Definition.—Challengerida without pharynx, with one or more adoral teeth, but without spines on the sagittal margin.
The genus Challengeria, and the following closely allied Challengeron, differ from the preceding Lithogromia, their ancestral form, in the development of teeth on the mouth of the shell. Challengeron has also radial spines on the sagittal margin, while these are wanting in Challengeria. The latter genus exhibits not less than twenty-one, the former twenty-five species, so that both together make by far the greatest part of the family (containing fifty-eight species). They are also more common and more widely distributed than the four other genera of Challengerida, and many species appear in great numbers in certain localities. With a few exceptions living on the surface, they are all inhabitants of great depths.
Definition.—Peristome with a single simple tooth, which is neither forked nor branched (Challengeriæ monodontes).
1. Challengeria naresii, John Murray.
Challengeria naresii, John Murray, 1876, Proc. Roy. Soc. Lond., vol. xxiv. pl. xxiv. fig. 1.
Challengeria naresii, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 236, pl. A, figs. 1, 1a-1e.
Shell circular or nearly circular, strongly compressed, lenticular. Peristome on the dorsal corner with a single simple vertical tooth, which is nearly straight, conical, with two sharp lateral edges on the base, about half as long as the shell.
Dimensions.—Diameter of the shell 0.5 to 0.6, length of the tooth 0.2 to 0.3.
Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, at depths between 1000 and 3000 fathoms.
2. Challengeria xiphodon, n. sp.
Shell circular, nearly spherical, slightly compressed. Peristome on the dorsal corner with a single simple vertical tooth, which is straight, three-sided prismatic, and as long as the shell.
Dimensions.—Diameter of the shell 0.1 to 0.13, length of the tooth 0.1 to 0.12.
Habitat.—Tropical Atlantic, Stations 349 to 352, surface.
3. Challengeria sigmodon, n. sp.
Shell circular, nearly spherical, slightly compressed. Peristome with a single simple tooth, which is S-shaped, more or less curved, and about one-third as long as the shell.
Dimensions.—Diameter of the shell 0.3 to 0.4, length of the tooth 0.1 to 0.14.
Habitat.—North Pacific, Station 231, depth 2250 fathoms.
4. Challengeria tritonis, n. sp. (Pl. 99, fig. 5).
Shell ovate, slightly compressed. Peristome with a single simple tooth, which is vertical, straight, slenderly conical, and about half as long as the shell.
Dimensions.—Diameter of the shell 0.15 to 0.2, length of the tooth 0.1 to 0.12.
Habitat.—North Atlantic, Færöe Channel, Gulf Stream, in great numbers, in depths from 100 to 600 fathoms. (Expedition of H.M.S. "Triton," 1882), John Murray.
5. Challengeria pyramidalis, n. sp.
Shell slenderly ovate, one and a half times as long as broad, slightly compressed. Peristome with a single, simple, large tooth, which is three-sided pyramidal, vertical, straight, and longer than half the shell.
Dimensions.—Length of the shell 0.6 to 0.8, breadth 0.4 to 0.5; length of the tooth 0.4 to 0.5.
Habitat.—South Atlantic, Station 318, depth 2040 fathoms.
6. Challengeria cyrtodon, n. sp.
Shell ovate, lenticular, strongly compressed. Peristome with a single simple tooth, which is crescent-shaped, curved over the mouth, and about half as long as the shell.
Dimensions.—Length of the shell 0.4 to 0.5, breadth 0.3 to 0.4; length of the tooth 0.2 to 0.25.
Habitat.—South Pacific, Station 289, depth 2550 fathoms.
Definition.—Peristome with a forked or bifid tooth, or with two parallel lateral teeth (Challengeria diodontes).
7. Challengeria sloggettii, John Murray (Pl. 99, fig. 4).
Challengeria harstoni, John Murray, 1879 (partim), in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 14.
Shell triangular, strongly compressed, with three rounded corners, or nearly semicircular; its aboral margin straight, horizontal, longer than the convex, dorsal, and ventral margins. Peristome with two parallel, triangular pointed teeth, which are obliquely ascending, lamellar, with inflated ovate base, and about as long as the shell-radius.
Dimensions.—Diameter of the shell 0.2 to 0.3, length of the teeth 0.1 to 0.15.
Habitat.—Tropical Atlantic, Stations 347, 348, depth 2250 to 2450 fathoms.
