Siphonasphis cristata, Haeckel, 1882, Manuscript.
Shell with numerous (one hundred to two hundred?) funnel-shaped dimples, each of which is pierced at the bottom by one or more pores. Twenty larger dimples in the centre of the plates are pierced by the radial main-spines; among these fourteen contain each a couple of aspinal pores; six others are much larger, and contain each six larger pores; these six plates are two opposite equatorial plates and four polar plates, placed in the same meridian plane (the "hydrotomical plane"); in each of these six "hydrotomical dimples" two pores are placed opposite to one another on the two edges of the leaf-shaped spine, four others being opposite in pairs on both flat sides of it. By this peculiar structure this species connects the true Hystrichaspis with Hexalaspis and Diploconus; however the twenty spines are of equal length, and the shell continues to be spherical. The twenty radial main-spines are leaf-like and compressed. The crests between the dimples are dentated by a series of small by-spines.
Dimensions.—Diameter of the shell 0.15, of the aspinal pores 0.01, of the sutural pores 0.005.
Habitat.—North Pacific, Station 240, surface.
Definition.—Shell-surface with numerous funnel-shaped dimples (commonly one hundred and seventy-six to 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 situated on the corners of the twenty plates; their number is commonly one hundred and four or one hundred and eight, sometimes more. The perforated dimples, alternating with the former, are usually seventy-two to seventy-four, sometimes more; twenty larger parmal dimples (each with a couple of aspinal pores, sometimes also with three such couples) and fifty-two to fifty-four sutural dimples, sometimes one hundred or more (each with one sutural pore). (Compare the definition of Ceriaspidium, p. 820.)
4. Hystrichaspis dorsata, n. sp. (Pl. 138, fig. 10).
Shell 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 aspinal pores are twice as broad as the circular sutural pores. The crests between the dimples are armed with simple scattered short by-spines; usually in the nodal points, where three combs meet, there exist three or two divergent by-spines. The twenty radial main-spines are thin and long, compressed.
Dimensions.—Diameter of the shell 0.22, of the aspinal pores 0.02, of the sutural pores 0.01.
Habitat.—Central Pacific, Station 271, surface.
5. Hystrichaspis armata, n. sp.
Shell 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. Crests between the dimples comb-like, armed with a series of simple by-spines. Twenty main-spines very stout, in the inner part cylindrical, in the outer shorter part conical.
Dimensions.—Diameter of the shell 0.25, of the aspinal pores 0.02, of the sutural pores 0.01.
Habitat.—South-East Pacific, Station 300, surface.
6. Hystrichaspis sulcata, n. sp.
Shell 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 nearly of the same size, very small. Crests between the dimples very high, sulcated, on the free edge serrate with short very numerous, simple by-spines. Radial main-spines very stout and short, conical.
Dimensions.—Diameter of the shell 0.2, of the pores 0.003.
Habitat.—South Atlantic, Station 325, surface.
7. Hystrichaspis foveolata, n. sp.
Shell with very numerous (three hundred to four hundred?) small and deep funnel-shaped dimples, the majority of which are blind, the minority perforated; among the latter there are forty larger aspinal pores; the other smaller (scarcely half as large) pores are sutural. Crests between the dimples densely armed with simple short by-spines. Radial main-spines stout, leaf-shaped.
Dimensions.—Diameter of the shell 0.12, of the aspinal pores 0.01, of the sutural pores 0.004.
Habitat.—Tropical Atlantic, Station 338, surface.
8. Hystrichaspis divaricata, n. sp.
Shell with numerous (two hundred to three hundred?) funnel-shaped dimples, the majority of which are blind, the minority perforated; among the latter there are forty larger aspinal pores. Crests between the dimples armed with long forked by-spines with divergent fork-branches. Radial spines cylindrical, very long and thick, longer than the diameter of the shell.
Dimensions.—Diameter of the shell 0.14, aspinal pores 0.08, sutural pores 0.03.
