Shell smooth, with sharp collar stricture. Relative length of the two joints = 5 : 3, breadth = 4 : 5. Cephalis ovate, with numerous irregular, roundish pores. Thorax truncate, conical, with a few small pores. From its upper part (below the collar stricture) there arise three thin, bristle-shaped, widely divergent wings, about as long as the cephalis. Mouth widely open.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.03 long, 0.05 broad.

Habitat.—Western Tropical Pacific, Stations 200 to 225, surface.

2. Psilomelissa phalacra, n. sp.

Shell smooth, with deep collar stricture. Relative length of the two joints = 5 : 6, breadth = 4 : 4. Cephalis ovate, hyaline, with few small pores only in the lower third. Thorax cylindrical, truncate, with small irregular, roundish pores. From its upper third there arise below the stricture three club-shaped, nearly horizontally divergent wings, as long as the thorax. The cephalis and the three feet are similar to those of Peromelissa phalacra, (Pl. 57, fig. 11); but the cylindrical thorax with irregularly scattered pores is completely different, and exhibits a truncate, wide open mouth.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.04 broad.

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

3. Psilomelissa hertwigii, Haeckel.

Shell rough, with obliterated collar stricture. Length of the two joints = 4 : 4, breadth = 5 : 5. Cephalis hemispherical. Thorax little larger, cylindrical. From its upper half there arise three very strong pyramidal divergent wings, about as long as the shell. Pores of both joints very small and numerous, circular. Mouth truncate, wide open.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.04 long, 0.05 broad.

Habitat.—Fossil in Barbados.

4. Psilomelissa calvata, n. sp. (Pl. 56, fig. 3).

Shell smooth, with sharp collar stricture. Length of the two joints = 7 : 5, breadth = 5 : 6. Cephalis ovate, large, with subregular, circular, double-contoured pores. Thorax smaller, ovate, with very irregular, roundish pores of different sizes. From its upper third there arise three conical, slender, widely divergent spines or wings of the same length. (In fig. 3 the cephalis with the three wings is alone represented.)

Dimensions.—Cephalis 0.07 long, 0.05 broad; thorax 0.05 long, 0.06 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

5. Psilomelissa sphærocephala, n. sp.

Shell rough, with deep collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis spherical. Thorax cap-shaped, flat and broad. From its upper half there arise three pyramidal wings, half as long, fenestrated at the base and nearly horizontally divergent. Mouth constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.03 diameter; thorax 0.06 long, 0.09 broad.

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

Genus 539. Spongomelissa,^[156] n. gen.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free lateral wings, or solid spines arising from the sides of the thorax. No terminal feet. Cephalis with one or more horns.

The genus Spongomelissa differs from its ancestral genus Lithomelissa only in the development of spongy framework in the shell-wall—a very rare production in the Cyrtoidea (compare Peripyramis, p. 1162, and Spongocyrtis, p. 1188).

1. Spongomelissa spongiosa, Haeckel.

Shell of dense spongy structure, with a deep collar stricture. The subspherical cephalis and the truncate abdomen of nearly equal size, both with irregular delicate spongy framework. Mouth wide open. Cephalis with a large vertical apical and a small oblique frontal horn. Thorax with three very stout, three-sided prismatic widely divergent lateral wings, which are covered with numerous irregularly ramified branches; the spongy framework arises by communication of the delicate branches.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Fossil in Barbados.

Genus 540. Clathrocanium,^[157] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 829.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three prominent lateral ribs on the thorax, alternating with three large holes (or thoracic gates). Cephalis with a horn.

The genus Clathrocanium is nearly allied to Dictyophimus and Lithomelissa, and, together with these two genera, may be regarded as surviving representatives of the oldest and most primitive forms of Dicyrtida. It differs from the latter mainly in the incomplete fenestration of the shell, three large interradial holes remaining between the three perradial thoracic ribs. It may therefore be derived either from Euscenium or from Tripospyris by the development of a terminal lattice-band between the three feet. Clathrocanium may be divided into two different subgenera: Clathrocanidium, with simple horn and smooth mouth, and Clathrocorona, with fenestrated horn and coronated mouth.

Subgenus 1. Clathrocanidium, Haeckel.

Definition.—Horn of the cephalis simple, not fenestrated. Peristome smooth.

