Shell slenderly conical, smooth, with straight axis, and eight to ten deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the third. In each joint three transverse rows of pores. Horn of the cephalis bristle-shaped, strongly curved, about as long as the shell (Ehrenberg confounds this species with Lithostrobus cuspidatus).

Dimensions.—Length of the shell (with eight joints) 0.16, of each joint 0.02; breadth of the fourth joint 0.04, of the eighth 0.08.

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

4. Lithostrobus tetrastichus, n. sp. (Pl. 80, fig. 6).

Shell slenderly conical, smooth, with straight axis and six to eight deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the second. In each joint four transverse rows of regular, circular pores with very thin bars. Horn of the cephalis conical, strong, curved, about as long as two joints.

Dimensions.—Length of the shell (with eight joints) 0.12, of each joint 0.015; breadth of the second joint 0.02, of the eighth 0.04.

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

5. Lithostrobus pentastichus, n. sp.

Shell slenderly conical, smooth, with straight axis, and six to eight slight strictures. All joints nearly of the same length, the sixth twice as broad as the third. In each joint five transverse rows of small circular pores. Horn of the cephalis pyramidal, of twice the length. (Similar to Eucyrtidium cienkowskii, Pl. 80, fig. 9, but regularly conical, with all the joints equal in length.)

Dimensions.—Length of the shell (with eight joints) 0.2, of each joint 0.025; breadth of the third joint 0.04, of the sixth 0.08.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

6. Lithostrobus hexastichus, n. sp. (Pl. 80, fig. 15).

Shell campanulate-conical, smooth, with straight axis, and six to eight slight strictures. All joints nearly of the same length, the sixth joint twice as broad as the second. In each joint six transverse rows of subregular, hexagonal pores, with thin bars. Horn of the cephalis conical, straight, of about the same length. (The specimen figured is a somewhat irregular one; other specimens found afterwards were perfectly conical and regular, with joints of equal length).

Dimensions.—Length of the shell (with six joints) 0.16, of each joint 0.027.

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

Subgenus 2. Cornustrobus, Haeckel.

Definition.—Shell horn-shaped, conical, with curved axis; all joints nearly equal in length, gradually increasing in breadth.

7. Lithostrobus cyrtoceras, n. sp. (Pl. 80, fig. 2).

Shell horn-shaped, conical, with curved axis, smooth, with six to eight deep strictures. All joints nearly of the same length, gradually increasing in breadth; the sixth joint twice as broad as the second. In each joint about four transverse series of regular circular pores. Horn of the cephalis conical, slightly curved, of the same length.

Dimensions.—Length of the curved axis of the shell (with eight joints) 0.24, length of each joint 0.03; breadth of the second joint 0.04, of the sixth 0.08.

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

8. Lithostrobus leptoceras, n. sp.

Shell horn-shaped, slenderly conical, with curved axis (like a quadrant of a circle), smooth, with twelve to fourteen slight strictures. All joints nearly of the same length, the tenth twice as broad as the second. In each joint only a single transverse row of small circular pores. Horn of the cephalis curved, bristle-shaped, half as long as the shell.

Dimensions.—Length of the curved axis of the shell (with twelve joints) 0.18, length of each joint 0.15; breadth of the second joint 0.02, of the tenth 0.04.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

9. Lithostrobus caloceras, n. sp. (Pl. 80, fig. 4).

Shell horn-shaped, conical, with curved axis, smooth, with six to eight deep strictures. All joints nearly of the same length, the sixth twice as broad as the third. On each joint a single circle of very large roundish pores, separated by two to four series of smaller pores. Horn of the cephalis conical, curved, of twice the length.

Dimensions.—Length of the curved axis of the shell (with six joints) 0.12, length of each joint 0.02; breadth of the third joint 0.04, of the sixth 0.08.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

10. Lithostrobus macroceras, n. sp.

Shell horn-shaped, slenderly conical, with curved, nearly semicircular axis, without external strictures, but with twelve to twenty internal septal rings. All joints nearly of the same length, the twelfth twice as broad as the third. On each joint three to four transverse rows of subregular, small, hexagonal pores. Horn of the cephalis conical, curved, of twice the length.

Dimensions.—Length of the curved axis of the shell (with sixteen joints) 0.32, length of each joint 0.02; breadth of the third joint 0.02, of the twelfth 0.04.

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

Subgenus 3. Cyrtostrobus, Haeckel.

Definition.—Shell conical (often more campanulate or irregular), with straight axis; joints of different lengths. Cephalis not lobate.

