Page:Scientific results HMS Challenger vol 18 part 1.djvu/793

Rh 6. Stylotrochus huxleyi, Haeckel.

Stylospongia huxleyi, Haeckel, 1862, Monogr. d. Radiol., p. 473, Taf. xxviii. fig. 7.

Spongy framework of the disk in the inner part with five concentric rings, in the outer part quite irregular. Ten marginal spines, conical at the base, about as long as the radius of the disk, without inner piercing prolongations.

Dimensions.—Diameter of the disk 0.12; length of the radial spines 0.06, basal breadth 0.003.

Habitat.—Mediterranean (Messina), Haeckel.

7. Stylotrochus geddesii, n. sp. (Pl. 41, fig. 11).

Stylospongidium geddesii, Haeckel, 1881, Atlas (pl. xli. fig. 11).

Spongy framework of the disk in the inner part with four to eight concentric rings (or partially spiral convolutions), in the outer part quite irregular. Thirty to fifty pyramidal marginal spines of variable size, one-fourth to one-half as long as the radius of the disk, outer prolongations of inner piercing radial beams, which arise from various concentric rings. I call this interesting species, which is intermediate between Stylodictya and Stylotrochus, in honour of the morphologist Mr. Patrick Geddes of Edinburgh.

Dimensions.—Diameter of the disk 0.15 to 0.25; length of the radial spines 0.03 to 0.06, basal breadth 0.004 to 0.01.

Habitat.—Pacific, central area, Stations 270 to 274, in 2350 to 2925 fathoms.

Definition.— with numerous solid radial spines (five to ten or more), which are scattered over the whole surface and the margin of the disk, or regularly disposed on both sides of it.

The genus Spongotrochus differs from the foregoing and nearly allied genus by the distribution of the numerous radial spines. These are not confined to the margin of the disk, but also scattered on its whole surface, and sometimes symmetrically disposed on both its sides in a regular manner. Also in this genus the spongy framework is sometimes quite irregular (Spongotrochiscus), at other times in the middle part with enclosed concentric rings (Stylospongidium).

Definition.—Spongy framework of the whole disk irregular, without concentric rings or spiral convolutions.