Dimensions.—Diameter of the disk (with five rings) 0.24, of the phacoid shell 0.1, of the medullary shell 0.05.
Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.
Genus 199. Amphicyclia,[[238]] Haeckel, 1881, Prodromus, p. 458.
Definition.—Coccodiscida with two opposite solid radial spines on the margin of the circular disk. Medullary shell double.
The genus Amphicyclia has the same form and structure as Stylocyclia, and differs from it only in the double concentric medullary shell. It bears therefore to the latter the same relation that Coccodiscus does to Lithocyclia.
1. Amphicyclia chronometra, n. sp. (Pl. [38], fig. 1).
Phacoid shell three times as broad as the outer and nine times as broad as the inner medullary shell, surrounded by two broad chambered rings, which are divided into irregular chambers by fifty to sixty radial beams of different distance. Margin of the disk thorny, lacerated. Pores irregular, roundish; twelve to sixteen on the radius of the phacoid shell, two to three on the breadth of each ring. The two opposite marginal spines strong, prismatic, with prominent edges, about as long as the diameter of the disk.
Dimensions.—Diameter of the disk (with two rings) 0.24, of the phacoid shell 0.15, outer medullary shell 0.05, inner 0.017.
Habitat.—Pacific, central area, Stations 265 to 268, depths 2700 to 2900 fathoms.
2. Amphicyclia amphistyla, n. sp. (Pl. [37], fig. 7).