8. Challengeria harstoni, John Murray.
Challengeria harstoni, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 14a.
Shell subcircular or somewhat triangular, with convex margins. Peristome with two parallel, slender, lanceolate teeth, which are obliquely ascending, and about half as long as the shell-radius.
Dimensions.—Diameter of the shell 0.15 to 0.18, length of the teeth 0.04 to 0.05.
Habitat.—North Pacific, Station 231, depth 2250 fathoms.
9. Challengeria campbelli, John Murray.
Challengeria campbelli, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 9.
Shell cordate, nearly triangular, compressed, with blunt apex. Peristome in the excavated middle of the broad base, with two short, parallel, triangular teeth. This species is very similar to Porcupinia cordiformis (Pl. 99, fig. 16), but differs from it in the absence of an internal pharynx and of external apical spines.
Dimensions.—Diameter of the shell 0.2 to 0.24; length of the teeth 0.03 to 0.05.
Habitat.—South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms.
10. Challengeria thomsoni, John Murray.
Challengeria thomsoni, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 2.
Shell ovate, slightly compressed, with rounded apical pole. Peristome semitubular, obliquely ascending, nearly straight, in the lower half an open half-cylinder, in the upper half forked, with two parallel, thin, oblique teeth. Sometimes a third small (dorsal) tooth is developed.
Dimensions.—Length of the shell 0.3 to 0.35, breadth 0.2 to 0.25; length of the peristome 0.08 to 0.12.
Habitat.—South Atlantic, Stations 318 to 330, surface, and in depths from 1900 to 2900 fathoms.
11. Challengeria bidens, n. sp.
Shell ovate, strongly compressed, lenticular. Peristome with two curved, long and thin bristle-shaped teeth, which are obliquely inclined over the mouth, and longer than the radius of the shell.
Dimensions.—Length of the shell 0.12 to 0.18, breadth 0.1 to 0.14; length of the teeth 0.08 to 0.1.
Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.
12. Challengeria havergalli, John Murray.
Challengeria havergalli, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, figs. 13, 13a.
Shell subspherical, slightly compressed. Peristome semitubular, slender, somewhat curved, in the lower half a simple half-cylinder, in the upper half forked, with two divergent teeth, nearly as long as the shell.
Dimensions.—Diameter of the shell 0.1 to 0.15, length of the peristome 0.08 to 0.12.
Habitat.—South Pacific, Station 300, depth 1375 fathoms.
13. Challengeria elephas, n. sp.
Shell ellipsoidal, not compressed. Peristome very similar to that of Challengeron diodon (Pl. 99, fig. 6), from which this species differs mainly in the absence of an apical spine, and in a more constricted mouth. The two conical teeth of the mouth are very large, nearly as long as the shell, straight, and almost parallel, each tooth has a large hole on the thickened base.
Dimensions.—Diameter of the shell 0.22, length of the teeth 0.2.
Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface.
Definition.—Peristome with three teeth or trifid, with an odd dorsal and two paired lateral teeth (Challengeriæ triodontes).
14. Challengeria macleari, John Murray.
Challengeria macleari, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 3.
Shell subcircular, lenticular, with a sharp marginal edge. Peristome semitubular, an oblique half-cylinder, with three divergent, short, triangular teeth; the dorsal odd tooth nearly vertical, the paired lateral teeth subhorizontal. Length of the peristome about one-third or one-fourth of the diameter of the shell.
Dimensions.—Diameter of the shell 0.25 to 0.35, length of the peristome 0.1 to 0.12.
Habitat.—South Atlantic, Stations 325 to 332, depth 1715 to 2900 fathoms.
15. Challengeria tridens, n. sp.
Shell subspherical, slightly compressed. Peristome about as long as the radius of the shell, with three diverging and obliquely descending teeth; the dorsal odd tooth twice as long as the paired lateral teeth.
Dimensions.—Diameter of the shell 0.08 to 0.12, length of the peristome 0.05 to 0.07.
Habitat.—North Atlantic, Færöe Channel (Gulf Stream), John Murray.
16. Challengeria trigona, Haeckel.
Challengeria macleari, var., John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 3b.
Shell triangular, with three rounded corners; the two lateral sides nearly straight, equal, the aboral side more or less convex and somewhat shorter. Peristome a curved half-tube (often longer than in Murray's figure), one-third to one-half as long as the shell, with three short triangular diverging and ascending teeth of equal length.