1. Clathrocanium squarrosum, Ehrenberg.

Cephalis campanulate, with irregular roundish pores and a pyramidal horn of the same length, bearing at the apex three short branches. Length of the two joints 2 : 3, breadth = 2 : 6. Thorax with three simple, prismatic, thin ribs, which are twice as long as the cephalis, separated by large triangular holes and connected only at the distal end by a small triangular ring of delicate lattice-work. Peristome smooth, wide, as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.12 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.

2. Clathrocanium sphærocephalum, n. sp. (Pl. 64, fig. 1).

Cephalis spherical, with regular circular pores and a prismatic horn of the same length, with three serrated edges. Length of the two joints = 2 : 3, breadth 2 : 4. Thorax with three broad, triangular, latticed, divergent ribs, which are separated by three large ovate holes (about as large as the cephalis), and connected at the distal end by a broad fenestrated circular ring of regular lattice-work (about six pores in its height). Peristome smooth, constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08 broad.

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

3. Clathrocanium coarctatum, Ehrenberg.

Cephalis spherical, thorny, with regular circular pores and a simple pyramidal horn of the same length. Length of the two joints = 2 : 3, breadth = 2 : 5. Thorax with three simple, prismatic, little prominent ribs, which are separated by three large ovate holes (twice as long as the cephalis), and connected below the prominent distal end by a narrow circular ring of delicate lattice-work. Peristome smooth, wide, little narrower than the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.06 long, 0.1 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.

4. Clathrocanium triomma, n. sp. (Pl. 64, fig. 3).

Cephalis spherical, thorny, with regular circular pores, and a slender prismatic horn of twice the length, bearing at its apex three short recurved branches. Length of the two joints = 2 : 4, breadth = 2 : 5. Thorax with three broad prismatic, fenestrated ribs, which are separated by three large subcircular holes, and below the prominent distal end by a broad, triangular, roundish ring of subregular lattice-work (with square pores). Peristome smooth, about half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.1 broad.

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

Subgenus 2. Clathrocorona, Haeckel, 1881, Prodromus, p. 431.

Definition.—Horn of the cephalis fenestrated. Peristome on the margin of the basal mouth with a corona of spines.

5. Clathrocanium diadema, n. sp. (Pl. 64, fig. 2).

Cephalis hemispherical, thorny, with irregular roundish pores, and a large prismatic horn of twice the length, the three edges of which are denticulate and fenestrated, each with a series of square pores. Length of the two joints = 1 : 3, breadth = 2 : 4. Thorax thorny, with three broad fenestrated divergent ribs, which are separated by three large ovate holes (twice as long as the cephalis) and have their prominent distal ends connected below by a broad circular ring of lattice-work (with irregular polygonal small meshes). Peristome wide, two-thirds as broad as the thorax, with a circular corona of small square pores and alternating prominent small teeth.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09 broad.

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

6. Clathrocanium reginæ, n. sp. (Pl. 64, fig. 4).

Cephalis hemispherical, with irregular roundish pores and a prismatic club-shaped horn of twice the length, the three edges of which are denticulate and fenestrated. Length of the two joints = 1 : 3, breadth = 1 : 4. Thorax thorny, with three broad triangular, fenestrated and nodulated ribs, which are separated by three large ovate holes (twice as long as the cephalis) and have their prominent distal ends connected below by a circular ring of lattice-work. Peristome constricted, as broad as the thorax, with a corona of short spines.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.08 long, 0.12 broad.

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

Genus 541. Lamprodiscus,^[158] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 831.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three divergent lateral ribs in the wall of the flat, conical, discoidal, or pyramidal thorax. Cephalis with a horn. Peristome smooth, without corona of spines.

The genus Lamprodiscus, and the following nearly allied Lampromitra, differ from all preceding Sethopilida in the complete connection of the three thoracic feet by lattice-work, so that they are imbedded in the thorax-wall as prominent ribs and are not prolonged beyond the margin as free feet. The shell is commonly very flat, conical or pyramidal, sometimes nearly discoidal. The margin of Lamprodiscus is simple, smooth.

1. Lamprodiscus monoceros, Ehrenberg.

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 8. Cephalis spherical, hyaline, without pores, with an oblique conical horn of the same length. Thorax flat, campanulate, nearly hemispherical, with convex lateral outlines, and regular hexagonal meshes, increasing gradually in size towards the mouth. Bars very thin. Peristome smooth.

Dimensions.—Cephalis 0.02 diameter; thorax 0.1 long, 0.16 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), Station 200, surface.

