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, 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.

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).

Subgenus 1. Tessarasparium, Haeckel.

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. , 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.

Dorataspis diodon, Haeckel, 1862, Monogr. d. Radiol., p. 417, Taf. xxii. figs. 1-5.

Parmal meshes roundish, for the most part nearly circular, three to four times as broad as the bars, and on an average smaller than the roundish sutural meshes. Radial spines in the inner part cylindrical; the outer part very short (only one-third or one-fourth of the radius), divided completely into two parallel conical pointed teeth by a deep incision.

Dimensions.—Diameter of the shell 0.12, of the parmal pores 0.01 to 0.012, of the sutural pores 0.01 to 0.03, bars 0.004.

Habitat.—Mediterranean (Messina), surface.

9. Tessaraspis quadriforis, n. sp.

Parmal meshes irregular, roundish, of nearly equal size, four to six times as broad as the bars, and on an average of the same size as the roundish sutural meshes. Radial spines quadrangular, prismatic in the inner part, which is somewhat longer than the conical outer part.

Dimensions.—Diameter of the shell 0.16, of the pores 0.012 to 0.018, bars 0.003.

Habitat.—North Atlantic, Canary and Cape Verde Islands, Station 353, surface.

10. Tessaraspis irregularis, n. sp.

Parmal meshes irregular, roundish, of unequal size, three to six times as broad as the bars, and on an average larger than the irregular sutural meshes. Radial spines cylindrical, the outer part longer than the inner part.

Dimensions.—Diameter of the shell 0.13, parmal pores 0.006 to 0.012, sutural pores 0.005 to 0.01; bars 0.002.

Habitat.—Central Pacific, Station 270, surface.

Subgenus 2. Tessaraspidium, Haeckel.

Definition.—Condyles of the neighbouring plates grown together and sutures obliterated; therefore the whole shell forms a single piece of acanthin.

11. Tessaraspis quadrata, n. sp.

Tessaraspidium quadratum, Haeckel, 1882, Manuscript.

Parmal meshes square, four times as broad as the thin bars, on an average of the same size as the polygonal sutural meshes. Radial spines stout, tetrapterous, prismatic, in the outer part longer than in the inner. Sutures of the shell completely obliterated, therefore the whole shell forms one piece.

Dimensions.—Diameter of the shell 0.16, of the parmal pores 0.012, sutural pores 0.01 to 0.015.

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

12. Tessaraspis rotunda, n. sp.

Parmal meshes circular, of equal size, twice as broad as the thick bars, on an average smaller than the roundish sutural meshes. Radial spines cylindrical in the inner part, which is somewhat longer than the outer conical part. Sutures of the shell completely obliterated, therefore the whole shell forms one piece.

Dimensions.—Diameter of the shell 0.12, parmal pores 0.008, sutural pores 0.005 to 0.015.

Habitat.—North Atlantic, Station 354, surface.

13. Tessaraspis concreta, n. sp. (Pl. fig. 5).

Parmal meshes irregular, polygonal or roundish, six to eight times as broad as the narrow and high bars, much larger than the irregular sutural meshes. Radial spines leaf-shaped, compressed, two-edged, pointed at both ends; inner and outer part nearly of equal size. Shell very thick walled; meshes therefore funnel-shaped; sutures completely obliterated, therefore the whole shell forms a single piece.

Dimensions.—Diameter of the shell 0.09, parmal pores 0.02, sutural pores 0.01.

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

Genus 363. Lychnaspis, Haeckel, 1862, Prodromus, p. 468.

Definition.—Dorataspida with twenty plates, which are perforated by eighty aspinal pores (four crossed pores in each plate). Surface covered with numerous by-spines.

The genus Lychnaspis, the largest and most common of all Dorataspida, exhibits the same structure of the shell as its ancestral form Tessaraspis, and differs from it only in the development of by-spines on the sutural condyles. Many species of this genus are very widely distributed, and appear in large numbers, and some of them are amongst the most graceful and elegant of the Radiolaria.

Subgenus 1. Lychnasparium, Haeckel.

