Chapter XXXVII: Section IV: STICHOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., p. 280, 312 (12)

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

5. _Castanarium huxleyi_, n. sp.

Pores irregularly polygonal, two to three times as broad as the bars, separated by prominent polygonal crests. Radial bristles half as long as the radius.

_Dimensions._--Diameter of the shell 0.45, of the pores 0.02 to 0.05.

_Habitat._--South Pacific (off Australia), Station 165, surface.

Genus 706. _Castanella_,[323] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# without radial main-spines, with a dentate mouth.

The genus _Castanella_ comprises the most common and most widely distributed species of Castanellida. It agrees in general shape with its ancestral form, the preceding _Castanarium_, differing from it only in the possession of strong teeth, which form a corona around the mouth.

{1683}1. _Castanella wyvillei_, n. sp. (Pl. 113, fig. 6).

Pores regular, circular, of equal size, hexagonally framed, of the same breadth as the bars. Radial bristles twice as long as the diameter of one pore. Mouth with five to six parallel, conical strong teeth, which are twice as long as a bristle (fig. 6_a_).

_Dimensions._--Diameter of the shell 0.5 to 0.7, of the pores 0.02 to 0.03.

_Habitat._--North Pacific, Stations 252 to 256, surface.

2. _Castanella thomsoni_, n. sp.

Pores regular, circular, of equal size, hexagonally framed, twice as broad as the bars. Radial bristles about as long as the diameter of one pore. Mouth with four strong, conical teeth, forming a regular cross, four times as long as a bristle.

_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.03.

_Habitat._--South Pacific, Stations 295 to 298, surface.

3. _Castanella campbelli_, n. sp.

Pores regular, circular, hexagonally framed, three times as broad as the bars. Radial bristles half as long as the radius of the shell. Mouth with a coronet of eight conical, parallel teeth, of the same length as the bristles, but four to six times as thick.

_Dimensions._--Diameter of the shell 0.4 to 0.45, of the pores 0.025.

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

4. _Castanella sloggetti_, n. sp.

Pores subregular, circular, without frames, of different sizes, about twice as broad as the bars. Radial bristles three times as long as one pore. Mouth with five or six strong, conical teeth, twice as long as the bristles.

_Dimensions._--Diameter of the shell 0.3 to 0.36, of the pores 0.02 to 0.03.

_Habitat._--Tropical Atlantic, Stations 347 to 349, surface.

5. _Castanella balfouri_, n. sp.

Pores irregular, roundish, two to three times as broad as the bars. Bristles about one-fourth as long as the radius. Mouth with four strong conical teeth, forming a cross, somewhat longer and much thicker than the bristles.

_Dimensions._--Diameter of the shell 0.22 to 0.28, of the pores 0.01 to 0.02.

_Habitat._--North Pacific, Stations 240 to 245, surface.

{1684}6. _Castanella channeri_, n. sp.

Pores irregular, roundish, two to four times as broad as the bars. Bristles nearly half as long as the radius. Mouth with seven to nine short conical teeth, shorter than the bristles, but much thicker.

_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.02 to 0.025.

_Habitat._--North Atlantic, Stations 352 to 354, surface.

7. _Castanella horstoni_, n. sp.

Pores irregular, polygonal, three to four times as broad as the bars. Bristles about as long as the radius. Mouth with six stout pyramidal teeth, which are scarcely one-third as long as the radius.

_Dimensions._--Diameter of the shell 0.55, of the pores 0.02 to 0.025.

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

Genus 707. _Castanidium_,[324] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida#, with simple radial main-spines and a simple smooth mouth.

The genus _Castanidium_ agrees with its ancestral form _Castanarium_ in the simple shape of the smooth and toothless mouth, but differs from it in the possession of long radial main-spines, which are scattered between the constant radial bristles or by-spines of the surface. The shell agrees therefore in its general shape with the Astrosphæride _Heliosphæra_, as defined above (p. 217, Pl. 26, fig. 9), but differs from it in the possession of the shell-mouth wanting in all #Sphæroidea#.

1. _Castanidium willemoesi_, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars. Bristles three times as long as the diameter of one pore. Radial main-spines straight, conical, smooth, as long as the radius.

_Dimensions._--Diameter of the shell 0.3 to 0.4, of the pores 0.012 to 0.016.

_Habitat._--Central Pacific, Station 263 to 274, surface.

2. _Castanidium wildi_, n. sp.

Pores regular, circular, hexagonally framed, of the same breadth as the bars. Bristles twice as long as one pore. Radial main-spines straight and short, cylindrical, with dimpled surface (as in Pl. 113, fig. 1), as broad as one pore and as long as the diameter of the shell.

_Dimensions._--Diameter of the shell 0.66, of the pores 0.045.

_Habitat._--South Pacific, Station 297, surface.

{1685}3. _Castanidium buchanani_, n. sp. (Pl. 113, fig. 7).

Pores regular, circular, without frames, twice as broad as the bars, of variable size. Bristles five to six times as long as one pore. Radial main-spines numerous, straight, slender, cylindrical, about as long as the diameter of the shell.

_Dimensions._--Diameter of the shell 0.25 to 0.3, of the pores 0.012 to 0.02.

_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.

4. _Castanidium murrayi_, n. sp. (Pl. 113, figs. 5, 5_a_).

Pores subregular, circular, without frames, three times as broad as the bars. Bristles three times as long as one pore. Radial main-spines cylindrical, stout, irregularly curved, longer than the shell-diameter, covered with longish hexagonal dimples, which are separated by a network of prominent crests (fig. 5_a_).

_Dimensions._--Diameter of the shell 0.4 to 0.5, of the pores 0.02 to 0.025.

_Habitat._--North Atlantic, Station 352 to 354, surface.

5. _Castanidium aldrichi_, n. sp.

Pores subregular, circular, without frames, of variable size, about as broad as the bars. Bristles four times as long as one pore. Radial main-spines conico-cylindrical, irregularly curved, straight, about as long as the radius. (The conical base of the spines is inflated and fenestrated, therefore the shell is nearly polyhedral.)

_Dimensions._--Diameter of the shell 0.35 to 0.4, of the pores 0.012 to 0.015.

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

6. _Castanidium bromleyi_, n. sp.

Pores irregular, roundish, two to four times as broad as the bars. Bristles half as long as the radius. Radial main-spines cylindrical, straight, slender, longer than the shell-diameter.

_Dimensions._--Diameter of the shell 0.22 to 0.26, of the pores 0.006 to 0.02.

_Habitat._--Indian Ocean and Southern Pacific, Stations 162 to 169, surface.

7. _Castanidium bethelli_, n. sp.

