Definition.—Dorataspida with twenty radial spines, each of which bears two opposite apophyses. The spherical shell is composed either of the meeting branches of these apophyses (Phractaspida), or of twenty perforated plates, produced by concrescence of their branches (Ceriaspida).
Definition.—Dorataspida without perforated plates; the spherical shell is composed only of the meeting branches of the two opposite apophyses, which arise from each radial spine. Therefore the meshes of the shell are all sutural.
Definition.—Dorataspida without perforated plates; shell composed only of the meeting branches of the two opposite apophyses, which arise from each radial spine. Condyles of the branch-ends without by-spines.
The genus Phractaspis is the most simple and primitive form among all Dorataspida, and may be regarded as the common ancestral form either of this whole family, or at least of its first subfamily, the Diporaspida. In all members of this subfamily the spherical shell is composed of twenty radial spines, each of which bears two opposite apophyses; but the mode of composition is different in the two tribes of the subfamily, in the Phractaspida and Ceriaspida. In the simpler tribe, the Phractaspida, the shell is composed only of the meeting branches of the apophyses of neighbouring spines; there are no peculiar perforated plates or shields. In the Ceriaspida, however, both apophyses of each single spine form a perforated plate or shield by union of their branches, and the shell is formed of the meeting edges of these shields. Of course the Ceriaspida must be derived from the simpler Phractaspida. Phractaspis, as the common ancestral form of both, exhibits a very simple structure of the shell (Pl. 137, figs. 1, 2). Commonly, if the fork-branches of each apophysis be not again branched, the shell possesses only twenty-two large meshes and forty sutures. More rarely their number increases, the fork-branches of the apophyses being again branched (Phractaspidium, Pl. 137, fig. 3).
Definition.—Shell with twenty-two meshes, and forty sutures, each spine with only four branches, its two apophyses being simply forked.
1. Phractaspis prototypus, n. sp. (Pl. 137, fig. 2).
Radial spines cylindrical, thin, pointed; the outer and inner halves of nearly equal size. Each spine bears in its middle part two opposite apophyses, which are simply forked; the four condyles of each spine (or the thickened ends of the fork-branches) are united with the meeting condyles of the neighbouring spines by sutures. Therefore the network of the spherical shell is composed of twenty-two large meshes: two square polar meshes on each pole (a a a a and e e e e); eight triangular circumpolar meshes (each between two polar and one tropical spine, a b a and e d e); eight tropical rhomboidal meshes (each between one polar, one equatorial, and two tropical spines: a b c b and e d c d); and four rhomboidal equatorial meshes (each between two tropical and two equatorial spines c b c d).
Dimensions.—Diameter of the shell 0.1, of the meshes 0.03 to 0.04; breadth of the spines and bars 0.005.
Habitat.—Cosmopolitan; Mediterranean (Corfu), Atlantic (Stations 348, 354), Indian Ocean (Ceylon), Pacific (Stations 253, 265, 274), &c., surface.
2. Phractaspis complanata, n. sp. (Pl. 137, fig. 1).
Radial spines leaf-shaped, strongly compressed, two-edged, pointed; their outer part longer than the inner. Each spine with two opposite apophyses which are simply forked, therefore with four condyles. The network with forty sutures and twenty-two large meshes, as in the foregoing species. The broad faces of the eight polar spines lie in two meridian planes, of the four equatorial spines in the equatorial plane, of the eight tropical spines in two planes parallel to the latter. The planes of the leaf-shaped fork-branches lie in the spherical face.
Dimensions.—Diameter of the shell 0.1, of the meshes 0.02 to 0.03; breadth of the fork-branches 0.012.
Habitat.—South Atlantic, Station 343, surface.
3. Phractaspis condylophora, n. sp.
Radial spines quadrangular, thin; their outer pyramidal part shorter than the inner. Each spine with four branches, its two opposite apophyses being simply forked. The eighty condyles (or sutural ends of the branches) much thickened, twice to four times as broad as the branches themselves. Network with forty sutures and twenty-two large meshes, as in both foregoing species.
Dimensions.—Diameter of the shell 0.12, of the meshes 0.03 to 0.04; breadth of the condyles 0.01.
