Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) with an apical horn on the cephalis, without basal terminal spine.
The genus Cyrtocapsa and the two following genera represent together the small subfamily of Stichocapsida, or of those Cyrtoidea in which the many-jointed shell bears no radial appendages, and the terminal mouth is closed by a lattice-plate. They have been derived from the Stichocorida by development of such a closing plate. Cyrtocapsa bears an apical horn on the cephalis, and may be derived therefore directly from Eucyrtidium.
Definition.—Shell with three annular strictures (or internal septa) and four distinct joints.
1. Cyrtocapsa tetrapera, n. sp. (Pl. 78, fig. 5).
Shell rough, pear-shaped, with three deep strictures. The three first joints are of equal lengths, and each half as long as the hemispherical fourth joint. Cephalis subspherical, with an oblique conical horn of the same length. The third joint is the broadest, three times as broad as long. Pores regular, circular.
Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.09; length of each of the three first joints 0.03, of the last 0.06.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
2. Cyrtocapsa compacta, n. sp. (Pl. 77, fig. 8).
Eucyrtidium compactum, Haeckel, 1878, Atlas, loc. cit.
Shell rough, pear-shaped, with three slight strictures. The hemispherical cephalis bears a thick pyramidal spine of the same length, and is half as long as the second and the third joints, one-third as long as the hemispherical fourth joint. The third joint is the broadest, three times as broad as long. Pores subregular, circular. In the centre of the basal pole is one larger pore, the remnant of the constricted mouth of Eucyrtidium.
Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.04, d 0.06.
Habitat.—Western Tropical Pacific, Station 206, depth 2100 fathoms.
3. Cyrtocapsa inflata, n. sp.
Shell spiny, pear-shaped, with three deep strictures. The inflated third joint is twice as long as the second and fourth joints, and three times as long as the hemispherical cephalis, which bears a large conical horn of three times the length. Fourth joint flat, vaulted, inversely cap-shaped. The third joint is the broadest, being twice as broad as long. Pores regular, circular, double-contoured.
Dimensions.—Length of the shell 0.14, breadth 0.11. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.03.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
4. Cyrtocapsa pyrum, n. sp. (Pl. 78, fig. 8).
Shell thorny, pear-shaped, without external strictures, but with three internal annular septa. Length of the four joints = 2 : 5 : 6 : 7. The fourth joint is the broadest, being about twice as broad as long, and hemispherical. The small subspherical cephalis bears a stout conical horn of the same length. Pores large, regular, circular.
Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.12. Length of the single joints, a 0.02, b 0.05, c 0.06, d 0.07.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
5. Cyrtocapsa cornuta, n. sp. (Pl. 78, fig. 9).
Shell rough, very thick-walled, nearly pear-shaped, with three annular strictures; the second of which is very sharp, the first and third slight. Length of the four joints = 3 : 4 : 5 : 6. The third joint is the broadest, being about twice as broad as long; the fourth joint is hemispherical. Cephalis subspherical, with a large, conical, curved horn of twice the length. Pores regular, circular, hexagonally framed.
Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.12. Length of the single joints, a 0.03, b 0.04, c 0.05, d 0.06.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
6. Cyrtocapsa diploconus, n. sp. (Pl. 78, fig. 6).
Shell rough, doubly conical, with three annular septa. Length of the four joints = 3 : 4 : 4 : 8. The third joint is the broadest, two and a half times as broad as long; the fourth is inversely conical, acute. Cephalis hemispherical, with a pyramidal horn of the same length. Pores irregular, roundish.
Dimensions.—Length of the shell (with four joints) 0.19, breadth 0.1. Length of the single joints, a 0.03, b 0.04, c 0.04, d 0.08.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
7. Cyrtocapsa fusulus, n. sp. (Pl. 78, fig. 7).
Shell smooth, spindle-shaped, with three distinct strictures. Length of the four joints = 1 : 1 : 4 : 3. The third joint is the broadest, somewhat longer than broad. The fourth joint is inversely conical. Cephalis hemispherical, with a coronal of large, ovate pores, and a pyramidal, sulcate, oblique horn of twice the length. Pores regular, circular.
Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.07. Length of the single joints, a 0.02, b 0.02, c 0.08, d 0.06.
Habitat.—South Pacific, Station 295, depth 1500 fathoms.
Definition.—Shell with four or more annular septa, and five or more joints.
8. Cyrtocapsa incrassata, Haeckel.
Eucyrtidium incrassatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 105, Taf. iv. fig. 9.
Shell rough, spindle-shaped, with four annular septa. Length of the five joints = 2 : 3 : 4 : 4 : 4. The third joint is the broadest, nearly three times as broad as long. The fourth joint is inversely conical, acute. Cephalis small, spherical, with two short, conical, divergent horns. Pores small, regular, circular.
Dimensions.—Length of the shell (with five joints) 0.17, breadth 0.11. Length of the single joints, a 0.015, b 0.035, c 0.04, d 0.04, e 0.04.
Habitat.—Fossil in Tertiary rocks of Sicily, Grotte.
9. Cyrtocapsa costata, n. sp.
Shell smooth, spindle-shaped, twice as long as broad, with numerous longitudinal ribs, and four annular septa. Length of the five joints = 1 : 4 : 3 : 2 : 8. The third joint is the broadest. Fourth joint inversely conical, acute. Cephalis small, hemispherical, with a small conical horn. Pores regular, circular.
Dimensions.—Length of the shell (with five joints) 0.18, breadth 0.09. Length of the single joints, a 0.01, b 0.04, c 0.03, d 0.02, e 0.08.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
10. Cyrtocapsa colatractus, n. sp.
Shell smooth, spindle-shaped, with eight internal annular septa (without external stricture). All nine joints are nearly equal in length, the first somewhat shorter, the last longer. The fourth joint is the broadest, four times as broad as long. Last joint inversely conical, blunt. Cephalis subspherical, with a conical horn of the same length. Pores small and numerous, regular, circular.
