Page:Scientific results HMS Challenger vol 18 part 2.djvu/171

Rh secondary or interradial; an odd sternal foot (opposed to the odd caudal) and two paired tergal feet (opposed to the two paired pectoral).

Definition.—Feet simple, not branched nor forked.

1. Hexaspyris alterna, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture and irregular polygonal pores; on each side of the stricture two pairs of larger square annular pores. Basal plate also with four larger collar pores. Apical horn twice as long as the shell, conical. Three primary feet (the apical and the two pectoral) slender, curved, as long as the horn; three secondary feet (the sternal and the two tergal) are half as long as the former and more highly inserted; all six feet strongly divergent, cylindrical, pointed.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.15 long, feet 0.08 to 0.14 long.

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

2. Hexaspyris setigera, Haeckel.

Ceratospyris setigera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 11.

Ceratospyris setigera, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. figs. 11a, 11b.

Shell nut-shaped, tuberculate, with a complete internal sagittal ring and numerous small circular pores. Basal plate with four larger central and a circle of twelve to twenty smaller peripheral pores. Apical horn half as long as the shell, bristle-shaped. Three primary feet longer and more deeply inserted than the three secondary feet; all six feet strongly divergent, bristle-shaped, shorter than the shell.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.03 long; primary feet 0.05, secondary 0.02 long.

Habitat.—Fossil in Barbados.

3. Hexaspyris bütschlii, Haeckel.

Ceratospyris triomma, Bütschli (non Ehrenberg), 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. fig. 12, a, b.

Shell nut-shaped, spinulate, with a complete internal sagittal ring and subregular circular pores. Basal plate with twelve pores (four larger central and eight smaller peripheral). Apical horn stout, oblique, as long as the shell. Six feet of equal length, slightly divergent, nearly vertical, slender, three to four times as long as the shell.

Dimensions.—Shell 0.05 long, 0.07 broad; horn 0.06, feet 0.15 to 0.2 long.

Habitat.—Fossil in Barbados.