Habitat.—Central Pacific, Station 266, surface.
9. Hystrichaspis fruticata, n. sp. (Pl. 138, fig, 7).
Shell with numerous (one hundred and fifty to two hundred?) funnel-shaped dimples, the majority of which are blind, the minority perforated; forty aspinal pores elliptical, of the same size as the circular sutural pores. Crests between the dimples bearing elegant arborescent by-spines. Twenty radial main-spines long and thin, cylindrical or a little compressed.
Dimensions.—Diameter of the shell 0.17, pores 0.01.
Habitat.—Tropical Pacific, Station 275, surface.
10. Hystrichaspis serrata, n. sp.
Shell with numerous (two hundred to three hundred?) funnel-shaped dimples, the majority of which are blind, the minority perforated; forty aspinal pores of the same size as the sutural pores. Crests between the dimples covered with denticulated by-spines. Twenty radial main-spines compressed, two-edged, with serrated edges, about as long as the diameter of the shell.
Dimensions.—Diameter of the shell 0.21, pores 0.012.
Habitat.—North Pacific, Station 238, surface.
Definition.—Doratispida with twenty plates, which are perforated by eighty to two hundred or more parmal pores (two aspinal and two to ten or more coronal pores in each plate). Surface without by-spines.
The genus Coscinaspis, together with the following nearly allied genus Acontaspis, may be separated from the other Ceriaspida as a peculiar tribe, Coscinaspida. This tribe is characterised by the larger number of the parmal pores. Whilst in all other Ceriaspida this number is constantly forty (only two pores in each plate), here it may be from eighty to two hundred or more; in each shield the two primary "aspinal pores" are surrounded by a circle of two to ten or more (commonly eight to twelve) "coronal pores." The number of sutural pores in this group is also usually larger.
Definition.—Plates of the shell smooth, without crests, not dimply.
1. Coscinaspis peripora, n. sp. (Pl. 138, fig. 1).
Shell thin walled, with smooth surface, without crests and dimples, perforated by pores of very different sizes. Forty aspinal pores, roundish or elliptical, of about the same size as the fifty or sixty violin-shaped sutural pores, and three to four times as broad as the small roundish coronal pores, which are irregularly formed and distributed, four to eight occurring on each plate (altogether one hundred to one hundred and twenty). Radial spines roundish, somewhat compressed; inner and outer half nearly of the same length.
Dimensions.—Diameter of the shell 0.12, aspinal pores 0.01 to 0.012, coronal pores 0.003.
Habitat.—North-West Pacific, Station 235, surface.
2. Coscinaspis stigmopora, n. sp.
Shell very thin walled, with smooth surface, without crests and dimples, perforated by pores of very different sizes. Forty aspinal pores, roundish, of about the same size as the fifty or sixty violin-shaped sutural pores, their diameter being about one-fifth of that of the plates. Coronal pores very numerous (two hundred to four hundred) and very small, irregularly scattered, ten to twenty occurring in each plate. Sutures strongly denticulated. Radial spines very thin and short, cylindrical.
Dimensions.—Diameter of the shell 0.12 to 0.15, aspinal and sutural pores 0.01, coronal pores 0.001 to 0.003.
Habitat.—North Pacific, Station 257, surface.
3. Coscinaspis rhacopora, n. sp.
Shell very thin walled, with smooth surface, without crests and dimples, perforated by very irregular pores of very different sizes and forms; commonly more or less lobed or sinuate. Forty aspinal pores and fifty to eighty sutural pores, larger than the numerous (one hundred to two hundred) irregularly scattered coronal pores. Sutures very sinuate. Radial spines cylindrical, thin and long.
Dimensions.—Diameter of the shell 0.15 to 0.18, aspinal and sutural pores 0.01 to 0.02, coronal pores 0.001 to 0.005.
Habitat.—Central Pacific, Station 274.
