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) without radial ribs in the wall of the campanulate or ovate shell. Mouth with a coronet of radial feet. Apex with a horn.

The genus _Halicalyptra_ and the two following closely allied genera differ from the preceding Archiphormida in the absence of radial ribs. The multiradiate structure is indicated only by the terminal spines or feet, forming a coronet around the mouth. These feet are either the free ends of reduced ribs, or new productions of the peristome. _Halicalyptra_ may be derived from _Calpophæna_ and _Petalospyris_ by loss of the basal lattice-plate of the cephalis. But it is also possible that it has been derived from _Anthocyrtis_ by loss of the cephalis, and that its shell corresponds to the thorax of the latter.

Subgenus 1. _Acrocalpis_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Shell smooth, without spines or thorns (other than the feet and the apical horn).

{1169}1. _Halicalyptra virginica_, Ehrenberg.

_Halicalyptra virginica_, Ehrenberg, 1854, Mikrogeol., Taf. xviii. fig.
110.

_Halicalyptra virginica_, Haeckel, 1862, Monogr. d. Radiol., p. 289.

_Haliomma virginicum_, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, p. 71.

_Acrocalpis virginica_, Haeckel, 1881, Prodromus, p. 427.

Shell smooth, campanulate, nearly hemispherical. Pores subregular circular, about as broad as the bars. Horn conical, half as long as the shell. Peristome scarcely constricted, with six conical divergent feet, as long as the horn.

_Dimensions._--Shell diameter 0.04 to 0.05, length of the feet 0.02.

_Habitat._--Fossil in tertiary rocks of Barbados and North America (Richmond, Virginia).

2. _Halicalyptra campanula_, n. sp.

_Podocyrtis spinosa_, Bury, 1862, Polycystins of Barbados, pl. xvii. fig.
3.

Shell smooth, campanulate. Pores irregular, roundish, about as broad as the bars. Horn large conical, about as long as the shell. Peristome not constricted, with six large divergent feet, which are as long as the shell, lamellar, with dentate edges.

_Dimensions._--Shell diameter 0.07, length of the feet 0.07.

_Habitat._--Fossil in Barbados.

3. _Halicalyptra ampulla_, n. sp.

_Petalospyris foveolata_, var., Bury, 1862, Polycystins of Barbados, pl.
ix. fig. 1.

Shell smooth, subspherical, inflate. Pores regular, circular, twice as broad as the bars. Horn slender conical, about as long as the shell. Peristome constricted, with six divergent cylindrical, irregularly curved feet, twice to three times as long as the shell.

_Dimensions._--Shell diameter 0.12, feet 0.2 to 0.3 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.

4. _Halicalyptra novena_, n. sp.

Shell smooth, campanulate. Pores irregular, roundish. Horn slender conical, about as long as the shell. Peristome slightly constricted, with nine slender divergent feet of the same length. (Very similar to _Petalospyris foveolata_, Ehrenberg, but without internal columella and ring, with perfectly simple shell-cavity and open mouth.)

_Dimensions._--Shell 0.09 diameter, feet 0.1 long.

_Habitat._--Fossil in Barbados.

5. _Halicalyptra petalospyris_, n. sp. (Pl. 98, fig. 12).

Shell smooth, campanulate. Pores small, circular, irregularly scattered. Horn stout, pyramidal, about as long as the shell. Peristome scarcely constricted, with fifteen to twenty broad {1170}lamellar or lanceolate feet, which are twice to three times as long as the shell, parallel and vertical. (Very similar to _Petalospyris flabellum_, &c., Ehrenberg, 1875, _loc. cit._, Taf. xxii. figs. 6-8, but without any trace of sagittal ring or columella.)

_Dimensions._--Shell 0.05 to 0.08 diameter, feet 0.15 to 0.25 long.

_Habitat._--Central Pacific, Stations 266 to 268, depth 2700 to 2900 fathoms.

Subgenus 2. _Echinocalpis_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Shell spiny, covered with numerous spines or thorns (besides the feet and the apical horn).

6. _Halicalyptra spinosa_, n. sp.

Shell spiny, ovate, inflate in the apical half. Pores irregular polygonal, four to eight times as broad as the bars. Peristome constricted, half as broad as the shell, with nine slender divergent feet, which like the apical horn are curved, twice to three times as long as the shell and five to ten times as long as the numerous bristles of the surface.

_Dimensions._--Shell 0.08 long, 0.06 broad; feet 0.15 to 0.25 long.

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

7. _Halicalyptra castanella_, n. sp.

Shell spiny, nearly spherical. Pores irregular roundish. Peristome constricted, scarcely one-third as broad as the shell, with twelve to twenty slender, widely divergent feet, which like the horn are irregularly curved, and longer than the shell. (Very similar to certain forms of the Phæodarium _Castanella_, Pl. 113, fig. 2.)

_Dimensions._--Shell 0.13 diameter, feet 0.15 to 0.18 long.

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

Genus 520. _Carpocanistrum_,[137] n. gen.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) without radial ribs in the wall of the campanulate or ovate shell. Mouth with a corona of radial feet. Apex without horn.