Habitat.—South Pacific, Station 288, surface.
4. Phractaspis bipennis, Haeckel.
Dorataspis bipennis, Haeckel, 1862, Monogr. d. Radiol., p. 413, Taf. xxi. figs. 1, 2.
Phractasplenium bipenne, Haeckel, 1882, Manuscript.
Radial spines very thin, quadrangular; their outer pyramidal part shorter than the inner. Each spine with four bent branches, its two opposite apophyses being simply forked. Eighty condyles, very thin, pointed. In the specimens of this remarkable species, which I first observed in Messina, two opposite equatorial spines had quite free apophyses, not connected with the neighbouring spines; therefore the thin lattice-work of the shell exhibited only thirty-six sutures and twenty meshes (two meshes with six sutures, six meshes with four sutures, and twelve meshes with three sutures). In similar specimens, which I afterwards observed in the Canary Islands, all four equatorial spines were connected in the same manner with the neighbouring spines; therefore they possessed forty sutures and twenty-two meshes, like Phractaspis prototypus (Pl. 137, fig. 2). Perhaps the Mediterranean species represents a peculiar genus, Phractasplenium bipenne.
Dimensions.—Diameter of the shell 0.1, of the meshes 0.03 to 0.05; breadth of the spines 0.002.
Habitat.—Mediterranean (Messina), Canary Islands (Lanzerote), surface.
Definition.—Shell with forty to eighty or more meshes, and eighty to one hundred or more sutures. Each spine with six to eight or more branches, its two apophyses being doubly forked or more ramified.
5. Phractaspis constricta, n. sp. (Pl. 137, fig. 3).
Radial spines strongly compressed, two-edged, pointed; their outer half twice constricted and somewhat longer than the inner half. Each spine with two opposite forked apophyses, the branches of which are again forked; therefore eight condyles on each spine. The network of the spherical shell with eighty sutures and sixty-two meshes (twenty-two large primary meshes and forty smaller secondary meshes, the latter between the distal fork-branches).
Dimensions.—Diameter of the shell 0.11, of the large meshes 0.04 to 0.05, of the small meshes 0.01; breadth of the spines 0.01.
Habitat.—South Atlantic, Station 348, depth 2450 fathoms.
6. Phractaspis cataphracta, Haeckel.
Acanthometra cataphracta, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 49, Taf. x. figs. 7, 8.
Dorataspis cataphracta, Haeckel, 1862, Monogr. d. Radiol., p. 415.
Radial spines thin, quadrangular; their outer pyramidal part shorter than the inner. Each spine with six to eight condyles, the fork-branches of their two opposite apophyses being (all or partly) again forked. The network with sixty to eighty sutures and meshes: sometimes as regular as in the preceding species, at other times more or less irregular.
Dimensions.—Diameter of the shell 0.1, of the meshes 0.02 to 0.04; breadth of the bars 0.004 to 0.008.
Habitat.—Mediterranean (Cette), Müller (Messina), Haeckel; North Atlantic, Station 353, surface.
Definition.—Dorataspida without perforated plates; shell composed only of the meeting branches of the two opposite apophyses, which arise from each radial spine. Condyles of the branch ends bearing by-spines.
The genus Pleuraspis has quite the same structure of the shell as the foregoing Phractaspis, and differs from it only in the development of external by-spines; commonly each condyle of the branch end of the apophyses bears one zigzag by-spine, which is directed parallel to the radial main-spine from which the apophyses arise. Therefore each suture of the shell is armed with two divergent by-spines (Pl. 137, fig. 4).
Definition.—Shell regularly developed with twenty-two meshes and forty sutures (sometimes twenty to twenty-four meshes and thirty-six to forty-eight sutures); each spine commonly with four branches, its two apophyses being simply forked.
1. Pleuraspis horrida, n. sp. (Pl. 137, fig. 4).
Radial spines roundish, somewhat compressed, very thick, conical, pointed at both ends, outer part nearly twice as long as the inner. Two apophyses of each spine simply forked, with short and broad branches and thickened condyles. Forty sutures, very broad. Twenty-two large meshes three to four times as broad as the bars. By-spines much developed, as long as the radius, zigzag, with alternating recurved hooks.