Pores irregular, roundish or polygonal, two to three times as broad as the bars. Bristles one-third as long as the radius. Radial main-spines conico-cylindrical, irregularly curved, with dimpled surface, somewhat longer than the radius.

_Dimensions._--Diameter of the shell 0.5 to 0.6, of the pores 0.015 to 0.03.

_Habitat._--North Pacific, Stations 235 to 245, surface.

{1686}8. _Castanidium moseleyi_, n. sp. (Pl. 113, fig. 2).

Pores irregular, roundish or polygonal, two to four times as broad as the bars. Bristles about as long as the diameter of one pore, or a little longer. Radial main-spines cylindrical, irregularly curved, somewhat longer than the diameter of the shell; their base is more or less inflated and fenestrated, therefore the shell is nearly polyhedral.

_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.01 to 0.04.

_Habitat._--Tropical Atlantic, Stations 346 to 349, surface.

Genus 708. _Castanissa_,[325] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# with simple radial main-spines and a dentate mouth.

The genus _Castanissa_ agrees with the preceding _Castanidium_ in the possession of large radial main-spines, scattered between the numerous bristles or by-spines of the surface; but it differs from it in the possession of teeth around the mouth, identical with those of _Castanella_; it may be derived therefore either from the latter by development of main-spines, or from the former by formation of teeth.

1. _Castanissa challengeri_, n. sp. (Pl. 113, fig. 1).

Pores regular, circular, three times as broad as the bars. Bristles one-fourth as long as the radius. Radial main-spines (about twelve) very stout, straight, cylindrical, at the distal end conical, pointed, with dimpled surface, about half as long as the radius. Mouth very large, circular, about one-third as broad as the shell, with a corona of twelve to sixteen very large, triangular, parallel teeth.

_Dimensions._--Diameter of the shell 0.7 to 0.8, of the pores 0.03.

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

2. _Castanissa pearceyi_, n. sp.

Pores regular, circular, twice as broad as the bars. Bristles half as long as the radius. Radial main-spines (about twenty) slender, cylindrical, smooth, irregularly curved, about as long as the radius. Mouth large, half as broad as the radius, with a corona of ten to twelve irregular, slender teeth.

_Dimensions._--Diameter of the shell 0.5 to 0.6, of the pores 0.02.

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

{1687}3. _Castanissa richardsi_, n. sp.

Pores subregular, circular, about as broad as the bars. Bristles twice as long as one pore. Radial main-spines (about twenty) slender, cylindrical, irregularly curved, with dimpled surface (like those in Pl. 113, fig. 5_a_). Mouth with a corona of six stout, parallel, triangular teeth.

_Dimensions._--Diameter of the shell 0.3 to 0.35, of the pores 0.015.

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

4. _Castanissa crosbiei_, n. sp.

Pores irregular, roundish, two to three times as broad as the bars. Bristles one-third as long as the radius. Radial main-spines very numerous, straight, cylindrical, smooth, about as long as the diameter of the shell. Mouth with ten or twelve irregular, conical, parallel teeth.

_Dimensions._--Diameter of the shell 0.28, of the pores 0.01 to 0.015.

_Habitat._--North Pacific, Stations 231 to 235, surface.

5. _Castanissa macleani_, n. sp.

Pores irregular, roundish or polygonal, two to four times as broad as the bars. Bristles about one-fourth as long as the radius. Radial main-spines numerous, straight, conical, stout, with dimpled surface, shorter than the radius. Mouth with six to eight irregular conical teeth.

_Dimensions._--Diameter of the shell 0.32, of the pores 0.012 to 0.024.

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

6. _Castanissa hoylei_, n. sp.

Pores irregular, polygonal, two to three times as broad as the bars. Bristles nearly half as long as the radius. Radial main-spines (about thirty) very long and thin, cylindrical, irregularly curved, at the conical base inflated and fenestrated; shell therefore slightly polyhedral. Mouth with five strong conical teeth.

_Dimensions._--Diameter of the shell 0.35 to 0.4, of the pores 0.02 to 0.03.

_Habitat._--North Pacific, Station 245 to 250, surface.

Genus 709. _Castanopsis_,[326] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# with branched radial main-spines and a simple smooth mouth.

The genus _Castanopsis_ differs from its ancestral form _Castanidium_ in the ramification of the radial main-spines; the branches are usually very irregular and often partly {1688}confluent. The shell is very similar to the Astrosphæride _Cladococcus_ (compare above p. 223, Pl. 27), but differs from it in the possession of the shell-mouth, absent in all #Sphæroidea#.

1. _Castanopsis naresi_, n. sp. (Pl. 113, fig. 3).

Pores subregular, circular, about twice as broad as the bars. Bristles twice as long as one pore. Radial main-spines somewhat shorter than the diameter of the shell, straight, cylindrical, in the proximal half simple, in the distal half irregularly branched, each with ten to twelve partly confluent branches.

_Dimensions._--Diameter of the shell 0.6 to 0.7, of the pores 0.02 to 0.03.

_Habitat._--Tropical Atlantic, Station 347 to 349, surface.

2. _Castanopsis macleari_, n. sp.

Pores irregular, roundish, two to four times as broad as bars. Bristles half as long as the radius. Radial main-spines about as long as the radius, stout and straight, cylindrical, forked at the distal end, with two or three unequal fork-branches.

_Dimensions._--Diameter of the shell 0.42, of the pores 0.015 to 0.03.

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

3. _Castanopsis fergusoni_, n. sp.

Pores irregular, roundish or polygonal, about as broad as the bars. Bristles three times as long as one pore. Radial main-spines somewhat longer than the diameter of the shell, cylindrical, with irregular and partly confluent lateral branches (similar to Pl. 113, fig. 4_a_).

_Dimensions._--Diameter of the shell 0.55, of the pores 0.012 to 0.016.

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

Genus 710. _Castanura_,[327] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Castanellida# with branched radial main-spines and a dentate mouth.

The genus _Castanura_ differs from the preceding _Castanopsis_ in the possession of a corona of teeth surrounding the mouth, similar to that of _Castanissa_. It differs from the latter in the ramification of the radial main-spines, wherein it agrees with the former. _Castanura_ may therefore be derived either from _Castanissa_ by ramification of the main-spines, or from _Castanopsis_ by development of teeth around the mouth.

{1689}1. _Castanura tizardi_, n. sp. (Pl. 113, fig. 4, 4_a_).

Pores regular, circular, without hexagonal frames, twice as broad as the bars. Bristles twice as long as one pore. Radial main-spines somewhat longer than the radius, straight, very stout, with irregular lateral branches, which are partly confluent. Mouth with six strong conical teeth.