The genus _Carpocanistrum_ differs from the similar preceding _Halicalyptra_ in the loss of the apical horn. It is very nearly related to the Dicyrtid _Carpocanium_ and may be easily confounded with it. But in the latter the uppermost part of the shell-cavity includes a rudimentary cephalis with a cortinar septum, whilst in _Carpocanistrum_ {1171}the cephalis is entirely lost, and the inner cavity quite simple. The number of the feet of the peristome is from nine to twenty, sometimes more. The mouth is commonly more or less constricted.

1. _Carpocanistrum novenum_, n. sp.

Shell ovate, smooth, one and a third times as long as broad. Pores regular circular, hexagonally framed, three times as broad as the bars, eight to ten on the greatest breadth of the shell. Peristome strongly constricted, one-third as broad as the shell, with nine large ovate lamellar, slightly convergent feet.

_Dimensions._--Shell 0.08 long, 0.06 broad; mouth 0.02 broad.

_Habitat._--South Atlantic, Station 325, surface.

2. _Carpocanistrum flosculum_, n. sp. (Pl. 52, fig. 9).

Shell campanulate, rough, thick-walled, of equal breadth and length. Pores regular circular, of the same breadth as the bars, twelve to fifteen on the greatest breadth of the shell. Peristome slightly constricted, with twelve elegant lanceolate, nearly vertical, a little convergent feet.

_Dimensions._--Shell 0.07 long, 0.07 broad; mouth 0.05 broad.

_Habitat._--Equatorial Atlantic, Station 347, surface.

3. _Carpocanistrum giganteum_, n. sp.

Shell ovate, smooth, very thick-walled, one and a third times as long as broad. Pores very numerous and small, subregular circular, forty to fifty on the greatest breadth of the shell, of about the same breadth as the bars. Peristome small, constricted, scarcely one-fourth as broad as the shell, with twelve to fifteen short triangular vertical feet.

_Dimensions._--Shell 0.28 to 0.31 long, 0.21 to 0.23 broad; mouth 0.06 to 0.07 broad.

_Habitat._--Fossil in Barbados.

4. _Carpocanistrum acephalum_, n. sp. (Pl. 52, fig. 10).

Shell ovate, smooth, thin-walled, one and a fifth times as long as broad. Pores subregular circular, twice as broad as the bars, sixteen to twenty on the greatest breadth of the shell. Peristome slightly constricted, with fifteen to eighteen slender, slightly bent, nearly vertical, and parallel feet, which are half as long as the shell.

_Dimensions._--Shell 0.12 long, 0.1 broad; mouth 0.07 broad.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.

{1172}5. _Carpocanistrum evacuatum_, n. sp. (Pl. 52, fig. 11).

Shell urceolate, smooth, thin-walled, one and a half times as long as broad. Pores regular circular, sixteen to twenty on the greatest breadth of the shell. Peristome slightly constricted, with twenty to twenty-five small triangular vertical feet.

_Dimensions._--Shell 0.1 long, 0.07 broad; mouth 0.05 broad.

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

6. _Carpocanistrum pyriforme_, Haeckel.

_Lithocarpium pyriforme_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 97,
Taf. iii. fig. 10.

Shell pear-shaped or subspherical, one and a fourth times as long as broad. Pores roundish, polygonally framed (or with square meshes ?). Peristome strongly constricted, one-fourth as broad as the shell, somewhat tubular, with twelve to twenty short vertical and parallel feet. The position of this species is doubtful; perhaps it represents a peculiar genus.

_Dimensions._--Shell 0.17 long, 0.14 broad; mouth 0.035 broad.

_Habitat._--Fossil in Tertiary rocks of Sicily (Grotte) Stöhr.

Genus 521. _Arachnocalpis_,[138] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archiphormida# (vel Monocyrtida multiradiata aperta) with an ellipsoidal or nearly spherical double shell; outer shell arachnoidal or spongy. Peristome small, constricted with a corona of numerous radial feet. No apical horn.

The genus _Arachnocalpis_ differs from the other Archiphormida by possessing a double shell (like _Peripyramis_). The large shell, reaching nearly half a millimeter in length is either ellipsoidal or nearly spherical, and composed of an inner primary and an outer secondary shell. Its network is very delicate, in the outer envelope either spongy or arachnoidal. This very remarkable genus has probably no true relation to the other Archiphormida but has been derived from true #Calpoidea# (_Mitrocalpis_) by development of a corona around the mouth.

1. _Arachnocalpis ellipsoides_, n. sp. (Pl. 98, fig. 13).

Shell ellipsoidal, one and a half times as long as broad, on the apical pole hemispherical, on the basal pole coronate, with an elegant prominent funnel-shaped peristome, which is one-eighth as broad as the shell, fenestrated by very fine pores, and bears fifteen to twenty short conical divergent teeth. Inner shell with irregular polygonal meshes of very different size, separated by thin, {1173}finely-denticulate bars. Outer spongy shell very delicate, arachnoidal, with numerous prominent conical spongy papillæ. Central capsule ellipsoidal, half as long and broad as the shell.