11. Lithostrobus conulus, n. sp. (Pl. 80, fig. 1).

Shell slenderly conical, smooth, with straight axis, and seven to ten distinct strictures. Joints of different lengths; the fourth and fifth about twice as long as the preceding and following joints, the former with four to five, the latter with two to three transverse rows of large irregular pores; the seventh joint twice as broad as the third. Horn of the cephalis short, pyramidal.

Dimensions.—Length of the shell (with eight joints) 0.14, length of the fifth joint 0.03; breadth 0.06.

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

12. Lithostrobus picus, Bütschli.

Shell slenderly conical, smooth, with straight axis, and six to eight slight strictures. Joints of different lengths, the second twice as long as each of the three following, and four times as long as each of the last joints; the sixth joint one and a-half times as broad as the second. Small circular pores in regular transverse rows; six rows in the first and the second, three rows in the third, fourth, and fifth, a single row in each of the last joints. Horn of the cephalis cylindrical, half as long as the shell.

Dimensions.—Length of the shell (with eight joints) 0.12, length of the second joint 0.03; breadth 0.04.

Habitat.—Fossil in Barbados.

13. Lithostrobus argus, Bütschli.

Shell conical, thorny, with straight axis, and five to seven slight strictures. Joints of different lengths, each of the three first twice as long as each of the following. Pores large, roundish, in transverse rows; three rows in the first and the second joints (which in the figure of Ehrenberg are not separated), two rows in the third joint, a single row in each of the following joints. Horn of the cephalis large, conical, curved, half as long as the shell.

Dimensions.—Length of the shell (with seven joints) 0.2, length of the fourth joint (and each following) 0.02; breadth 0.1.

Habitat.—Fossil in Barbados.

14. Lithostrobus acuminatus, Haeckel.

Shell slenderly conical, smooth, with straight axis, and four to six deep strictures. Joints gradually increasing in length. Pores in regular, transverse rows, commonly three rows in the first, four in the second, five in the third, six in the fourth, seven in the fifth, &c. (sometimes the increase of the number is more or less irregular). Horn of the cephalis strong, conical, straight, about as long as the fourth or sixth joint.

Dimensions.—Length of the shell (with six joints) 0.2; length of the fourth joint 0.04, breadth 0.06.

Habitat.—Fossil in Barbados.

15. Lithostrobus cuspidatus, Haeckel.

Shell, slender, conical, smooth, with straight axis, and ten to twelve distinct strictures. Joints gradually increasing slightly in length, the tenth twice as long as the third. Pores circular, in regular transverse rows; commonly two rows in the first, three in the second, four in the third, seven in the eighth and following joints. Horn of the cephalis long, bristle-shaped, curved. This species called Eucyrtidium cuspidatum by Ehrenberg, differs from Lithostrobus tristichus (compare above), to which Bailey had given the same name.

Dimensions.—Length of the shell (with ten joints) 0.2; length of the tenth joint 0.03, breadth 0.06.

Habitat.—North Atlantic (Greenland, Ehrenberg); Station 348, depth 2450 fathoms.

16. Lithostrobus cornutella, Bütschli.

Shell slender, conical, smooth, with straight axis, and seven to nine slight strictures. Joints gradually increasing slightly in length, the sixth or seventh about twice as long as the third. Pores circular, in regular transverse rows; two or three in the three or four first joints, three or four in the following, four or five in the last joints. Horn of the cephalis thin, bristle-shaped, curved.

Dimensions.—Length of the shell (with eight joints) 0.1; length of the eighth joint 0.01, breadth 0.04.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; many stations, surface.

17. Lithostrobus tornatus, Haeckel.

Shell campanulate-conical, smooth, with straight axis, and four to six deep strictures. Joints broad, gradually increasing in length, the fifth twice as long as the second. Pores small, circular, in regular transverse rows; in the second and third joints three or four rows, in the fifth seven rows, &c. Horn of the cephalis small, double or forked.

Dimensions.—Length of the shell (with five joints) 0.1; length of the fifth joint 0.04, breadth 0.08.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

18. Lithostrobus seriatus, n. sp. (Pl. 79, fig. 15).

Shell slender, conical, smooth, with straight axis, and four or five deep strictures. Joints little different in length, increasing towards the inflated last joint, which is twice as long as the preceding. On each joint four or five transverse rows of small circular pores. Horn small, bristle-shaped, oblique. This common species is rather variable.