Definition.—Condyles of the neighbouring plates connected by permanent open sutures; therefore the whole shell is composed of twenty separate pieces of acanthin.

1. Lychnaspis giltschii, n. sp. (Pl. , fig. 3).

Parmal meshes pentagonal, about ten or twelve times as broad as the thin bars, on an average of the same size as the irregular polygonal sutural meshes. By-spines (two hundred to three hundred) very delicate, half as long as the radius, barbed, and zigzag. Radial main-spines very thin and long, straight, cylindrical; their outer part longer than the inner part.

Dimensions.—Diameter of the shell 0.2, of the parmal pores 0.02, sutural pores 0.01 to 0.03, bars 0.002.

Habitat.—Tropical Atlantic, Stations 338 to 348, surface.

2. Lychnaspis capillaris, n. sp.

Parmal meshes pentagonal, twenty to thirty times as broad as the very thin thread-like bars, on an average of the same size as the irregular polygonal sutural meshes. By-spines (two hundred to two hundred and fifty) very delicate, zigzag, with very small denticles, one-third as long as the radius. Radial main-spines very thin and long, cylindrical, more or less undulated.

Dimensions.—Diameter of the shell 0.25, parmal pores 0.025, sutural pores 0.02 to 0.04, bars 0.001.

Habitat.—North Pacific, Station 250, surface.

3. Lychnaspis maxima, n. sp.

Parmal meshes pentagonal, six to eight times as broad as the thick bars, for the most part larger than the irregular sutural meshes. By-spines (four hundred to five hundred) nearly as long as the radius, zigzag, with short denticles. Radial spines very long and stout, quadrangularly-prismatic, with four smooth edges.

Dimensions.—Diameter of the shell 0.3, parmal pores 0.03, sutural pores 0.01 to 0.025, bars 0.004.

Habitat.—Central Pacific, Stations 271 to 274, surface.

4. Lychnaspis serrata, n. sp.

Parmal meshes pentagonal, three to four times as broad as the thick bars, smaller than the irregular sutural meshes. By-spines (two hundred to three hundred) scarcely one-third as long as the radius, zigzag, with strong denticles. Radial spines very long, stout, quadrangularly-prismatic, with four serrated edges.

Dimensions.—Diameter of the shell 0.22, parmal pores 0.015, sutural pores 0.012 to 0.03, bars 0.004.

Habitat.—South Atlantic, Station 330, surface.

5. Lychnaspis wagenschieberi, n. sp.

Parmal meshes tetragonal, nearly rhombic, three to four times as broad as the thick bars, smaller than the large irregular sutural meshes. By-spines (about two hundred) large, as long as the radius, with long recurved denticles, very zigzag. Radial main-spines very long, four-sided prismatic. This species differs by the form and size of the spines, and by the square form of the parmal pores from the similar Lychnaspis polyancistra, of which the late excellent engraver Wagenschieber, of Berlin, has given such a beautiful figure in my monograph (Taf. xxi. fig. 8).

Dimensions.—Diameter of the shell 0.16, parmal pores 0.014, sutural pores 0.015 to 0.02, bars 0.004.

Habitat.—Central Pacific, Station 266, surface.

6. Lychnaspis polyancistra, Haeckel.

Dorataspis polyancistra, Haeckel, 1862, Monogr. d. Radiol., p. 418, Taf. xxi. figs. 7-9.

Parmal meshes roundish, tetragonal, or nearly square, two to three times as broad as the thick bars, smaller than the irregular sutural meshes. By-spines (about two hundred) thin, half as long as the radius, zigzag, with blunt denticles. Radial main-spines stout, in the inner half cylindrical, in the outer half (of the same length) conical, pointed.

Dimensions.—Diameter of the shell 0.12, parmal pores 0.012, sutural pores 0.01 to 0.04, bars 0.004.

Habitat.—Mediterranean (Messina), surface.