_Dimensions._--Shell 0.46 long, 0.32 broad; mouth 0.045 broad.

_Habitat._--Central Pacific, Stations 271 to 274, surface.

2. _Arachnocalpis sphæroides_, n. sp.

Shell spheroidal, of the same structure as the preceding ellipsoidal species, with the same form of the spongy envelope; differing from it in the globose form and the shorter peristome, bearing only nine or ten small conical divergent teeth. Central capsule spherical.

_Dimensions._--Shell 0.3 diameter, mouth 0.04 broad.

_Habitat._--Central Pacific, Stations 265 to 270, surface.

Subfamily 2. ARCHIPHÆNIDA, Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Phænocalpida# with the basal mouth of the shell fenestrated (vel Monocyrtida multiradiata clausa).

Genus 522. _Phænocalpis_,[139] n. gen.

_Definition._--#Archiperida# (vel Monocyrtida multiradiata clausa) with an internal axial simple columella, prolonged outside into an apical horn.

The genus _Phænocalpis_ and the following _Phænoscenium_ comprise those Archiphænida in which the vertical axis of the shell-cavity is occupied by a simple or branched columella, arising from the centre of the base and prolonged into an apical horn. This columella may be either the vertical rod of a _Plectaniscus_ or the remnant of an original ring of _Petalospyris_. The latter genus differs by its sagittal constriction.

1. _Phænocalpis petalospyris_, n. sp. (Pl. 97, fig. 4).

Shell subspherical, rough, with irregular, roundish pores, larger than the bars. Columella straight, central, thin, prolonged into a large apical horn with three dentate edges. Six basal feet curved, divergent, lamellar, with a middle rib and dentate edges.

_Dimensions._--Shell 0.07 long, 0.05 broad; horn and feet 0.06 long.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

{1174}2. _Phænocalpis ocellata_, Haeckel.

_Petalospyris ocellata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 80, Taf. xxii. fig. 9.

Shell subspherical, smooth, with irregular roundish pores, about as broad as the bars. Columella slightly curved and excentric, prolonged into a slender conical horn of the same length. Six basal feet similar to the horn, slightly divergent.

_Dimensions._--Shell 0.06 long, 0.07 broad; horn and feet 0.05 long.

_Habitat._--Fossil in Barbados.

3. _Phænocalpis carinata_, Haeckel.

_Petalospyris carinata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 80, Taf. xxii. fig. 6.

Shell campanulate, rough, with irregular roundish pores, smaller than the bars. Columella straight, central, prolonged into a stout conical horn of the same length. Nine basal feet slender, triangular, longer than the shell, nearly vertical, with a middle rib in the basal half.

_Dimensions._--Shell 0.05 long, 0.06 broad; horn 0.04 long, feet 0.08 long.

_Habitat._--Fossil in Barbados.

4. _Phænocalpis flabellum_, Haeckel.

_Petalospyris flabellum_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, Taf. xxii. fig. 7.

Shell campanulate smooth, with very small circular pores, half as broad as the bars. Columella straight, central, prolonged into a pyramidal horn of half the length. Twelve to fifteen basal feet lamellar, linear, twice to three times as long as the shell, parallel and vertical, pointed at the distal end.

_Dimensions._--Shell 0.04 long, 0.05 broad; horn 0.02 long, feet 0.1 to 0.12 long.

_Habitat._--Fossil in Barbados.

Genus 523. _Phænoscenium_,[140] n. gen.

_Definition._--#Archiphænida# (vel Monocyrtida multiradiata clausa) with an internal axial branched columella, prolonged outside into an apical horn.

The genus _Phænoscenium_ differs from the preceding _Phænocalpis_ in the branched columella, which is connected by three or six ascending branches with the inner wall of the shell. It bears therefore to the latter the same relation that _Cladoscenium_ exhibits to _Euscenium_. The former genera may have been derived from the latter by interpolation of new interradial feet between the three primary perradial feet.

{1175}1. _Phænoscenium hexapodium_, n. sp. (Pl. 98, fig. 9).

Shell campanulate, smooth, about as long as broad. Network delicate, with irregular polygonal pores and thin bars. Columella with four to six ascending three-branched verticils, prolonged into the conical hollow apical horn (with six to eight smaller verticils) which is about as long as the shell. Six basal feet curved, divergent, of the same length, with pinnate middle rod.

_Dimensions._--Shell 0.1 long, 0.11 broad; horn and feet 0.08 to 0.09 long.

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

2. _Phænoscenium cladopodium_, n. sp.

Shell campanulate, conical, smooth, somewhat broader than long. Network with irregular roundish pores, about as broad as the bars. Columella with a single verticil of three ascending branches. Horn pyramidal, stout, as long as the shell, with three dentate edges. Six feet divergent, slightly curved, very unequal; three primary (or perradial) very large, longer than the shell, three sided pyramidal, with three dentate edges; three secondary (or interradial) much smaller, simple, shorter than the shell.

_Dimensions._--Shell 0.05 long, 0.06 broad; horn and feet 0.04 to 0.07 long.

