Definition.—Disk circular.
1. Ommatodiscus decipiens, Stöhr.
Ommatodiscus decipiens, Stöhr, 1880, Palæontogr., vol. xxvi. p. 115, Taf. vi. figs. 8, 8a.
Disk circular, with two chambered rings around the spherical central chamber, of equal breadth. Chambers twice as high as broad. Pores very small, one-third as broad as the bars between them, two on the breadth of each ring. Osculum of the same breadth as the central chamber, surrounded by numerous very short teeth.
Dimensions.—Diameter of the disk 0.12; breadth of the central chamber and of each ring 0.03; pores 0.0015.
Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.
2. Ommatodiscus stöhrii, n. sp.
Disk circular with three chambered rings around the spherical central chamber, of equal breadth. Chambers broader than high. Pores of the same breadth as the bars between them, four on the breadth of each ring. Osculum of the same breadth as the central chamber, surrounded by a corona of ten to twenty thin, bristle-shaped teeth, as long as its diameter.
Dimensions.—Diameter of the disk 0.2; breadth of the central chamber and of each ring 0.03; pores 0.004.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.