7. Lychnaspis rottenburgii, n. sp. (Pl. , fig. 4).

Parmal meshes roundish, about twice as broad as the thick bars, and for the most part smaller than the irregular sutural meshes. By-spines (about two hundred to two hundred and fifty) thin, zigzag, half as long as the radius. Radial main-spines very strong, cylindrical in the inner half, in the outer half much thicker and conical, pointed. I call this species in honour of my learned friend, the great patron of zoological studies, Mr. Paul Rottenburg, of Glasgow.

Dimensions.—Diameter of the shell 0.15, parmal pores 0.012, sutural pores 0.01 to 0.03, bars 0.006.

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

8. Lychnaspis undulata, n. sp. (Pl. , fig. 2).

Parmal meshes circular, twice as broad as the thick bars, on an average of the same size as the irregular sutural meshes. By-spines (one hundred and fifty to two hundred) very thin, barbed and zigzag, as long as the radius. Radial main-spines cylindrical; their outer pointed part longer than the inner part.

Dimensions.—Diameter of the shell 0.1, parmal pores 0.01, sutural pores 0.01, bars 0.005.

Habitat.—Tropical Atlantic, Station 343, surface.

9. Lychnaspis longissima, n. sp. (Pl. , fig. 6).

Parmal meshes circular, very small, of the same breadth as the thick bars, much smaller than the irregular sutural meshes. By-spines (one hundred to one hundred and ten) very long and thin, zigzag, twice as long as the diameter of the shell. Radial main-spines very long and strong, cylindrical (at the base quadrangular, pyramidal), four to six times as long as the diameter of the shell, and one fourth as thick as its radius.

Dimensions.—Diameter of the shell 0.08, parmal pores 0.002, sutural pores 0.01 to 0.015, bars 0.003; length of the radial spines 0.3 to 0.5.

Habitat.—Tropical Pacific (Philippines), Stations 200 to 215, surface.

10. Lychnaspis minima, n. sp. (Pl. , figs. 2, 7, 8).

Parmal meshes circular, very small, only half as broad as the thick bars, much smaller than the irregular sutural meshes. By-spines (one hundred to one hundred and ten) half as long as the radius, zigzag. Radial main-spines thick, in the inner part cylindrical, in the outer shorter part conical, of very variable size.

Dimensions.—Diameter of the shell 0.05, parmal pores 0.002, sutural pores 0.006 to 0.012, bars 0.004.

Habitat.—Antarctic Ocean, Station 154, surface.

Subgenus 2. Lychnaspidium, Haeckel.

Definition.—Condyles of the neighbouring plates grown together and sutures obliterated, therefore the whole shell forms a single piece of acanthin.

11. Lychnaspis echinoides, Haeckel.

Haliomma echinoides, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p.36, Taf. v. figs. 3, 4.

Haliommatidium echinoides, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 22.

Haliommatidium echinoides, Haeckel, 1862, Monogr. d. Radiol., p. 422.

Parmal meshes pentagonal or somewhat roundish, four times as broad as the bars, and of about the same size as the polygonal meshes. By-spines (about two hundred) short, zigzag. Radial spines thin; their outer conical part shorter than the inner cylindrical part. Sutures perfectly obliterated, but recognisable by the characteristic pair of divergent by-spines. (Some recent observations on this species, made during 1880 in Portofino, have convinced me that the interpretation of it given in my Monograph, 1862, loc. cit., was quite correct.)

Haliomma ligurinum, J. Müller (= Haliommatidium ligurinum, Haeckel, L. N. , p. 423) seems to be closely allied to the preceding.

Dimensions.—Diameter of the shell 0.12 to 0.14, parmal pores 0.015, sutural pores 0.01 to 0.02, bars 0.004.

Habitat.—Mediterranean, Nice, Saint Tropez (J. Müller); Portofino near Genoa (Haeckel).

12. Lychnaspis haliommidium, n. sp.

Lychnaspidium haliommidium, Haeckel, 1882, Manuscript.

Parmal meshes circular, twice as broad as the bars, smaller than the irregular sutural meshes. By-spines (about two hundred) barbed and zigzag, as long as the radius. Radial main-spines four-sided; their outer pyramidal part shorter than the inner prismatic part. Sutures perfectly obliterated.