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

3. _Phænoscenium polypodium_, n. sp.

Shell subspherical, about as long as broad, smooth. Network with regular circular pores, twice as broad as the bars. Columella with two verticils of three ascending branches, prolonged into a stout conical horn of twice the length. Twelve to fifteen conical curved divergent feet, about as long as the shell. The three primary feet are directly connected with the base of the columella.

_Dimensions._--Shell 0.08 diameter, horn 0.15 long, feet 0.07 to 0.09 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.

Genus 524. _Calpophæna_,[141] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiphænida# (vel Monocyrtida multiradiata clausa) with an apical horn and simple internal cavity of the shell without axial columella.

The genus _Calpophæna_ and the following closely tied _Archiphæna_ differ from the two preceding genera of Archiphænida in the simple shell cavity, which encloses no columella. They may be derived either from the preceding _Phænocalpis_ by loss of the columella, or directly from the Zygospyrida by reduction of the sagittal constriction and loss of the primary ring. Different subgenera may be distinguished in _Calpophæna_ according either to the number of the feet or to their shape (being simple or branched).

{1176}Subgenus 1. _Acrocorona_, Haeckel, 1881, Prodromus, p. 430.

_Definition._--Feet simple, not branched nor forked.

1. _Calpophæna tetrarrhabda_, n. sp.

Shell subspherical, tuberculate, with subregular circular pores. Apical horn conical, about as long as the shell. Basal plate with a regular cross of four equal cortinar pores, separated by four bars; these are crossed in the sagittal and frontal diameter, and prolonged into four equal conical divergent feet, about as long as the shell.

_Dimensions._--Shell 0.1 diameter, horn and feet 0.1 to 0.12 long.

_Habitat._--South Pacific, Station 297, depth 1775 fathoms.

2. _Calpophæna hexarrhabda_, n. sp. (Pl. 53, figs. 17, 18).

Shell subspherical, rough, with irregular roundish pores. Apical horn conical, shorter than the shell. Basal plate (fig. 18) with three pairs of triangular pores, two larger (cardinal) pores in the middle, two smaller (cervical) at the dorsal, and two intermediate (jugular) at the ventral side. The bars between them are prolonged into six equal cylindrical divergent feet, nearly as long as the shell, provided with a spiny knob at the end.

_Dimensions._--Shell 0.09 long, 0.08 broad; horn and feet 0.06 to 0.08 long.

_Habitat._--Tropical Pacific, Station 224, depth 1850 fathoms.

3. _Calpophæna ennearrhabda_, n. sp.

Shell subspherical, spiny, with irregular, roundish pores. Apical horn cylindrical, longer than the shell. Basal plate with nine collar pores, three larger central alternating with three pairs of smaller peripheral (like Pl. 87, fig. 2). Corona with nine slender cylindrical, slightly curved, divergent feet, somewhat longer than the shell.

_Dimensions._--Shell 0.11 long, 0.1 broad; horn and feet 0.12 to 0.15 long.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.

4. _Calpophæna enneaphylla_, n. sp.

Shell ovate, smooth, with regular circular pores. Apical horn pyramidal, half as long as the shell. (Basal plate with four cortinar pores?) Corona with nine broad, lamellar, truncate, vertical feet, about as long as the horn.

_Dimensions._--Shell 0.12 long, 0.09 broad; horn and feet 0.06 long.

_Habitat._--Central Pacific, Station 271, surface.

{1177}5. _Calpophæna petalospyris_, n. sp.

Shell campanulate, tuberculate, with irregular, roundish pores. Apical horn conical, shorter than the shell. (Basal plate with nine pores?) Corona with twelve to twenty broad, lamellar, truncate, vertical feet, of different sizes, somewhat irregular.

_Dimensions._--Shell 0.08 long, 0.09 broad; horn and feet 0.07 to 0.12 long.

_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 2. _Cladocorona_, Haeckel, 1881, Prodromus, p. 430.

_Definition._--Feet branched or forked.

6. _Calpophæna tetracorethra_, n. sp.

Shell subspherical, smooth, with irregular, roundish pores. Basal plate with four larger pores. Apical horn and the four divergent basal feet of equal size and similar form, three to four times as long as the shell, slender, bristle-shaped, curved, in the distal half irregularly branched. (Very similar to the remarkable _Tetraspyris tetracorethra_, Pl. 53, figs. 19, 20, but with shorter appendages and with simple spherical shell, which exhibits no trace of sagittal ring and constriction.)

_Dimensions._--Shell 0.12 diameter, horn and feet 0.3 to 0.5 long.

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

7. _Calpophæna hexacorethra_, n. sp.

Shell subspherical, smooth, similar to the preceding species. Basal plate with six pores. Apical horn and the six divergent feet twice to three times as long as the shell, bristle-shaped, irregularly curved and branched. (Similar to _Hexaspyris hexacorethra_, Pl. 95, fig. 8, but without sagittal ring and constriction.)

_Dimensions._--Shell 0.11 long, 0.13 broad; horn and feet 0.2 to 0.3 long.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.