Dimensions.—Length of the shell 0.25 to 0.3, breadth 0.2 to 0.25; length of the peristome 0.08 to 0.12.
Habitat.—South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms.
17. Challengeria trifida, n. sp.
Shell ovate, more or less compressed, about two-thirds as long as broad. Peristome semitubular, obliquely ascending, about one-third as long as the shell, in the lower half simple, in the upper trifid, with three curved divergent teeth; the dorsal odd tooth shorter than the paired lateral teeth.
Dimensions.—Length of the shell 0.3 to 0.36, breadth 0.24 to 0.28.
Habitat.—South Pacific, Station 289, depth 2550 fathoms.
Definition.—Peristome with four to six or more teeth.
18. Challengeria quadridens, n. sp.
Shell subglobose, with nearly circular perimeter. Peristome an oblique short and broad tube, the breadth of which is twice as great as its length and equal to the radius of the shell. Margin of the peristome with four divergent, short, triangular teeth, the two dorsal teeth half as long as the two ventral.
Dimensions.—Diameter of the shell 0.22 to 0.24, breadth of the peristome 0.1.
Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.
19. Challengeria bromleyi, n. sp. (Pl. 99, fig. 3).
Shell ovate, lenticular, strongly compressed. Peristome a broad, trapezoidal, horizontal lamella, the breadth of which is twice as great as its length and nearly equal to the diameter of the shell; its margin with four divergent triangular lamellar teeth, the two dorsal teeth three times as long as the two ventral.
Dimensions.—Length of the shell 0.08 to 0.1, breadth 0.05 to 0.07; breadth of the peristome 0.08.
Habitat.—North Pacific, Stations 244 to 253, surface, and in various depths.
20. Challengeria wildi, n. sp. (Pl. 99, fig. 2).
Shell subspherical, slightly compressed. Peristome semitubular, curved, as long as the shell-radius; with five curved lamellar teeth, an odd longer dorsal tooth and two pairs of lateral teeth.
Dimensions.—Diameter of the shell 0.12 to 0.18, length of the peristome 0.08 to 0.12.
Habitat.—Tropical Atlantic, Stations 347 to 348, depth 2250 to 2450 fathoms.
21. Challengeria aldrichi, John Murray, Challengeria aldrichi1876, L. N. 27, pl. 24, fig. 2.
Challengeria aldrichi, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 4.
Shell subspherical, slightly compressed. Peristome a collar-like curved lamella, the breadth of which is twice as great as its length, and equals the radius of the shell; its margin with six short triangular teeth, two convergent ventral, two external horizontal lateral, and two ascending dorsal.
Dimensions.—Diameter of the shell 0.2, breadth of the peristome 0.1.
Habitat.—North Pacific, Station 244 to 248, depth 2050 to 2900 fathoms.
22. Challengeria murrayi, n. sp. (Pl. 99, fig. 1).
Shell subcircular, lenticular, strongly compressed. Peristome a trapezoidal, curved, collar-like lamella, the breadth of which is three times as great as its length and equal to the diameter of the shell; its margin with six triangular teeth, disposed like the preceding species, but larger.
Dimensions.—Diameter of the shell 0.15, breadth of the peristome 0.15.
Habitat.—North-Western Pacific (south of Japan), Station 231, depth 2250 fathoms.
Definition.—Challengerida without pharynx, with one or more teeth on the mouth, and with marginal spines.
The genus Challengeron has in general the same shape as the preceding closely allied Challengeria, but differs from it in the development of radial spines on the sagittal margin of the shell, which in the latter genus is smooth. According to the different number and arrangement of these marginal spines, which give a very singular appearance to them, we divide the twenty-five species of this cosmopolitan genus into four subgenera:—(1) with a single, odd apical spine; (2) with two opposed aboral spines (a dorsal and a ventral); (3) with a bunch of aboral spines; (4) with numerous radial spines along the whole sagittal margin of the shell.
Definition.—Margin of the shell with a single spine on the apical pole, opposite to the peristome (Challengeriæ caudatæ).
1. Challengeron monodon, n. sp.
Shell subspherical, slightly compressed, with a single straight conical spine on the apical pole, about as long as the radius. Peristome with a single vertical, straight, conical tooth, diametrically opposite to the apical spine and of the same length. (Similar to Challengeria naresii.)
Dimensions.—Diameter of the shell 0.2 to 0.3, length of the two opposite spines 0.1 to 0.15.
Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.
2. Challengeron cochlear, n. sp.
Shell nearly circular, lenticular, strongly compressed, with a single straight conical spine on the apical pole, about half as long as the radius. Peristome spoon-shaped, obliquely curved and inclined over the mouth, with a single terminal tooth, somewhat longer than the radius.
Dimensions.—Diameter of the shell 0.1, length of the peristome 0.06.
Habitat.—Indian Ocean, Cocos Islands, Rabbe, surface.
3. Challengeron diodon, n. sp. (Pl. 99, fig. 6).
Shell ovate, slightly compressed, with a single straight conical spine on the aboral pole, half as long as the radius. Peristome short and broad, collar-shaped, about twice as broad as long, and half as long as the radius, obliquely inclined over the mouth, with two divergent straight teeth, which are conical and longer than the shell-radius; beyond each tooth a large ovate hole in the wall of the peristome.
Dimensions.—Diameter of the shell 0.08 to 0.1, length of the teeth 0.06 to 0.08.
Habitat.—South-Eastern Pacific, Station 298, depth 2225 fathoms.
4. Challengeron pearceyi, n. sp. (Pl. 99, fig. 7).
Shell ellipsoidal or subspherical, scarcely compressed, with a single straight conical spine on the apical pole, about as long as the diameter. Peristome slender, semitubular, nearly as long as the diameter, somewhat obliquely inclined over the mouth, with three divergent triangular or lanceolate teeth; the dorsal odd tooth about twice as large as the paired lateral teeth.
Dimensions.—Diameter of the shell 0.08 to 0.12, length of the peristome 0.08 to 0.1.
Habitat.—Antarctic Ocean, between Kerguelen and Heard Island, Station 157.
5. Challengeron swirei, John Murray.
Challengeria swirei, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 11.
Shell subspherical or somewhat ovate, with a single straight conical spine on the apical pole, about as long as the radius. Peristome slender, semitubular, straight and vertical, nearly as long as the shell, with three pointed teeth, an odd longer terminal and two paired shorter lateral.
Dimensions.—Diameter of the shell 0.06 to 0.08, length of the peristome 0.05 to 0.06.
Habitat.—Antarctic Ocean, Station 157, surface, common.
6. Challengeron triodon, n. sp.
Shell ovate, one and a half times as long as broad, not compressed, with a single short and stout conical spine on the apical pole, shorter than half the radius. Peristome short and broad, collar-shaped, nearly half as broad and one-third as long as the shell, with three divergent terminal teeth, an odd dorsal and two paired lateral.
Dimensions.—Length of the shell 0.25 to 0.3, breadth 0.15 to 0.2; length and breadth of the peristome 0.1.
Habitat.—North Pacific, Station 245, surface.
Definition.—Margin of the shell with two widely distant aboral spines, opposite in the sagittal plane, a dorsal and a ventral.
7. Challengeron balfouri, John Murray.
Challengeria balfouri, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 10.
Shell subcircular, lenticular, strongly compressed, with two short divergent spines on the apical margin (a dorsal and a ventral). Peristome slender, semitubular, as long as the radius, vertical, in the distal half forked, with two parallel teeth.
Dimensions.—Diameter of the shell 0.08 to 0.16, length of the peristome 0.04 to 0.08.
Habitat.—North Atlantic, Stations 353 to 354, Hebrides, surface.
8. Challengeron golfense, n. sp.
Shell ovate, lenticular, compressed, with two short divergent spines on the apical margin (a dorsal and a ventral). Peristome slender, semitubular, half as long as the radius, with three terminal teeth, two short, vertically ascending, paired teeth and a larger odd tooth, which is inclined obliquely over the mouth.
Dimensions.—Diameter of the shell 0.15 to 0.2, peristome 0.05 to 0.07.
Habitat.—North Atlantic, Færöe Channel, Gulf Stream, surface and at various depths, John Murray.
9. Challengeron richardsii, n. sp. (Pl. 99, fig. 8).
Shell subcircular, lenticular, strongly compressed, with two stout, divergent, straight spines on the aboral margin (a dorsal and a ventral) which reach the length of the radius. Peristome slender, semitubular, slightly curved, about as long as the radius, with three short, divergent, terminal teeth. Mouth obliquely truncate. The dorsal odd tooth is nearly vertical, the two lateral paired teeth almost horizontal.