Dimensions.—Diameter of the shell 0.15, of the meshes 0.04 to 0.06; breadth of the bars 0.01 to 0.015.
Habitat.—Tropical Pacific (east of Philippines), Station 215, surface.
2. Pleuraspis amphithecta, n. sp.
Radial spines two-edged, leaf-shaped, strongly compressed, pointed at both ends; outer half longer than the inner. Two apophyses of each spine simply forked, with short and very broad branches; condyles not thickened. Forty sutures, broad. Twenty-two large meshes twice to three times as broad as the bars. By-spines zigzag, half as long as the radius. (Resembles Phractaspis complanata, Pl. 137, fig. 1.)
Dimensions.—Diameter of the shell 0.12, of the meshes 0.02 to 0.03; bars 0.012.
Habitat.—Central Pacific, Station 274, surface.
3. Pleuraspis costata, Haeckel.
Acanthometra costata, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 49, Taf. ii. fig. 1, Taf. x. figs. 4-6.
Dorataspis costata, Haeckel, 1862, Monogr. d. Radiol., p. 414, Taf. xxiii. fig. 1.
Radial spines roundish, conical, pointed at both ends; outer and inner halves of nearly equal length. Two apophyses of each spine simply forked, with broad branches and thickened condyles. Forty sutures, broad. Twenty-two large meshes, four to five times as broad as the bars. By-spines straight, denticulate, half as long as the radius. (This common species is rather variable in size and details.)
Dimensions.—Diameter of the shell 0.1 to 0.13, meshes 0.03 to 0.06, bars 0.005 to 0.01.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.
4. Pleuraspis pyramidalis, n. sp.
Radial spines quadrangular, their outer part pyramidal, very thick, about half as long as the prismatic inner part. Two apophyses of each spine simply forked, with very short and broad branches. Condyles much thickened. Forty sutures, very broad. Twenty-two meshes small, the largest twice as broad as the bars; the smaller only half as broad. By-spines short, straight, denticulate, half as long as the radius.
Dimensions.—Diameter of the shell 0.14, meshes 0.005 to 0.03.
Habitat.—Western Tropical Pacific, Station 222, surface.
Definition.—Shell with forty to eighty or more meshes and eighty to one hundred or more sutures; each spine with six to eight or more branches, its two apophyses being forked twice or oftener.
5. Pleuraspis ramosa, n. sp.
Radial spines roundish, stout, somewhat compressed; their inner and outer half nearly of equal length. Two apophyses of each spine doubly forked or more irregularly branched; therefore commonly eight (sometimes six, seven, nine, or ten to twelve) thickened condyles on each spine. Sutures eighty to one hundred, broad. Irregular meshes sixty to eighty; three to five times as broad as the bars. By-spines zigzag, ramified, half as long as the radius.
Dimensions.—Diameter of the shell 0.15, of the meshes 0.007 to 0.014, breadth of the bars 0.003.
Habitat.—Central Pacific, Station 272, surface.
Definition.—Dorataspida, the spherical shell of which is composed of twenty perforated plates, produced by union of the branches of the two opposite apophyses, which arise from each radial spine. Therefore the meshes of the shell are partly sutural, partly parmal.
Definition.—Dorataspida with twenty plates, which are perforated by forty aspinal pores (two pores in each plate). Surface of the shell without combs, dimples, and by-spines.
The genus Dorataspis opens the long series of the Ceriaspida, or of those Dorataspida in which the shell is composed of twenty plates, each of which is perforated by two primary aspinal pores. This tribe has arisen from the simpler Phractaspida by reunion of the branches of the apophyses in each single spine. If in Phractaspis, their common ancestral form (Pl. 137, figs. 1, 2), the neighbouring fork-branches of both opposite apophyses in each radial spine become recurved and united, they will produce a shield, which is perforated by two pores and between them by the spine itself. These two "primary aspinal pores" are characteristic of all Ceriaspida; among these Dorataspis itself is the most simple form. Its shell exhibits therefore constantly forty aspinal pores, and besides these a variable number of "sutural pores" (in the sutures between the twenty plates). If in each suture there be only a single pore, we get on the whole fifty-two or fifty-four pores; if in each suture there be two or three pores, that number becomes doubled or tripled.