Genus 525. _Archiphæna_,[142] Haeckel, 1881, Prodromus, p. 429.

_Definition._--#Archiphænida# (vel Monocyrtida multiradiata clausa), with simple internal cavity of the shell, without apical horn and axial columella.

The genus _Archiphæna_ has the same simple cavity of the shell as the preceding _Calpophæna_, but differs from it in the loss of the apical horn. It bears therefore to the latter the same relation that _Gorgospyris_ does to _Petalospyris_. The two former genera may be derived from the two latter by loss of the sagittal ring and constriction.

{1178}Subgenus 1. _Coronophæna_, Haeckel, 1881, Prodromus, p. 429.

_Definition._--Feet simple, not branched nor forked.

1. _Archiphæna gorgospyris_, n. sp. (Pl. 98, figs. 10, 10_a_).

Shell hemispherical, smooth, with small subregular, circular pores. Collar septum with four large pores (fig. 10_a_). Twelve to fifteen feet, divergent, lamellar, truncate, about as long as the shell. (Similar to certain forms of _Gorgospyris_, Pl. 87, figs. 1 to 3, but with simple shell cavity, without sagittal ring and constriction, and without a columella.)

_Dimensions._--Shell 0.08 long, 0.04 broad; feet 0.03 to 0.04 long.

_Habitat._--North Pacific, Station 244, depth 2900 fathoms.

2. _Archiphæna corona_, n. sp.

Shell crown-shaped, somewhat broader than long, at the base flattened, papillate, with irregular roundish pores. Twenty to twenty-five feet, broad, lamellar, truncate, nearly vertical, about twice as long as the shell.

_Dimensions._--Shell 0.1 long, 0.12 broad; feet 0.2 to 0.22 long.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.

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

_Definition._--Feet branched or forked.

3. _Archiphæna stephanoma_, n. sp.

Shell campanulate, somewhat longer than broad, with subregular, circular pores. Margin of the flattened base with a corona of about twenty unequal feet, which are partly simple, partly irregularly branched, and about as long as the shell.

_Dimensions._--Shell 0.11 long, 0.03 broad; feet 0.08 to 0.12 long.

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

Family LXI. #CYRTOCALPIDA#, n. fam.

Archicorida et Archicapsida, Haeckel, 1881, Prodromus, pp. 427, 428.

_Definition._--#Monocyrtida# eradiata. (#Cyrtoidea# with a simple, not jointed shell, representing a simple cephalis without radial apophyses.)

The family #Cyrtocalpida#, composed of the Archicorida and Archicapsida of my {1179}Prodromus, comprises those #Cyrtoidea# in which the lattice-shell is quite simple, without transverse constriction, and without radial apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Archicorida is a simple wide opening, but in the Archicapsida is closed by a lattice-plate.

Only a few species of this family were formerly known. Ehrenberg, in 1838, founded upon these the genus _Cornutella_, one of the three oldest genera of Polycystina (_Cornutella_, _Lithocampe_, _Haliomma_). In 1862 I described some living forms, with a central capsule, as _Cyrtocalpis_. The Challenger collection contains a large number of new genera and species.

Probably the family Cyrtocalpida is an artificial group, comprising two or more different subfamilies of very different origin. The Cornutellida (_Cornutella_, _Cornutanna_) have probably been derived from the Sethocorida by loss of the cephalis, so that their conical shell represents a thorax alone. The Mitrocalpida on the other hand (genera 528-531) may be originally simple ovate shells (like _Gromia_ and _Lecythium_), arising independently from the Nassellida. The Archicapsida (_Halicapsa_, _Archicapsa_) are probably derived from the Zygospyrida (_Dictyospyris_, _Circospyris_) by loss of the sagittal ring and constriction. This is nearly certain, when the three or four typical cortinar pores appear in their basal plate. Some forms of _Halicapsa_ may be easily confounded with some forms of Prunoidea (_Lithapium_).

Those Cyrtocalpida, which possess a central capsule with three or four lobes, are probably derived from Tripocyrtida by loss of the three feet, or from Sethocyrtida by loss of the cephalis, since the lobes indicate the original presence of cortinar pores and of a cephalis. Those Cyrtocalpida, however, in which a simple ovate shell encloses a simple central capsule without lobes, may be original "Monocyrtida eradiata," without relation to any radial ancestral forms.

_Synopsis of the Genera of Cyrtocalpida._

-------------------------------------------------------------------------
I. Subfamily Archicorida. Basal mouth of the shell a simple wide opening.
--------------------
Shell with simple lattice-work (not double or spongy).
-------------------------------------------------------------------------
Shell conical, gradually { With horn, 526. _Cornutella_.
dilated towards {
the mouth. { No horn, 527. _Cornutanna_.

Shell ovate or urceolate, { With horn, 528. _Archicorys_.
with constricted {
mouth. { No horn, 529. _Cyrtocalpis_
-------------------------------------------------------------------------
Shell not simply latticed.
-------------------------------------------------------------------------
Shell ovate, double, with an external 530. _Mitrocalpis_.
mantle,

Shell ovate, with spongy irregular,
lattice-work 531. _Spongocyrtis_.
-------------------------------------------------------------------------
II. Subfamily Archicapsida. Mouth closed by a lattice plate.
-------------------------------------------------------------------------
Shell with an apical horn, 532. _Halicapsa_.

