6. Eusyringium fistuligerum, Haeckel.

Shell with four joints, thin-walled, smooth. Cephalis subspherical, with numerous very small pores, and a stout, pyramidal horn of the same length. Thorax hemispherical. Third joint subspherical, four times as long as the thorax, and of the same length as the slender, inversely conical or cylindrical, fourth joint. Pores irregular, roundish or circular, in the fourth joint twice as broad as in the two preceding joints.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.02, c 0.08, d 0.08; breadth 0.09.

Habitat.—Fossil in Barbados.

Subgenus 2. Eusyringoma, Haeckel.

Definition.—Shell with four or more strictures, and five or more joints; the last joint is strongly constricted, and forms a narrow cylindrical tube.

7. Eusyringium lagenoides, Haeckel.

Shell with five joints, and four sharp strictures, nearly spindle-shaped. The third joint is twice as long as the second and the fourth. Cephalis small, cap-shaped, with a thin conical horn of the same length. The fifth joint is in Stöhr's figure broken off, but well conserved in a specimen from Caltanisetta, and represents a slender cylindrical tube, with few pores, half as long as the shell. Pores small, subregular, circular, quincuncial.

Dimensions.—Length of the shell (with five joints) 0.24, breadth 0.08; length of the third joint 0.06, of the second and the fourth 0.03, of the fifth 0.1; breadth of the basal tube 0.027.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).

8. Eusyringium rhaphanus, Haeckel.

Shell with six or seven joints of very different lengths, in the upper half campanulate, in the lower cylindrical. The second and the two last joints are the longest. Cephalis small, subspherical, with a short conical horn. The last joint is a narrow cylindrical tube of variable length, scarcely one-fourth as broad as the preceding joints. Pores in the upper joints regular, circular, in the lower irregular, roundish.

Dimensions.—Length of the shell (with seven joints) 0.2, breadth 0.1; length of the second and last joints 0.03 to 0.04; breadth of the basal tube 0.025.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte).

9. Eusyringium siphonostoma, n. sp. (Pl. 80, fig. 14).

Shell with eight joints, in the upper half slender, conical, in the lower half cylindrical. The single joints are separated by seven internal annular septa. The third and the seventh joints are the largest, twice as long as the three intercalated joints. Cephalis small, cap-shaped, with a conical horn of twice the length. The last joint (broken off in the specimen figured) is a narrow cylindrical tube, one-third as long and one-third as broad as the shell. Pores regular, circular, quincuncial.

Dimensions.—Length of the shell (with eight joints) 0.24, breadth 0.08; length of the single joints 0.02 to 0.04; breadth of the basal tube 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

10. Eusyringium cannostoma, n. sp. (Pl. 80, fig. 13).

Shell with nine or ten joints, slender ovate. The single joints are separated by eight or nine internal annular septa. The third joint is the longest, about twice or three times as long as each following joint. Cephalis hemispherical, with a curved, conical horn of the same length. The last joint is a narrow, cylindrical tube, about as long as the third joint, but only one-fourth as broad. Pores small, regular, circular, quincuncially disposed, and hexagonally framed.

Dimensions.—Length of the shell (with ten joints) 0.22, breadth 0.08; length of the third joint 0.04, of the other joints 0.01 to 0.02, of the basal tube 0.04; breadth of the latter 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 649. Siphocampe,^[266] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis with an oblique, open, apical tube.

The genus Siphocampe differs from the closely allied genera Lithocampe and Eucyrtidium in a very remarkable character, viz., the development of a hollow cylindrical tube on the cephalis. This probably serves for the emission of a bunch of pseudopodia. It has the same position and the same oblique direction on the cephalis as the solid apical horn of Eucyrtidium.

Subgenus 1. Siphocampula, Haeckel.

Definition.—All joints of the shell (excepting the first) are nearly equal in length.