_Dimensions._--Diameter of the shell 0.6, of the pores 0.03.

_Habitat._--Tropical Atlantic, Station 346, surface.

2. _Castanura havergali_, n. sp.

Pores regular, circular, hexagonally framed, as broad as the bars. Bristles three times as long as one pore. Radial main-spines as long as the shell-diameter, in the basal half simple, in the distal half with irregular, not confluent, lateral branches. Mouth with ten to twelve irregular, parallel, conical teeth of different sizes.

_Dimensions._--Diameter of the shell 0.5, of the pores 0.045.

_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.

3. _Castanura swirei_, n. sp.

Pores regular, circular, hexagonally framed, as broad as the bars. Bristles half as long as the radius. Radial main-spines straight, longer than the shell-diameter; on the distal end with a few irregular, confluent, lateral branches. Mouth with six larger and six alternate smaller, parallel, conical teeth.

_Dimensions._--Diameter of the shell 0.28, of the pores 0.015.

_Habitat._--North Pacific, Station 253, surface.

4. _Castanura carpenteri_, n. sp.

Pores irregular, roundish, twice to four times as broad as the bars. Bristles about as long as the largest pores. Radial main-spines irregularly curved, longer than the shell-diameter, with inflated and fenestrated conical base; in the distal half irregularly branched, with simple, not confluent, lateral branches. Mouth with six to nine irregular, strong, conical teeth.

_Dimensions._--Diameter of the shell 0.3, of the pores 0.012 to 0.025.

_Habitat._--South Atlantic, Station 331, depth 1715 fathoms.

Family LXXXI. #CIRCOPORIDA#, Haeckel, 1879 (Pls. 114-117).

_Circoporida_, Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec.
12, p. 5.

_Definition._--PHÆODARIA with a spherical or polyhedral shell, exhibiting a peculiar solid porcellanous structure, with a stellate circle of radial pores around the base of the hollow radial spines. Mouth usually with teeth. Surface of the shell {1690}tabulate, panelled or dimpled. Central capsule excentric, placed in the aboral half of the shell-cavity.

The family #Circoporida# comprises those PHÆODARIA in which the simple spherical or polyhedral shell exhibits a peculiar porcellanous structure, possesses a simple mouth, and is particularly distinguished by the constant character denoted by their name, viz., by circles of pores surrounding the base of the radial spines. It agrees in these striking peculiarities with the following family, the Tuscarorida, but differs from them essentially by the spherical or polyhedral form of the shell, which is never ovate, with the main axis prolonged. The radial spines, variable in number, are regularly or symmetrically disposed in all Circoporida, whilst they are arranged around the poles of the main axis in all Tuscarorida. Whilst the latter are always extremely large, more than a millimeter in size, the former are much smaller and never reach the diameter of a millimeter. The number of genera and species in this family is not large, and the majority are very rare, but they belong to the most remarkable Radiolaria by the peculiar structure, as well as by the geometrical regularity of the polyhedral shell.

The Circoporida may be divided into two different subfamilies, the Circogonida and the Haeckelinida. The latter are represented by the single genus _Haeckeliana_ (Pl. 114), and possess a spherical shell with numerous small dimples between the circles of pores, and numerous simple radial spines which do not exhibit a regular arrangement. The Circogonida, on the other hand, comprise all other genera (Pls. 115-117) and possess a panelled shell with polygonal plates, and a certain number of radial spines, which are regularly disposed on the corners of the polyhedral shell, and usually armed with verticillate bristles and terminal forks or spathillæ. Perhaps the Circogonida and Haeckelinida may be better considered as two separate families.

The geometrical fundamental form of the shell is in the Circoporida of the highest interest, since it exhibits regular proportions, which are very rare in other organic forms, generally some rare forms of regular polyhedrons. The shell in all members of this family belongs to that group of geometrical forms which I have called in my General Morphology "_Polyaxonia_" (vol. i., 1866, pp. 406-416). The shell therefore is constantly an "endospherical polyhedron," _i.e._, a polyhedron, all the corners of which lie in a spherical surface. The corners are always indicated by the bases of the radial spines arising from the surface of the shell and marking its axes, and it is immaterial whether the shell itself is a true polyhedron or a sphere; for in the latter case also the radial spines mark the axes of the polyhedron.

The six genera which we here distinguish among the Circoporida, represent six different fundamental forms. _Circoporus_ (Pl. 115, figs. 1-3; Pl. 117, figs. 5, 6) possesses six radial spines, opposite in pairs in three diameters, perpendicular one to another; it agrees therefore with the Cubosphærida (p. 169, Pls. 21-25) and {1691}represents the regular octahedron, with eight congruent triangular faces and six corners. It has the same form as the well-known antheridia of Chara (Gener. Morphol., vol. i. p. 412). _Circogonia_ (Pl. 115, figs. 8-10; Pl. 117, fig. 1) exhibits twelve radial spines, opposite in pairs in six equidistant diameters. The surface of the shell is divided into twenty equal and equilateral triangles, and agrees therefore with the regular icosahedron. The same form appears also in some forms of _Aulosphæra_, and in several Astrosphærida (Gener. Morphol., vol. i. p. 411). _Circorrhegma_ (Pl. 117, fig. 2) possesses a regular shell with twelve equal pentagonal faces and twenty equidistant corners, from which arise twenty regularly disposed radial spines. It represents therefore the regular "pentagonal dodecahedron," the same remarkable form which is found in some Astrosphærida, and in the pollen-grains of some plants, _e.g._, _Bucholzia maritima_, _Fumaria spicata_, _Polygonum amphibium_, &c. (Gener. Morphol., vol. i. p. 412, Taf. ii. fig. 18).

The three genera of Circoporida mentioned therefore represent three different forms of regular polyhedrons, in the exact mathematical sense, viz., _Circoporus_, the regular octahedron, _Circogonia_, the regular icosahedron, and _Circorrhegma_, the regular dodecahedron. In each of these three regular forms all the faces, edges, and corners are equal. The remaining three genera of Circoporida represent, however, three forms of subregular or irregular endospherical polyhedra, which are not perfectly regular. _Circospathis_ (Pl. 115, figs. 4-7; Pl. 117, fig. 3) is a rather common form, and constantly possesses nine symmetrically disposed radial spines; the shell is either spherical or polyhedral, with fourteen triangular faces and thirty edges; the nine spines lie in three meridional planes, which are crossed at equal angles (three equidistant spines in each plane). We call this remarkable form the tetradecahedron; it appears also in some Astrosphærida (_e.g._, in _Haliomma echinaster_, figured in my Monograph, Taf. xxiv. fig. 1). _Circostephanus_ (Pl. 116, fig. 3) exhibits a subregular polyhedral shell with a variable number of triangular faces and of radial spines (twenty-four to forty or more). _Circostephanus sexagenarius_ possesses sixty triangular equilateral faces, which are disposed in twelve pentagonal groups (each with five faces), so that the shell seems to be derived from a regular pentagonal dodecahedron, the twelve regular faces of which are divided each into five congruent triangles. From its corners arise thirty-two radial spines (twelve from the central points of the pentagons, twenty from the meeting corners of every three pentagons). In other cases the number of faces and radial spines seems to be larger and their arrangement more irregular. The same may be said of _Haeckeliana_, in which the dimpled shell is constantly spherical, and possesses a variable number of radial spines, from sixteen to fifty-five (usually between thirty and forty).