Dimensions.—Length of the shell (with nine joints) 0.22, breadth 0.1; length of the cephalis 0.015, of the last joint, 0.03, of each of the seven other joints, 0.022 to 0.028.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
11. Cyrtocapsa chrysalidium, n. sp. (Pl. 76, fig. 9).
Shell rough, nearly spindle-shaped, with seven distinct strictures. Length of the eight joints = 4 : 6 : 11 : 8 : 5 : 5 : 4 : 3. The third and fourth joints are the broadest. The last joint is small, inversely cap-shaped. Cephalis subspherical, with an oblique, dentate horn of the same length. Pores very numerous, subregular, circular.
Dimensions.—Length of the shell (with eight joints) 0.23, breadth 0.1. Length of the single joints, a 0.02, b 0.03, c 0.055, d 0.04, e 0.025, f 0.025, g 0.02, h 0.015.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) without apical horn, and without basal spine.
The genus Stichocapsa differs from the preceding Cyrtocapsa in the absence of an apical horn, and bears therefore to it the same relation as Lithocampe does to Eucyrtidium. It may be derived either from Cyrtocapsa by loss of the horn, or from Eucyrtidium by closure of the terminal mouth.
1. Stichocapsa tetracola, n. sp. (Pl. 78, fig. 1).
Shell smooth, spindle-shaped, half as broad as long, with three slight strictures. Length of the four joints = 3 : 4 : 4 : 11. The fourth joint is the broadest, inversely conical, with acute basal pole. Pores subregularly square in the second and third joints, more irregular in the fourth joint.
Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.02, c 0.02, d 0.055; breadth 0.055.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
2. Stichocapsa quadrigata, n. sp. (Pl. 78, fig. 3).
Shell smooth, pear-shaped, half as broad as long, with three deep strictures. Length of the four joints = 3 : 8 : 8 : 5. The second joint is the broadest. The fourth joint is scarcely larger than the hemispherical cephalis, inversely conical, with blunt basal pole. Pores subregular, square, in transverse rows, in the second and third joints of equal size, in the fourth smaller.
Dimensions.—Length of the shell (with four joints) 0.12. Length of the single joints, a 0.015, b 0.04, e 0.04, d 0.025; breadth 0.06.
Habitat.—Central Pacific, Station 270, depth 2925 fathoms.
3. Stichocapsa tricincta, n. sp. (Pl. 78, fig. 2).
Shell smooth, spindle-shaped, twice as long as broad, with three deep strictures. Length of the four joints = 2 : 5 : 5 : 10. The third joint is the broadest. Fourth joint inversely conical, with acute basal pole. Cephalis small, subconical. Pores irregular, roundish, of very different sizes.
Dimensions.—Length of the shell 0.11. Length of the single joints, a 0.01, b 0.025, e 0.025, d 0.05; breadth 0.055.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
4. Stichocapsa subglobosa, n. sp.
Shell thorny, broad, pear-shaped, nearly spherical, almost as broad as long, with three internal septal rings. Length of the four joints = 1 : 2 : 7 : 2. Cephalis small, subspherical. Thorax flat, conical. Third joint very large, inflated, about twice as broad as the second and fourth joints. The latter is flat, cap-shaped, with rounded basal pole. Pores regular, circular, hexagonally framed, in the third joint twice as broad as in the second and fourth joints.
Dimensions.—Length of the shell 0.24. Length of the single joints, a 0.02, b 0.04, c 0.14, d 0.04; breadth 0.2.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
5. Stichocapsa compressa, Haeckel.
Lithocampe compressa, Stöhr, 1880, Palæontogr., vol. xxvi. p. 103, Taf. iv. fig. 5.
Shell rough, broad, pear-shaped, almost as broad as long, with three internal septal rings. Length of the four joints = 1 : 2 : 3 : 2. Cephalis very small, spherical. Thorax conical. The third joint is the broadest, strongly inflated. The fourth joint (in the figure of Stöhr broken off) is in a well preserved specimen inversely hemispherical, with rounded basal pole. Pores very small, regular, circular.
Dimensions.—Length of the shell 0.1. Length of the single joints, a 0.013, b 0.027, c 0.04, d 0.022; breadth 0.08.
Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.
6. Stichocapsa pyriformis, n. sp.
Shell rough, pear-shaped, about twice as long as broad, with three internal septal rings. Length of the four joints = 2 : 5 : 2 : 9. Cephalis small, spherical, hyaline. Thorax conical. Third joint very short and broad; the fourth joint is the broadest, half as long as the shell, with an inversely hemispherical basal pole. Pores subregular, circular, small and numerous, larger in the basal third.
Dimensions.—Length of the shell 0.18. Length of the single joints, a 0.02, b 0.05, c 0.02, d 0.09; breadth 0.1.
Habitat.—Fossil in Barbados.
7. Stichocapsa monstrosa, n. sp. (Pl. 78, fig. 4).
Shell tuberculate, twice as long as broad, irregular, horn-shaped or inversely conical, with curved axis, and with three internal septal rings. Length of the four joints = 2 : 7 : 3 : 4. Cephalis subspherical, with small, circular pores. The thorax is the broadest joint, half as long as the shell. The fourth joint is small, inversely conical, with a blunt, curved, basal pole. Pores irregular, roundish, partly double-contoured.
Dimensions.—Length of the shell (with four joints) 0.16. Length of the single joints, a 0.02, b 0.07, c 0.03, d 0.04; breadth 0.08.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
8. Stichocapsa pentacola, n. sp. (Pl. 76, fig. 1).
Shell smooth, slender, pear-shaped, twice as long as broad, with four sharp strictures. Length of the five joints = 1 : 1 : 1 : 2 : 3. The three first joints are nearly equal in length, but increase in breadth. The fifth joint is the broadest, nearly spherical, with rounded basal pole. Pores irregular, roundish.
Dimensions.—Length of the shell (with five joints) 0.13. Length of the single joints, a 0.017, b 0.017, c 0.017, d 0.028, e 0.05; breadth 0.07.
Habitat.—Central Pacific, Station 273, depth 2350 fathoms.
9. Stichocapsa hexacola, n. sp. (Pl. 76, fig. 2).
Shell rough, slender, pear-shaped, twice as long as broad, with five internal septal rings. The five first joints are nearly equal in length. The sixth joint is the broadest, half as long as the shell, with a rounded, hemispherical basal pole. Pores small and numerous, subregular, circular, larger in the inflated basal third.