1. Siphocampe tubulosa, n. sp. (Pl. 79, fig. 13).

Shell slender nearly spindle-shaped, with eight deep transverse strictures, and elegant longitudinal ribs. Nine joints slightly different in length and shape. Cephalis flat, cap-shaped, with three or four transverse rows of small pores, and a cylindrical, oblique tubule of twice the length. Each successive joint with a single transverse row of regular, circular pores at its lower edge, separated by divergent, longitudinal ribs. Last joint shorter, with a hyaline annular peristome of the same length. Mouth half as broad as the middle part of the shell.

Dimensions.—Length of the shell (with nine joints) 0.24; length of each joint (on an average) 0.02 to 0.03; breadth 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Siphocampe annulosa, n. sp. (Pl. 79, fig. 10).

Shell slender, subcylindrical, with nine slight transverse strictures, and interrupted longitudinal ribs. Ten joints nearly equal in length and shape, excepting the two first, which together form a hemispherical cephalothorax, with six to eight transverse rows of pores. Tubule of the cephalis short and wide, truncate, conical. Each of the eight abdominal joints with a single transverse row of small pores. Mouth constricted, without tubulose peristome, half as broad as the shell.

Dimensions.—Length of the shell (with ten joints) 0.18; length of each joint (on an average) 0.02, breadth 0.07.

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

3. Siphocampe caminosa, n. sp. (Pl. 79, fig. 12).

Shell slender, subcylindrical, with six deep transverse strictures. Seven joints nearly equal in length and breadth. Cephalis hemispherical, with an oblique, cylindrical tubule of twice the length (in the figure the greater part is broken away). Small circular pores in transverse rows and in variable number; usually three rows in the first and the last joint, five rows in the fourth joint, four rows in each of the other joints. Mouth constricted, with a short tubulose peristome, only one-third as broad as the shell.

Dimensions.—Length of the shell (with seven joints) 0.18; length of each joint (on an average) 0.025, breadth 0.055.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Siphocampe erucosa, n. sp. (Pl. 79, fig. 11).

Shell slender, nearly spindle-shaped, with five slight transverse strictures. Six joints nearly equal in length. The two first joints are united, and form together a hemispherical cephalothorax, with a short, oblique, cylindrical tubule. Pores regular, circular, double-contoured, in regular, transverse rows; two rows in the first and the last joints, four rows in each of the four middle joints. Mouth constricted, without peristome, only one-third as broad as the shell.

Dimensions.—Length of the shell (with six joints) 0.14; length of each joint (on an average) 0.02, breadth 0.07.

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

Subgenus 2. Siphocampium, Haeckel, 1881, Prodromus, p. 437.

Definition.—The joints of the shell are very different in length.

5. Siphocampe quadrantalis, n. sp.

Shell nearly spindle-shaped, with three deep strictures. Four joints of very different lengths. Cephalis subspherical with an oblique cylindrical tubule of twice the length, and with few small pores. Thorax ovate, half as long as the shell, with twelve transverse rows of small pores. Abdomen with two short joints, each of which has two transverse rows of pores. Mouth constricted, one-third as broad as the thorax.

Dimensions.—Length of the shell (with four joints) 0.18; length of the thorax 0.1, breadth 0.08.

Habitat.—Western Tropical Pacific; North Coast of New Guinea, Station 220, depth 1100 fathoms.

6. Siphocampe spiralis, n. sp. (Pl. 79, fig. 14).

Shell nearly spindle-shaped, with eight slight strictures. Nine joints of very different lengths. Cephalis subspherical, with an oblique cylindrical tubule of the same length, and numerous small pores. Thorax conical, one-fourth as long as the shell, with eight transverse rows of small pores. Abdomen with numerous prominent, spirally convoluted ribs, and spiral rows of pores between them. The first abdominal joint is from two to three times as long as each of the six following joints. Abdominal pores larger, roundish, disposed in eleven transverse rows. Four rows in the first abdominal joint, one row in each of the five following, and two rows in the last joint. Mouth slightly constricted, two-thirds as broad as the shell.

Dimensions.—Length of the shell (with nine joints) 0.17, cephalis 0.02, thorax 0.04, abdomen 0.11; breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados.

Genus 650. Lithocampe,^[267] Ehrenberg, 1838, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 128 (sensu emendato).

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis without horn and tube.

