Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
Genus 134. Prunocarpus,[[173]] n. gen.
Definition.—Druppulida with simple ellipsoidal cortical shell and double medullary shell, with numerous radial spines, but without polar tubes.
The genus Prunocarpus differs from Prunulum only in the radial spines of the cortical shell, and exhibits therefore the same relation to it that Druppocarpus bears to Druppula. While in the latter the medullary shell is simple, in the former it is double.
Subgenus 1. Prunocarpetta, Haeckel.
Definition.—Network of the cortical shell regular, with meshes of equal size and similar form.
1. Prunocarpus datura, n. sp.
Cortical shell thick walled, with regular, circular pores, twice as broad as the bars; ten to twelve on the half equator. Between every three meshes arises a short conical spine, twice to three times as long as one pore. Both medullary shells spherical. (Differs mainly from Ellipsidium datura and from Druppocarpus castanea in the double medullary shell. The outer network resembles Haliomma castanea, figured 1862 in my Monograph, Taf. xxiv. fig. 4.)
Dimensions.—Major axis of the ellipsoid 0.16, minor 0.12; pores 0.012, bars 0.006; length of the radial spines 0.03; diameter of the medullary shells 0.06 and 0.04.
Habitat.—North Atlantic, Færöe Channel, John Murray, surface.