Page:Scientific results HMS Challenger vol 18 part 2.djvu/798

1674 14. Gazelletta dendronema, n. sp. (Pl. 120, fig. 16).

Shell hemispherical, thorny, with a broad, alveolate velum which bears irregular hollow thorns on the inside and on the free margin (fig. 16). Feet divergent, irregularly curved, with scattered arborescent lateral spines, which are irregularly branched, and bear at the distal end of each branch a small spathilla with four to six teeth. The distal ends of the feet are dichotomously branched, with stouter simple fork-branches.

Dimensions.—Length of the shell 0.17, breadth 0.36; length of the feet 0.5 to 0.7.

Habitat.—North Pacific, Station 252, surface.

15. Gazelletta melusina, n. sp. (Pl. 118, fig. 1).

Shell campanulate, spiny. Feet divergent, strongly curved, with scattered arborescent lateral spines, which are richly and dichotomously branched, with thin, simple, terminal branches. The distal ends of the feet bear three or four much larger and stouter branches, which are again dichotomously branched.

Dimensions.—Length of the shell 0.2, breadth 0.15; length of the feet 0.5 to 0.8.

Habitat.—South Pacific, Station 293, depth 2025 fathoms.

Definition.— with twelve articulate feet on the peristome, six ascending and six alternate descending.

The genus Gorgonetta is the most highly developed of all hitherto observed Medusettida, and belongs to the most remarkable forms of Radiolaria. Its general shape is very similar to that of a larva of a Geryonia or Carmarina, in which six interradial larval tentacles are directed upwards, six alternating perradial permanent tentacles downwards. The six ascending feet are in all the four species observed smaller, more or less branched, and armed with spathillæ. The six descending feet are much larger and covered with very elegant pencils, the single threads of which bear a double spathilla. The distal ends of the feet are forked or branched.

1. Gorgonetta mirabilis, n. sp. (Pl. 119, figs. 1-4).

Shell cap-shaped, flatly vaulted, or nearly hemispherical, about twice as broad as long, with smooth surface. Six ascending feet widely divergent, about twice as long as the breadth of the shell, nearly straight, arborescent, with numerous curved branches, each of which bears at the distal end a spathilla with four to six short recurved teeth (fig. 2). Six descending feet about twice as