2. Lamprodiscus coscinodiscus, Ehrenberg.

Shell smooth, with sharp collar stricture. Thorax of the same form and structure as in the preceding species, differing from it mainly in the structure of the smooth circular margin, which is composed of a ring of very small square pores. Length of the two joints = 1 : 4, breadth = 1 : 8. Cephalis with small hexagonal pores, without horn or with a short rudimentary horn. Lateral outlines of the campanulate thorax in the upper part concave, in the lower convex.

Dimensions.—Cephalis 0.02 diameter; thorax 0.08 long, 0.16 broad.

Habitat.—Tropical Pacific, Stations 206, 224, 266, &c., surface.

3. Lamprodiscus tricostatus, n. sp.

Shell smooth with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 7. Cephalis spherical, with an oblique conical horn of twice the length and small circular pores. Thorax flatly conical, twice as broad as high, with straight lateral outline, and regular hexagonal meshes, increasing gradually in size towards the mouth; bars very thin. Peristome or margin of the basal mouth circular, smooth. Very similar to Theopilium tricostatum (Pl. 70, fig. 6), but without abdomen. Differs from the two preceding species mainly in the conical form of the thorax and the less delicate network.

Dimensions.—Cephalis 0.03 diameter; thorax 0.1 long, 0.2 broad.

Habitat.—Cosmopolitan, Mediterranean, Atlantic, Indian, Pacific; surface.

4. Lamprodiscus lævis, Haeckel.

Shell smooth, with distinct collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with small circular pores and an oblique conical horn of twice the length. Thorax flat, pyramidal, twice as broad as long, with three strong, straight divergent edges and subregular roundish pores. Peristome smooth.

Dimensions.—Cephalis 0.025 diameter; thorax 0.08 long, 0.16 broad.

Habitat.—Mediterranean (Messina), R. Hertwig, surface.

Genus 542. Lampromitra, Haeckel,^[159] 1881, Prodromus, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three divergent lateral ribs in the wall of the flat conical or pyramidal thorax. Cephalis commonly with a horn. Peristome with a corona of spines.

The genus Lampromitra differs from the preceding and nearly allied Lamprodiscus only in the development of a dentated peristome, or an elegant corona of teeth around the wide open mouth. It bears therefore to the latter the same relation that Clathrocorona does to Clathrocanium.

1. Lampromitra coronata, n. sp. (Pl. 60, fig. 7, 7a).

Shell flat, conical, with slight collar stricture. Length of the two joints = 1 : 2, breadth = 2 : 7. Cephalis hemispherical, with a conical oblique horn of twice the length, and small subregular hexagonal pores. Thorax with larger, subregular, hexagonal meshes, six to eight times as broad as the bars. Peristome or basal margin of the thorax circular, with a marginal ring of smaller polygonal meshes and a triple coronal of short spines; two external rings of short conical centrifugal spines, and an internal ring of thin centripetal rods (fig. 7a). In fig. 7 the shell is seen from below and exhibits very distinctly the internal cross of the collar septum, composed of the four divergent cortinar bars; between the latter descend the four pear-shaped lobes of the central capsule (each containing an oil globule), whilst the apical part of the capsule (with the nucleus) is hidden in the large cap-shaped cephalis.

Dimensions.—Cephalis 0.03 long, 0.07 broad; thorax 0.06 long, 0.2 broad.

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

2. Lampromitra quadricuspis (Pl. 58, fig. 7).

Shell flat, conical, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 2 : 10. Cephalis hemispherical, with subregular circular pores and an oblique, conical, occipital horn of twice the length, bearing three divergent lateral branches, which are directed upwards, and correspond to the three thoracic ribs. Further down, near the collar stricture, a short divergent frontal horn arises. Thorax with irregular roundish pores of different sizes, three to six times as broad as the bars. Peristome with a simple coronal of short, conical, divergent spines, about as long as the diameter of the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.2 broad.

Habitat.—North Atlantic, Canary Islands, surface.

3. Lampromitra furcata, n. sp. (Pl. 58, fig. 8).

Shell flat, conical, with deep collar stricture, very similar in form and structure to the preceding species; differs from it in the shape of the peristome and the armature of the cephalis, which bears a conical, forked, occipital horn of the same length, and a small rudimentary divergent frontal horn. Length of the two joints = 1 : 2, breadth = 1 : 6. The four pores of the collar septum (two larger cardinal and two smaller jugular) exhibit in this species a peculiar asymmetry (fig. 8). The peristome bears a simple coronal of spines as long as the diameter of the cephalis. The major part of them is forked, some irregularly branched.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.18 broad.