Shell without horn on the apex, 533. _Archicapsa_.

{1180}Subfamily 1. ARCHICORIDA, Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Cyrtocalpida#, with the basal mouth of the shell open (vel Monocyrtida eradiata aperta).

Genus 526. _Cornutella_,[143] Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 128.

_Definition._--#Archicorida# with conical shell, gradually dilated towards the wide open mouth. Apex armed with a horn.

The genus _Cornutella_ is one of the three oldest genera of Polycystina, described by Ehrenberg, in 1838 (_Cornutella_, _Lithocampe_, and _Haliomma_). He afterwards enumerated, in 1872 and 1875, a large number of fossil and living species, the majority of which, however, belong to other genera of Monocyrtida and Dicyrtida (at least six or seven different genera). We retain here as the true type of the genus the oldest known species:--_Cornutella clathrata_, and the nearly allied forms _Cornutella stylophæna_, _Cornutella mitra_, _Cornutella circularis_, &c. The simple conical shell exhibits no distinct trace of an original cephalis, excepting the apical horn; it may have originated either independently, or been derived from _Sethoconus_, by loss of the cephalis.

Subgenus 1. _Cornutellium_, Haeckel.

_Definition._--Axis of the conical shell straight. Pores polygonal, or roundish with polygonal frames.

1. _Cornutella hexagona_, n. sp. (Pl. 54, fig. 9).

Shell slender, conical, with straight outlines. Pores subregular, hexagonal, gradually increasing in size towards the mouth; in about ten to twelve longitudinal series, in the upper part very small. Horn slenderly conical, nearly bristle-shaped, long.

_Dimensions._--Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

_Habitat._--Central Pacific, Stations 265 to 274, surface, and at different depths.

2. _Cornutella sethoconus_, n. sp. (Pl. 54, fig. 10).

Shell slender, conical, with undulate outlines. Pores subregular, hexagonal, gradually increasing in size towards the mouth, in about fifteen to eighteen longitudinal series, in the upper part circular. Horn small, conical, short. The network is not so delicate as in the preceding similar species.

_Dimensions._--Shell 0.12 to 0.16 long, 0.06 to 0.08 broad.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

{1181}3. _Cornutella distenta_, Ehrenberg.

_Cornutella distenta_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 287, Taf. vi. III. fig. 3.

Shell slender, conical, with straight outlines. Pores small, circular, regularly disposed in six to eight alternating longitudinal rows, each pore surrounded by a large rhombic frame. The connected frames form together a regular rhombic framework with obliquely crossed crests. Horn conical, stout, large.

_Dimensions._--Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

_Habitat._--North Pacific, Californian Sea, depth 2600 fathoms, Ehrenberg.

4. _Cornutella stiligera_, Ehrenberg.

_Cornutella stiligera_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 1;
Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 68, Taf. ii. fig. 3.

Shell slender, conical, with straight outlines. Pores subregular, rhombic or nearly square, disposed in oblique series, separated by parallel obliquely ascending rings, which are crossed by interrupted parallel bars. Horn slenderly conical or bristle-shaped, thin and long.

_Dimensions._--Shell 0.08 to 0.12 long, 0.03 to 0.04 broad.

_Habitat._--Fossil in Barbados.

Subgenus 2. _Cornutissa_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Axis of the conical shell straight. Pores circular or roundish, without polygonal frames.

5. _Cornutella circularis_, Ehrenberg.

_Cornutella circularis_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 68, Taf. ii. fig. 4.

Shell wide, conical or funnel-shaped, with straight outlines. Pores very large, circular, ten to twenty times as broad as the bars, in about nine to twelve longitudinal alternating rows, increasing gradually towards the mouth. Horn very large, cylindrical.

_Dimensions._--Shell 0.1 to 0.15 long, 0.08 to 0.12 broad.

_Habitat._--Fossil in Barbados.

6. _Cornutella mitra_, Ehrenberg.

_Cornutella mitra_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 68, Taf. ii. fig. 8.

Shell wide, conical, campanulate, with convex outlines. Pores subregular, circular, nearly equal in size, not regularly disposed in rows. Horn conical, stout.

_Dimensions._--Shell 0.12 to 0.16 long, 0.08 to 0.12 broad.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

{1182}7. _Cornutella clathrata_, Ehrenberg.

_Cornutella clathrata_, Ehrenberg, 1838, Monatsber. d. k. preuss. Akad.
d. Wiss. Berlin, p. 129; Mikrogeol., Taf. xxii. fig. 39.

_Cornutella clathrata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, Taf. ii. fig. 9.

Shell wide, conical with slightly convex outlines. Pores regular, circular, gradually increasing in size towards the mouth, disposed in twelve to fifteen longitudinal alternating rows. Horn short and stout, conical. (Compare _Cornutella curvata_.)