The genus Lithocampe is the oldest of all "Polycystina," being founded by Ehrenberg in 1838 upon Lithocampe radicula. Afterwards numerous other species, which belong to very different genera, were described by him. In 1862 I attempted to give a more strict definition of this genus in my Monograph (p. 312 to 315), and separated it from the closely allied and often confounded Eucyrtidium by the absence of a cephalic horn. The great number of species afterwards discovered leads to the stricter definition given above.

Subgenus 1. Lithocampula, Haeckel.

Definition.—All joints of the shell (except often the first) are equal or nearly equal in length.

1. Lithocampe eupora, Haeckel.

Shell smooth, ovate or subconical, with three deep strictures. Four joints equal in length, gradually increasing in breadth, each with three transverse rows of regular, circular, hexagonally-framed pores; the fourth joint is the broadest. Mouth little constricted, of the same breadth as the third joint.

Dimensions.—Length of the shell (with four joints) 0.08; length of each joint 0.02, greatest breadth 0.06.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; North Atlantic, depth 3600 fathoms (Morse).

2. Lithocampe platycephala, Haeckel.

Shell smooth, subconical or slenderly ovate, with three slight strictures. Four joints equal in length, slightly increasing in breadth towards the mouth. The hemispherical cephalis with longitudinal ribs and irregular pores, each of the three other joints with four transverse rows of regular, circular pores. Mouth strongly constricted, half as broad as the third and fourth joints.

Dimensions.—Length of the shell (with four joints) 0.12; length of each joint 0.03, greatest breadth 0.06.

Habitat.—North Atlantic, depth 3600 fathoms (Morse).

3. Lithocampe nereidum, Haeckel.

Shell smooth, slenderly ovate, with four deep strictures. Five joints equal in length, the fourth being the broadest. Each joint with three transverse rows of small, regular, circular pores (sometimes in the fourth joint there are four rows). Mouth constricted, half as broad as the fourth joint. (In Ehrenberg's figure all five joints are delineated, but the greater part of the hemispherical cephalis is broken off.)

Dimensions.—Length of the shell (with five joints) 0.1, of each joint 0.02; breadth of the fourth joint 0.05.

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

4. Lithocampe radicula, Ehrenberg.

Shell smooth, spindle-shaped, with five sharp strictures. Six joints equal in length, each with four transverse rows of regular, circular, double-edged pores. The third and fourth joints are the broadest, and equal. The constricted mouth is not broader than the hemispherical cephalis, scarcely one-fourth as broad as the third and the fourth joints. This remarkable species is the oldest known skeleton of a Radiolarian, a figure of it being given in 1838, loc. cit. (compare my Monograph, 1862, p. 3, 4, 331). But this figure of Ehrenberg is not quite accurate, and differs from other figures of the same species, which he afterwards (1854) published in his Mikrogeologie (loc. cit.). The best of these is fig. 23a in pl. xxii., and is identical with the typical form (common in Barbados), and according to this I have here framed my description. The sixth joint possesses a distinct (though small) terminal mouth; when this becomes closed, the species passes over into Stichocapsa radicula.

Dimensions.—Length of the shell (with six joints) 0.18, length of each joint (on an average) 0.03; breadth of the third and fourth joints 0.08, of the second and fifth 0.06, of the terminal mouth and the cephalis 0.03.

Habitat.—Fossil in Tertiary rocks of Barbados.

5. Lithocampe ventricosa, Haeckel.

Shell ovate, with six slight strictures. Seven joints nearly equal in length, each with four (or sometimes three or five) transverse rows of small, regular, circular pores, in the last joint the pores are larger. The fourth and fifth joints are the broadest, and are twice as broad as the constricted mouth.

Dimensions.—Length of the shell (with seven joints) 0.13 to 0.14; length of each joint 0.017 to 0.02, greatest breadth 0.083, mouth 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.

6. Lithocampe fusiformis, n. sp.

Shell smooth, spindle-shaped, decreasing uniformly towards the two blunt poles, with eight or nine sharp strictures, and nine or ten joints of equal lengths, each with four transverse rows of regular, hexagonal pores. The fourth and fifth joints are the broadest. The constricted mouth is twice as broad as the hemispherical cephalis, half as broad as the fourth joint.