Dimensions.—Length of the shell (with five joints) 0.14; length of the fifth joint 0.05, breadth 0.06.

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

19. Lithostrobus cornutus, n. sp. (Pl. 77, fig. 6).

Shell slender, conical, subcampanulate, smooth, with three or four deep strictures. Joints of different lengths, the third and the fourth twice as long as the second, four times as long as the first. Transverse rows of small circular pores; three in the first joint, five in the second, eight in the third and in the fourth. Horn large, pyramidal, about as long as the third joint.

Dimensions.—Length of the shell (with four joints) 0.12; length of the third joint 0.04, breadth 0.06.

Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms.

20. Lithostrobus microporus, Bütschli.

Shell slender, conical, smooth, very similar to the preceding species, differs mainly in the more slender form and the smaller pores. The first joint has four, the second eight, the third ten transverse rows of pores. Horn conical, as long as the cephalis. The third joint in this and the preceding species is campanulate, and large.

Dimensions.—Length of the shell (with four joints) 0.11; length of the third joint 0.05, breadth 0.04.

Habitat.—Fossil in Barbados.

21. Lithostrobus quadratus, n. sp.

Shell broad, conical, smooth, with straight axis, and six to eight deep strictures. Joints of different lengths, usually alternately longer and shorter. The seventh joint five times as broad as long, twice as long as the sixth and the fourth; six transverse rows of pores in the seventh, three in the sixth joint. Horn small, conical. This species differs from all others in the subregular square form of the small pores.

Dimensions.—Length of the shell (with seven joints) 0.15; length of the seventh joint 0.024, breadth 0.12.

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

22. Lithostrobus hexagonalis, n. sp. (Pl. 79, fig. 20).

Shell broad, conical, smooth, with straight axis, and five to eight prominent girdles between six and nine constricted broad joints. The first and the third joints are half as long as the second, the fourth, and each of the following joints. The sixth joint is five times as broad as long. Pores subregular, hexagonal, in regular transverse rows; three to four rows in the first and the second joints, six to eight in the third, the fourth, and each following joint. Cephalis with some small spines, and a larger, oblique, curved horn.

Dimensions.—Length of the shell (with six joints) 0.2; length of the sixth joint 0.04, breadth 0.2.

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

Subgenus 4. Botryostrobus, Haeckel.

Definition.—Shell conical, with straight axis, joints of different lengths. Cephalis lobate, with some irregular constrictions. (Perhaps derived from Botryodea?).

23. Lithostrobus botryocyrtis, n. sp. (Pl. 79, figs. 18, 19).

Shell slender, conical, smooth, with straight axis, and three deep strictures. Joints of different lengths. The length of the fourth joint equals two-thirds of its breadth, and of the length of the three preceding joints together. Each of the latter bears three transverse rows of small, quadrangular pores, the fourth joint has six rows. The cephalis is irregularly lobate, with four to six prominent lobes, and two small divergent horns (fig. 19).

Dimensions.—Length of the shell (with four joints) 0.1; length of the fourth joint 0.04, breadth 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

24. Lithostrobus lithobotrys, n. sp. (Pl. 79, fig. 17).

Shell slender, conical, smooth, with straight axis, and four deep strictures. Joints of different lengths, gradually increasing towards the mouth, the length of the fifth joint equals half its breadth, and one-third of the length of the whole shell. The single joints bear each four or five transverse rows of small, roundish pores. Cephalis irregularly lobate, with four to six prominent lobes, and the same number of small, conical horns.

Dimensions.—Length of the shell (with five joints) 0.12; length of the fifth joint 0.04, breadth 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 643. Dictyomitra,^[260] Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 80.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta), with conical shell gradually dilated towards the wide open mouth. Cephalis without horn.

The genus Dictyomitra agrees with the preceding Lithostrobus in the slender, conical form of the multiarticulate shell, but differs from it in the absence of a horn on the cephalis; the horn is here completely lost.

Subgenus 1. Dictyomitrella, Haeckel.

Definition.—Shell smooth, with joints nearly equal in length.

1. Dictyomitra articulata, Haeckel.

Shell slender, conical, smooth, with six to eight deep strictures. All joints nearly equal in length, gradually increasing in breadth, the eighth four times as broad as long, and twice as broad as the fourth joint. In each joint three to four transverse series of small, regular, circular pores.

Dimensions.—Length of the shell (with eight joints) 0.12, of each joint 0.015; breadth of the fourth joint 0.04, of the eighth joint 0.08.

Habitat.—Fossil in Barbados.

