Dimensions.—Length of the three joints, a 0.025, b 0.1, c 0.3; breadth, a 0.03, b 0.1, c 0.2.

Habitat.—Fossil in Barbados.

6. Cycladophora spinosa, n. sp.

Shell spiny, with two deep strictures. Length of the three joints = 1 : 4 : 3, breadth = 1 : 5 : 4. Cephalis subspherical, with a stout conical horn of the same length. Thorax ovate, with regular, circular pores, and numerous conical spines. Abdomen truncate, conical, with irregular, roundish pores, and six strong, divergent ribs. Mouth circular.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.09; breadth, a 0.03, b 0.15, c 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Barbados.

Subgenus 3. Lamptonium, Haeckel.

Definition.—Abdomen with nine radial ribs (three primary or perradial, and six secondary or interradial).

7. Cycladophora enneapleura, n. sp.

Shell spiny, with two sharp strictures. Length of the three joints = 1 : 5 : 3, breadth = 2 : 7 : 4. Cephalis hemispherical, with a conical horn of twice the length. Thorax campanulate, with regular, circular pores, and conical thorax. Abdomen cylindrical, with nine straight, parallel ribs, and irregular, roundish pores. Mouth circular. (Similar to Cycladophora gigas, Ehrenberg, 1875, loc. cit., Taf. xviii. fig. 1, but differing in the possession of nine abdominal ribs.)