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

4. Lampromitra pyramidalis, n. sp.

Shell flat, pyramidal, smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 9. Cephalis subspherical, with an oblique pyramidal horn of twice the length, and small circular pores. Thorax with three strong, divergent, straight ribs and three flat triangular sides between them, with subregular hexagonal pores, increasing in size towards the mouth. Peristome with a simple coronal of large and numerous divergent, conical spines, half as long as the shell.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.18 broad.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms.

5. Lampromitra huxleyi, Haeckel (Pl. 59, fig. 1).

Shell flat, conical, spiny, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a short conical horn of the same length. Thorax with irregular polygonal pores. Peristome with three coronals of divergent bristle-shaped spines; the first directed obliquely upwards, the second outwards, and the third nearly vertically, downwards; the bristles of the latter are much longer, about as long as the height of the shell.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.16 broad.

Habitat.—Australia (east coast), Station 169, surface.

6. Lampromitra schultzei, Haeckel.

Shell flat, conical, smooth, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a small conical horn of half the length, and very small roundish pores. Thorax with three strong, straight ribs and irregular polygonal pores, which are much larger in the middle part than in the upper or lower part. Peristome with a double coronal of short, conical, divergent spines; the superior obliquely ascending, the inferior vertically descending. (Named in honour of the late Professor Max Schultze, the illustrious histologist.)

Dimensions.—Cephalis 0.025 diameter; thorax 0.07 long, 0.2 broad.

Habitat.—Mediterranean, Messina, surface.

7. Lampromitra arborescens, n. sp, (Pl. 60, fig. 8, 8a).

Shell flat, pyramidal, spiny, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 2 : 10. Cephalis cap-shaped, with an oblique, slender, conical horn of twice the length, and small circular pores. Thorax with three slight almost obliterated ribs and three vaulted sides between them, with irregular roundish pores. The three ribs are distinct in the proximal, not in the distal part. Peristome with a double coronal of smaller squarish pores and numerous divergent spines; the larger spines are irregularly branched and as long as the diameter of the cephalis.

Dimensions.—Cephalis 0.15 long, 0.03 broad; thorax 0.04 long, 0.2 broad.

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

8. Lampromitra dendrocorona, n. sp. (Pl. 58, fig. 9).

Shell flat, conical, with smooth surface and deep collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with a slender occipital horn of three times the length, and a small divergent frontal horn. Thorax with three strong prominent straight ribs and irregular polygonal meshes, increasing in size towards the mouth. Peristome with a dense coronal of numerous short conical spines and twenty-four to thirty larger arborescent spines, longer than the diameter of the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

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

Genus 543. Callimitra,^[160] Haeckel, Prodromus, 1881, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three vertical latticed wings, which stretch between the three divergent lateral ribs of the thorax and the vertical horn of the cephalis. No frontal horn.

The genus Callimitra, and the two following nearly allied genera, Clathromitra and Clathrocorys, form together a peculiar small group, the Callimitrida, living in the Central Pacific, and differing from the other Sethopilida in some remarkable points, derived perhaps directly from the Archiscenida, Archiscenium and Pteroscenium, by the development of thoracic network between the three cortinar feet. In the centre of the collar septum, where these feet are united, there arises a vertical free columella, prolonged over the top of the cephalis as a free horn, and this horn is connected with the three thoracic ribs by three vertical fenestrated wings.

1. Callimitra carolotæ, n. sp. (Pl. 63, figs. 1, 7, 8).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin bristle-shaped apical horn of the same length. Length of the two joints = 3 : 6, breadth = 2 : 6. Thorax in the upper half with irregular network, in the lower half with parallel transverse bars; in each of its three sides descend two convergent pairs of stronger, parallel, curved ribs, not confluent at the peristome. Each of the three vertical wings with eight stronger ribs, three arising from the cephalis, five from each foot. Dedicated to my dear mother Charlotte Sethe.

Dimensions.—Cephalis 0.07 long, 0.05 broad; thorax 0.15 long, 0.15 broad.

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

2. Callimitra annæ, n. sp. (Pl. 63, fig. 2).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin bristle-shaped horn of the same length. Length of the two joints = 1 : 2, breadth = 1 : 3. Thorax nearly in its whole extent with parallel transverse bars, which are crossed by two convergent systems of parallel beams; in each of its three sides descend four convergent pairs of stronger, parallel, curved ribs, not confluent at the peristome. Each of the three vertical wings with six stronger ribs, three arising from the cephalis, three from each foot. Dedicated to my dear first wife Anna Sethe.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.12 long, 0.18 broad.

