Dimensions.—Diameter of the disk 0.04, of the gates 0.015.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
3. Triodiscus spinosus, n. sp. (Pl. [48], fig. 14).
Disk subcircular, four times as broad as the triangular central chamber. Three arm-chambers club-shaped, at the base one-third, at the distal end two-thirds as broad as the semicircular gates. Surface thorny. On the margin fifteen larger radial spines, three on the corners of the disk (in the radius of the gates), twelve on the two faces of the arms ends (two opposite on the edge of each end.) (Differs from Triopyle spinigera mainly by the delicate hexagonal network closing the gates.)
Dimensions.—Diameter of the disk 0.05, of the gates 0.02.
Habitat.—North Atlantic, Canary Islands (Lanzerote, Haeckel).
Subfamily 2. Hexapylida, Haeckel.
Definition.—Pylodiscida with triopyle-shaped medullary shell, surrounded by three distal arm-chambers, which are separated by three open notches or gates.
Genus 248. Pylolena,[[287]] n. gen.
Definition.—Pylodiscida with triopyle-shaped medullary shell, surrounded by three distal arm-chambers. Notches between the three arms open.