Dimensions.—Diameter of the central capsules 0.1 to 0.12, length of the spicula-shanks 0.05 to 0.1.
Habitat.—South Pacific, Station 295, surface.
2. Sphærozoum medusinum, n. sp.
Spicula all (or nearly all) quadriradiate, composed of four (or sometimes in few spicula three) needle-like shanks (mostly of unequal length), diverging from one common point. Shanks slightly curved, pointed, thorny, covered with small spinules. Central capsules ellipsoidal, containing several (four to eight) oil-vesicles. This species may be regarded as the social form of the solitary Thalassoxanthium medusinum (Pl. [2], fig. 5).
Dimensions.—Diameter of the central capsules 0.15 to 0.18, length of the spicula-shanks 0.08 to 0.12.
Habitat.—North Pacific, Station 236, surface.
3. Sphærozoum hamatum, n. sp.
Spicula all (or nearly all) quadriradiate, composed of four (or sometimes in few spicula three) needle-like shanks, mostly of very different size, diverging from one common point. Shanks strong, straight, curved, or hook-like; thorny, covered with small spinules on the distal extremity. Central capsules ellipsoidal, large, containing many (ten to twenty) oil-globules. This large species is distinguished by the very irregular form and size of the spicula.
Dimensions.—Diameter of the central capsules 0.2 to 0.25, length of the spicula-shanks 0.12 to 0.18.
Habitat.—Central Pacific, Station 265, surface.