Dimensions.—Diameter of the shell 0.2 to 0.25, length of the spines and the peristome 0.08 to 0.12.
Habitat.—Antarctic Ocean, Station 157, surface, common.
10. Challengeron fergusoni, n. sp. (Pl. 99, fig. 9).
Shell isosceles triangular, with three slightly convex edges and two short, nearly vertically descending spines on the two corners of the aboral margin. Peristome inversely funnel-shaped, with a deep ventral incision on the base, and three broad, ovate, triangular teeth. The dorsal odd tooth is nearly vertical, whilst the two lateral paired teeth are almost horizontal; therefore the angle between the former and the latter is about a right angle.
Dimensions.—Diameter of the shell 0.2 to 0.3, length of the peristome 0.1.
Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.
11. Challengeron tizardi, John Murray.
Challengeria tizardi, John Murray, 1879, in litteris, Narr. Chall. Exp., vol i. p. 226, pl. A, figs. 7-7b.
Shell nearly equilateral triangular, with concave ventral, convex dorsal and aboral edges, on the two corners of the latter two opposite horizontal spines (a dorsal and a ventral). Peristome auriculate and bilobate, with a deep ventral incision on the base, and three pointed triangular teeth, the upper margins of which are nearly horizontal.
Dimensions.—Diameter of the shell 0.22 to 0.3, length and breadth of the peristome 0.01 to 0.12.
Habitat.—South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms.
12. Challengeron triangulum, n. sp. (Pl. 99, fig. 10).
Shell nearly equilateral triangular, with three slightly convex or nearly straight sides, and two opposite obliquely descending and diverging spines on the two corners of the aboral margin. Peristome auriculate and bilobate, with a very thin basal neck and a deep incision on its ventral side; its distal margin is obliquely truncate, and exhibits an odd ascending dorsal tooth and two parallel, paired, descending, lateral teeth.
Dimensions.—Diameter of the shell 0.2 to 0.3; length and breadth of the peristome 0.1 to 0.12.
Habitat.—North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.
Definition.—Margin of the shell smooth on the dorsal and the ventral side, but with three to five or more large spines (or a bunch of spines) on the aboral side; the middle spine is placed in the main axis, and larger than the others.
13. Challengeron bisternum, n. sp.
Shell subcircular, lenticular, strongly compressed, with three stout conical spines on the aboral pole; the middle spine is placed in the main axis, as long as the radius and three times as long as the two others. Peristome semitubular, straight, vertical, about as long as the radius, with three divergent teeth, the middle of which is odd and twice as large as the two paired lateral teeth.
Dimensions.—Diameter of the shell 0.22; length of the peristome 0.1.
Habitat.—Indian Ocean, Madagascar (Rabbe), surface.
14. Challengeron heptacanthum, n. sp.
Shell ovate, slightly compressed, with a series of five stout, conical, radial spines on the aboral margin; the middle spine is placed in the main axis and longer than the radius, twice as long as the two next, and three times as long as the more distant spines. Peristome short and broad, collar-shaped, with two large, divergent, straight teeth, each of which is longer than the shell-radius and bears at its base a large hole.
Dimensions.—Length of the shell 0.09 to 0.11, breadth 0.07 to 0.08; length of the teeth 0.07.
Habitat.—Tropical Atlantic, Stations 347, 348, depth 2250 and 2450 fathoms.
15. Challengeron crosbiei, n. sp. (Pl. 99, fig. 11).
Shell ovate, strongly compressed, with a series of seven to nine conical spines on the aboral margin; the middle spine is placed in the main axis, as long as the radius, and much larger than the six or eight other spines. Peristome short and broad, collar-like, with several small spines and two slender, widely distant, conical teeth, which are half as long as the shell, and curved towards one another like a pincer, each with a large hole at its base.
Dimensions.—Length of the shell 0.08 to 0.09, breadth 0.06 to 0.07; length of the two larger teeth 0.04 to 0.05.
Habitat.—Central Pacific, Station 270 to 274, depth 2350 to 2925 fathoms.
16. Challengeron buchanani, n. sp. (Pl. 99, fig. 12).
Shell ovate, slightly compressed, with a terminal comb of nine to twelve conical radial spines, densely crowded on the aboral pole; the middle spine is placed in the main axis, about half as long as the shell and much larger than the others. Peristome subconical, semitubular, recurved, half as long as the shell, with five triangular teeth; the dorsal odd tooth is inclined backwards, the two parallel pairs of lateral teeth directed ventrally.