4. Coscinaspis coscinopora, n. sp.
Shell thin walled, with smooth surface, without crests and dimples, perforated by very numerous pores of circular form, but of different sizes. Forty aspinal pores and one hundred to two hundred sutural pores much larger than the coronal pores, which are very small and very numerous (fifty to sixty on each plate). Sutures sinuate. Radial spines compressed, outer and inner half nearly of equal length.
Dimensions.—Diameter of the shell 0.3, aspinal and sutural pores 0.01 to 0.015, coronal pores 0.001 to 0.002.
Habitat.—Tropical Atlantic, Station 338, surface.
5. Coscinaspsis polypora, n. sp. (Pl. 136, fig. 8).
Shell very thin walled, with smooth surface, without crests and dimples, the two aspinal pores of each plate narrow, lanceolate, ten to twelve times as long as broad and half as long as the radius of each plate. Coronal pores irregular, polygonal, very numerous (two hundred to three hundred on each plate), commonly arranged more or less regularly in ten to twelve series parallel to the longitudinal diameter of the aspinal spines (ten to twenty pores in each series). Sutural pores irregular, polygonal, very numerous. Radial spines very thin and long, cylindrical.
Dimensions.—Diameter of the shell 0.24; length of the aspinal pores 0.04, breadth 0.004; coronal and sutural pores 0.002 to 0.01.
Habitat.—Tropical Atlantic, Station 349, surface.
6. Coscinaspis orthopora, n. sp.
Shell very thin walled, with smooth surface, without crest and dimples. All pores of nearly equal size and form; quadrangular, mostly rectangular; one hundred to two hundred, separated by two systems of parallel bars, perpendicular one to another, occur in each plate. Sutural pores mostly triangular. Radial spines very thin and long, cylindrical, somewhat compressed. (Similar to those of Phatnaspis lacunaria, Pl. 136, fig. 9, but spherical, not ellipsoidal.)
Dimensions.—Diameter of the shell 0.2, pores 0.008 to 0.012.
Habitat.—Central Pacific, Station 272, surface.
7. Coscinaspis parmipora, n. sp. (Pl. 137, fig. 9).
Craniaspis parmipora, Haeckel, 1866, Manuscript.
Dorataspis parmipora, Haeckel, 1881, Prodromus, Atlas.
Shell thin walled, with smooth surface, without crests and dimples. There are no sutural pores, since all twenty plates are connected by perfect sinuate sutures (therefore this excellent species may perhaps better represent a peculiar genus, called by me in 1866 Craniaspis). All pores are parmal pores; each plate with two elliptical aspinal pores, which are twice to five times broader than the numerous, roundish irregularly scattered coronal pores (thirty to fifty occurring on each plate). The radial spines are quite internal, that is, not prolonged on the outside of the shell; in this respect they resemble those of Sphærocapsa.
Dimensions.—Diameter of the shell 0.16, aspinal pores 0.01, coronal pores 0.002 to 0.005.
Habitat.—North Atlantic, Canary Islands (Lanzerote), surface.
8. Coscinaspis isopora, n. sp. (Pl. 134, figs. 13, 14).
Shell thick walled, with smooth surface, without crests and dimples. All pores of the shell nearly of the same size and of similar form, about as broad as the bars between them, and about two hundred in number, viz., fifty to sixty (regularly fifty-two or fifty-four) sutural pores and one hundred and forty to one hundred and fifty parmal pores (forty aspinal kidney-shaped pores, and one hundred to one hundred and ten coronal circular pores: six in the angles of each equatorial plate, and five in the angles of each tropical and polar plate; if the disposition be quite regular, one hundred and four or one hundred and eight). Radial spines short, rudimentary, conical.
Dimensions.—Diameter of the shell 0.2, of the pores and bars 0.012.
Habitat.—Tropical Pacific, Station 218 (off New Guinea), surface.
Definition.—Surface of the shell dimply, with a network of prominent crests.