Dimensions.—Length of the shell (with six joints) 0.2. Length of each of the first five joints 0.02, of the sixth joint 0.1; breadth 0.1.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms; also fossil in Barbados.
10. Stichocapsa compacta, n. sp. (Pl. 76, fig. 3).
Shell rough very thick-walled, slender, pear-shaped, twice as long as broad, without external stricture, but with eight internal septal rings. The eight first joints, gradually increasing in breadth, are nearly equal in length. The eighth joint is the broadest, and one-third as long as the shell, inversely hemispherical. Pores small, circular, in the last joint larger.
Dimensions.—Length of the shell (with nine joints) 0.25. Length of each of the eight first joints about 0.02, of the ninth joint 0.08; breadth 0.13.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.
11. Stichocapsa radicula, Haeckel.
Lithocampe radicula, Ehrenberg, 1838 (partim); Mikrogeol., 1854, Taf. xxii. fig. 23b.?
Shell smooth, spindle-shaped, decreasing from the broader middle towards the two rounded poles, with four or five slight strictures. All five or six joints nearly equal in length, the middle (third and fourth) are the broadest. Pores subregular, circular. (To this species those forms of Lithocampe radicula, Ehrenberg, must be referred, in which the basal opening is perfectly closed by lattice-work. The other forms in which the basal mouth remains open, and which are connected with the former by transitional forms, constitute the true type of the genus Lithocampe (page 1503).
Dimensions.—Length of the shell (with six joints) 0.12 to 0.15, breadth 0.06 to 0.07.
Habitat.—Fossil in Barbados.
12. Stichocapsa subligata, Haeckel.
Lithocampe subligata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 102, Taf. iv. fig. 1.
Shell rough, subcylindrical, irregular, with seven slight strictures. All eight joints of slightly different lengths, the third joint is the broadest; the seventh joint is much broader than the sixth and the eighth joints. The latter is inversely hemispherical. Cephalis very small, spherical. Pores regular, circular, very small and numerous.
Dimensions.—Length of the shell (with eight joints) 0.24; length of the single joints (on an average) 0.025 to 0.035, breadth 0.08.
Habitat.—Fossil in Tertiary rocks of Sicily (Grotte).
13. Stichocapsa paniscus, n. sp. (Pl. 76, fig. 4).
Shell smooth, cylindrical, with a blunt, conical cephalis, and a hemispherical last joint, without external strictures, but with seven or eight internal septa. Eight or nine joints nearly equal in length, the second and the last somewhat longer. Pores circular, of unequal sizes.
Dimensions.—Length of the shell (with seven joints) 0.16; length of each joint (on an average) 0.02 to 0.03, breadth 0.07.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
14. Stichocapsa cylindrica, n. sp.
Shell rough, cylindrical, four times as long as broad, with hemispherical cephalis and last joint, without external stricture, but with ten or eleven internal septa. All eleven or twelve joints are nearly equal in length, and are three times as broad as long. Only the flat cephalis is shorter, and the vaulted last joint longer than each of the nine or ten other joints. Pores regular, circular.
Dimensions.—Length of the shell (with twelve joints) 0.24; length of each joint (on an average) 0.02, breadth 0.06.
Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.
Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) with an apical horn on the cephalis, and a basal terminal spine on the last joint.
The genus Artocapsa differs from Cyrtocapsa, its ancestral form, by the development of a vertical terminal spine, or a bunch of spines, on the base of the last joint, and bears therefore to it the same relation as Rhopalatractus does to Rhopalocanium.
1. Artocapsa fusiformis, n. sp. (Pl. 76, fig. 5).
Shell spindle-shaped, rough, with five slight strictures, decreasing uniformly from the broader middle towards both poles, with a strong, pyramidal, terminal spine at each pole. Length of the six joints = 2 : 5 : 3 : 3 : 2 : 5. Cephalis hemispherical, hyaline, without pores, its horn half as large as the basal spine. Pores small and numerous, subregular, circular.
Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the single joints, a 0.02, b 0.05, c 0.03, d 0.03, e 0.02, f 0.05.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
2. Artocapsa spinosa, n. sp. (Pl. 76, fig. 10).
Shell spindle-shaped, spiny, with five distinct strictures. Length of the six joints = 2 : 3 : 2 : 5 : 4 : 4. The fourth joint is the broadest, and much larger than the five other joints. The first and the last joints are similar in size and form, hemispherical, armed with some larger, irregular, conical spines. Pores irregular, roundish, of variable sizes.
Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the single joints, a 0.02, b 0.03, c 0.02, d 0.05, e 0.04, f 0.04.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
3. Artocapsa infraculeata, Haeckel.
Eucyrtidium infraculeatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 106, Taf. iv. fig. 13.
Shell subcylindrical, rough, with five annular septa. Length of the six joints = 2 : 3 : 4 : 4 : 4 : 3. The third, fourth, and fifth joints are nearly equal in length and breadth, whilst the second and sixth are cupola-shaped. The cephalis is very small, subspherical (regarded by Stöhr as a "large pore"), and bears a short conical horn. The last joint bears a bunch of basal spines.
Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the cephalis 0.02, second and sixth joints 0.03, third, fourth, and fifth joints 0.04.
Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr), Caltanisetta (Haeckel).
4. Artocapsa quadricamera, n. sp.
Shell spindle-shaped, smooth, with three sharp strictures. Length of the four joints = 2 : 3 : 4 : 8. The third joint is the broadest. The fourth joint is inversely conical, nearly as long as the three other joints together, and bears a strong, conical, basal spine, of half the length. The cephalis is small, subspherical, and bears a conical horn of the same length. Pores subregular, circular.
Dimensions.—Length of the shell (with four joints) 0.17, breadth 0.08. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.08.
Habitat.—Fossil in Barbados.
5. Artocapsa armata, n. sp.
Shell slender, inversely ovate, spiny, with six deep strictures. Length of the seven joints = 2 : 4 : 6 : 5 : 4 : 3 : 2. The third joint is the broadest, inflated, and much larger than the four following, which gradually decrease in size. The small, hemispherical cephalis bears a stout pyramidal horn of twice the length. The last hemispherical joint is armed with a bunch of stout spines, one of which is much the larger, and as long as the third joint. Pores irregular, roundish.