Dimensions.—Length of the shell 0.15 to 0.18, breadth 0.1 to 0.12; length of the peristome 0.06 to 0.08.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.
Definition.—Margin of the shell dentated or serrated, with a continuous series of numerous short radial spines.
17. Challengeron channeri, John Murray.
Challengeron channeri, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 12.
Shell subcircular, lenticular, strongly compressed, with fourteen to eighteen slender, straight, radial spines on the margin; the spines are straight, equidistant, cylindrical, and about as long as the radius of the shell. Peristome short, with two parallel, vertical, lateral, straight teeth, which are less than half the length of a spine.
Dimensions.—Diameter of the shell 0.14 to 0.17; length of the spines 0.06 to 0.08.
Habitat.—North Pacific, Station 231, depth 2250 fathoms.
18. Challengeron moseleyi, n. sp. (Pl. 99, fig. 14).
Shell circular, lenticular, strongly compressed, with thirty to forty slender, straight, equidistant, radial spines on the margin, larger and smaller spines alternating; the larger spines are about as long as the radius, the smaller only half as long. Peristome short, tubular, with two divergent ovate or nearly triangular teeth, a dorsal and a ventral, about as long as the shorter marginal spines.
Dimensions.—Diameter of the shell 0.13 to 0.15; length of the larger spines 0.06 to 0.07, of the smaller 0.03 to 0.04.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
19. Challengeron bethelli, John Murray.
Challengeron bethelli, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 6.
Shell subcircular, lenticular, strongly compressed, with numerous (twenty to thirty) short conical spines on the margin (often wanting in the upper part of the dorsal margin). Peristome with a deep labial incision and two parallel triangular lateral teeth, the upper margin of which is horizontal.
Dimensions.—Diameter of the shell 0.2 to 0.25; length of the spines 0.02 to 0.03.
Habitat.—North Pacific, Stations 238, 241 (off Japan), depth between 2300 and 3950 fathoms.
20. Challengeron bathybium, n. sp.
Shell subcircular, lenticular, slightly compressed, with a corona of numerous (thirty to forty or more) short, conical, radial spines on the margin. Peristome helmet-shaped, nearly as long as the radius, with two widely divergent, conical, curved teeth, a vertical dorsal and a nearly horizontal ventral tooth.
Dimensions.—Diameter of the shell 0.22; length of the peristome 0.1.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
21. Challengeron johannis, n. sp.
Shell ovate, slightly compressed, with a corona of numerous (forty to sixty or more) short radial spines on the margin, ten to fifteen of them (in the aboral half) are pyramidal, and much larger than the others. Peristome helmet-shaped, about one-third as long as the shell, with a deep bosom and two widely divergent teeth on the concave upper margin, a forked dorsal and a conical ventral.
Dimensions.—Length of the shell 0.13, breadth 0.1; length of the peristome 0.04.
Habitat.—North Atlantic, Færöe Channel (Gulf Stream), John Murray.
22. Challengeron carpenterii, John Murray.
Challengeron carpenterii, John Murray, 1877, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 8.
Shell ovate, with a series of twelve to fifteen short, conical, radial spines on the aboral half of the margin. Peristome slender, semitubular, nearly as long as the shell, in the upper half forked, with two short parallel teeth.
Dimensions.—Length of the shell 0.13 to 0.18, breadth 0.1 to 0.14; length of the peristome 0.1 to 0.12.
Habitat.—Tropical Atlantic, Stations 347 to 348, depth 2250 to 2450 fathoms.
23. Challengeron ciliatum, n. sp.
Shell ovate, slightly compressed, with numerous (forty to fifty or more) short and thin, bristle-shaped, radial spines on the margin. Peristome obliquely truncate, with three curved spines; the dorsal odd spine subvertical, nearly as long as the radius, and much stronger than the two parallel, nearly horizontal, lateral spines.
Dimensions.—Length of the shell 0.15, breadth 0.11; length of the peristome 0.1.
Habitat.—North Pacific, Station 231, depth 2250 fathoms.