9. Coscinaspis ceriopora, n. sp.
Shell thick-walled, with numerous (one hundred and sixty to two hundred?) funnel-shaped dimples, which are separated by prominent crests; on the bottom of each dimple there is a simple or double circular pore. If this species be quite regularly developed, it closely resembles the preceding, differing from it mainly in the prominent combs of the surface. It resembles also Ceriaspis favosa, Pl. 138, fig. 6; but whilst in this latter the majority of the dimples are blind, here they are all perforated. The twenty aspinal dimples (in the centre of each plate) present at the bottom a couple of pores, all other dimples a single pore. Among the latter there are fifty to sixty sutural pores and one hundred to one hundred and ten coronal pores, viz., six in each equatorial plate, and five in each of the other plates; but the number is not quite constant. Radial spines strong, in the inner part cylindrical, in the outer conical.
Dimensions.—Diameter of the shell 0.15, of the pores and bars 0.01.
Habitat.—Tropical Pacific, Station 215, surface.
Definition.—Dorataspida with twenty plates, which are perforated by eighty to two hundred or more parmal pores (in each plate two aspinal and two to ten or more coronal pores). Surface covered with by-spines.
The genus Acontaspis has the same characteristic structure of the shell as Ceriaspis, differing from it only in the presence of numerous by-spines. Each plate is perforated by four to sixteen or more (commonly ten to twelve) parmal pores, the two central of which are primary "aspinal pores," all the others being secondary "coronal pores."
Definition.—Plates of the shell not dimply, without prominent crests.
1. Acontaspis lanceolata, n. sp.
Shell thin walled, even, without crests and dimples between them, perforated by about three hundred pores of different sizes: forty aspinal pores elliptical, about as large as the irregular (fifty to sixty) sutural pores, and two to four times as broad as the small circular coronal pores (eight to twelve being on each plate, altogether about two hundred). Between the pores numerous short conical by-spines. Radial main spines lanceolate, about as long as the radius. (Similar to Coscinaspis peripora, Pl. 138, fig. 1, but with broad lanceolate spines and numerous short by-spines.)
Dimensions.—Diameter of the shell 0.15, aspinal and sutural pores 0.012 to 0.015, coronal pores 0.004 to 0.008.
Habitat.—South Atlantic, Station 325, surface.
Definition.—Surface of the shell dimply, with a network of prominent crests.
2. Acontaspis hastata, n. sp. (Pl. 134, fig. 16).
Shell thick walled, with numerous (one hundred and seventy to one hundred and ninety) dimples, which are separated by an elevated network of prominent crests. In the centre of each plate a larger dimple with a couple of aspinal pores, surrounded by a corona of ten or twelve smaller dimples, each of which contains a single pore (a coronal and sutural alternately). All pores circular or roundish, nearly of the same size. If the shell be quite regularly developed, there are fifty to sixty sutural pores and one hundred to one hundred and ten coronal pores (six in each equatorial plate, five in each of the other plates). The knobs of the meeting crests are conical, and bear each a simple short by-spine. Radial main spines compressed, at the distal end spear-shaped, with a rhomboidal plate below the apex, about as long as the radius.
Dimensions.—Diameter of the shell 0.18, of the pores and bars 0.01.
Habitat.—Western Tropical Pacific (off the Philippines), Station 215.
3. Acontaspis furcata, n. sp.
Shell thick walled, dimply, with a network of crests, of the same composition as in the foregoing species, with one hundred and seventy to one hundred and ninety dimples (twenty aspinal, one hundred to one hundred and ten coronal and fifty to sixty sutural dimples). All dimples and pores nearly of the same size. Each node of the crested network bears a stout by-spine, which is forked on the base, with two divergent straight branches (similar to those of Hystrichaspis furcata, Pl. 138, fig. 9). Radial main spines two-edged, sword-like, nearly as long as the diameter of the shell.
Dimensions.—Diameter of the shell 0.13, of the pores 0.008.