Dimensions.—Length of the shell (with seven joints) 0.26, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.05, e 0.04, f 0.03, g 0.02.
Habitat.—Western Tropical Pacific, Station 225, depth 4575 fathoms.
6. Artocapsa octocamera, n. sp.
Shell subcylindrical, smooth, with seven internal annular septa. Five joints (the third to the seventh) are nearly equal in size, while the second and eighth are cupola-shaped, somewhat longer. The cephalis is smaller, with a conical horn of the same length. The last joint bears a bunch of divergent, conical spines, of different lengths. Pores small, regular, circular.
Dimensions.—Length of the shell (with eight joints) 0.16, breadth 0.08. Length of the cephalis 0.016, second and eighth joints 0.033, each of the five other joints 0.022.
Habitat.—South Pacific, Station 285, depth 2375 fathoms.
7. Artocapsa elegans, n. sp. (Pl. 76, fig. 8).
Shell spindle-shaped, smooth, with eight internal, broad, annular septa. The second and third joints are the largest, the fourth and fifth of medium size, while the cephalis and the four last joints are nearly equal in length, and much shorter. The third joint is the largest. The subspherical cephalis bears a bristle-shaped horn of the same length, while the last joint is armed with a bunch of conical spines. Pores small, in the upper half of the shell regular, hexagonal, in the lower half irregular.
Dimensions.—Length of the shell (with nine joints) 0.2, breadth 0.09. Length of the first and the four last joints, each 0.014; of the fourth and fifth, each 0.02; of the third 0.04, second 0.05.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
vel Cannopylea, vel Pansolenia (Pls. 99-128).
Phæodaria, Haeckel, 1879.
Tripylea, Hertwig, 1879.
Cannopylea, Haeckel, 1881.
Pansolenia, Haeckel, 1878.
Definition.—Radiolaria with a double membrane surrounding the central capsule, which bears on one pole of the main axis a peculiar astropyle, or a tubular main-opening, in the centre of a circular radiate operculum. Usually (but not constantly) a pair of small, lateral, accessory openings (or parapylæ) on the opposite pole of the main axis. Extracapsulum constantly with a phæodium, or with a voluminous aggregation of peculiar dark pigment bodies (phæodella) covering the astropyle of the central capsule. Skeleton siliceous or silicated, always extracapsular, very rarely wanting. Fundamental form very variable, originally monaxon, often dipleuric or bilateral.
The legion Phæodaria, or Cannopylea, in the extent here defined, was constituted by me in 1878, in my Protistenreich (p. 102) under the name Pansolenia. This name was given on the supposition that the skeleton of these interesting Radiolaria is always composed of hollow tubules, in contrast to that of the other Radiolaria, where it is never tubular. But I was soon convinced that this supposition was erroneous, that in a great part of the Pansolenia the skeleton is not composed of hollow tubules but of solid bars, and that a constant, very characteristic, and never failing mark of this group is to be found in the peculiar phæodium, a voluminous, constant, extracapsular pigment body. Therefore, in 1879, I changed the name into Phæodaria, and having discovered in the collection of the Challenger an astonishing number of new and wonderful types of this group, I described, in a preliminary note on it, four different orders and ten families with thirty-eight genera (Ueber die Phæodarien, eine neue Gruppe kieselschaliger mariner Rhizopoden; in Sitzungsberichte der Jenaischen Gesellschaft für Medicin und Naturwissenschaft. Sitzung vom 12th December 1879).
In the same year (1879), Richard Hertwig, in his excellent work entitled Der Organismus der Radiolarien, published the first accurate description of the intimate structure of the soft body of the Pansolenia, and mainly of their central capsule; and having always observed, in the few representatives examined by him, three openings in the capsule (one main-opening and two accessory openings), he called them Tripylea (loc. cit. p. 87), being guided by the erroneous supposition that these three openings are constant in all members of the group. But this is by no means the case. The two accessory openings are completely absent in several families, whilst in others their number is increased. A constant and very striking character, however, of all Phæodaria, is the peculiar structure of their tubular main-opening, which I call astropyle, with its radiate operculum and cannular proboscis. On account of this important and startling characteristic I proposed in 1881 to call this group Cannopylea. The two names Phæodaria and Cannopylea both express a very striking and quite constant character of these curious Radiolaria, whilst the two names Pansolenia and Tripylea are applicable only to a part of the whole legion.
The history of our knowledge of the Phæodaria is short, but very remarkable. Although hundreds of species, many of them cosmopolitan, are distributed over all oceans and all zones, although their size is in general much greater than that of the other Radiolaria (usually 1 to 2 mm., often even 5 to 10 mm. or more), and although their form and structure are usually striking, nevertheless the Phæodaria remained completely unknown up to the year 1859. During that year I observed the first forms living in the Gulf of Messina, and described and figured in 1862 in my Monograph five genera and seven species, viz., (1) Aulacantha scolymantha (p. 263), (2) Thalassoplancta cavispicula (p. 261, now Cannobelos cavispicula), (3) Aulosphæra trigonopa, and Aulosphæra elegantissima (p. 359), (4) Spongodictyum trigonizon (p. 459, now Sagoplegma trigonizon), and (5) Cœlodendrum ramosissimum, and Cœlodendrum gracillimum (p. 361). I recognised the structure of the three genera enumerated as 1, 3, and 5, as so remarkable and so different from that of the other Radiolaria, that I founded three peculiar families for them, the Aulacanthida, Aulosphærida, and Cœlodendrida.