The structure of the shell in the Circoporida is the same as in the Tuscarorida, of a peculiar porcellanous nature. The shell-wall is very thick, more or less opaque, and in direct light whitish or yellowish. Its surface is dimpled, with numerous small, circular, {1692}roundish or polygonal dimples in _Haeckeliana_ (Pl. 114, figs. 1-6). In the Circogonida, however, the surface is panelled, with regular or irregular polygonal plates, often separated by high prominent crests (Pl. 115, figs. 4-9, &c.). Numerous simple thin needles of silica lie tangentially disposed and irregularly scattered in the porcellanous or cement-like substance of the thick shell-wall. Under a strong lens this substance appears finely punctate, being probably pierced by numerous very fine pores. The surface of the shell is therefore minutely roughened, and often appears quite black under the microscope, by the adhesion of innumerable fine air-bubbles. In all Circoporida, as well is in the Tuscarorida, the porcellanous shell has not the perfect transparency of the purely siliceous shells of other Radiolaria; its refractive power is somewhat different from the latter; it becomes deeply stained by carmine and browned by fire, and seems therefore to consist of a peculiar carbonic silicate.

The shell in all Circoporida exhibits a simple, excentric mouth, which corresponds to the main osculum of the central capsule. The excentric position of this shell-mouth has no influence on the regular form of the shell. The mouth is either circular or polygonal, usually about as large as a basal circle of pores. It is always armed with prominent conical or pyramidal teeth, the number of which is variable and seems to depend partly upon the number of the shell-faces or the radial spines. _Circoporus_ has usually four cruciate teeth (Pl. 115, fig. 1; Pl. 117, figs. 4, 5). _Circorrhegma_ exhibits a pentagonal mouth with five teeth (Pl. 117, fig. 2). _Circogonia_ possesses a hexagonal mouth with six teeth (Pl. 115, fig. 8; Pl. 117, fig. 1). _Circospathis_ has no constant number; some species have five teeth (Pl. 115, fig. 4), others four (Pl. 115, fig. 10), others nine (Pl. 117, fig. 3_a_). _Circostephanus_ is also variable; one species exhibits eight teeth (Pl. 116, fig. 3_a_), another ten, another twelve. In _Haeckeliana_ (Pl. 114, fig. 3) the teeth are smaller and more numerous. Usually the teeth arise vertically from the surface of the shell and are spinulate; more rarely their points are directed towards the centre of the mouth. Sometimes numerous thin needles arise between the teeth (Pl. 115, fig. 10).

The radial spines of the Circoporida are tubular, usually cylindrical and conical at the thickened base, more rarely prismatic or slenderly pyramidal, with three or more edges; sometimes the edges are spirally wound around the axis (Pl. 115, fig. 6). In the majority of species their length is about equal to the diameter of the shell; often they are somewhat shorter, more rarely longer. Their tubular structure is always the same as in the Tuscarorida; the wall of the tube is thick, and in the axis of its cavity lies an axial cord or funicle, which is connected with the wall by numerous horizontal, simple, or branched threads (Pl. 115, figs. 6, 7). The axial funicle itself is either a simple thread of silica, or a strand, composed of three to fifteen or more filaments, which are closely twisted like a rope around the axis of the spine, and arise separately from the bridges between the pores of the basal circle (Pl. 115, figs. 7, 9). The number of {1693}pores in these circles is very variable, commonly from three to nine, sometimes twelve to fifteen or more; their form is usually irregularly ovate (Pl. 115, figs. 7, 9). The bridges between the pores usually bear numerous siliceous threads or bristles, which are curved downwards or upwards (Pl. 115, figs. 4-6). Sometimes the spines are entirely covered with similar bristles or cilia (Pl. 117, figs. 2-5), more rarely with regular verticils of lateral branches (Pl. 117, fig. 6).

The distal ends of the radial spines are simple in _Haeckeliana_ (Pl. 114), whilst in the other Circoporida they are usually (or perhaps constantly) either forked or armed with a verticil of terminal branches. When the spines are simply forked, their two terminal branches lie in certain meridional planes (Pl. 117, fig. 5). The same is probably the case when they bear three divergent branches (Pl. 115, figs. 1, 2), or four crossed branches (Pl. 117, figs. 4, 6). The larger species usually bear a corona of five curved branches disposed around the distal apex of each spine (Pl. 116, fig. 3; Pl. 117, figs. 1, 2). Sometimes the formation of these coronas is twice or more often repeated, so that the spines appear verticillate.

The _central capsule_ of the Circoporida (Pl. 115, fig. 8; Pl. 117, fig. 6) is usually about half as large as the enclosing shell, and lies excentrically in that half of its cavity which is remote from the shell-mouth (Pl. 115, fig. 8). The other half (near the mouth) is filled up by the cap-shaped, dark phæodium. The proboscis, or the central tubule of the astropyle, is hidden in the axis of the blackish phæodium, and is directed towards the mouth of the shell; it is often S-shaped, more or less curved. The circular radiate operculum of the astropyle, placed on the base of the proboscis, exhibits numerous branched radial ribs, and closes the main-opening like the lid of a tea-kettle (Pl. 115, fig. 3). The number of the parapylæ, or the accessory openings of the capsule, which in the majority of PHÆODARIA is two, seems to be usually increased in the Circoporida. In _Circoporus_ the capsule seems to posses six and in _Circospathis_ nine secondary openings, and therefore there is some probability that each circle of pores on the base of a radial spine corresponds to a secondary opening of the capsule. In _Haeckeliana_, however (Pl. 114), I could observe no parapylæ at all. These accessory openings are always very small in the Circoporida, and may be easily overlooked. Furthermore, the number of observations respecting this difficult point is too small, and their certainty not satisfactory; it requires therefore further accurate examination, as also does the whole central capsule of the Circoporida.