Dimensions.—Diameter of the shell 0.1, parmal pores 0.01, sutural meshes 0.015 to 0.02.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

13. Lychnaspis rabbeana, n. sp.

Parmal meshes circular, very small, of the same breadth as the bars, and much smaller than the irregular sutural meshes. By-spines (about one hundred) very long and thin, zigzag, about as long as the diameter of the shell. Radial main-spines cylindrical, thick, twice to three times as long as the diameter of the shell. Sutures perfectly obliterated, with thickened condyles. Named in honour of Captain Henrik Rabbe (of Bremen), to whom I am indebted for many new Indian and Atlantic Radiolaria.

Dimensions.—Diameter of the shell 0.086, parmal pores 0.002, sutural pores 0.012, bars 0.002.

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

14. Lychnaspis cataplasta, n. sp.

Parmal pores very small, circular, half as broad as the bars, and much smaller than the irregular sutural pores. By-spines zigzag, as long as the diameter of the shell. Radial main-spines very thin and long, needle-shaped, cylindrical, five to six times as long as the diameter of the shell. Sutures perfectly obliterated. (This stunted species is one of the smallest of the Dorataspida.)

Dimensions.—Diameter of the shell 0.05, parmal pores 0.0015, sutural pores 0.01, bars 0.002.

Habitat.—Antarctic Ocean (off Kerguelen Island), Station 149, surface.

Genus 364. Icosaspis, Haeckel, 1881, Prodromus, p. 468.

Definition.—Dorataspida with twenty plates, which are perforated by one hundred and sixty to three hundred or more parmal pores (in each plate four crossed aspinal pores, and around them four to twelve or more coronal pores). Surface without by-spines.

The genus Icosaspis and the closely allied Hylaspis differ from all other Tessaraspida in the increased number of the parmal pores. Whilst this number in all other genera is eighty (only four crossed pores in each plate), here it amounts to one hundred and sixty to three hundred or more (sometimes more than a thousand); in each shield four primary, crossed "aspinal pores" being surrounded by a circle of four to twelve or more "coronal pores." The number of sutural pores in these two genera is also increased.

Subgenus 1. Icosasparium, Haeckel.

Definition.—Condyles of the neighboring plates connected by permanent open sutures; therefore the whole shell composed of twenty separated pieces of acanthin.

1. Icosaspis tabulata, n. sp. (Pl. , fig. 2).

Parmal meshes all of nearly equal size and form, square, four times as broad as the bars, little larger than the triangular or polygonal sutural meshes. In each plate fifty to seventy (regularly sixty-four) quadrangular pores, viz., four primary square aspinal meshes, forming together a regular square surrounded by two to three coronas of rectangular (not quite regular) coronal meshes (six to eight in each transverse row). Radial spines tetrapterous, prismatic, with four thin and broad wings, from which arise the crossed bars between the four primary pores. Outer part of the spines longer than the inner. Commonly the condyles of the plates are only contiguous; sometimes they grow together, and this form approaches Icosaspis tetragonopa.

Dimensions.—Diameter of the shell 0.25 to 0.3, of the pores 0.02, bars 0.005.

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

2. Icosaspis elegans, n. sp. (Pl. , fig. 4; Pl. , fig. 9).

Tessaraspis elegans, Haeckel, 1882, Manuscript et Atlas.

Parmal meshes of very different size and form; in the centre of each plate a cross of four primary, pear-shaped "aspinal pores" (the largest of all); between them four secondary, little smaller, crossed, egg-shaped "angular pores"; around this rosette of eight larger meshes an inner complete circle of sixteen to twenty polygonal coronal pores, and an outer incomplete circle of thirty to forty very small marginal pores. The latter are smaller than the irregular sutural meshes, which are constricted in the middle, about forty to sixty around each plate. Radial spines thin, cylindrical, or a little compressed; their outer part longer than the inner. In this elegant and very common species the condyles usually remain separated by sutures; but sometimes the latter become obliterated, and the whole shell then forms a single piece, Icosaspidium elegans.