Definition.—Shell with fifty-two sutures; four polar plates on each pole of the main axis meeting in one point (in the pole itself); therefore all eight polar plates pentagonal and of equal size. Spherical shell therefore composed of four (equatorial) hexagonal plates and of sixteen pentagonal (eight tropical and eight polar plates).
1. Dorataspis fusigera, n. sp. (Pl. 138, fig. 2).
Shell with fifty-two sutures and fifty-two sutural meshes, with four hexagonal and sixteen pentagonal plates. Both aspinal meshes of each plate elliptical, twice to four times as broad as the sutural meshes. Radial spines in the outer half fusiform, somewhat longer than the inner cylindrical half.
Dimensions.—Diameter of the shell 0.08 to 0.09, of the parmal meshes 0.1 to 0.2, of the sutural meshes 0.004 to 0.01.
Habitat.—Central Pacific, Station 271, surface.
2. Dorataspis macracantha, n. sp.
Shell with fifty-two sutures and fifty-two sutural meshes; with four hexagonal and sixteen pentagonal plates. Both aspinal meshes of each plate circular, small, twice as broad as the small sutural meshes. Radial spines quadrangular, prismatic, their outer half twice to three times as long as the inner half.
Dimensions.—Diameter of the shell 0.12, of the parmal pores 0.008, of the sutural meshes 0.004.
Habitat.—South Pacific, Station 288, surface.
3. Dorataspis macropora, n. sp.
Shell with fifty-two sutures and one hundred to one hundred and fifty sutural meshes, with four hexagonal and sixteen pentagonal plates. Both aspinal meshes nearly circular, very large, five to ten times as broad as the small circular sutural meshes; the number of the latter is in this species multiplied, in each suture being two to three (commonly three) small pores. Radial spines in the outer half leaf-shaped, compressed, nearly lanceolate, longer than in the inner cylindrical half.
Dimensions.—Diameter of the shell 0.16, of the parmal pores 0.03 to 0.04, of the sutural pores 0.004 to 0.006.
Habitat.—Indian Ocean (Madagascar), Rabbe, surface.
Definition.—Shell with fifty-four sutures; four polar plates on each pole of the main axis different in pairs; two major hexagonal meeting in a polar suture (the "hydrotomical suture"); two minor pentagonal, not meeting together (separated by that hydrotomical suture). Spherical shell therefore composed of eight hexagonal plates (four equatorial and four polar) and by twelve pentagonal plates (eight tropical and four polar plates).
4. Dorataspis loricata, Haeckel.
Dorataspis loricata, Haeckel, 1862, Monogr. d. Radiol., p. 415, Taf. xxi. figs. 3-6.
Shell with fifty-four sutures and fifty-four sutural meshes, with eight hexagonal and twelve pentagonal plates. Both aspinal meshes of each plate kidney-shaped or roundish, nearly of the same size as the sutural meshes. Radial spines cylindrical; their outer half on the pointed distal end two-edged and longer than the inner half.
Dimensions.—Diameter of the shell 0.14, of its meshes 0.008 to 0.016.
Habitat.—Mediterranean (Messina), North Atlantic (Canary Islands), Azores, surface.
5. Dorataspis typica, n. sp. (Pl. 138, figs. 4, 4a).
Shell with fifty-four crest-like sutures and fifty-four circular sutural meshes, with eight hexagonal and twelve pentagonal plates. Both aspinal meshes of each plate elliptical, twice to three times as broad as the sutural meshes. Aspinal meshes of the four equatorial plates twice as broad as those of the sixteen other plates. The meshes are surrounded by elevated and denticulated crests (incipient spine-sheaths). Radial spines compressed, more or less two-edged; outer pointed half somewhat larger than the inner half. (In this typical species the composition of the shell prevailing in the majority of Ceriaspida is very clear.)
Dimensions.—Diameter of the shell 0.15 to 0.18, of the aspinal pores 0.02 to 0.03, of the sutural pores 0.01.
Habitat.—Central Pacific, Stations 270 to 274, surface and in various depths.