The numerous and remarkable characters of shape and structure, which we have described above as occurring in the Circoporida, are also found in the following closely allied family, the Tuscarorida; all the species are inhabitants of great depths. Perhaps it may therefore be more convenient to separate these two families from the other PHÆOGROMIA as a peculiar order, under the name PHÆOCALPIA.

{1694}_Synopsis of the Genera of Circoporida._

-------------------------------------------------------------------------
I. Subfamily Circogonida.
Shell spherical or polyhedral with panelled structure and polygonal
plates. A certain number of radial spines are geometrically disposed.
-------------------------------------------------------------------------
Shell octahedral (or
spherical), Six radial spines, 711. _Circoporus_.

Shell tetradecahedral, Nine radial spines, 712. _Circospathis_.

Shell icosahedral, Twelve radial spines, 713. _Circogonia_.

Shell dodecahedral, Twenty radial spines, 714. _Circorrhegma_.

Shell polyhedral, Twenty-four to forty
or more radial spines, 715. _Circostephanus_.
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II. Subfamily Haeckelinida.
-------------------------------------------------------------------------
Shell spherical, with dimpled structure, and a
variable number of radial spines (without
polygonal plates), 716. _Haeckeliana_.

Subfamily 1. CIRCOGONIDA, Haeckel.

_Definition._--#Circoporida# with panelled shell, composed of polygonal plates. The shell is usually polyhedral, more rarely spherical, and the radial spines are usually (or perhaps constantly) branched and regularly arranged.

Genus 711. _Circoporus_,[328] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Circoporida# with a spherical or regularly octahedral shell, composed of eight congruent, triangular plates, with six corners from which arise six radial spines, opposite in pairs in three diameters, perpendicular one to another.

The genus _Circoporus_, the simplest among the Circoporida, is distinguished by the regular octahedral form of the shell, with the three equal axes of the regular crystalline system perpendicular one to another. Six equal radial spines, arising from the six corners, lie opposite in pairs in those three dimensive axes. The eight equal triangular faces of the octahedron are sometimes plane, sometimes concave or convex, and sometimes the shell becomes spherical. In this case it becomes very similar to the Hexastylida among the #Sphæroidea#.

1. _Circoporus sexfurcus_, Haeckel (Pl. 117, fig. 5).

_Challengeria_ sp., John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv.
pl. xxiv. fig. 5.

Shell spherical, covered with irregular, polygonal plates. Six radial spines shorter than the diameter of the shell, covered with thin curved bristles, in the proximal half cylindrical, in the distal half forked, each with two equal curved fork-branches. Around the ciliated base of each spine a {1695}corona of twelve to sixteen pores surrounded by a circle of numerous, curved, longer bristles. Mouth cruciform, with four triangular, convergent teeth.

_Dimensions._--Diameter of the shell 0.55, length of the spines 0.4.

_Habitat._--South Pacific, Station 289, depth 2550 fathoms.

2. _Circoporus hexastylus_, n. sp. (Pl. 117, fig. 4).

Shell regularly octahedral, with eight plane, congruent, triangular faces, which are covered with a very delicate network of small, regular, hexagonal plates. Six radial spines as long as the radius of the shell, four-sided pyramidal, simple, in the basal half covered with numerous curved bristles. Around the base of each spine a corona of four equal pores, surrounded by a circle of twelve short teeth. Apex with four crossed, curved branches (like those of _Circospathis tetrodon_). Mouth cruciform, with four smooth teeth.

_Dimensions._--Diameter of the shell 0.24, length of the spines 0.12.

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

3. _Circoporus characeus_, n. sp.

Shell spherical, covered with a delicate network of irregular polygonal plates. Six radial spines longer than the diameter of the shell, cylindrical, covered with numerous curved bristles, each with eight pores at the base surrounded by a circle of long bristles. Apex of each spine with a trident or fuscina, similar to that of the following species. Similar to an antheridium of Chara.

_Dimensions._--Diameter of the shell 0.32, length of the spines 0.4.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.

4. _Circoporus sexfuscinus_, n. sp. (Pl. 115, figs. 1-3).

Shell subregular, octahedral, with eight triangular, concave, somewhat unequal faces, which are covered with an extremely delicate network of small square dimples, and furrowed by radial crests arising from the bases of the spines (fig. 2). Six radial spines about as long as the diameter of the shell, four-sided, prismatic, with rounded edges; each in the basal half with a verticil of four crossed, curved bristles (fig. 1), sometimes with two verticils (fig. 2); on the distal apex inflated, armed with a trident or fuscina. Around the base of each spine four crossed elliptical pores. Mouth cruciform, with four small teeth (fig. 1).

_Dimensions._--Diameter of the shell 0.2 to 0.25, length of the spines 0.2 to 0.25.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

5. _Circoporus octahedrus_, n. sp. (Pl. 117, fig. 6).

Shell regularly octahedral, with eight plane, or slightly convex, congruent, triangular faces, which are covered with very small, regular, triangular plates (like those of _Polypetta tabulata_, Pl. 116, fig. 2). Six stout radial spines, about as long as the diameter of the shell, four-sided prismatic, {1696}covered with three or four verticils of four long curved bristles; at the distal apex inflated, with four crossed, divergent, stout, curved horns. Around the pyramidal base of each spine a corona of eight pores (two on each of the four faces). Mouth cruciform, with four triangular, convergent teeth.

_Dimensions._--Diameter of the shell 0.16, length of the spines 0.18.

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

Genus 712. _Circospathis_,[329] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Circoporida# with a subregular, spherical, or polyhedral shell, composed of fourteen triangular, nearly equal plates, with nine corners, from, which arise nine radial spines, symmetrically disposed.

The genus _Circospathis_ exhibits the remarkable and peculiar form of a "Tetradecahedron," or a subregular polyhedron with fourteen triangular faces, thirty edges, and nine corners, from which arise nine radial spines. These lie in three meridional planes, which are crossed at equal angles (three equidistant spines in each plane). The same interesting form occurs also in some Astrosphærida, which bear nine regularly disposed radial spines, as _Haliomma echinaster_. All four observed species of _Circospathis_ are South Atlantic.

1. _Circospathis furcata_, n. sp. (Pl. 115, figs. 4-6).

Shell polyhedral or nearly spherical, with nine prominent corners, from which arise nine radial spines, about as long as the diameter of the shell. The polygonal plates of the shell are separated by high crests, usually hexagonal or pentagonal, irregular, about twelve to fifteen on the half meridian. Radial spines cylindrical, straight, about as long as the diameter of the shell, with spirally turned edges, covered with numerous curved bristles, at the distal end forked; the two fork branches curved, one-third as long as the simple basal part. The inflated base of each spine is surrounded by a corona of nine to twelve ovate basal pores. Mouth pentagonal, with five thick, mammillate and spinulate, somewhat convergent teeth (fig. 5).