Dimensions. —Length of the shell (with ten joints) 0.2, of each joint 0.02; breadth of the fourth joint 0.06, mouth 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subgenus 2. Lithocampium, Haeckel, 1881, Prodromus, p. 437.

Definition.—The joints of the shell are very different in length.

7. Lithocampe ovata, n. sp. (Pl. 77, fig. 1).

Shell smooth, urceolate or ovate, with three sharp strictures. Four joints of different lengths, having the proportion 1 : 2 : 2 : 6. The fourth joint is inflated and the broadest. The mouth is constricted, short, tubular, of the same breadth as the hemispherical cephalis. Pores small, circular, in regular transverse rows; four rows in the first, four in the second, two in the third, and five in the fourth joint. The middle stricture is crossed by longitudinal ribs.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.01, b 0.02, c 0.02, d 0.06; greatest breadth 0.055.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Lithocampe aquilonaris, Haeckel.

Shell smooth, subconical, with three distinct strictures. Four joints of different lengths, having the proportion 3 : 1 : 3 : 4. The fourth joint is the broadest, suddenly constricted, with a short tubular mouth of half the breadth. Pores subregular, circular, in transverse rows; three rows in the first joint, two in the second, four in the third, and three in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.03, b 0.01, c 0.03, d 0.04; breadth 0.06.

Habitat.—North Pacific, Kamtschatka (Bailey), Station 241, depth 2300 fathoms.

9. Lithocampe quadrarticulata, Haeckel.

Shell smooth, spindle-shaped, with three deep strictures. Four joints of different lengths = 1 : 3 : 4 : 3. The third joint is the broadest, being twice as broad as the constricted mouth of the fourth joint. Pores small, regular, circular, in transverse rows; two being in the first, three in the second, four in the third, three in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.03, c 0.04, d 0.025; greatest breadth 0.05.

Habitat.—North Atlantic (Greenland, depth 1600 fathoms, Ehrenberg), Station 64, surface.

10. Lithocampe multiseriata, Haeckel.

Shell smooth, spindle-shaped, or slenderly ovate, with three sharp strictures. Four joints of different lengths = 3 : 4 : 5 : 10. The third and fourth joints nearly equal in breadth, and twice as broad as the hemispherical cephalis. The truncate mouth is slightly constricted. Pores very small and numerous, in regular transverse rows. Three or four rows in the first, five or six in the second, seven or eight in the third, and fifteen to twenty 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 0.025, d 0.05; breadth 0.045.

Habitat.—Tropical Pacific (Philippine Sea, Ehrenberg), Stations 206, 224, 266, in various depths.

11. Lithocampe diploconus, n. sp. (Pl. 77, fig. 3).

Shell rough, doubly conical, with three distinct strictures. Four joints of different lengths = 2 : 5 : 5 : 8. The third joint is the broadest. The three first joints form together a broad cone, and the fourth an inverse truncate cone; the latter is distinguished by convergent longitudinal ribs. Pores regular, circular, alternating with the ribs in the fourth joint. Truncate mouth hyaline, half as broad as the third joint.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.05, c 0.05, d 0.08; breadth (in the middle part) 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

12. Lithocampe diaphana, Haeckel.

Shell smooth, hyaline, spindle-shaped, decreasing uniformly towards both poles, with three distinct strictures. Four joints of different lengths; the second and third equal in breadth, twice as broad and three times as long as the first and the fourth. Pores very small and scarce, in transverse interrupted rows, commonly two rows in the first, two or three in the second, three or four in the third, and only one in the last joint. Mouth constricted, two-thirds as broad as the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.13. Length of the single joints, a 0.015, b 0.05, c 0.05, d 0.015; breadth (in the middle part) 0.06, mouth 0.02.

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

13. Lithocampe hispida, Haeckel.

Shell thorny, slenderly ovate, or nearly spindle-shaped, with four sharp strictures. Five joints of different lengths = 3 : 3 : 4 : 6 : 4. The fourth joint is the broadest, and nearly twice as broad as the constricted mouth. Pores small, circular, separated by longitudinal, spiny ribs, regularly disposed in transverse rows; three rows in the first and second, four rows in the third and fifth, six rows in the fourth joint.

