2. Stylotrochus craticulatus, Haeckel.
Spongotrochus craticulatus, Stöhr, 1880, Palæontogr., vol. xxvi. p. 118, Taf. vi. fig. 12.
? Spongodiscus aculeatus, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 246.
Spongy framework of the whole disk irregular. Sixteen to twenty short marginal spines (twice to four times as long as the diameter of one mesh of the framework), free prolongations of internal radial beams which arise from the darker centre of the disk. (The interruption of the disk-margin on one point of its circumference, figured by Stöhr as osculum or "Mündungs-Oeffnung," is probably an accidental abnormality; I did not find it in other specimens.)
Dimensions.—Diameter of the disk 0.2 to 0.25; length of the radial spines 0.005 to 0.018, basal breadth 0.001 to 0.003.
Habitat.—Pacific, central area, Stations 266 to 268, surface; fossil in Barbados and Sicily.
3. Stylotrochus helianthus, n. sp.
Spongy framework of the whole disk irregular. Thirty to fifty very large, conical radial spines, about as long as the diameter of the disk, and at the base two to four times as broad as one mesh of the framework (without internal prolongations).
Dimensions.—Diameter of the disk 0.15 to 0.2; length of the radial spines 0.16 to 0.24, basal breadth 0.008 to 0.016.
Habitat.—Pacific, central area, Station 272, surface.