6. Dorataspis micropora, n. sp. (Pl. 138, fig. 3).
Shell with fifty-four sutures and fifty-four very small sutural meshes, with eight hexagonal and twelve pentagonal plates. Both aspinal meshes of each plate elliptical, four to six times as broad as the sutural meshes. Radial spines in the outer half conical, somewhat shorter than in the inner cylindrical half.
Dimensions.—Diameter of the shell 0.11, of the aspinal pores 0.01 to 0.02, of the sutural pores 0.003.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
7. Dorataspis gladiata, n. sp.
Shell with fifty-four sutures and one hundred to one hundred and twenty sutural meshes, with eight hexagonal and twelve pentagonal plates. Both aspinal meshes elliptical, three times as broad as the small sutural meshes; commonly two meshes in each suture. Radial spines sword-shaped, two-edged, tapering from the shell towards the two ends. (Resembles Belonaspis datura, Pl. 139, fig. 9, but differs in the spherical shell, the equal size of the four equatorial spines, and the absence of by-spines.)
Dimensions.—Diameter of the shell 0.12, of the aspinal pores 0.012, of the sutural pores 0.004.
Habitat.—Indian Ocean (Madagascar), Rabbe, surface.
8. Dorataspis polypora, n. sp.
Shell with fifty-four sutures and one hundred and sixty to two hundred sutural meshes, with eight hexagonal and twelve pentagonal plates. Commonly three meshes (sometimes four) on each suture. Both aspinal meshes kidney-shaped, four times as broad as the small sutural meshes. Radial spines thick, in the inner longer part cylindrical, in the outer shorter part conical. (Differs from all other species in the multiplication of the sutural pores.)
Dimensions.—Diameter of the shell 0.2, of the aspinal pores 0.016, of the sutural pores 0.004.
Habitat.—Equatorial Atlantic, Station 347, surface.
Definition.—Dorataspida with twenty plates, which are perforated by forty aspinal pores (two pores in each plate). Surface of the shell without combs and dimples, but armed with numerous by-spines.
The genus Diporaspis has the same characteristic structure of the shell as the typical Dorataspis, and differs from it only in the development of numerous by-spines on the surface. The number of the sutures between the twenty plates is sometimes fifty-two, at other times fifty-four, and in each suture we find occasionally a single pore, at other times two or three such pores.
Definition.—Shell with fifty-two sutures, four polar plates on each pole of the main axis meeting in one common point; therefore all eight polar plates pentagonal and of equal size. Shell therefore composed of four (equatorial) hexagonal plates, and of sixteen pentagonal (eight tropical and eight polar) plates.
1. Diporaspis nephropora, n. sp. (Pl. 134, fig. 15).
Shell with fifty-two sutures and fifty-two sutural pores, with four hexagonal and sixteen pentagonal plates. Both aspinal pores of each plate kidney-shaped, about twice as broad as the circular sutural pores. Radial spines thin, cylindrical, longer than the radius. By-spines forked, only one-third as long as the radius.
Dimensions.—Diameter of the shell 0.13, parmal pores 0.03, sutural pores 0.07.
Habitat.—North Pacific, Station 244, surface.
2. Diporaspis circopora, n. sp.
Shell with fifty-two sutures and one hundred to one hundred and fifty sutural pores, with four hexagonal and sixteen pentagonal plates. Both aspinal pores of each plate circular, very large, six to eight times as broad as the small circular sutural pores (in each suture two to three pores). Radial spines strongly compressed, two-edged; outer half shorter than the inner. By-spines undulate, half as long as the radius.
Dimensions.—Diameter of the shell 0.12, of the parmal pores 0.02 to 0.03, of the sutural pores 0.003 to 0.004.
Habitat.—South Pacific, Station 287, surface.
Definition.—Shell with fifty-four sutures, four polar plates on each pole of the main axis different in pairs: two major hexagonal meeting in a polar ("geotomical") suture, two minor pentagonal, not meeting together (separated by that suture). Shell therefore composed of eight hexagonal plates (four equatorial and four polar) and of twelve hexagonal plates (eight tropical and four polar).