Dimensions.—Diameter of the shell 0.2 to 0.3, commonly 0.25; larger parmal pores 0.02, smaller 0.001 to 0.003; sutural pores 0.005 to 0.015; bars 0.003.

Habitat.—Tropical and Subtropical Atlantic, Canary Islands to Ascension Island, Stations 340 to 354, surface.

3. Icosaspis cruciata, n. sp. (Pl. , fig. 10).

Parmal meshes very different; in the centre of each plate a cross of four primary, nearly oblong, rectangular "aspinal pores"; between these four secondary, triangular, egg-shaped "angular pores" (the largest of all), and around this rosette a single circle of twelve to twenty-four small "coronal pores." The latter are of about the same size as the irregular sutural meshes, of which there are twenty to thirty around each plate. Radial spines thin, cylindrical, or a little compressed; their outer part longer than the inner.

Dimensions.—Diameter of the shell 0.2 to 0.3, commonly 0.25; larger parmal pores 0.025, smaller 0.005 to 0.01; bars 0.005.

Habitat.—Tropical and Subtropical Pacific, Sandwich to Marquesas Islands, Stations 256 to 274, surface.

4. Icosaspis ornata, n. sp.

Parmal meshes very different; in the centre of each plate a cross of four primary octagonal aspinal pores (the largest of all); between them four secondary, rhombic angular pores, and around this rosette a circle of twelve to sixteen smaller, polyhedral coronal pores, which are however larger than the irregular sutural pores (surrounding each plate to the number of twenty to thirty). Radial spines thin, quadrangular, prismatic; the outer part longer than the inner.

Dimensions.—Diameter of the shell 0.25; larger parmal pores 0.03, smaller 0.01; sutural pores 0.004 to 0.008; bars 0.006.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

5. Icosaspis spectabilis, n. sp.

Parmal meshes very different; in the centre of each plate four very large, pentagonal aspinal pores, and around these two to three circles of smaller polygonal coronal pores, which are very numerous, and not larger than the small sutural pores. Radial spines quadrangular, prismatic, stout, very long; the outer part two to three times as long as the inner.

Dimensions.—Diameter of the shell 0.4, of the larger aspinal meshes 0.03, of the outer meshes 0.002 to 0.02, bars 0.005.

Habitat.—South Atlantic, Station 333, surface.

6. Icosaspis multiforis, n. sp.

Parmal meshes very numerous, more than one hundred in each plate; in the centre four larger pear-shaped pores, and around these four to five circles of smaller pores, gradually smaller towards the margin of the plate; the sutural meshes also very small and numerous (more than fifty around each plate), so that the number of all the pores together amounts to two thousand or even more. Radial spines thin, cylindrical, very long.

Dimensions.—Diameter of the shell 0.32; larger aspinal pores 0.02, smaller 0.002 to 0.01; bars 0.003.

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

Subgenus 2. Icosaspidium, Haeckel.

Definition.—Condyles of the neighbouring plates grown together, and sutures obliterated; therefore the whole shell forms a single piece of acanthin.

7. Icosaspis tetragonopa, Haeckel.

Haliommatidium tetragonopum, Haeckel, 1862, Monogr. d. Radiol., p.421, Taf. xxii. fig. 13.

Parmal meshes all of nearly equal size and form, square, three times as broad as the bars, little larger than the sutural meshes. In each plate commonly sixteen equal square meshes, viz., four primary aspinal and twelve secondary, surrounding the former as a square corona. Radial spines tetrapterous, stout; the outer pyramidal half somewhat longer than the inner. This species differs from the similar Icosaspis tabulata (Pl. , fig. 2) in the concrescence of the sutures, the smaller number of pores, and the form of the stouter spines. The figure in my Monograph, drawn from a broken fragment, is not quite correct.

Dimensions.—Diameter of the shell 0.18, pores 0.009, bars 0.003.

Habitat.—Mediterranean (Messina, Corfu), surface.