Habitat.—Central Pacific, Station 272, surface.
4. Acontaspis capillata, n. sp.
Shell very dark and thick walled, non-transparent, with very numerous (three hundred to four hundred or more?) deep funnel-shaped dimples, each of which is perforated by a small circular pore (forty aspinal, two hundred to three hundred coronal, and fifty to one hundred sutural pores?). The high crests between the dimples bear very numerous simple by-spines, nearly half as long as the radius, so that the shell appears covered with hairs. Radial main spines very long and thin, cylindrical, longer than the diameter of the shell.
Dimensions.—Diameter of the shell 0.2, of the pores 0.012.
Habitat.—North Pacific, Station 244, surface.
Definition.—Dorataspida with twenty radial spines, each of which bears four crossed apophyses (opposite in pairs). The spherical shell is composed either of the meeting branches of these apophyses (Stauraspida), or of twenty perforated plates, produced by concrescence of their branches (Lychnaspida).
Definition.—Dorataspida with spherical shell, which is composed either of the meeting branches of the four crossed apophyses only, or exhibits four to twelve perforated plates which are produced by the crossed apophyses of four to twelve radial spines (but never of all twenty spines). Each plate bears four crossed pores.
Definition.—Dorataspida without perforated plates; shell composed only of the meeting branches of the four crossed apophyses, which arise (opposite in pairs) from each radial spine. Condyles of the branch-ends without by-spines.
The genus Stauraspis is the most simple and primitive form among all Tessaraspida, or that subfamily of Dorataspida, in which the shell is composed of twenty radial spines, each of which bears four crossed apophyses. The subfamily may be divided into two different tribes, the Stauraspida and Lychnaspida. In the Stauraspida either all twenty spines, or a part of them, bear no perforated plates, and the shell is composed wholly or partially of the meeting branches of their apophyses. In the Lychnaspida, however, the four apophyses of each single spine form, by reunion of their recurved branches, a plate or shield with four crossed aspinal pores. The Lychnaspida represent therefore a more developed stage in the shell-formation than the simpler Stauraspida. Stauraspis, as the common ancestral form of both, may be derived phylogenetically from Xiphacantha or Stauracantha, which differ only by the apophyses or branches of the apophyses not meeting. These branches (originally eight on each spine) are either simple or again branched.
Definition.—Apophyses of the spines simple, not branched; therefore each spine with four sutural condyles.
1. Stauraspis cruciata, n. sp. (Pl. 134, fig. 5).
Radial spines thin, quadrangular, prismatic; outer and inner half nearly of equal length. Central bases pyramidal, with wing-like edges. Four apophyses of each spine simple, not branched, with thin condyles. Large meshes of the shell ten to twenty times as broad as the bars. This and the following species greatly resemble the simplest forms of Phractaspis (Pl. 137, figs. 1, 2); they differ from these, however, by the equal size and distance of the four branches of each spine, which thus form a rectangular cross.
Dimensions.—Diameter of the shell 0.1; breadth of the spines and bars 0.002.
Habitat.—Central Pacific, Station 268, surface.
2. Stauraspis xiphacantha, n. sp.
Radial spines stout, cylindrical in the inner half, conical in the shorter outer half. Four apophyses of each spine simple, not branched, broad, with thick condyles. Meshes of the shell six to eight times as broad as the bars.
Dimensions.—Diameter of the shell 0.12; breadth of the spines and bars 0.008 to 0.01.
Habitat.—South Pacific, Station 290, surface.
Definition.—Apophyses of the spines branched; therefore each spine with eight to twenty or more sutural condyles.
3. Stauraspis furcata, n. sp.
Radial spines thin, quadrangular, prismatic; outer and inner halves nearly of equal length. The four apophyses of each spine simply forked (or partly with bifid fork-branches); each spine with eight to twelve sutural condyles. Meshes of the shell ten to twenty times as broad as the bars.