The first note on the numerous remarkable Phæodaria discovered by the Challenger, and mainly on the large-sized inhabitants of the deep-sea, was published in 1876 by Dr. John Murray, in his Preliminary Reports on Work done on Board the Challenger (Proc. Roy. Soc., vol. xxiv., read March 16, 1876). He pointed out (loc. cit., p. 535), that the tow-nets, sent down to a great depth (according to a new plan, adopted in April 1875) brought up on every occasion a great many new and peculiar Rhizopods, which had never been observed in the nets used near the surface. "The shells of all have an exceedingly beautiful tracery, a fenestrated appearance often, which a closer examination shows to be caused by pit-like depressions. Some have only one, others have several openings, through which the sarcode flows. The sarcode of all these deep-sea Rhizopods has many large black-brown pigment-cells. At times they come up with a good deal of the sarcode outside of the shell; and two specimens have been seen to throw out elongated pseudopodia" (loc. cit., p. 536). Dr. John Murray distinguished at that time not less than fifty species of these interesting deep-sea Rhizopods and called them provisionally Challengerida; a term which we retain here for the largest and most characteristic family. He gave at the same time, in an accompanying plate (xxiv.), six figures of new Phæodaria, the names of which (as found by me in 1879 in the corresponding preparations) are the following; (1) Challengeria naresii, (2) Challengeria aldrichii, (3) Bivalva compressa (now = Conchopsis compressa), (4) Tuscarora belknapii, (5) Challengeria circopora (now = Circoporus sexfurcus), and (6) Haeckeliana porcellana. A great number of these Challengerida (twenty species) were afterwards figured by Dr. John Murray in the Narrative of the Cruise of H.M.S. Challenger, 1885, vol. i. part 1, p. 226, Pl. A; viz., fourteen species of Challengeria and six species of Tuscarora.
The most important advance in the knowledge which we had of the peculiar organisation of the Phæodaria, was made by the accurate description which Richard Hertwig published, in 1879, of the intimate structure of their central capsule, and mainly of its peculiar openings. He examined living at Messina the following three forms, described in my Monograph; (1) Aulacantha scolymantha, (2) Aulosphæra elegantissima, and (3) Cœlodendrum ramosissimum. Besides, he described an interesting new genus, Cœlacantha anchorata; and another new form, which he placed in the Aulosphærida, as Aulosphæra gracilis, but which really was a new genus of Sagosphærida, here described as Sagoscena gracilis. Finally, Hertwig first discovered that the peculiar bodies, described by Ehrenberg as Dictyocha and placed by him in the Diatomea (Polygastrica), were the isolated pieces of the skeleton of a true Phæodarium, and that they were scattered loosely in great numbers over the surface of the jelly-sphere, just as are the hollow spicula of Thalassoplancta or Cannobelos.
The six species mentioned, of which Hertwig gave a very accurate description and very instructive figures, belong to six different genera, and these represent six different families of Phæodaria, viz.; Aulacanthida, Aulosphærida, Cœlodendrida, Cannosphærida, Sagosphærida and Cannorrhaphida. He found that all these six forms, in spite of great differences in the form and structure of their skeleton, were identical in the structure of the central capsule; and since he observed constantly three openings in its double wall (a large main-opening on the oral pole, and a pair of lateral accessory openings on the aboral pole of its main axis) he called them Tripylea (loc. cit., p. 87, 94). But he also pointed out the remarkable shape of their voluminous extracapsular body, and especially the characteristic position, size, colour and composition of the large pigment body, which I had called the phæodium.
The accurate description of the gigantic and elegant skeleton of a new Phæodarium, surpassing all other known Radiolaria in its extraordinary size (15 mm.), was published in 1882 by O. Bütschli (in Zeitschr. f. wiss. Zool., vol. xxxvi. p. 486, Taf. xxxi.). He called it Cœlothamnus davidoffii, in honour of its discoverer, who had found it floating on the surface of the Gulf of Villafranca, near Nice. He placed it among the Cœlodendrida; it belongs, however, to that part of this group which possesses a nasal tube, and which I afterwards separated under the name Cœlographida.
The total number of Phæodaria, hitherto described and illustrated by figures, amounts therefore to seventeen species, viz., the seven species first described by myself (in 1862); the six new species figured by Dr. John Murray (in 1876); the three new species discovered by Hertwig (in 1879) and the single species last-mentioned described by Bütschli (in 1882). The rich collection of the Challenger has added to this small number such an astonishing wealth of new and remarkable forms, that I can describe in the following system of Phæodaria not less than eighty-four genera and four hundred and sixty-five species. These belong to fifteen different families and four different orders. But this great number is probably only a small part of the numerous interesting Phæodaria, which are abundantly distributed over all the oceans; those (e.g.) of the Indian and of the Arctic Oceans are almost unknown.
The great majority of these wonderful Phæodaria are inhabitants of the deep-sea, mainly of the southern hemisphere, and are so common in many stations explored by the Challenger, that its collection contains many thousands (or rather hundreds of thousands) of well-preserved specimens. A smaller part of the legion is found on the surface, widely distributed over all oceans; some of these are very common (as, e.g., Aulacantha, Aulosphæra, Sagosphæra, Cœlodendrum, Castanella, &c.) and it is difficult to explain how they could entirely escape the eyes of all former observers.
The three general characters which distinguish the Phæodaria easily and constantly from all the other Radiolaria are the following:—(1) the double membrane, a thick outer and a thin inner envelope, of the big central capsule; (2) its typical main-opening or astropyle, placed on the oral pole of the main axis, and distinguished by a peculiar radiate operculum, with tubular proboscis; (3) the phæodium, or the peculiar voluminous pigment-body, which constantly lies in the oral half of the calymma, surrounds the oral part of the central capsule, and is composed of numerous phæodella, or singular pigment-granules of green, olive, brown or black colour.
Besides these three general and never failing marks of the Phæodaria, the majority of this legion (but by no means all) possess the three following peculiarities; (1) two parapylæ or accessory openings of the central capsule, placed laterally (at the right and left) on the aboral pole of the main axis (wanting in the Challengerida, Medusettida, Castanellida, and perhaps in some other families); (2) a characteristic skeleton which is always extracapsular, wanting only in the Phæodinida, incomplete in the Cannorrhaphida and Aulacanthida, but perfectly developed and of very various shapes in the twelve other families; usually this silicated skeleton is composed of hollow tubules, which are filled up by jelly (Pansolenia); but in some families it is composed of ordinary solid network, not different from that of the other Radiolaria, e.g., especially in the Castanellida and Sagosphærida; (3) an extraordinary size of the body, as well of the central capsule and its nucleus, as of the extracapsular skeleton; the majority of Phæodaria have a diameter of 1 to 2 mm., and are therefore from ten to twenty times as large as the majority of the other Radiolaria; in some gigantic forms the diameter of the unicellular body reaches 20 or even 30 mm.