2. Dictyomitra macilenta, Haeckel.

Shell slender, conical, smooth, with five to seven deep strictures. All joints nearly equal in length, gradually increasing in breadth, the sixth joint three times as broad as long, and twice as broad as the second. In each joint only two transverse series of small, regular, circular pores.

Dimensions.—Length of the shell (with seven joints) 0.08, of each joint 0.012; breadth of the sixth joint 0.036, of the second 0.018.

Habitat.—Western Tropical Pacific, Stations 200 to 225, in various depths.

3. Dictyomitra conica, n. sp.

Shell widely conical, with six to eight prominent strictures. All joints nearly equal in length, gradually increasing in breadth, the eighth five times as broad as long, and twice as broad as the third. In each joint three to four transverse rows of regular, hexagonal pores. (Similar to Lithostrobus hexagonalis, Pl. 79, fig. 20, but more slender, and without cephalic horn.)

Dimensions.—Length of the shell (with seven joints) 0.16, of each joint 0.022; breadth of the sixth 0.08.

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

Subgenus 2. Dictyomitrissa, Haeckel.

Definition.—Shell smooth, with joints of very different lengths.

4. Dictyomitra polypora, Zittel.

Shell slender, conical, rough, with six to nine deep strictures. Breadth and length of the joints gradually increasing, so that the eighth joint is twice as long and broad as the third. Pores regular, circular, in transverse rows, four rows in each joint, in the last joint five to six rows.

Dimensions.—Length of the shell (with eight joints) 0.24; length of the eighth joint 0.04, breadth 0.1; length of the third joint 0.02, breadth 0.05.

Habitat.—Fossil in secondary rocks of Northern Germany (chalk of Brunswick, &c.), Zittel.

5. Dictyomitra eurythorax, n. sp. (Pl. 77, fig. 4).

Shell campanulate, conical, rough, with three deep strictures. Cephalis small, hemispherical. Thorax large, inflated, hemispherical, with six transverse rows of pores. Abdomen with two broader joints, together as long as the thorax, each with three to four rows of pores.

Dimensions.—Length of the shell (with four joints) 0.14, of the thorax 0.06; breadth of the thorax 0.08, of the last joint 0.1.

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

6. Dictyomitra microcephala, Haeckel.

Shell broadly conical, smooth, with six to eight distinct strictures. Breadth of the joints gradually increasing, length unequal. The three first joints short, only one-half or one-third as long as each of the following joints; in each of the former three to four transverse rows, in each of the latter six to eight transverse rows of small, regular, circular pores.

Dimensions.—Length of the shell (with six joints) 0.09, of the three first joints 0.03, of the three following 0.06; breadth of the sixth joint 0.08, of the fourth 0.04.

Habitat.—Mediterranean (Candia) Spratt, depth 1620 fathoms.

7. Dictyomitra demersissima, Haeckel.

Shell slender, conical, smooth, with four internal septal rings (without external strictures). Breadth of the five joints gradually increasing, length unequal; the third joint the longest, twice as long as the second, and longer than any of the following. Pores very small and numerous, in longitudinal rows.

Dimensions.—Length of the shell (with five joints) 0.09, of the second joint 0.015, of the third 0.03; breadth of the second joint 0.03, of the third 0.05.

Habitat.—Tropical Pacific, Philippine Sea, depth 3300 fathoms.

Subgenus 3. Dictyomitroma, Haeckel.

Definition.—Shell with longitudinal ribs and furrows between them, with joints of different lengths.

8. Dictyomitra costata, n. sp.

Shell slender, conical, with prominent longitudinal ribs, and six to eight deep strictures. Length of the majority of joints nearly equal, the two or three first joints shorter, the last a little longer. In each joint only a single transverse series of pores at the distal end (one pore in each furrow). (Similar to Siphocampe tubulosa, Pl. 79, fig. 13, but conical, and without cephalic tube.)

Dimensions.—Length of the shell (with eight joints) 0.16, of each middle joint 0.03, of the first 0.02; breadth of the last joint 0.06.

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

9. Dictyomitra multicostata, Zittel.

Shell slender, conical, with prominent longitudinal ribs, and eight to ten deep strictures. Length and breadth of the joints gradually increasing, the eighth joint twice as long and broad as the fourth joint. Pores regular, circular, one series in each longitudinal furrow, three to four pores on each joint.

Dimensions.—Length of the shell (with eight joints) 0.2, of the fourth joint 0.02, of the eighth joint 0.04; breadth of the fourth joint 0.04, of the eighth 0.08.