Dimensions.—Diameter of the shell 0.15; breadth of the spines and bars 0.003.
Habitat.—Central Pacific, Station 266, surface.
4. Stauraspis stauracantha, n. sp. (Pl. 137, figs. 5, 6).
Radial spines thin, in the inner longer half cylindrical, in the outer half conical with thickened base. Four apophyses of each spine doubly forked or dichotomously (more or less irregularly) branched; each spine with sixteen to twenty-four sutural condyles. Meshes of the shell of very different sizes and forms; the largest ten to fifteen, the smallest two to three times as broad as the bars.
Dimensions.—Diameter of the shell 0.14; breadth of of the spines 0.002 to 0.01, of the bars 0.002.
Habitat.—Tropical Atlantic, Station 343, surface.
Definition—Dorataspida without perforated plates; shell composed only of the meeting branches of the four crossed apophyses, which arise (opposite in pairs) from each radial spine. Condyles of the branch-ends bearing by-spines.
The genus Echinaspis exhibits the same structure of the shell as its ancestral form Stauraspis, and differs from it only in the development of by-spines on the sutural condyli.
1. Echinaspis dichotoma, n. sp.
Radial spines cylindrical, thin, outer half longer than the inner. Four apophyses of each spine simply forked (or partly with bifid fork-branches); therefore each spine usually possesses eight (sometimes ten to twelve) sutural condyles. Meshes of the shell ten to twelve times as broad as the bars. Each condyle bears a zigzag by-spine, half as long as the radius.
Dimensions.—Diameter of the shell 0.12, of the spines 0.004 to 0.006.
Habitat.—North Pacific, Station 253, surface.
2. Echinaspis diadema, n. sp.
Radial spines thin and long, quadrangular, prismatic; outer half two to three times as long as the inner. Four apophyses of each spine simply forked (or partly with bifid fork-branches); each spine with eight to twelve sutural condyles. Meshes of the shell fifteen to twenty-five times as broad as the bars. Each condyle bears a simple bristle-shaped by-spine, nearly as long as the radius.
Dimensions.—Diameter of the shell 0.11; breadth of the spines and bars 0.002.
Habitat.—South Atlantic, Station 333, surface.
3. Echinaspis echinoides, n. sp. (Pl. 137, figs. 7,8).
Radial spines roundish, in the outer half conical, and two to three times as broad as in the inner half. Four apophyses of each spine doubly forked or dichotomously (more or less irregularly) branched; each spine with sixteen to twenty-four sutural condyles. Meshes of the shell four to eight times as broad as the bars. Each condyle bears a zigzag by-spine, one-third as long as the radius.
Dimensions.—Diameter of the shell 0.15; breadth of the spines 0.004 to 0.01, of the bars 0.002.
Habitat.—Central Pacific, Station 266, surface.
Definition.—Dorataspida with four plates, each of which is perforated by four crossed aspinal pores; these four plates are formed by the united branches of the other spines (eight polar and eight tropical) form no lattice-plates by union. Each condyle bears a by-spine.
The genus Zonaspis differs from all other Dorataspida in the peculiar formation of the four equatorial spines, which form by union of the recurved branches of their apophyses four perforated plates (each with four crossed pores), whilst the branches of the sixteen other plates do not unite to form plates, but simply meet the branches of the neighboring spines.
1. Zonaspis fragilis, n. sp.
Radial spines very thin and long, cylindrical. Four meshes of each equatorial plate pentagonal, ten to twelve times as broad as the bars. By-spines zig-zag, nearly as long as the radius.
Dimensions.—Diameter of the shell 0.16, of the parmal pores 0.018.
Habitat.—South Atlantic, Station 332, surface.
2. Zonaspis cingulata, n. sp. (Pl. 134, figs. 3, 4).
Radial spines cylindrical in the inner half, with thickened pyramidal bases (fig. 3), conical in the outer half; both halves of equal length. The four meshes of each equatorial plate egg-shaped, four to six times as broad as the bars. By-spines zigzag, half as long as the radius.