The Central Capsule of the Phæodaria is the most important part of their body and preserves in all families of this legion the same essential structure, and nearly the same form, in striking contrast to the extraordinary variety and complication of the skeleton. As already mentioned, it differs from the central capsule of all the other Radiolaria in two most important peculiarities; firstly, the double membrane of the spheroidal capsule, and secondly, the singular structure of its constant main-opening, the astropyle. A third constant character is the considerable size of the enclosed nucleus, the diameter of which usually equals about half of that of the capsule itself.
The diameter of the capsule is, in the majority of Phæodaria, 0.1 to 0.2 mm., often also 0.3 to 0.4, rarely more than 0.5, or less than 0.05 mm.
The position of the central capsule is somewhat different in the four orders into which we have divided the Phæodaria. It lies in the centre of the spherical, concentric calymma in all the Phæocystina, or in those Phæodaria which possess no complete lattice-shell—Phæodinida, Cannorrhaphida, and Aulacanthida (Pls. 101-105). The Phæosphæria (comprising the Orosphærida, Sagosphærida, Aulosphærida, and Cannosphærida, Pls. 106-112) all possess a very big, usually spherical lattice-shell, and here the central capsule is much smaller than the latter and lies in its centre. Another position is constantly occupied by the central capsule in all Phæogromia (Pls. 99, 100, 113-120; the families Challengerida, Medusettida, Castanellida, Circoporida, Tuscarorida), which have a peculiar mouth on the lattice-shell, placed on the oral pole of its main axis; the central capsule lies in the opposite aboral half of the shell cavity. The Phæoconchia finally (Pls. 121-128, the families Concharida, Cœlodendrida, and Cœlographida) all possess a bivalved shell, and the capsule is here enclosed between the two valves of the shell.
The form of the central capsule is constantly spheroidal, slightly depressed in the direction of the main axis, and therefore comparable to the spheroidal form of our globe. The depression is generally very slight, so that the proportion of the minor vertical main axis to the major horizontal or equatorial axis is about 4 : 5 or 5 : 6, often even 8 : 9 or less; but sometimes the proportion becomes 3 : 4, or even 2 : 3, so that the capsule becomes nearly lenticular; very rarely its form becomes almost perfectly spherical (Pl. 101, fig. 1). The main axis stands always vertically, and is distinctly marked by the peculiar shape of the astropyle, placed on its oral pole. Usually this pole, in the living and freely floating Phæodaria seems to be the lower pole, directed downwards (as also in the Nassellaria); but in some families it seems to be inversely directed upwards, as in the Challengerida and Tuscarorida, (Pls. 99, 100).
The two membranes of the central capsule possess in all Phæodaria a very different shape, and were in all preparations which I could accurately examine (some hundreds belonging to all families) separated by a clear, rather wide interval, filled up either by a colourless fluid or by a structureless jelly (Pl. 103, fig. 1; Pl. 123, figs. 8, 9, &c.). They are in direct connection only at the openings. In the living Phæodaria, however, their distance is very small, or they are in immediate contact without any interval (Pl. 101, fig. 10; Pl. 102, fig. 1). According to the observations of Hertwig, the two membranes are always in close contact, and without interspace, in the living Phæodaria; and the space between them is an artificial product due to the influence of the preserving fluid or of certain chemical agents. In every case it is very easy to separate both membranes completely, except at the openings, where they are in direct connection. We distinguish both membranes shortly as ectocapsa and endocapsa.
The ectocapsa, or the outer membrane of the central capsule, is rather firm and durable, double-contoured, elastic and difficult to destroy. Its physical and chemical qualities seem to approach those of chitin. It becomes, however, stained red by carmine, and yellow by nitric acid. Usually it appears structureless and refracts the light strongly. In a few cases, however, it exhibits, when examined by strong lenses, a fine punctation; and in some Aulacanthida (especially in some big forms of Aulographis and Aulospathis) the entire ectocapsa was densely covered with peculiar curved, or S-shaped dark corpuscles (Pl. 114, fig. 13). They were all of the same length, about 0.01, and seemed to lie on its inner face.
The endocapsa, or the inner membrane of the central capsule, is much thinner than the outer, with which it is in immediate connection only at the openings. It encloses the entire contents of the capsule, and becomes very distinct, as soon as the latter are dissolved by chemical agents, or stained by carmine. In the majority of well-preserved preparations it is irregularly plicated, and resembles a thin, but firm, crumpled paper. Isolated pieces of the endocapsa are completely structureless, but exhibit also a considerable resistance, in spite of their minute thickness.
The openings of the central capsule exhibit in the Phæodaria a greater variety than their discoverer, R. Hertwig, supposed. The majority of the legion, certainly, possess the three openings described by him, and are therefore true Tripylea. Some families, however, have only one opening, the astropyle, which is generally present (Challengerida, Medusettida, Castanellida, and Phæocolla among the Phæodinida, Pl. 101, fig. 1). In some other families there is a variable number of accessory openings or parapylæ, one, three, or more, e.g., especially in the Circoporida and Tuscarorida. The former may be called Astropylea, the latter Sporopylea. Thus only a single opening to the central capsule is constant in all Phæodaria without exception, and that is the astropyle, or the large main-opening with its peculiar structure.
The astropyle, or the single constant main-opening of the central capsule, is distinguished by a very remarkable structure, and is sufficient of itself to separate the Phæodaria from all the other Radiolaria, and from the other Rhizopoda in general. It is always placed on the oral pole of the main axis, forming here a peculiar cap-shaped or flatly conical elevation, the centre of which is prolonged into a short, cylindrical tubule; we call the latter shortly a proboscis, and the former an operculum. To understand better the different forms which these important parts assume in the different families, compare Pl. 101, figs. 1-6; Pl. 102, fig. 1; Pl. 103, fig. 1; Pl. 104, figs. 1-3; Pl. 111, fig. 2; Pl. 123, figs. 1-9; Pl. 127, figs. 4-6; Pl. 128, fig. 2, &c. Compare also the first very accurate figures which R. Hertwig has given in 1879 (loc. cit.) in his Taf. x.