_Dimensions._--Diameter of the shell 0.6, length of the spines 0.5.

_Habitat._--South Atlantic (east of Buenos Ayres), Station 325, depth 2650 fathoms.

2. _Circospathis novena_, n. sp. (Pl. 117, figs. 3, 3_a_).

Shell polyhedral (tetradecahedral), with fourteen triangular, plane, or slightly convex faces, covered with small, irregular, polygonal (usually hexagonal) plates, and nine prominent corners, from which arise nine radial spines, shorter than the diameter of the shell. Each spine is surrounded at the broader base by a circle of twelve to sixteen pores and a corona of bristles, and bears at the {1697}inflated distal apex a trident or fuscina, similar to that of _Circoporus sexfuscinus_ (Pl. 115, fig. 2). Mouth with nine convergent, conical, denticulate teeth (fig. 3_a_).

_Dimensions._--Diameter of the shell 0.6, length of the spines 0.4.

_Habitat._--South Atlantic, Station 318 (east of Patagonia), depth 2040 fathoms.

3. _Circospathis tetradeca_, n. sp.

Shell spherical, covered with irregular, polygonal plates. Nine radial spines, cylindrical, as long as the radius of the shell, bristly, armed at the distal apex with a trident. (In one specimen six spines possessed three terminal branches, two spines two branches, and one spine four branches.) The broader base of each spine is surrounded by a corona of nine pores and a circle of curved bristles. Mouth with nine smooth conical teeth.

_Dimensions._--Diameter of the shell 0.55, length of the spines 0.3.

_Habitat._--South Atlantic, Station 332 (west of Tristan da Cunha), depth 2200 fathoms.

4. _Circospathis tetrodonta_, n. sp. (Pl. 115, fig. 10).

Shell subspherical or polyhedral, with fourteen triangular, convex faces, covered with irregular polygonal plates. Nine radial spines cylindrical, nearly smooth, about as long as the diameter of the shell; at the distal apex with four strong curved horns, like those of _Circoporus hexastylus_, Pl. 117, fig. 4. Each spine is surrounded at the base by a corona of nine irregular pores. Mouth with four large, prominent, conical teeth, which are spinulate, with vertical inner edge (fig. 10).

_Dimensions._--Diameter of the shell 0.5, length of the spines 0.45.

_Habitat._--South Atlantic, Station 323 (east of Buenos Ayres), depth 1900 fathoms.

Genus 713. _Circogonia_,[330] n. gen.

_Definition._--#Circoporida# with a regular icosahedral shell, composed of twenty congruent, triangular plates, with twelve corners, from which arise twelve radial spines.

The genus _Circogonia_ is remarkable for the regular icosahedral form of its shell, a geometrical fundamental form, which occurs very rarely in organised bodies (as in _Aulacantha icosahedra_, and in some Astrosphærida with twelve regularly disposed radial spines). The shell is composed of twenty triangular, equilateral and congruent plates, which are sometimes separated by prominent crests; their surface is panelled by smaller hexagonal or polygonal secondary plates. The thirty edges between the plates are sometimes thickened. From the twelve corners of the regular icosahedron (where every five triangular plates meet), twelve equal radial spines arise, each of which is surrounded at the base by a corona of nine to sixteen pores. Two species only of _Circogonia_ have been observed; the one has smooth spines, forked at the distal end, {1698}the other bears numerous curved bristles around each spine, and at the distal end a verticil of five curved branches. The mouth of the shell (placed in the centre of one of the triangular plates) is in both species armed with six teeth. Both species are found in the Tropical Atlantic.

1. _Circogonia icosahedra_, n. sp. (Pl. 117, figs. 1, 1_a_).

Shell regularly icosahedral, with twenty equal, triangular, nearly plane faces, which are separated by thirty prominent, crest-like edges, and covered by a delicate network of small, subregular, hexagonal plates. Twelve radial spines nearly conical, one and a half times as long as the radius of the shell, with five prominent edges. The campanulate base of each spine is covered with numerous long, curved bristles, surrounded by a circle of twelve to sixteen ovate, irregular pores, and separated from the slender distal part by a constriction. The distal apex of the spine is surrounded by a verticil of five conical, curved branches (corresponding to the five edges of the spines, and to the five faces, which meet in the corners where the spine arises). Mouth hexagonal, with six conical, spinulate teeth, convergent towards its centre (fig. 1_a_).

_Dimensions._--Diameter of the shell 0.75, length of the spines 0.5.

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

2. _Circogonia dodecacantha_, n. sp. (Pl. 115, figs. 8, 9).

Shell subregularly icosahedral, with twenty equal, triangular, slightly convex faces, which are not separated by prominent crests, but covered with a network of irregular polygonal plates. Twelve radial spines, cylindrical, smooth, about as long as the diameter of the shell, forked at the distal end with two divergent, slightly curved branches (similar to _Circospathis furcata_, Pl. 115, figs. 4-6). The conical base of each spine is surrounded by a circle of nine to twelve irregular, ovate pores (fig. 9). Mouth circular, with a corona of six conical, smooth teeth which arise perpendicularly from the shell (in the upper part of fig. 8, at left).

_Dimensions._--Diameter of the shell 0.6, length of the spines 0.7.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

Genus 714. _Circorrhegma_,[331] n. gen.

_Definition._--#Circoporida# with a regular dodecahedral shell, composed of twelve congruent, pentagonal plates, with twenty corners, from which arise twenty radial spines.

The genus _Circorrhegma_ is remarkable for the geometrical regularity of its shell, which represents a pentagonal dodecahedron. The shell is therefore composed of twelve equal and regular pentagonal plates, and these are separated in the only known {1699}species by thirty prominent crest-like edges. From the corners of the dodecahedron, at which every three pentagons meet, arise twenty radial spines, opposite in pairs in ten equidistant axes.

1. _Circorrhegma dodecahedra_, n. sp. (Pl. 117, figs. 2, 2_a_).

Shell dodecahedral, with twelve equal and regular, plane, pentagonal plates, which are separated by thirty prominent crests, and bear a network of numerous polygonal (usually also pentagonal), smaller plates. Twenty radial spines about as long as the radius of the shell, three-sided prismatic, covered with numerous bristles; each surrounded at the thickened base by a circle of twelve to sixteen pores, and at the distal apex by a corona of five curved, terminal branches. Mouth pentagonal, with five conical, subvertical, spinulate teeth (fig. 2_a_).

_Dimensions._--Diameter of the shell 0.8, length of the spines 0.5.

_Habitat._--Indian Ocean, Madagascar (Rabbe).