Dimensions.—Length of the shell (with five joints) 0.1. Length of the single joints, a 0.015, b 0.015, c 0.02, d 0.03, e 0.02; greatest breadth 0.05.

Habitat.—Arctic Ocean (in different depths), Ehrenberg.

14. Lithocampe tumidula, Haeckel.

Shell smooth, nearly spindle-shaped, with four sharp strictures, very similar to the preceding in size and form. It differs in the smooth surface, the absence of longitudinal ribs, and the unequal size of the pores, which form four transverse series in each joint, and are much larger in the broadest (fourth) joint. Proportion of the five joints = 2 : 2 : 3 : 5 : 4.

Dimensions.—Length of the shell (with five joints) 0.1. Length of the single joints, a 0.012, b 0.012, c 0.02, d 0.03, e 0.025; greatest breadth 0.05.

Habitat.—Cosmopolitan; Atlantic, Pacific; many stations, in different depths.

15. Lithocampe heteropora, Haeckel.

Shell smooth, subconical, obtuse, with four distinct strictures. Five joints of different lengths = 2 : 4 : 3 : 3 : 2. The fourth joint is the broadest. Mouth slightly constricted. Pores regular, circular, in the second joint much larger than in the four others, disposed in transverse series; two rows in the first and fifth, three rows in the second, four rows in the third and fourth joints.

Dimensions.—Length of the shell (with five joints) 0.14. Length of the single joints, a 0.02, b 0.04, c 0.03, d 0.03, e 0.02; greatest breadth 0.07.

Habitat.—North Atlantic (depth 2000 fathoms, Ehrenberg), Canary Islands, surface, Haeckel.

16. Lithocampe meta, Stöhr.

Shell rough, subconical, obtuse, with four slight strictures. Five joints of different lengths = 2 : 4 : 5 : 4 : 2. The fourth joint is the broadest, and three times as broad as the constricted mouth. Pores, small, regular, circular, quincuncially disposed, equal in size; two transverse rows in the first and fifth, five rows in the second and fourth, six rows in the third joint.

Dimensions.—Length of the shell (with five joints) 0.14. Length of the single joints, a 0.017, b 0.033, c 0.04, d 0.033, e 0.017; greatest breadth 0.083.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr), Caltanisetta (Haeckel).

17. Lithocampe urceolata, n. sp. (Pl. 77, fig. 2).

Shell rough, wide, urceolate, without external strictures, but with four internal septal rings (not visible in the figure), each of which contains an internal circle of horizontal pores. Five joints of different lengths = 2 : 3 : 6 : 4 : 2. The third joint is the broadest, and three times as broad as the constricted mouth. Pores of very different sizes, irregular, roundish, with prominent polygonal frames. A very remarkable species.

Dimensions.—Length of the shell (with five joints) 0.17. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.04, e 0.02; greatest breadth 0.13.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

18. Lithocampe clava, Ehrenberg.

Shell smooth, club-shaped, or slenderly ovate, with five internal septal rings. Six joints of very different lengths = 5 : 2 : 3 : 4 : 5 : 18. The sixth joint is the broadest, and as long as the five others together. Pores small, circular, in the basal half of the last joint irregular and larger. Constricted mouth as broad as the subspherical, hyaline cephalis.

Dimensions.—Length of the shell (with six joints) 0.15. Length of the single joints, a 0.02, b 0.011, c 0.013, d 0.016, e 0.02, f 0.07.

Habitat.—Fossil in Barbados.

19. Lithocampe hexacola, n. sp. (Pl. 79, fig. 7).

Shell smooth, nearly spindle-shaped, without external strictures, but with five internal septal rings. Six joints of different lengths = 4 : 8 : 5 : 5 : 5 : 10. The fourth joint is the broadest, and four times as broad as the constricted mouth. Pores subregular hexagonal, or irregular polygonal, with thin bars.