Habitat.—Fossil in secondary rocks of North Germany (chalk of Brunswick, &c.), Zittel.

Genus 644. Stichocorys,^[261] Haeckel, 1881, Prodromus, p. 438 (sensu emendato).

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with a middle constriction of the shell, the upper half of which is conical, the lower cylindrical. Mouth truncate. Cephalis with a horn.

The genus Stichocorys is intermediate between the two preceding and the two following genera; the upper half of the shell with the three first joints is conical, the lower half with the fourth and the following joints cylindrical, of equal breadth. The third joint of the shell (or the abdomen of Theoconus) is constantly the largest, being broader than all the other joints. Stichocorys is a very common and characteristic form, and may be derived from Theoconus by development of a post-abdomen.

1. Stichocorys wolffii, n. sp. (Pl. 80, fig. 10).

Shell in the upper half (with three joints) thorny, in the lower half (with two joints) smooth. Pores of the former double-contoured, in subregular, transverse rows. Pores of the latter smaller, simple, scarcely scattered. Cephalis with a pyramidal horn of the same length. Thorax with prominent, longitudinal divergent ribs. Dedicated to Caspar Friedrich Wolff (Halle, 1759).

Dimensions.—Length of the shell (with five joints) 0.16; breadth of the third joint 0.08, of the fourth 0.05.

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

2. Stichocorys panderi, n. sp. (Pl. 80, fig. 7).

Shell in the upper conical half (with three joints) spiny, in the lower subcylindrical half (with three joints) smooth. Pores small, circular, irregularly scattered, simple. Cephalis with a conical horn of the same length. No longitudinal ribs. Dedicated to Christian Pander (Würzburg, 1817.)

Dimensions.—Length of the shell (with six joints) 0.18; breadth of the third joint 0.08, of the fourth 0.05.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Stichocorys baerii, n. sp. (Pl. 80, fig. 8).

Shell in the upper conical half (with three joints) spiny, in the lower cylindrical half (with three joints) sulcate, with prominent longitudinal ribs, alternating with longitudinal rows of small pores. Pores of the upper half smaller, quincuncially disposed. Cephalis with a stout pyramidal horn of the same length. Dedicated to Carl Ernst Baer (Königsberg, 1828).

Dimensions.—Length of the shell (with six joints) 0.2; breadth of the third joint 0.09, of the fourth 0.07.

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

4. Stichocorys okenii, n. sp. (Pl. 80, fig. 5).

Shell smooth, without spines or ribs; the upper conical half (with three joints) about the same length as the lower subcylindrical half (with three joints). Pores subregular, circular, in the inflated third joint twice as large as in the five other joints. At the lumbar stricture (between the second and third joints) a coronal of nine very large pores. Cephalis with a curved horn of half the length. Dedicated to Lorenz Oken (Jena, 1806).

Dimensions.—Length of the shell (with six joints) 0.2; breadth of the third joint 0.09, of the fourth 0.07.

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

5. Stichocorys huschkei, n. sp. (Pl. 80, fig. 3).

Shell in the upper conical half (with three joints) thorny, in the lower cylindrical half (with five joints) smooth, roundish. Pores irregularly scattered, always double-contoured, in the second joint three times as large as in the third. At the third stricture (between the third and fourth joints) a coronal of larger pores. Cephalis with a small, conical horn of half the length. No longitudinal ribs. Dedicated to Emil Huschke (Jena, 1832).

Dimensions.—Length of the shell (with eight joints) 0.18; breadth of the third joint 0.08, of the fourth joint 0.07.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

6. Stichocorys rathkei, n. sp.

Shell spiny, everywhere covered with short conical spines. The upper conical part of the shell (with three joints) half as long as the lower cylindrical part (with six joints). Pores irregular, roundish, in the thorax twice to three times as large as in the eight other joints. Cephalis with a pyramidal horn of the same length. No longitudinal ribs. Dedicated to Heinrich Rathke (Königsberg, 1839).

Dimensions.—Length of the shell (with nine joints) 0.24; breadth of the third joint 0.08, of the fourth joint 0.06.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

7. Stichocorys mülleri, n. sp.

Shell in the upper conical part (with three joints) spiny, in the lower cylindrical part (with seven joints) smooth. Pores in the former irregularly scattered, roundish, in the latter circular, regularly disposed in longitudinal series, alternate, with prominent ribs. The upper conical part of the shell is about half as long as the lower cylindrical part. Cephalis with a large, pyramidal horn of three times the length. Dedicated to Johannes Müller (Berlin, 1858).