The operculum of the astropyle, the most important part of this main opening ("der Oeffnungshof der Hauptöffnung," in the description of Hertwig), is a circular convex plate, always more strongly vaulted than the surrounding part of the capsule membrane, and is sharply separated from it by a circular, often thickened and double-contoured margin. The operculum covers the main-opening like the lid of a tea-kettle, and the proboscis arising from its centre is comparable to the handle of that lid. The diameter of the circular operculum is usually about half as long (rarely as long) as the radius of the central capsule, therefore in the majority of Phæodaria 0.03 to 0.06, sometimes 0.1 and more. Its form is sometimes more conical, sometimes more like a mamma. Its height is usually about equal to half its diameter. It always exhibits a very distinct radial striation, produced by numerous prominent radial ribs, which arise in the centre and end at the circular sharply truncated margin. The usual number of these radial ribs may be, in the operculum of smaller capsules, from thirty to fifty, in those of medium size from sixty to ninety, and in the largest two hundred to three hundred or more. Usually the ribs are simple (Pl. 101, figs. 1, 2, 6, 10; Pl. 127, figs. 4-6; also in all figures given by Hertwig); but sometimes, mainly in the biggest Aulacanthida, they are distinctly branched in a centrifugal direction (Pl. 114, fig. 13; Pl. 115, fig. 3). Hertwig is of the opinion that the radial ribs are thickened ridges of the endocapsa ("leistenartige Verdickungen der inneren Membran"), and that the ectocapsa covering it is structureless (compare his figs. 1 and 1a, in Taf. x.). But I am convinced now, by numerous experiments and observations, that the radiate operculum is a part of the outer, not of the inner membrane. That part of the latter which lies immediately beyond the former, and which may be called the "inner operculum," also exhibits usually a fine radial striation; but this is probably only the cast of the stronger and much more prominent radial ribbing of the "outer operculum" belonging to the ectocapsa. The latter exhibits a large circular opening with thickened margin, when the radiate operculum is taken from it. The operculum becomes stained intensely red by carmine, yellow by nitric acid, corresponding to the ectocapsa, the main-opening of which is closed by it.
The proboscis, or the cylindrical tubule, which arises in the centre of the operculum, is often rather short, and bears the same relation to it as the nipple does to the human breast (Pl. 104, fig. 2). But usually it is more or less prolonged and often about as long as the radius of the capsule, rarely nearly as long as its diameter (Pl. 101, fig. 1). Its form is usually a slender cylinder, sometimes somewhat conical and tapering towards the distal end. It is more or less curved or S-shaped in the majority of preparations (Pl. 115, fig. 3; Pl. 127, fig. 6, &c.). Its thin wall is a direct prolongation of the outer membrane of the capsule, therefore it appears as a direct apophysis of the operculum, when this is detached from the latter. The opening at the distal end of the proboscis, through which the endosarc is thrown out, is circular.
The parapylæ, or the accessory openings of the central capsule, exhibit in all Phæodaria the same form and structure, but vary in number and disposition. They are recognised with difficulty in the smaller species, since they are always of small size, and may be easily overlooked. They seem to be completely wanting in the following families:—Challengerida (Pl. 99), Medusettida (Pls. 118-120), Castanellida (Pl. 113), and in single genera of other families, as in Phæocolla (Pl. 101, fig. 1). The majority of Phæodaria seem to possess the two lateral parapylæ, first described by Hertwig, placed at a variable distance on each side of the aboral pole, to the right and left (Pl. 101, figs. 2, 6, 10; Pl. 103, fig. 1a; Pl. 104, figs. 1, 2a; Pl. 123, figs. 1, 8a &c.). The horizontal axis, on which the two parapylæ lie, is the the frontal or lateral axis; and the plane, which passes through the three openings of these "Tripylea," is the frontal or lateral plane. The number of the parapylæ seems to be variable in the two families, Circoporida and Tuscarorida, which also differ from the other Phæodaria in the peculiar (porcellanous) structure of their shell-wall. The number seems to vary even in the single species of one genus; and the following cases may be found: (A) a single parapyle, placed on the aboral pole of the main axis and directly opposed to the astropyle (on the oral pole), as in Tuscaridium (Pl. 100, fig. 8); (B) three equidistant parapylæ, one of which is placed in the sagittal plane, and the two others one on each side of it, to the right and left, is in Tuscarora (Pl. 100, figs. 1-6); the three parapylæ seem to correspond here to the three long feet, or the tubular aboral apophyses of the shell, which are arranged in a similar manner to the three cortinar feet of the Nassellaria; (C) four equidistant parapylæ, placed in pairs on the poles of the diagonal axes of a horizontal plane, as in Tuscarora (Pl. 100, fig. 7); they seem here to correspond to the four crossed aboral feet; (D) six to eight or more parapylæ probably in the different genera of Circoporida (Pls. 114-117); perhaps each radial tube, which is surrounded on its base by a circle of pores, here corresponds to a separate parapyle. The number of well-preserved central capsules belonging to the two latter families, however, which I could examine was relatively small and their examination very difficult; therefore these numbers are not stated with satisfactory certainty and require a further more accurate examination. The minute structure of the parapylæ (or "Neben-Oeffnungen") has been described already very accurately by Hertwig (loc. cit., p. 95, Taf. x. figs. 1-11b). The two membranes of the capsule are in direct and immediate connection on each parapyle. The strong outer membrane arises in the form of a ring or of a short cylindrical tubule (collare paraboscidis or "Oeffnungshals"), is then reflected inwards, and connected at the bottom of the cylindrical cavity with the delicate inner membrane. From this connective ring arises a short conical or cylindrical tubule, which we call shortly the "paraboscis." According to Hertwig (who calls it "Oeffnungskegel") the paraboscis is a direct prolongation of the inner membrane only. My own observations have led me to the opinion, that the paraboscis of each parapyle is a direct prolongation of the outer membrane (similarly to the larger proboscis of the astropyle), and that the basal connective ring is, therefore, the inner opening of the paraboscis, through which the entosarc enters, being protruded through its outer circular opening. Usually the paraboscis of each parapyle is only a short cylinder, arising by a conical base; but sometimes, especially in some Aulosphærida and Sagosphærida, it is prolonged into a slender tubule, nearly as long as the radius of the central capsule. It has been already figured by Hertwig (loc. cit., Taf. x. figs. 6-8). It seems, therefore, that the paraboscis of the accessory openings is developed in a way similar to the proboscis of the main-opening, and that the chief difference between the two is indicated by the large radiate operculum of the latter.