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

3. Callimitra agnesæ, n. sp. (Pl. 63, fig. 5).

Cephalis pear-shaped, with irregular, square pores, and a slender bristle-shaped horn twice as long. Length of the two joints = 1 : 3, breadth = 1 : 5. Thorax in its whole extent with parallel transverse bars, which are crossed by two converging and crossed systems of parallel beams; in each of its three sides descend five convergent pairs of stronger, parallel, curved ribs, the two or three upper of which are crossed at the peristome. Each of the three vertical wings with five stronger ribs, three arising from the cephalis and the horn, two from each foot. Dedicated to my dear second wife Agnes Huschke.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.15 long, 0.22 broad.

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

4. Callimitra elisabethæ, n. sp. (Pl. 63, fig. 6).

Cephalis nearly hemispherical, with irregular square pores, and a strong prismatic horn thrice the length. Length of the two joints = 2 : 7, breadth = 2 : 9. Thorax in the upper third with irregular network, in the lower two-thirds with parallel transverse bars which are crossed by two convergent systems of parallel beams; in each of its three sides descend three convergent pairs of stronger, parallel, curved ribs; the two ribs of the uppermost pair are united and confluent in a single odd rib in the lower half of the thorax. Each of the three vertical wings with seven stronger ribs, three arising from the cephalis and the horn, four from each foot. Dedicated to my dear elder daughter Elizabeth Haeckel.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.15 long, 0.2 broad.

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

5. Callimitra emmæ, n. sp. (Pl. 63, figs. 3, 4).

Cephalis campanulate, with irregular, polygonal pores, and very thin bars (of the same shape as in the thorax) and with a thin bristle-shaped horn twice the length. Length of the three joints = 3 : 6, breadth = 2 : 9. Thorax in its whole extent with an arachnoidal network similar to that in the cephalis and the three wings, composed of very numerous parallel threads, which are crossed by two crossed diagonal systems of parallel threads. In each of the three sides of the thorax descend five convergent pairs of stronger ribs, the three upper of which are crossed and form large rhomboidal meshes. Each of the three vertical wings with ten stronger ribs, four arising from the cephalis and each horn, six from each foot. Dedicated to my dear younger daughter Emma Haeckel.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.15 long, 0.22 broad.

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

Genus 544. Clathromitra,^[161] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three vertical latticed wings, which stretch between the three divergent lateral ribs of the thorax and the vertical horn of the cephalis. The front of the latter is armed with a large frontal horn.

The genus Clathromitra differs from the preceding similar Callimitra in the development of a free frontal or sternal horn, a prolongation of an internal obliquely ascending rod, opposite to the caudal foot. Therefore the shell in this genus possesses five divergent free spines, two cephalic horns, and three thoracic feet. The lattice-work of the three vertical wings is not so delicate as in Callimitra.

1. Clathromitra pterophormis, n. sp. (Pl. 57, fig. 8).

Cephalis very large, hemispherical, about as long and half as broad as the three-sided pyramidal thorax; both with irregular, polygonal meshes. Apical horn three to four times as long as the frontal horn and the three basal feet. All five spines three-sided prismatic, with nearly smooth edges. Three lateral wings half as broad as the cephalis.

Dimensions.—Cephalis 0.05 long, 0.1 broad; thorax 0.05 long, 0.15 broad.

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

2. Clathromitra pentacantha, n. sp.

Cephalis large, hemispherical, half as long as the three-sided pyramidal thorax; both with irregular, roundish meshes. Apical horn of about the same length as the frontal horn, and twice as long as the three basal feet. All five spines three-sided prismatic, with denticulated edges. Three lateral wings about as broad as the cephalis.

Dimensions.—Cephalis 0.04 long, 0.08 broad; thorax 0.1 long, 0.2 broad.

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

Genus 545. Clathrocorys,^[162] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three prominent lateral ribs on the thorax, alternating with three large holes (or thoracic gates). The three ribs are connected with the central apical horn of the cephalis by three vertical latticed wings.

The genus Clathrocorys differs from the two preceding nearly allied genera in the incomplete fenestration of the thorax, the three perradial ribs of which are separated by three large interradial holes. It has therefore the same relation to Callimitra that Clathrocanium bears to Dictyophimus.