Dimensions.—Length of the shell (with ten joints) 0.22; breadth of the third joint 0.09, of the fourth joint 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 645. Artostrobus,^[262] n. gen.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis with a horn.

The genus Artostrobus and the following Dictyomitra differ from all the other Stichocorida in the cylindrical or nearly cylindrical form of the shell, all the joints of which are nearly equal in breadth, and are very short, often with a single transverse row of pores only. The first joint or cephalis is usually different from the following, often hemispherical or cap-shaped joints. The last joint is truncate, and has a wide open mouth. Since the constrictions between the single joints are often very slight, some species are very similar to the Dicyrtide Sethocorys.

Subgenus 1. Artostrobulus, Haeckel.

Definition.—A single transverse row of small, circular pores on each joint. (Sometimes on the uppermost joints two or three rows.)

1. Artostrobus annulatus, Haeckel.

Shell slender, cylindrical, smooth, without external strictures, but with ten to twenty internal annular septa. On each joint only a single transverse row of small pores. Cephalis hemispherical, with a single or double small horn. Each joint about four times as broad as long.

Dimensions.—Length of the shell (with twenty joints) 0.2; length of each joint 0.01, breadth 0.04.

Habitat.—Arctic Ocean, Kamtschatka (Bailey); Greenland (Ehrenberg).

2. Artostrobus elegans, Haeckel.

Shell cylindrical, smooth, with eight to ten internal annular septa. Cephalis subspherical, with a short, conical horn. Thorax campanulate, with two transverse rows of pores. Abdomen with six to eight equal joints, each with a single row of pores. (May be described, perhaps, better as Theocyrtis elegans. Eucyrtidium pauperum, Ehrenberg, loc. cit., may be a variety of this species.)

Dimensions.—Length of the shell (with nine joints) 0.1; length of each abdominal joint 0.01, breadth 0.03.

Habitat.—Fossil in Barbados.

Subgenus 2. Artostrobium, Haeckel.

Definition.—All (or the majority) of the joints of the shell with several transverse rows of pores, in variable number.

3. Artostrobus auritus, Haeckel.

Shell subcylindrical, with five sharp strictures. All six joints nearly equal in length; each with four or five transverse rows of small pores. Cephalis small, flat, hemispherical, with two or three small, conical, oblique horns. Mouth of the sixth joint a little constricted.

Dimensions.—Length of the shell (with six joints) 0.12; length of each joint (on an average) 0.02, breadth 0.04 to 0.05.

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

4. Artostrobus biseriatus, n. sp.

Shell cylindrical, smooth, with ten to twelve deep strictures. All joints nearly equal in size; each with two transverse rows of small circular pores. Cephalis hemispherical, with a long, bristle-shaped, curved horn.

Dimensions.—Length of the shell (with twelve joints) 0.24; length of each joint 0.02, breadth 0.04.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

5. Artostrobus articulatus, n. sp. (Pl. 79, fig. 16).

Shell subcylindrical, with elegant longitudinal ribs and five sharp strictures. All six joints nearly equal in length, each with three or four transverse rows of small circular pores. The middle joints twice as broad as long. Cephalis hemispherical with a conical, oblique horn.

Dimensions.—Length of the shell (with six joints) 0.16, length of a single joint 0.02 to 0.03, breadth 0.04 to 0.05.

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

Genus 646. Lithomitra,^[263] Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 529.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis without horn.

The genus Lithomitra differs from the preceding genus Artostrobus in the absence of a cephalic horn, and therefore bears to it the same relation as Dictyomitra does to Lithostrobus. In many species the joints are very short, and bear only a single transverse row of pores, and since the constrictions between the joints are often very slight, Lithomitra becomes very similar to the Dicyrtide Dictyocephalus.

Subgenus 1. Lithomitrella, Haeckel.

Definition.—A single transverse row of small circular pores on each joint. (Sometimes on the uppermost joints two or three rows.)

1. Lithomitra pachyderma, Bütschli.

Shell thick-walled, subcylindrical, with longitudinal ribs, slightly dilated in the middle, with ten to twelve subequal joints. On the lower edge of each joint a single row of small circular pores. No external strictures. This and the following species (though separated by Ehrenberg as four different species) may be united.

Dimensions.—Length of the shell (with ten joints) 0.11; length of each joint 0.01 to 0.012, breadth 0.04.

Habitat.—Fossil in Barbados.