Dimensions.—Diameter of the shell 0.15, of the parmal meshes 0.015.
Habitat.—Tropical Pacific (east coast off Philippines), Station 275, surface.
3. Zonaspis æquatorialis, n. sp. (Pl. 135, fig. 5).
Radial spines stout, cylindrical in the shorter inner half, conical in the longer outer half. The four meshes of each equatorial plate circular, only twice as broad as the bars. By-spines zigzag, nearly as long as the radius.
Dimensions.—Diameter of the shell 0.11, of the parmal meshes 0.008.
Habitat.—Equatorial Atlantic, Station 347, surface.
Definition.—Dorataspida with twelve plates, each of which is perforated by four crossed aspinal pores; these twelve plates are formed by the united branches of the apophyses of four equatorial and eight polar spines. The branches of the apophyses of the eight tropical spines form no lattice-plates by union. Each condyle bears a by-spine.
The genus Dodecaspis differs from all other Dorataspida in the peculiar composition of its shell; twelve spines (four equatorial and eight polar spines) form by union of the branches of their apophyses twelve plates, each of which exhibits four crossed pores, whilst the eight other (tropical) spines form no perforated plates, but simply unite with the neighbouring spines by meeting branches. Some irregularity is often to be found in this genus; instead of four pores in each plate there may be two closed, the other two which are opposite being open. Several times I observed a peculiar "hemihedral" variety: only six spines of one meridian plane (the two equatorial and the four polar spines of the "hydrotomical" plane) exhibited complete shields, whilst the branches of the other fourteen plates remained open. This "hemihedral" form may perhaps represent a peculiar genus, Hemiaspis.
1. Dodecaspis tricinata, n. sp. (Pl. 134, fig. 1).
Radial spines thin and long, cylindrical. The four meshes of each equatorial and each polar plate of equal size, pentagonal, about eight times as broad as the bars. By-spines zigzag, nearly as long as the radius. In this species the hemihedral variety, Hemiaspis, often occurs.
Dimensions.—Diameter of the shell 0.15, of the parmal pores 0.016.
Habitat.—South-east Pacific (west coast of Patagonia), Station 302, surface.
2. Dodecaspis trizonia, n. sp.
Radial spines thin, cylindrical in the longer inner half, conical in the shorter outer half. The four meshes of each equatorial and each polar plate of equal size, roundish or nearly circular, five to six times as broad as the bars. By-spines straight, denticulated, scarcely half as long as the radius.
Dimensions.—Diameter of the shell 0.12, of the parmal pores 0.012.
Habitat.—South-west Pacific (east coast of New Zealand), Station 169, surface.
Definition.—Dorataspida with twenty perforated plates or fenestrated shields (each plate at least with four pores), produced by union of the branches of the four crossed apophyses, which arise, opposite in pairs, from each radial spine. The spherical shell is composed of the twenty plates united by sutures (rarely by concrescence).
Definition.—Dorataspida with twenty plates, which are perforated by eighty aspinal pores (four crossed pores in each plate). Surface smooth, without by-spines.
The genus Tessaraspis introduces the series of Lychnaspida, which comprise all those Dorataspida in which the shell is composed of twenty plates, each of which is perforated by four primary aspinal pores. In Tessaraspis and Lychnaspis each plate exhibits only these four primary pores, whilst in Icosaspis and Hylaspis they become surrounded by a circle of secondary or coronal pores. If in Stauraspis, the common ancestral form of the Tessaraspida, the four crossed apophyses of each single radial spine became recurved and united together, we should have the typical plate of Tessaraspis, in which the piercing radial spine is surrounded by four crossed pores of equal size. The number of sutural pores, between the neighbouring plates, is variable; usually each plate is surrounded by a circle of eight to twelve sutural pores. The sutures between the meeting condyles of the apophyses usually remain open; but in some species they become obliterated (subgenus Tessaraspidium).