The cavity of the endocapsa, or the spheroidal space enclosed by the inner membrane of the central capsule, is filled up in its central part by the big nucleus, in its peripheral part by the endoplasm, or by the internal protoplasm, which is in communication with the outer or extracapsular protoplasm by the openings of that capsule. The endoplasm, or the intracapsular sarcode, is rather opaque, finely granulated, and usually filled up by numerous small clear spherules of equal size, which are more or less regularly arranged and equidistant. These spherules have usually a diameter of 0.01 to 0.015, rarely more than 0.02 or less than 0.005 mm.; their size is generally equal in each capsule. They have been already described and figured in my Monograph, as "wasserhelle kugelige Bläschen," and are probably vacuoles or small vesicles filled up by jelly or by a clear fluid. Usually each vesicle contains a small dark granule of fat, or a group of such granules connected together; and in these Hertwig observed a vibrating molecular motion. The central capsule of many Phæodaria contains, besides the vacuoles, often granules of pigment (usually red or yellow) and sometimes numerous groups of small crystals, placed mainly beyond the operculum of the astropyle (Pl. 127, figs. 4-7). The outer layer of the endoplasm, placed immediately beyond the endocapsa, often exhibits a fine striation, as if composed of delicate fibrillæ. This fibrillar striation is usually most distinct on the base of the openings, where also the endoplasm becomes stained very intensely by carmine. The astropyle as well as the parapylæ often exhibit here, when observed from the face, a distinct radial striation (compare Hertwig, loc. cit., p. 98, Taf. x. figs. 6-14) Perhaps the radiate shape of the operculum is only produced by radial folds of the endocapsa placed beyond it, and these folds may be in turn the product of the radial fibrillæ, which are prominent beyond the astropyle. On the other hand, these fibrillæ may be compared to the muscular fibrillæ or "myophane filaments" in the ectosarc of the Infusoria, and may perhaps effect by their contraction a dilatation of the openings of the capsule.
The nucleus of the Phæodaria is always very large, usually about half or two thirds as broad as the central capsule and placed either in its centre, or sometimes nearer to one pole of the main axis, which is common to the capsule and its nucleus. Therefore the diameter of the latter is usually half or even two thirds of that of the capsule, and may be in the majority 0.05 to 0.15, often 0.2 to 0.3, rarely more than 0.4 or less than 0.01 mm. The form of the nucleus is rarely spherical, usually spheroidal, and it is more depressed in the direction of the main axis than the capsule itself. In my Monograph, where I gave the first description of it, I called it "Binnenbläschen." The membrane of the vesicular nucleus is thin but rather firm, and contains a rather clear, finely granulated substance, in which numerous nucleoli are usually scattered. (Compare Pl. 101, figs. 1-10; Pl. 102-104; Pl. 123; Pl.127, &c.; the nucleus is marked by n, the nucleoli by l.)
The nucleoli are very different in respect to their form, size, number and arrangement. Since these differences are very great even in different specimens of a single species (as, e.g., in the common cosmopolitan Aulacantha scolymantha, Aulosphæra trigonopa, Cœlodendrum ramosissimum, &c.), it is probable that they represent different stages of development and multiplication, and that the smallest fragments of the nucleoli, or the final results of their repeated division, become the nuclei of the flagellate spores, which are developed in the Phæodaria just as in the other Radiolaria. In the majority of nuclei examined, the number of the enclosed nucleoli proved to be very great, fifty to eighty or more, often some hundreds, the greater their number the smaller their size. Their form is usually irregular, roundish, or even amœboid—probably the result of amœbiform motions (Pl. 101, fig. 1). Sometimes the nucleoli were regularly spherical, equidistant, and connected apparently by a delicate network (Pl. 101, fig. 2). (Compare Pl. 102-104, 111, 123, and also Taf. x. of Hertwig, loc. cit.).
The calymma, or the extracapsular jelly-veil, is in the Phæodaria always well developed and usually much larger than the enclosed central capsule. The entire volume of the calymma may be three to six times as great as that of the capsule in the majority of this legion; but in the large Aulacanthida, Aulosphærida, Cœlodendrida, Cœlographida, &c., the volume of the former is twenty to fifty as great as that of the latter, or even more. The jelly substance is rather firm and consistent, clear, structureless, and becomes more or less intensely stained by carmine. In the larger forms it is often filled by numerous large alveoles, which are usually absent in the smaller forms. These extracapsular alveoles are most strongly developed in the calymma of the Phæocystina, or the Phæodaria with incomplete skeleton, embracing the three families Phæodinida, Cannorrhaphida and Aulacanthida (Pls. 101-104). Usually the calymma is here very voluminous and entirely filled up by large alveoles, which are either spherical, irregularly roundish, or polyhedral by mutual compression. These alveoles or vacuoles have no peculiar wall, but are only cavities in the homogeneous substance of the jelly, and are filled by a clear aqueous fluid. Between these the network of the anastomosing pseudopodia is expanded. They exhibit, therefore, the same shape, as was first observed in Thalassicolla and in the Polycyttaria (Collozoida, Sphærozoida and Collosphærida).
The relation of the calymma to the skeleton is in the Phæodaria of the same importance as in the other Radiolaria, and we may also here distinguish a primary and a secondary calymma. The primary calymma is that on the surface of which at a certain period of life (in the "shell-building period") the fenestrated shell is secreted in the majority of Phæodaria. The secondary calymma, however, is formed after this period, and envelops the shell itself as well as its apophyses externally. Usually the entire skeleton seems to be enveloped by the secondary calymma.