24. Challengeron willemoesii, n. sp. (Pl. 99, fig. 13).
Shell broadly-ovate or nearly circular, lenticular, with numerous (fifty to sixty) short and stout, conical, radial spines on the margin, increasing in size towards the aboral pole; the spines are alternately larger and smaller, the largest about half as long as the radius. Peristome helmet-shaped or half conical, longer than the radius of the shell, with two pairs of conical, curved, divergent teeth; the terminal teeth are the halves of a forked dorsal tooth and diverge laterally; the lower teeth are nearly horizontal and directed ventrally.
Dimensions.—Diameter of the shell 0.13 to 0.15; length of the peristome 0.07 to 0.1.
Habitat.—Tropical Pacific, Stations 274 to 276, depth 2350 to 2750 fathoms.
25. Challengeron wyvillei, n. sp. (Pl. 99, fig. 15).
Shell ovate, lenticular, strongly compressed, with numerous (forty to fifty) short, conical, radial spines on the margin; the spines are larger on the aboral side and spinulate. Peristome narrow, with two parallel, lateral, lamellar, forked teeth, about as long as the radius; the upper branch of the forks is sabre-shaped, obliquely truncate, subvertical, ciliate, and much broader than the lower nearly horizontal branch, which is directed towards the ventral side and curved upwards.
Dimensions.—Length of the shell 0.12 to 0.16, breadth 0.1 to 0.14; length of the peristome 0.08 to 0.11.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
Definition.—Challengerida with a pharynx, or an internal prominent mouth tube.
Definition.—Challengerida with a pharynx, without teeth on the mouth, and without marginal spines.
The genus Entocannula and the two following genera represent together the subfamily Pharyngellida, differing from the preceding Lithogromida in the development of a peculiar pharynx, an internal, cylindrical, or funnel-shaped tube, which is conspicuous, leads from the mouth into the shell-cavity, and is provided with an inner and an outer opening. The Pharyngellida are much rarer than the Lithogromida; only ten species have been observed of the former, fifty of the latter. Entocannula is the simplest form of the Pharyngellida, having a smooth shell, without aboral teeth and marginal spines; it differs from Lithogromia only in the possession of the pharynx. One remarkable species is covered entirely with extremely thin, flinty hairs, and may represent therefore a peculiar genus, Trichogromia.
1. Entocannula circularis, n. sp.
Shell circular or nearly circular, lenticular, strongly compressed. Pharynx cylindrical, one-third or one-fourth as broad as the shell, twice as broad as long, its outer and inner apertures of equal breadth. Surface smooth.
Dimensions.—Diameter of the shell 0.20 to 0.32, of the pharynx 0.07 to 0.09.
Habitat.—North Pacific, Station 250, depth 3050 fathoms.
2. Entocannula subglobosa, n. sp.
Challengeria bromleyi, (partim), John Murray, 1879, in schedulis Chall. Coll.
Shell circular, nearly spherical, slightly compressed. Pharynx funnel-shaped, truncate, conical, its outer opening twice as broad as the inner. Surface smooth.
Dimensions.—Diameter of the shell 0.25 to 0.28, of the inner mouth 0.05.
Habitat.—South Pacific, Station 289, depth 2550 fathoms.
3. Entocannula infundibulum, n. sp. (Pl. 99, fig. 19).
Challengeria bromleyi (partim), John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 5.
Shell ovate, truncate at the mouth, slightly compressed. Pharynx funnel-shaped, its outer aperture two to three times as broad as the inner. Surface smooth.
Dimensions.—Length of the shell 0.22 to 0.28, breadth 0.2 to 0.25; inner mouth 0.04 to 0.08.
Habitat.—South Atlantic, Station 318, depth 2040 fathoms.
4. Entocannula hirsuta, n. sp. (Pl. 99, fig. 20).
Trichogromia hirsuta, Haeckel, 1881, Manuscript.
Shell ovate. Pharynx cylindrical, one-fourth as broad as the shell, its inner and outer apertures of equal breadth. The whole surface of the shell, and mainly the outer mouth, is densely covered with thin, curved, siliceous bristles.
Dimensions.—Length of the shell 0.27 to 0.36, breadth 0.2 to 0.3; mouth 0.05 to 0.08.
Habitat.—North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth 600 fathoms.
Definition.—Challengerida with a pharynx, and with one or more teeth on the mouth, but without marginal spines.
The genus Pharyngella differs from the preceding Entocannula, its ancestral form, in the development of one or more teeth on the peristome, and exhibits therefore the same relation to it that Challengeria bears to Lithogromia. Only a few species of this genus have been observed, all in the Atlantic.