3. Diporaspis zygopora, n. sp.
Shell with fifty-four sutures and fifty-four circular sutural pores: with eight hexagonal and twelve pentagonal plates. Both aspinal pores of each plate elliptical, three times as broad as the sutural pores. Radial spines compressed, two-edged; outer half shorter than the inner. By-spines very numerous, simple, one-third as long as the radius, forming coronels or elegant circles around the pores (a small coronel around each sutural pore, a large one around each couple of aspinal pores).
This typical species is nearly allied to Dorataspis typica (Pl. 138, fig. 4), and may be derived from it by development of the coronels of by-spines.
Dimensions.—Diameter of the shell 0.16, aspinal pores 0.03, sutural pores 0.01.
Habitat.—Central Pacific, Station 271, surface
Definition.—Dorataspida with twenty plates, which are perforated by forty aspinal pores (two pores in each plate). Surface of the shell without combs, dimples, and by-spines. Each radial spine bears outside of the shell two opposite free apophyses, which are either simple or branched.
The genus Orophaspis differs not only from its ancestral form, Dorataspis, but from all other Dorataspida in the development of peculiar free apophyses on the radial spines, outside the shell. These apophyses, two being opposite on each spine, appear as a repetition of the primary apophyses of Phractaspis; they are either simple or branched, and sometimes the branches are united together, forming an outer free shield with two or four pores. These outer plates represent the beginning of a second outer shell and form the transition to Phractopelta, the ancestral form of the Phractopeltida.
Definition.—Free apophyses of the radial spines simple, not branched.
1. Orophaspis astrolonche, n. sp.
Parmal pores of the shell circular, twice as large as the sutural pores and as the breadth of the bars. Radial spines very long, three to six times as long as the diameter of the shell, compressed, two-edged; each with two simple, opposite, triangular apophyses; their distance from the shell equal to its diameter.
Dimensions.—Diameter of the shell 0.05, parmal pores 0.004, sutural pores 0.002.
Habitat.—North Pacific, Station 239, surface.
2. Orophaspis gladiata, n. sp.
Parmal pores of the shell circular, of the same size as the sutural pores and the bars. Radial spines thick, spindle-shaped, scarcely longer than the diameter of the shell, each with two simple opposite conical apophyses; their distance from the shell about equal to its radius.
Dimensions.—Diameter of the shell 0.06, pores 0.003.
Habitat.—Central Pacific, Station 265, surface.
Definition.—Free apophyses of the radial spines branched, their branches free (not anastomosing).
3. Orophaspis furcata, n. sp. (Pl. 133, fig. 6).
Parmal pores of the shell roundish or elliptical, three times as broad as the sutural pores and the bars. Radial spines very long, compressed, each with two opposite apophyses, which are simply forked; their distance from the shell somewhat greater than its diameter.
Dimensions.—Diameter of the shell 0.06 to 0.08, parmal pores 0.006, sutural pores 0.002.
Habitat.—Central Pacific, Station 274, surface.
4. Orophaspis ramosa, n. sp.
Parmal pores of the shell circular, of the same size as the sutural pores and the bars. Radial spines compressed, very long, each with two opposite apophyses, which are more or less irregularly branched (commonly between eight and twelve thin branches on each spine); their distance from the shell smaller than its diameter.
Dimensions.—Diameter of the shell 0.08, pores 0.006.
Habitat.—North-West Pacific, Station 235, surface.
Definition.—Free apophyses of the radial spines branched, and by reunion of their anastomosing branches forming perforated shields.
5. Orophaspis diporaspis, n. sp.
Parmal pores of the shell circular, of the same size as the sutural pores and the bars. Radial spines sword-shaped, two-edged, very broad; each spine bears an elliptical free shield with two longish pores (opposite on the two flat sides of the sword). Distance of the twenty free two-pored shields from the shell about equal to its diameter.
Dimensions.—Diameter of the shell 0.04, of the pores 0.004.
Habitat.—South Pacific, Station 295, surface.
6. Orophaspis tessaraspis, n. sp.
Parmal pores of the shell roundish, somewhat larger than the sutural pores and the bars. Radial spines very long, compressed; each spine bears a roundish free shield with four irregular pores disposed in a cruciform manner, the two larger pores being opposite on the flat sides of the spine, the two smaller being opposite but on its two edges. Distance of the twenty free four-pored shields from the shell about equal to its radius.