Definition.—Condyles of the neighbouring plates connected by permanent open sutures; therefore the whole shell is composed of twenty separated pieces of acanthin.
1. Tessaraspis arachnoides, n. sp. (Pl. 136, fig. 1).
Parmal pores pentagonal, ten to twenty times as broad as the thin thread-like bars, on an average of about the same size as the irregular sutural meshes; the majority of the latter are either triangular or hexagonal. Radial spines very thin and long, cylindrical, their outer part two to four times as long as the inner. As the insertion of the spines is on the highest point of the plates, the shell becomes polyhedral (dodecahedral?).
Dimensions.—Diameter of the shell 0.15 to 0.17, of the parmal meshes 0.02 to 0.025, sutural meshes 0.01 to 0.03, bars 0.002.
Habitat.—Equatorial Atlantic, Station 347, surface.
2. Tessaraspis pentagonalis, n. sp.
Parmal meshes pentagonal, three to four times as broad as the thick bars, and on an average smaller than the irregular polygonal sutural meshes. Radial spines stout, quadrangular; their outer pyramidal part shorter than the inner prismatic part.
Dimensions.—Diameter of the shell 0.12, of the parmal pores 0.01 to 0.012, bars 0.003.
Habitat.—Central Pacific, Station 269, surface.
3. Tessaraspis tetragonalis, n. sp.
Parmal meshes tetragonal, or nearly square, six to eight times as broad as the thin bars, and on an average larger than the irregular polygonal sutural meshes. Radial spines thin, quadrangular, prismatic, their outer part longer than their inner.
Dimensions.—Diameter of the shell 0.16, of the parmal pores 0.012 to 0.016, bars 0.002.
Habitat.—South Pacific, Station 288, surface.
4. Tessaraspis hexagonalis, n. sp.
Parmal meshes hexagonal, ten to twelve times as broad as the thin bars, and on an average larger than the polygonal sutural meshes (the two proximal sides of each hexagonal parmal mesh two to three times as long as the four distal sides). Radial spines cylindrical, thin; their outer part longer than the inner.
Dimensions.—Diameter of the shell 0.15, of the parmal pores 0.01 to 0.015, bars 0.001.
Habitat.—North Pacific, Station 254, surface.
5. Tessaraspis trigonalis, n. sp.
Parmal meshes triangular, three to four times as broad as the thick bars, and on an average smaller than the irregular sutural meshes (in each plate all four parmal meshes of the same size, formed like an isosceles triangle, the distal base of which is somewhat curved, and convex towards the periphery, whilst the two proximal sides are straight). Radial spines thick, rounded; their outer conical part shorter than the inner cylindrical part.
Dimensions.—Diameter of the shell 0.1, of the parmal pores 0.01, of the sutural pores 0.01 to 0.02.
Habitat.—Tropical Atlantic (near Ascension), Station 345, depth 2010 fathoms.
6. Tessaraspis circularis, n. sp.
Parmal meshes circular, all eighty of equal size, quite regular, five to six times as broad as the thick bars, on an average larger than the roundish irregular sutural meshes. Radial spines quadrangular, prismatic, the outer part longer than the inner.
Dimensions.—Diameter of the shell 0.18, parmal pores 0.015 to 0.018, bars 0.003.
Habitat.—South-east Pacific, Station 300, surface.
7. Tessaraspis micropora, n. sp.
Parmal meshes circular, very small, all eighty of the same size, regular, scarcely as broad as the separating thick bars, and much smaller than the large irregular sutural meshes. Radial spines rounded, their outer conical part about as long as the inner cylindrical part.
Dimensions.—Diameter of the shell 0.08, of the parmal pores 0.003, of the sutural pores 0.005 to 0.015, bars 0.004.
Habitat.—Western Tropical Pacific, Station 225, surface.
8. Tessaraspis diodon, Haeckel.