_Dimensions._--Shell 0.15 to 0.2 long, 0.06 to 0.09 broad.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific; also fossil in tertiary rocks of Barbados, Nikobar and Sicily.

8. _Cornutella stylophæna_, Ehrenberg.

_Cornutella stylophæna_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 287, Taf. vi. III. fig. 1.

? _Cornutella tumens_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 287, Taf. vi. III. fig. 4.

Shell slender, conical, with undulate outlines. Pores subregular, circular, gradually increasing in size, disposed in six to nine quincuncial alternating longitudinal rows. Horn very long, cylindro-conical, sometimes about as long as the shell.

_Dimensions._--Shell 0.1 to 0.13 long, 0.04 to 0.06 broad.

_Habitat._--North Pacific, Californian Sea, depth 2600 fathoms.

9. _Cornutella granulata_, Ehrenberg.

_Cornutella granulata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 287, Taf. vi. III. fig. 5.

Shell slender, conical, nearly cylindrical, with straight outlines, rounded at the apex. Pores very small and numerous, punctiform, disposed into very numerous parallel transverse rows. Horn small, conical (may be perhaps the shell of a Tintinnoid Infusorium?).

_Dimensions._--Shell 0.08 long, 0.02 broad.

_Habitat._--North Pacific, Californian Sea, depth 2600 fathoms.

10. _Cornutella annulata_, Ehrenberg.

_Cornutella annulata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 287, Taf. ii. fig. 16.

Shell slender, conical, nearly cylindrical, with straight outlines, rounded at the apex. Pores small and numerous, regular circular, of equal size, regularly disposed in ten to fifteen parallel transverse series. Horn bristle-shaped. (Compare _Artostrobus annulatus_, _Cornutella annulata_, Bailey.)

_Dimensions._--Shell 0.1 to 0.13 long, 0.03 to 0.04 broad.

_Habitat._--Cosmopolitan, Atlantic, Pacific, surface.

{1183}Subgenus 3. _Cornutosa_, Haeckel, 1881, Prodromus, p. 427.

_Definition._--Axis of the conical shell curved. Pores circular or roundish.

11. _Cornutella curvata_, Haeckel.

_Cornutella clathrata_, var., Ehrenberg, 1854, Mikrogeol., Taf. xxii.
figs. 39_a_, _b_, _c_.

_Cornutosa clathrata_, Haeckel, 1881, Prodromus, p. 427.

Shell slender, conical, with curved axis; the curve lies in one plane and is not spirally convoluted. Pores subregular, circular, of nearly equal size, quincuncially disposed. Horn short, conical.

_Dimensions._--Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

_Habitat._--Fossil in tertiary rocks of Sicily (Caltanisetta).

12. _Cornutella spiralis_, n. sp.

_Cornutura spiralis_, Haeckel, 1881, Prodromus, p. 427.

Shell slender, conical, nearly cylindrical, very long, spirally contorted; its axis is an ascending spiral line with two or three windings, widely distant. Pores irregular, square, small and numerous.

_Dimensions._--Shell 0.2 to 0.25 long, 0.05 to 0.08 broad.

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

Genus 527. _Cornutanna_,[144] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archicorida# with conical shell, gradually dilated towards the wide open mouth. Apex without horn.

The genus _Cornutanna_ has the same simple conical shell as the preceding _Cornutella_, but differs from it in the total absence of an apical horn. It bears therefore to the latter the same relation that _Cyrtocalpis_ does to _Archicorys_. It may be derived from _Sethoconus_ by complete reduction of the cephalis and its horn.

1. _Cornutanna orthoconus_, n. sp.

Shell slender, conical, with straight axis and straight outlines. Pores subregular, circular, quincuncially disposed in nine to twelve alternating longitudinal series, gradually increasing in size towards the mouth.

_Dimensions._--Shell 0.1 to 0.12 long, 0.03 to 0.04 broad.

_Habitat._--Central Pacific, Stations 270 to 274, surface.

{1184}2. _Cornutanna cyrtoconus_, n. sp.

Shell slender, conical, with curved axis; the curve lies in one plane as in the similar _Cornutella curvata_; the pores are smaller and more numerous than in this latter species, and the rounded apex bears no horn.

_Dimensions._--Shell 0.12 to 0.16 long, 0.05 to 0.07 broad.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.

3. _Cornutanna loxoconus_, n. sp.

Shell wide, conical, with irregularly curved axis; the parts of the curve do not lie in one plane. Pores very small and numerous, of nearly equal size.

_Dimensions._--Shell 0.2 long, 0.12 broad.

_Habitat._--Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 528. _Archicorys_,[145] Haeckel, 1881, Prodromus, p. 427.

_Definition._--#Archicorida# with simple urceolate or ovate shell, constricted towards the mouth. Apex armed with a horn.

The genus _Archicorys_ and the following closely allied _Cyrtocalpis_ differ from the two preceding genera in the ovate or urceolate form of the shell, which is more or less constricted towards the terminal mouth. The upper pole in _Archicorys_ bears an apical horn, which is absent in _Cyrtocalpis_. The origin of these two genera may be the same, probably arising directly from Nassellida, and independently of the triradiate #Cyrtoidea# or bilocular #Spyroidea#. (Compare p. 1179.)