1. Clathrocorys murrayi, n. sp. (Pl. 64, fig. 8).

Cephalis pear-shaped, with irregularly square pores. From the centre of its base there arise four strong, prismatic, radial beams of nearly equal size, the vertical, straight, cephalic horn being little longer than the three divergent, somewhat curved feet. In the three meridional planes (between the horn and each foot) a few rather thick branches arise, which by communication of the ramules form the three vertical latticed wings; each wing with two large meshes, three to five meshes of medium size, and three to four parallel arachnoidal rows of small, square, distal meshes. The three walls of the flat pyramidal thorax (between every two feet) are formed in the upper part by squarish network similar to that of the cephalis, in the middle part by a single row of arches separated by thin threads, and in the lower part by a narrow band of arachnoidal network. Dedicated to Dr. John Murray.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.04 long, 0.15 broad; apical distance of every two feet 0.15, of each foot and the horn 0.17.

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

2. Clathrocorys teuscheri, n. sp. (Pl. 64, fig. 10).

Cephalis pear-shaped, with irregular, square pores. From the centre of its base there arise seven prismatic, radial beams of equal strength, supporting the lattice-work of the wall; the single vertical beam is prolonged into the apical horn; six others lie in the three meridian planes (between the horn and each foot); three ascending end in the wall of the cephalis, three descending are prolonged into the three strong feet, which are longer than the horn. In each meridional plane there arise four thicker and several thinner bars, which by communication of their ramules form the three latticed wings; each wing with a single very large mesh, two meshes of medium size, and a narrow marginal band of small, square pores. The three walls of the flat pyramidal thorax are formed in the upper part by squarish network similar to that of the cephalis, in the lower part by a narrow band of the same; between them a large hole. Dedicated to Dr. Reinhold Teuscher.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.15 broad; apical distance of every two feet 0.2, of each foot and the horn 0.2.

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

3. Clathrocorys giltschii, n. sp. (Pl. 64, fig. 9).

Cephalis pear-shaped, with irregular, polygonal pores. From the centre of its base there arise seven prismatic, radial beams of different strength; the single vertical beam bears six lateral branches (parallel to the three ascending supporting beams), and is prolonged into the apical horn; six others lie in the three meridional planes (between the horn and each foot); three weaker ascending beams end in the wall of the cephalis, three stronger descending are prolonged into the three large diverging feet, which are twice as long as the cephalic horn. The network of the three wings and of the three-sided pyramidal thorax is about the same as in the preceding species, but much more developed; the marginal bands with the squarish network are much broader, and an arachnoidal wicker-work of very thin thread-like bars fills out the large meshes. Dedicated to Mr. Adolf Giltsch.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.12 long, 0.2 broad; apical distance of every two feet 0.24, of each foot and the horn 0.2.

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

Genus 546. Eucecryphalus,^[163] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 836.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free collar wings or solid spines arising from the collar stricture, and freely prominent between the horned cephalis and the flat conical thorax.

The genus Eucecryphalus, according to the restricted definition here given, comprises only those Sethopilida in which the three primary cortinar beams are perfectly free divergent collar wings, i.e., free spines arising outside the shell from the collar stricture, between the cephalis and thorax. The type of this genus (which I formerly united with other Sethopilida) remains Eucecryphalus gegenbauri.

Subgenus 1. Eucyrtomphalus, Haeckel, 1881, Prodromus, p. 431.

Definition.—Peristome or margin of the basal mouth of the thorax smooth, without marginal spines.

1. Eucecryphalus corocalyptra, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with an oblique conical horn twice its length. Thorax conical, twice as broad as long, with regular hexagonal meshes and straight lateral outlines. From the collar stricture there arise three slender conical spines, about as long as the thorax, divergent downwards. Similar to Corocalyptra agnesæ (Pl. 59, fig. 3), but without lumbar stricture and abdomen. Peristome or basal margin of the mouth of the thorax smooth, simple.

Dimensions.—Cephalis 0.3 diameter; thorax 0.09 long, 0.18 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, surface.

2. Eucecryphalus halicalyptra, n. sp.

Shell flat, campanulate, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with two divergent conical horns, a major occipital and a minor frontal horn. Thorax with subregular hexagonal meshes and concave-convex lateral outlines, campanulate. From the collar stricture there arise three divergent bristle-shaped spines, nearly horizontal, about half as long as the thorax. Peristome smooth, with a marginal coronal of small square pores.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Stations 266 to 274, surface.

Subgenus 2. Eucecryphalium, Haeckel.

Definition.—Peristome or margin of the basal mouth of the thorax dentate, with a coronal of marginal spines.