Habitat.—Central Pacific, Station 271, surface.
4. Acanthocorys bütschlii, Haeckel.
? Clathrocanium ehrenbergii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 514, 539, Taf. xxxii. fig. 18, a, b.
Cephalis large, subspherical, with numerous small, circular pores and three to six divergent, slender, apical horns. Thorax flatly conical, smooth, not much larger than the cephalis, with six large, triangular or ovate basal holes between the six ribs. Three of these ribs are primary or perradial, and arise immediately from the collar septum, alternating with three secondary or interradial ribs, which arise more outside. The specimen observed by me exhibited six apical horns, and was more complete than that figured by Bütschli, the six ribs being prolonged over the connecting lattice-girdle into six short, divergent feet.
Dimensions.—Cephalis 0.06 long, 0.06 broad; thorax 0.08 long, 0.1 broad.
Habitat.—Fossil in Barbados.
Subgenus 2. Acanthocoronium, Haeckel.
Definition.—Thorax with nine divergent ribs or radial beams, three of which are primary or perradial, the other six secondary or interradial.
5. Acanthocorys umbellifera, Haeckel.
Arachnocorys umbellifera, Haeckel, 1862, Monogr. d. Radiol., p. 305, Taf. vi. fig. 12.