Dimensions.—Length of the shell (with six joints) 0.18, greatest breadth 0.09. Length of the six joints, a 0.02, b 0.04, c, d, and e each 0.025, f 0.05.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

20. Lithocampe heptacola, n. sp. (Pl. 79, fig. 8).

Shell smooth, subcylindrical, constricted at both poles, with six distinct strictures. Seven joints of different lengths, the five abdominal joints nearly equal, each half as long as the hemispherical, vaulted thorax, and twice as long as the subspherical, small cephalis. Mouth constricted, with a short, tubular, hyaline peristome (like an eighth joint without pores), about one-third as broad as each of the four middle joints. Pores subregular hexagonal, or irregular polygonal, with thin bars.

Dimensions.—Length of the shell (with seven joints) 0.24, greatest breadth 0.09. Length of the cephalis 0.02, thorax 0.06, each of the four following joints 0.03, of the last joint 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

21. Lithocampe octocola, n. sp. (Pl. 79, fig. 6).

Shell smooth, subcylindrical, thick-walled, constricted at both poles, without distinct, external strictures, but with seven internal septal rings. Eight joints of different lengths; four joints (the second to the fifth) being about twice as long as the four others (the first and the three last). The constricted mouth only one-third as broad as the four middle joints. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with eight joints) 0.19, breadth 0.09. Length of the second to the fifth joints, each 0.03; length of the four other joints, each about 0.016.

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

22. Lithocampe polycola, n. sp.

Shell smooth, subcylindrical, constricted at both poles, with twelve to fifteen distinct strictures. Fourteen to sixteen joints of different lengths. Cephalis flat, cap-shaped, hyaline, without pores. Thorax nearly hemispherical, with three transverse rows of small circular pores. Each following joint (each abdominal joint) only with a single row of small pores. The constricted mouth of the last joint only one-third as broad as the middle part of the shell. (Very similar to Lithomitra eruca, Pl. 79, fig. 3.)

Dimensions.—Length of the shell (with sixteen joints) 0.3, breadth 0.08. Length of the cephalis 0.02, thorax 0.06, each of the following joints 0.015, last joint 0.025.

Habitat.—Tropical Pacific, Station 224, depth 1850 fathoms.

Genus 651. Spirocyrtis,^[268] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with spirally-arranged constrictions on the shell. Cephalis with a horn.

The genus Spirocyrtis and the following closely allied genus Spirocampe differ from the other Stichocorida (and also from nearly all Cyrtoidea) in a very remarkable character. The annular constrictions of the multiarticulate shell and the corresponding internal annular septa are here not separated, and do not lie in parallel, transverse planes (as usually happens), but they are all or partly connected in the form of an ascending spiral, so that the joints are not perfectly separated. An irregularity or asymmetry of growth on the different sides of the shell is probably the cause of this strange, spiral structure.

Subgenus 1. Spirocyrtidium, Haeckel.

Definition.—Shell conical, gradually dilating towards the wide open terminal mouth.

1. Spirocyrtis scalaris, n. sp. (Pl. 76, fig. 14).

Shell conical, gradually dilating towards the wide open mouth, with ten to twelve spiral convolutions, which correspond to the same number of short and broad chambers or joints, gradually increasing in breadth; all joints form together a spirally winding staircase. The length or height of the single joints or stairs is about equal, and each bears four or five transverse rows of small, square pores. Cephalis flat, cap-shaped, with two or three short divergent horns.

Dimensions.—Length of the shell (with ten joints or turnings) 0.16, length of each joint (on an average) 0.016; breadth of the third joint 0.04, of the fifth joint 0.07, of the tenth joint 0.1.

Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

2. Spirocyrtis cornutella, n. sp. (Pl. 76, fig. 13).

Shell conical, gradually dilating towards the wide mouth, similar to the preceding, but differing in the curved axis, and the broader and shorter joints, each of which bears only two or three transverse rows of square pores. The turnings of the staircase are not so sharp, nor so distinct, as in the preceding species. Cephalis with a single short horn.

Dimensions.—Length of the shell (with eight joints) 0.1; breadth of the fourth joint 0.05, of the eighth joint 0.08.