8. Icosaspis icosahedra, n. sp.

Parmal meshes of different size and form; in the centre of each plate a cross of four pentagonal, primary aspinal pores, surrounded by a complete corona of twelve to sixteen polygonal coronal pores and an incomplete corona of thirty to forty very small marginal pores; the latter are not to be distinguished from the pores of the obliterated sutures. Radial spines quadrangular, the outer pyramidal part shorter than the inner prismatic part. Condyles grown together. As the plates are quite even, the shell becomes icosahedral.

Dimensions.—Diameter of the shell 0.16, pores 0.002 to 0.02, bars 0.005.

Habitat.—North Pacific, Station 241, surface.

9. Icosaspis icosastaura, n. sp. (Pl. , fig. 3).

Tessaraspis icosastaura, Haeckel, 1882, Manuscript et Atlas.

Parmal plates of different size and form; in the centre of each plate a cross of four larger primary, pyriform aspinal pores; between these four smaller roundish angular pores, and around this rosette a circle of ten to twenty (commonly sixteen) coronal pores, little larger than the very small sutural pores. Radial spines very thin and long, cylindrical or bristle-shaped. Condyles grown together; no suture visible.

Dimensions.—Diameter of the shell 0.14; larger pores of the cross 0.01, smaller pores 0.002 to 0.008; bars 0.002 to 0.004.

Habitat.—Central Pacific, Station 268, surface.

Genus 365. Hylaspis, n. gen.

Definition.—Dorataspida with twenty plates, which are perforated by one hundred and sixty to three hundred or more parmal pores (in each plate four crossed aspinal pores, and around them four to twelve or more coronal pores). Surface covered with numerous by-spines.

The genus Hylaspis exhibits the same structure of the shell as the nearly allied ancestral genus Icosaspis, and differs from it only in the development of by-spines. Some species of these two genera exhibit the highest degree of complication in the structure of the shell seen among the Dorataspida.

1. Hylaspis serrulata, n. sp. (Pl. , fig. 1).

Parmal meshes four hundred to five hundred; in the centre of each plate a cross of four very large pentagonal or roundish aspinal pores, and around this a circle of sixteen to twenty much smaller irregular, polygonal, coronal pores; the latter of about the same size as the sutural pores. On each condyle one thin zigzag-shaped by-spine, nearly as long as the radius. Twenty radial spines very long, quadrangular, prismatic; on the inside thinner and smooth, on the outside thickened, and armed with four rows of recurved teeth, serrated.

Dimensions.—Diameter of the shell 0.18, aspinal spines 0.02, other pores 0.002 to 0.01, bars 0.003.

Habitat.—South Atlantic, Station 326, surface.

2. Hylaspis coronata, n. sp.

Parmal meshes five hundred to six hundred; in the centre of each plate a cross of four long rectangular aspinal pores, between these four larger egg-shaped angular pores; around this rosette a circle of sixteen to twenty much smaller, irregular, roundish, coronal pores; the latter about of the same size as the sutural pores. On each condyle one bearded by-spine about one-third or one-fourth as long as the radius. Twenty radial spines, very long, smooth, quadrangular, prismatic.

Dimensions.—Diameter of the shell 0.25, aspinal pores 0.02, other pores 0.005 to 0.01, bars 0.004.

Habitat.—Central Pacific, Station 271, surface.

3. Hylaspis barbata, n. sp.

Parmal meshes twelve hundred to sixteen hundred; in the centre of each plate a cross of four large, somewhat oblong, octahedral aspinal pores, between these four rhombic smaller angular pores; around this rosette an inner circle of twelve to sixteen larger and an outer circle of fifty to sixty very small coronal pores; the latter smaller than the sutural pores. On each condyle one bristle-shaped zigzag by-spine, with recurved thin hooks, half as long as the radius. Twenty radial spines, very long, cylindrical, smooth.

Dimensions.—Diameter of the shell 0.25 to 0.3, aspinal pores 0.022, other pores 0.002 to 0.015, bars 0.002.

Habitat.—South Pacific, Station 295, surface.