Page:Scientific results HMS Challenger vol 18 part 1.djvu/709

Rh 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.

3. Ommatodiscus circularis, n. sp.

Disk circular, with four circular chambered rings around the spherical central chamber, of increasing breadth; the fourth ring twice as broad as the second. Chambers about as broad as high. Pores large, twice as broad as the bars, one to two on the breadth of each ring. Osculum twice as broad as the central chamber, surrounded by a coronal of strong conical teeth, twice as long as its diameter.

Dimensions.—Diameter of the disk 0.18; breadth of the central chamber and inner rings 0.015, of the outer rings 0.03; pores 0.01.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Definition.—Disk elliptical.

4. Ommatodiscus haeckelii, Stöhr.

Ommatodiscus haeckelii, Stöhr, 1880, Palæontogr., vol. xxvi. p. 115, Taf. vi. figs. 7, 7a.

Disk elliptical (6 : 7), with four chambered rings around the elliptical central chamber, of equal breadth. Chambers about as high as broad. Pores small, half as broad as the bars, two on the breadth of each ring. Osculum three times as broad as the central chamber, surrounded by a crown of strong conical teeth.

Dimensions.—Length of the disk 0.18, breadth 0.16; breadth of each ring and of the central chamber 0.02; pores 0.003.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr), Caltanisetta (Haeckel).