Habitat.—Fossil in Barbados.
6. Tricolocapsa schleidenii, n. sp. (Pl. [66], fig. 2).
Shell subconical, with two deep strictures. Length of the three joints = 2 : 3 : 6, breadth = 3 : 5 : 6. Cephalis subspherical. Pores subregular, circular, arranged in transverse girdles, three in the broad thorax, six in the subglobular abdomen. Basal pole rounded.
Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.03, b 0.05, c 0.06.
Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.
Genus 625. Phrenocodon,[[242]] n. gen.
Definition.—Theocapsida (vel Tricyrtida eradiata clausa) with an apical horn, and a lattice-plate between thorax and abdomen.
The genus Phrenocodon differs from the two preceding genera in the remarkable circumstance, that the basal lattice-plate closes not the terminal mouth itself, but the constricted opening between thorax and abdomen. It may therefore be regarded as a Sethocapsa, which has developed a third, open, abdominal joint. The cephalis bears an apical horn.
1. Phrenocodon clathrostomium, n. sp. (Pl. [70], figs. 7, 8).
Shell campanulate-conical, with two deep strictures. Length of the three joints = 2 : 6 : 3, breadth = 3 : 10 : 14. Cephalis hemispherical, with an oblique curved horn of the same length. Thorax subconical, with polygonal, roundish pores, increasing in size towards the girdle. A perfect fenestrated diaphragm, with irregular, roundish pores of very different sizes, separates the thorax from the abdomen. The latter is composed of three parallel, circular rings, which are connected by fifteen to twenty radial beams. As the middle ring is larger than the two others, the beams between the large quadrangular pores are divergent in the upper, convergent in the lower girdle. Short prolongations of the divergent beams form a coronal around the middle ring (compare fig. 7 profile, fig. 8 from below).