Dimensions.—Diameter of the shell 0.05, of the pores 0.003.
Habitat.—North Pacific, Station 239, surface.
Definition.—Dorataspida with twenty plates, which are perforated by forty aspinal pores (two pores in each plate). Surface of the shell with numerous dimples, separated by a network of elevated combs. No by-spines.
The genus Ceriaspis has the same structure of the shell, as its ancestral form Dorataspis, differing from it only in the development of high combs or crests, which form on the surface of the shell a peculiar elevated network. The dimples or funnel-shaped pits between these combs are either all or partly perforated by the pores of the shell. Both the aspinal pores of each plate are usually placed in one common dimple, whilst each sutural pore is placed in its peculiar smaller dimple.
Definition.—Shell-surface with seventy to one hundred or more small funnel-shaped dimples, each of which opens on the bottom by one pore or by a couple of apertures; twenty larger dimples in the centre of the plates (each with a couple of aspinal pores) and fifty to one hundred or more smaller dimples, each of which contains one sutural pore. No blind dimples between the perforated dimples.
1. Ceriaspis lacunosa, n. sp.
Shell spherical with seventy-two funnel-shaped dimples, each of which is perforated on the bottom by one or two apertures; twenty larger dimples in the centre of the plates, each with two elliptical aspinal pores, and fifty-two smaller sutural dimples between them, each with one circular pore of half the size. No blind dimples. Radial spines quadrangular, stout; their outer part shorter than the inner.
Dimensions.—Diameter of the shell 0.1, of the forty parmal pores 0.01, of the fifty-two sutural pores 0.005.
Habitat.—South Atlantic, Station 330, surface.
2. Ceriaspis scrobiculata, n. sp.
Shell spherical, with seventy-four funnel-shaped dimples, each of which is perforated on the bottom by one or two apertures; twenty larger dimples in the centre of the plates, each with two kidney-shaped large pores, and fifty-four smaller dimples on the sutures, each with one circular pore of one-fourth of the size of the reniform pores. No blind dimples. Radial spines cylindrical, the outer part longer than the inner.
Dimensions.—Diameter of the shell 0.12, of the forty parmal pores 0.016, of the fifty-four sutural pores 0.004.
Habitat.—Central Pacific, Station 270, surface.
Definition.—Shell-surface with funnel-shaped dimples (commonly one hundred and seventy-six or one hundred and eighty-two), which on the bottom are partly closed, partly perforated by one aperture (or by a pair of pores). The blind dimples are placed on the corners of the twenty plates, and are therefore either one hundred and four or one hundred and eight; if there be no polar suture, the blind dimples are one hundred and four (twenty-four on the four hexagonal equatorial plates, forty on the eight pentagonal tropical plates, and forty on the eight pentagonal polar plates); if, however, there be a polar suture on both main poles, the number of blind dimples is one hundred and eight (twenty-four on the four hexagonal equatorial and twenty-four on the four hexagonal polar plates, two opposite on each pole; forty on the eight pentagonal tropical plates and twenty on the four pentagonal polar plates, two opposite on each pole). Between the blind dimples there are usually seventy-two to seventy-four perforated dimples, twenty larger parmal dimples (enclosing a radial spine and a couple of aspinal pores) and fifty-two to fifty-four sutural dimples (sometimes one hundred or more), each of which encloses one sutural pore.
3. Ceriaspis inermis, n. sp. (Pl. 138, fig. 5).
Shell spherical, with one hundred and seventy-six funnel-shaped dimples, one hundred and four of which are blind and seventy-two perforated; of the latter, each of the fifty-two smaller contains a single sutural pore, each of the twenty larger a couple of aspinal pores. The elliptical or kidney-shaped aspinal pores are about twice as broad as the circular sutural pores. Radial spines thin, compressed, two-edged; their outer prolongation very short, rudimentary, scarcely higher than the axis of the surrounding funnel, and projecting but slightly from its aperture.
Dimensions.—Diameter of the shell 0.15, of the forty parmal pores 0.016, of the fifty-two sutural pores 0.008.