1. _Archicorys galea_, n. sp.

Shell smooth urceolate. Pores large, in the middle part hexagonal, towards both ends smaller and polygonal. Apical horn stout, three-sided pyramidal, half as long as the shell. Mouth with a short tubular peristome, about one-third as broad as the shell.

_Dimensions._--Shell (without horn) 0.15 long, 0.12 broad; horn 0.07 long, mouth 0.05 broad.

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

2. _Archicorys ampulla_, n. sp.

Shell smooth, thin-walled, bottle-shaped, in the upper half conical, in the lower half inflate, subspherical. Pores subregular, circular, of the same breadth as the bars. Horn conical, stout, {1185}/about one-third as long as the shell. Mouth truncate, without peristome, about half as broad as the shell.

_Dimensions._--Shell 0.15 long, 0.1 broad; horn 0.05, mouth 0.05.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.

3. _Archicorys microstoma_, n. sp. (Pl. 51, fig. 12).

Shell rough, thick-walled, ovate. Pores large, subregular, circular, twice to four times as broad as the bars. Horn small, conical, not larger than one pore. Mouth very small, truncate, scarcely larger than one pore.

_Dimensions._--Shell 0.1 long, 0.07 broad; horn 0.012, mouth 0.015.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

4. _Archicorys globosa_, n. sp.

Shell nearly spherical, thorny, thick-walled. Pores very large, circular, separated by spinulate frames, smaller towards each pole. Horn conical, large, nearly as long as the radius of the shell; mouth truncate, simple, about one-third as broad as the shell.

_Dimensions._--Shell diameter 0.13, horn 0.06, mouth 0.04.

_Habitat._--Fossil in Barbados.

5. _Archicorys ovata_, n. sp. (Pl. 51, fig. 10).

Shell ovate, rough, thick-walled. Pores regular, circular, of equal size, very small and numerous, quincuncially disposed. Horn small, conical, sometimes (as in the figured specimen) rudimentary. When it becomes lost, the species may be called _Cyrtocalpis ovata_. Mouth truncate, small, simple, one-sixth as broad as the shell.

_Dimensions._--Shell 0.2 long, 0.15 broad; horn 0.01 to 0.03 long, mouth 0.03 broad.

_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.

Genus 529. _Cyrtocalpis_,[146] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 835.

_Definition._--#Archicorida# with simple urceolate or ovate shell, constricted towards the mouth. Apex without horn.

The genus _Cyrtocalpis_ comprises a large number of common, very primitive Monocyrtida, which in the simple ovate or urceolate form of the shell resemble the well known _Gromia_ among the Thalamophora. Its basal mouth is more or less constricted, as in {1186}the preceding genus _Archicorys_, from which it differs in the total absence of an apical horn. There is no trace of any triradial structure, excepting in some smaller species, in which the basal part of the central capsule is trilobate; these may be derived from the Dicyrtides _Sethocorys_ or _Dictyocephalus_, by loss of the cephalis and the cortinar septum. But the larger species, which have a quite simple, ovate, central capsule (Pl. 51, fig. 13), have probably an independent origin, from _Cystidium_.

1. _Cyrtocalpis urceolus_, n. sp. (Pl. 51, fig. 13).

Shell smooth, urceolate, with very delicate and elegant network. Pores in the middle part large, regular, hexagonal, towards each pole smaller, irregular, roundish or polygonal. Mouth with broad, hyaline, annular peristome, about one-third as broad as the shell.

_Dimensions._--Shell 0.16 long, 0.12 broad; mouth 0.05 broad.

_Habitat._--Mediterranean (Portofino near Genoa), surface.

2. _Cyrtocalpis reticulum_, n. sp.

Shell smooth, urceolate, very similar to the preceding species, but differing from it in the densely reticulated framework of the shell, which is composed of very numerous and small, irregular, polygonal meshes of nearly equal size. Mouth without peristome, half as broad as the shell.

_Dimensions._--Shell 0.18 long, 0.15 broad; mouth 0.07 broad.

_Habitat._--Tropical Atlantic, Station 347, depth 2250 fathoms.

3. _Cyrtocalpis amphora_, Haeckel.

_Cyrtocalpis amphora_, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v.
fig. 2.

Shell smooth, urceolate with regular, circular pores of equal size, of about the same breadth as the bars. Mouth with smooth peristome, about half as broad as the shell.

_Dimensions._--Shell 0.12 long, 0.08 broad; mouth 0.04 broad.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific; surface, and at various depths.

4. _Cyrtocalpis urna_, Stöhr.

_Cyrtocalpis urna_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii.
fig. 7.

Shell smooth, urceolate, with subregular, circular pores of different sizes, gradually increasing towards the mouth, of about the same breadth as the bars. Mouth without peristome (?), about half as broad as the shell.

_Dimensions._--Shell 0.09 long, 0.06 broad; mouth 0.035 broad.

_Habitat._--Fossil in tertiary rocks of Sicily (Grotte).

{1187}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.