Chapter XI: Literature and History (36)

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).

Subgenus 1. _Pleurasparium_, Haeckel.

_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.

{812}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.

Subgenus 2. _Pleuraspidium_, Haeckel.

_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.

{813}B. Tribe II. #Ceriaspida#, Haeckel.

_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.

Genus 351. _Dorataspis_,[391] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 811.

_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.

Subgenus 1. _Doratasparium_, Haeckel.

_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 {814}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.

Subgenus 2. _Dorataspidium_, Haeckel.

_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 {815}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, 4_a_).

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 {816}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.

Genus 352. _Diporaspis_,[392] n. gen.

_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.

Subgenus 1. _Diporasparium_.

_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). {817}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.

Subgenus 2. _Diporaspidium_, Haeckel.

_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

Genus 353. _Orophaspis_,[393] Haeckel, 1881, Prodromus, p. 468.

_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.

{818}Subgenus 1. _Orophasparium_, Haeckel.

_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.

Subgenus 2. _Orophaspidium_, Haeckel.

_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.

{819}Subgenus 3. _Stegaspis_, Haeckel, 1881, Prodromus, p. 468.

_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.

Genus 354. _Ceriaspis_,[394] Haeckel, 1881, Prodromus, p. 468.

_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.

Subgenus 1. _Ceriasparium_, Haeckel.

_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 {820}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.

Subgenus 2. _Ceriaspidium_, Haeckel.

_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 {821}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 {822}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.

Genus 355. _Hystrichaspis_,[395] n. gen.

_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.

Subgenus 1. _Hystrichasparium_, Haeckel.

_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 {823}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).

_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.

Subgenus 2. _Hystrichaspidium_, Haeckel.

_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 {824}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. {825}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.

Genus 356. _Coscinaspis_,[396] n. gen.

_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.

{826}Subgenus 1. _Coscinasparium_, Haeckel.

_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 {827}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.

{828}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.

Subgenus 2. _Coscinaspidium_, Haeckel.

_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.

Genus 357. _Acontaspis_,[397] Haeckel, 1881, Prodromus, p. 468.

_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."

{829}Subgenus 1. _Acontasparium_, Haeckel.

_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.

Subgenus 2. _Acontaspidium_, Haeckel.

_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 {830}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.

Subfamily 2. TESSARASPIDA, Haeckel.

_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).

A. Tribe II. #Stauraspida#, Haeckel, 1881, Prodromus, p. 467.

_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.

Genus 358. _Stauraspis_,[398] Haeckel, 1881, Prodromus, p. 467.

_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 {831}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.

Subgenus 1. _Staurasparium_, Haeckel.

_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.

Subgenus 2. _Stauraspidium_, Haeckel.

_Definition._--Apophyses of the spines branched; therefore each spine with eight to twenty or more sutural condyles.

{832}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.

Genus 359. _Echinaspis_,[399] Haeckel, 1881, Prodromus, p. 467.

_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.

{833}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.

Genus 360. _Zonaspis_,[400] n. gen.

_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.

{834}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.

Genus 361. _Dodecaspis_,[401] n. gen.

_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.

{835}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.

B. Tribe II. #Lychnaspida#, Haeckel, 1881, Prodromus, p. 467.

_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).

Genus 362. _Tessaraspis_,[402] Haeckel, 1881, Prodromus, p. 468.

_Definition._--#Dorataspida# with twenty plates, which are perforated by eighty aspinal pores (four crossed pores in each plate). Surface smooth, without by-spines.