Habitat.—South Pacific, Station 289, surface.
4. Ceriaspis favosa, n. sp. (Pl. 138, fig. 6).
Shell polyhedral (icosahedral), with one hundred and eighty-two funnel-shaped dimples, one hundred and eight of which are blind and seventy-four perforated; of the latter, each of the fifty-four smaller contains a single sutural pore, each of the twenty larger a couple of aspinal pores. All pores roundish, nearly of the same size. Radial spines thin, compressed, two-edged; their outer part somewhat longer than the inner.
Dimensions.—Diameter of the shell 0.12 to 0.13, of the pores 0.01 to 0.015.
Habitat.—Central Pacific, Station 274, surface.
5. Ceriaspis icosahedra, n. sp.
Shell polyhedral (icosahedral), with one hundred and eighty-two funnel-shaped dimples, one hundred and eight of which are blind and seventy-four perforated; of the latter, each of the fifty-four smaller contains one small sutural pore, each of the twenty larger a couple of aspinal pores. The kidney-shaped aspinal pores are very large, four to six times as broad as the small circular sutural pores. Radial spines strong, quadrangular, their outer part from two to three times as long as the inner part.
Dimensions.—Diameter of the shell 0.16, of the parmal pores 0.015 to 0.02, of the sutural pores 0.003 to 0.004.
Habitat.—Tropical Atlantic, Station 349, surface.
6. Ceriaspis cicatricosa, n. sp.
Shell spherical, with two hundred and fifty to three hundred (or more) small funnel-shaped dimples, the majority of which are blind, the minority perforated by pores; of the latter forty are aspinal pores (two at the base of each spine), the others sutural pores. All pores nearly of the same size. As the shell of this species is very dark and thick-walled, it was impossible to obtain more information with regard to the pores. Radial spines very stout; the outer conical part shorter than the inner cylindrical part.
Dimensions.—Diameter of the shell 0.2, of the pores 0.006 to 0.008.
Habitat.—North Pacific, Station 236, surface.
Definition.—Dorataspida with twenty plates, which are perforated by forty aspinal pores (two pores in each plate). Surface of the shell with numerous dimples, separated by a network of elevated combs. Numerous by-spines.
The genus Hystrichaspis has the same structure with regard to the shell, as its ancestral form Ceriaspis, and differs from the latter only in possessing numerous by-spines. Moreover, in the former the dimples of the shell-surface are either all perforated by pores, or some of them are blind.
Definition.—Shell with seventy to one hundred or more funnel-shaped dimples, each of which opens on the bottom by one aperture or by a couple of pores; twenty larger dimples in the centre of the plates (each with a couple of pores, sometimes also three couples) and fifty to one hundred or more smaller dimples, each of which contains one sutural pore. No blind dimples between the perforated dimples.
1. Hystrichaspis pectinata, n. sp. (Pl. 138, fig. 8).
Shell with numerous (one hundred to two hundred?) funnel-shaped dimples, each of which is pierced at the bottom by one or two pores; twenty larger dimples in the centre of the plates (each with two aspinal pores), and fifty to one hundred and fifty or more smaller dimples (each with one sutural pore). No blind dimples. Crests between the dimples armed with a continuous series of simple by-spines. Radial main spines stout, in the inner half cylindrical, in the outer conical, more or less compressed.
Dimensions.—Diameter of the shell 0.13, of the pores 0.004 to 0.006.
Habitat.—Tropical Atlantic, Station 352, surface.
2. Hystrichaspis furcata, n. sp. (Pl. 138, fig. 9).
Shell with numerous (one hundred to two hundred?) funnel-shaped dimples, each of which is pierced at the bottom by one or two pores; twenty larger dimples in the centre of the plates (each with two large aspinal pores), and fifty to one hundred and fifty or more smaller dimples (each with one small sutural pore). No blind dimples. Crests between the dimples armed with forked by-spines. Radial main spines stout, leaf-shaped, tapering towards both ends.
Dimensions.—Diameter of the shell 0.12, parmal pores 0.01, sutural pores 0.005.
Habitat.—Central Pacific, Station 276, surface.
3. Hystrichaspis cristata, n. sp. (Pl. 138, fig. 11).