Genus 715. _Circostephanus_,[332] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.

_Definition._--#Circoporida# with a subregular, polyhedral or nearly spherical shell, composed of thirty to sixty or more triangular plates, with twenty-four to thirty-two or more corners, from which arise radial spines, symmetrically disposed.

The genus _Circostephanus_ comprises those Circoporida in which the porcellanous shell is an endospherical polyhedron, with numerous (thirty to sixty or more) triangular faces, and has a variable number of radial spines (twenty-four to forty or more), arising from its corners. The number of faces and corners seems to be variable in this genus, but may perhaps be typical in some species. _Circostephanus sexagenarius_ has the typical form of a "Sexagenal-Polyhedron," with sixty equal triangular faces and thirty-two corners, and may be derived from the "Pentagonal-Dodecahedron" (_Circorrhegma_) by dividing its twelve pentagonal faces each into five congruent triangles.

1. _Circostephanus coronarius_, n. sp. (Pl. 116, figs. 3, 3_a_, 3_b_).

Shell polyhedral, with thirty-two to forty triangular, concave faces of nearly equal size, which are separated by high prominent crests. From the elevated corners of the polyhedron arise twenty-four to thirty radial spines, which are three-sided prismatic or nearly cylindrical, about as long as the radius of the shell, and covered with long curved bristles. The distal end of each spine is surrounded by a verticil of five stout, curved branches, its pyramidal base by a corona of five (or {1700}sometimes six) ovate, basal pores (fig. 3_b_). Mouth armed with a corona of eight short, conical, vertical, spinulate teeth (fig. 3_a_).

_Dimensions._--Diameter of the shell 0.4 to 0.5, length of the spines 0.2 to 0.25.

_Habitat._--South-Eastern Pacific (off Valparaiso), Station 298, depth 2225 fathoms.

2. _Circostephanus sexagenarius_, n. sp.

Shell polyhedral, with sixty triangular, equilateral congruent faces which are nearly plane, and separated by high prominent crests. They are disposed in twelve pentagonal groups, each with five faces, so that they appear as if derived from a regular pentagonal dodecahedron, the twelve regular faces of which are each divided into five congruent triangles, meeting in its centre. From the elevated corners of the polyhedron arise thirty-two radial spines (twelve in the central points of the pentagons, twenty in the meeting corners of every three pentagons). The radial spines are nearly as long as the diameter of the shell, cylindrical, spinulate, and surrounded at the distal end by a verticil of five stout, curved branches, and at the pyramidal base by a corona of twelve to sixteen basal pores. Mouth armed with a corona of twelve conical, vertical, spinulate teeth.

_Dimensions._--Diameter of the shell 0.75, length of the spines 0.6.

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

3. _Circostephanus polygonarius_, n. sp.

Shell polyhedral, with sixty to eighty subregular, triangular, concave faces, which are separated by prominent crests. From the elevated corners of the polyhedron arise thirty to forty radial spines, which are longer than the diameter of the shell, densely covered with curved bristles and three-sided prismatic, with three spirally convoluted edges. Their distal end is surrounded by a verticil of eight or nine curved branches, and their pyramidal base by a corona of eight or nine basal pores. Mouth armed with a corona of ten conical, vertical, spinulate teeth.

_Dimensions._--Diameter of the shell 0.8, length of the spines 0.9.

_Habitat._--South Pacific, Station 288, depth 2600 fathoms.

Subfamily 2. HAECKELINIDA.

_Definition._--#Circoporida# with dimpled spherical shell, not composed of polygonal plates. The shell is covered with small roundish dimples, never polyhedral, and the radial spines are simple, not branched, and usually not regularly arranged.

Genus 716. _Haeckeliana_, John Murray, 1879, _in schedulis_, Chall. Coll.

_Definition._--#Circoporida# with spherical shell of a peculiar dimpled, porcellanous structure, and with a variable number of simple radial main-spines which are usually not regularly arranged.

{1701}The genus _Haeckeliana_ comprises the spherical Circoporida, with dimpled, porcellanous shell, which are widely distributed, but rather rare, in depths between 2000 and 3000 fathoms. All the known species (six in number) are very closely related, and though the extreme forms appear very different in size and structure, they are so connected by a continuous series of intermediate forms, that they may be regarded as varieties of a single species, first observed by Dr. John Murray, and called by him _Haeckeliana porcellana_. The number of radial spines may be from sixteen to fifty-five, and is usually between thirty and forty. Each is surrounded by a basal coronet of aspinal pores, usually five, more rarely four or six; the number, however, is not constant in any one species. Each coronet is armed with an outer ring of by-spines. The surface of the shell between the coronets is dimpled. The mouth (Pl. 114, fig. 3) is about as large as a corona, and also armed with a ring of by-spines. The structure of the thick porcellanous shell and the radial spines is different from the other Circoporida.

1. _Haeckeliana porcellana_, John Murray (Pl. 114, fig. 6).

_Haeckeliana porcellana_, John Murray, 1879, _in schedulis_, Chall. Coll.

Shell with forty to forty-five coronets, the majority of which have five pores (more rarely four or six). Coronets broader than their intervals, and twice as broad as the length of the by-spines. Dimples subcircular, of the same breadth as the pores. Main-spines about as long as the radius.

_Dimensions._--Diameter of the shell 0.37 to 0.42, of the coronets 0.06 to 0.07.

_Habitat._--South Pacific, Stations 289 to 293, depth 2025 to 2550 fathoms.

2. _Haeckeliana maxima_, n. sp. (Pl. 114, fig. 5).

Shell with fifty to fifty-five coronets, the majority of which have six pores (more rarely five or seven). Coronets broader than their intervals, and eight to ten times as broad as the length of the by-spines. Dimples irregularly polygonal, of about the same breadth as the pores. Radial main-spines about as long as the diameter of the shell.

_Dimensions._--Diameter of the shell 0.5 to 0.52, of the coronets 0.08 to 0.09.

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

3. _Haeckeliana lamarckiana_, n. sp. (Pl. 114, fig. 4).

Shell with thirty-five to forty coronets, the majority of which have five pores (more rarely six or four). Coronets broader than their intervals; each funnel-shaped pore on the inside with a circle of small conical thorns. By-spines rudimentary or wanting. Dimples irregularly polygonal, half as broad as the pores. Radial main-spines shorter than the radius.

_Dimensions._--Diameter of the shell 0.38 to 0.45, of the coronets 0.06 to 0.07.

_Habitat._--South Atlantic, Stations 318 to 333, depth 2000 to 2900 fathoms.

{1702}4. _Haeckeliana murrayana_, Haeckel.