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

Subgenus 2. Spirocyrtoma, Haeckel.

Definition.—Shell ovate, or nearly spindle-shaped, more or less tapering towards the narrower, somewhat constricted mouth.

3. Spirocyrtis holospira, n. sp. (Pl. 76, fig. 16).

Shell subovate, twice as long as broad, without external strictures, but with an internal regularly descending spiral septum, which separates seven to nine broad joints of nearly equal lengths; the first and second joints together are conical, and about as long as each of the following joints. Cephalis small, hemispherical, with a thick pyramidal horn of the same length. The fifth joint is the broadest, the truncate mouth is slightly constricted (in the specimen figured it is broken off). Pores regular, circular, quincuncial.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1; length of each joint, about 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Spirocyrtis hemispira, n. sp.

Shell slender, nearly spindle-shaped, three times as long as broad, without external strictures, but with ten to eleven internal septa. The five or six upper of these are perfectly separate, complete parallel rings; the five or six lower are spirally connected. The eleven or twelve joints gradually taper in length and breadth, from the broadest middle towards the two constricted ends of the shell. The middle (fifth or sixth) joint is the broadest, and is three to four times as broad as the constricted mouth. Cephalis small, hemispherical, with a conical horn of the same length. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with twelve joints) 0.25, breadth 0.09; length of the middle joint 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Spirocyrtis merospira, n. sp. (Pl. 76, fig. 15).

Shell ovate, with six to eight slight strictures, twice as long as broad. The three or four upper joints are perfectly separated by annular septa, the three or four lower joints connected by an internal spiral septum. The spiral line is often more or less irregular or interrupted (as is also the case in the specimen figured). Mouth rather wide. Pores small, subregular, circular. A rather variable species.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

6. Spirocyrtis diplospira, n. sp. (Pl. 76, fig. 17).

Shell slender, ovate, with seven to eight slight strictures. All eight or nine joints are connected by an internal double spiral septum, the first spiral beginning from the ventral side, the second from the dorsal side of the collar stricture. Length and breadth of the single joints rather variable and irregular; the broadest joint is commonly the fifth. Mouth more or less constricted. Pores subregular, circular. This remarkable species differs from all other Cyrtoidea by the double spiral septum of the joints.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1.

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

Genus 652. Spirocampe,^[269] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with spirally arranged constrictions on the shell. Cephalis without horn.

The genus Spirocampe has the same peculiar spiral structure of the shell as the preceding Spirocyrtis, and differs from it only in the absence of a cephalic horn. It exhibits, therefore, the same relation to the latter as the similar Lithocampe bears to Eucyrtidium.

1. Spirocampe callispira, n. sp. (Pl. 76, fig. 11).

Shell ovate, smooth, with six joints, connected in the form of a complete winding staircase. All the windings are nearly at equal distances; each bears one row of large roundish pores, enclosed by two rows of smaller pores. Cephalis hemispherical, of about the same breadth as the constricted, short tubular mouth.

Dimensions.—Length of the shell (with six joints) 0.15, breadth 0.09; mouth 0.03 diameter.

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

2. Spirocampe allospira, n. sp. (Pl. 76, fig. 12).

Shell subcylindrical, or nearly spindle-shaped, smooth, very thick-walled, with eight joints alternately longer and shorter, and connected in the form of an irregular spiral. The distance between the windings is very variable. Pores small, regular, circular. Cephalis hemispherical, of about the same size as the short tubular mouth.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.08; mouth 0.03 diameter.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

3. Spirocampe polyspira, n. sp.

Shell cylindrical, rough, with twelve joints nearly equal in length, connected in the form of a regular, complete spiral. All windings are at the same distance. Pores regular, circular, three rows on each turning. Cephalis flat, cap-shaped, half as broad as the slightly constricted, not tubular mouth.

Dimensions.—Length of the shell (with twelve joints) 0.24, breadth 0.07; mouth 0.05 diameter.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subfamily 2. Stichocapsida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Lithocampida with the terminal mouth of the shell fenestrated (vel Stichocyrtida eradiata clausa).