_Challengeria_ sp., John Murray, 1876, Proc. Roy. Soc., vol. xxiv, pl.
xxiv. fig. 6.

Shell with twenty to twenty-five coronets, the majority of which have five pores (more rarely four or six). Coronets of about the same breadth as their intervals, and twice as broad as the by-spines. Dimples subcircular, of about the same breadth as the pores. Radial main-spines about as long as the radius.

_Dimensions._--Diameter of the shell 0.35 to 0.4, of the coronets 0.06 to 0.07.

_Habitat._--Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

5. _Haeckeliana goetheana_, n. sp. (Pl. 114, fig. 3).

Shell with sixteen to twenty coronets, the majority of which have four pores (more rarely five and very rarely six). Coronets smaller than their intervals. By-spines very short or rudimentary. Dimples subcircular, half as broad as the pores. Radial main-spines shorter than the radius.

_Dimensions._--Diameter of the shell 0.25 to 0.3, of the coronets 0.04 to 0.05.

_Habitat._--North Pacific (south of Japan), Station 231, depth 2250 fathoms.

6. _Haeckeliana darwiniana_, n. sp. (Pl. 114, figs. 1, 2).

Shell with twenty-six to thirty-two coronets, the majority of which have five pores (rarely four or six). Coronets smaller than their intervals and than the length of the by-spines. Dimples subcircular, half as broad as the pores, Radial main-spines longer than the radius.

_Dimensions._--Diameter of the shell 0.30 to 0.42, of the coronets 0.07 to 0.08.

_Habitat._--North Pacific (east of Japan), Stations 241 to 245, depth 2300 to 2900 fathoms.

Family LXXXII. #TUSCARORIDA#, n. fam. (Pl. 100).

_Definition._--PHÆODARIA with an ovate, spindle-shaped, or nearly spherical shell exhibiting a peculiar solid porcellanous structure; with a few radial pores around the base of the hollow tubules, which are symmetrically arranged around the main axis and the mouth. Surface of the shell smooth or spiny, not tabulate nor panelled. Central capsule excentric, placed in the aboral half of the shell-cavity.

The #Tuscarorida#, and the preceding closely allied family, the Circoporida, represent together a peculiar small group, which differs from the other PHÆODARIA in the singular porcellanous structure of the shell-wall, and may be called #Phæocalpia#; their hollow radial spines are distinguished by peculiar basal pores, forming a circle around their base. The shell of the Tuscarorida is monaxonian, ovate, spindle-shaped {1703}or nearly spherical, whilst in the Circoporida it is polyaxonian, spherical or polyhedral; the hollow radial spines are arranged in the former around the main axis, in the latter around the common central point. All #Phæocalpia# (the Tuscarorida as well as the Circoporida) are inhabitants of great depths, usually between 2000 and 3000 fathoms.

Though the number of Tuscarorida at present known is small (only three genera, with ten species), they represent a very distinct and remarkable family of PHÆODARIA, as well by their considerable size, as by the peculiar arrangement of the radial spines and the structure of the shell-wall, which in some species is more solid and thicker than in any other Radiolaria. The diameter of the shell is always more than 1 mm., usually between 1 and 2, and sometimes more than 3 mm.

The dry shell of the Tuscarorida is not hyaline and transparent as is usual in the other Radiolaria, but perfectly opaque, milk-white or yellowish-white. This opacity is caused by innumerable very fine pores, which everywhere pierce the thick, apparently solid, fundamental substance of the shell-wall. Besides those very small pores, it is also pierced by a certain number of larger pores, which are scattered at wide distances (Narr. Chall. Exp., vol. i. pl. A, fig. 15_b_). These larger pores or pore-channels have a diameter of about 0.01 mm., and pierce the shell-wall either in a perpendicular or in an oblique direction. Very numerous straight, simple, and thin needles, usually 0.1 to 0.2 mm. in length, similar to the thin tangential needles of the Aulacanthida, are everywhere scattered tangentially in the cement-like fundamental substance, which seems to be a peculiar carbonic silicate; their axis is parallel to the shell-surface.

The general form of the shell is somewhat different in the three genera of Tuscarorida; ovate or spherical in _Tuscarora_ and _Tuscarusa_, which bear no caudal axial spine (Pl. 100, figs. 1-7), or sometimes three-sided pyramidal (fig. 4); it is spindle-shaped in _Tuscaridium_, which bears on the aboral pore an axial caudal spine (Pl. 100, fig. 8). In every case the main axis of the shell, determining its monaxonian fundamental form, is indicated by the mouth, which is placed in the oral pole of the main axis and prolonged into a short tube or proboscis.

The hollow apophyses, arising from the shell of the Tuscarorida, are always cylindrical, long and thin tubules, the narrow cavity of which communicates directly with the large shell-cavity. In the axis of the tubules lies a thin axial chord or funicle, composed of a few (usually three or four) siliceous threads which arise from bridges between the basal pores of the apophyses, and are twisted together like the strands of a rope. The axial funicle is connected with the thin wall of the tubular apophyses by innumerable very thin radial beams, perpendicular to the axis (Pl. 100, fig. 3_a_, 5_b_). The surface of the apophyses is almost constantly covered with numerous small bristles or spines, which are usually curved and directed towards their distal ends.

_Tuscarora_ (Pl. 100, figs. 1-6) exhibits two different groups of apophyses, which may be distinguished according to their different position and direction as "circoral {1704}teeth" and "aboral feet"; the teeth immediately surround the opening of the mouth, whilst the feet are remote from it and usually placed in the aboral half of the body, more rarely in the equator or in the oral half. The general form and structure are the same in both groups of apophyses, but their position and direction is different; the circoral teeth are directed forwards, often parallel (at the base at least), while the aboral feet are either divergent and directed backwards, or they diverge forwards in the basal part, then form a large arch, and finally curve backwards.

The number of the aboral feet, and their position relative to the circoral teeth, are different but probably constant in each single species, and serve, in the first place, for the distinction of genera and species. _Tuscarora_ (in restricted sense) (Pl. 100, figs. 1-6), has constantly three feet (comparable to the three cortinar feet of the tripodal NASSELLARIA); _Tuscarusa_ (Pl. 100, fig. 7) has four feet, opposite in pairs and forming a regular cross; _Tuscaridium_, finally (Pl. 100, fig. 8), has only one foot, which is situated in the main axis, on its aboral pole, and may therefore be called a caudal spine.

The number of the circoral teeth varies from two to four, and is usually three. Originally these three teeth alternate regularly with the three aboral feet, so that the latter may be regarded as perradial, the former as interradial (Pl. 100, figs. 1-4). The proportion of the number of each group of apophyses in the different species is synoptically shown in the following table:--