MOLLUSCA. 
381 
undulated transverse clouds. Six inches long. Inhabits the 
Indian Ocean. 
Genus 12.—NUMMULITES.— Lamarck. 
Generic Character. — Shell lenticular, attenuated at the mar¬ 
gins ; spire internal, discoid, multilocular, covered over by seve¬ 
ral tables ; the outer partitions complicated, produced, extending 
and uniting on each side of the centre ; cells very numerous, 
small, alternate, and formed by transverse imperforate septa. 
Nummulites complanatus. — The Flat Nummulites. 
Plate LXXXIII. fig. 9. 
Orbicular, broad, depressed at the sides, and smooth; margin 
undulated. One and a half inches long. Fossil in France. 
Genus 13.—VORTICIALIS.— Lamarck. 
Generic Character —Shell discoid, spiral, multilocular; volu¬ 
tions contiguous, but not appearing externally; septa trans¬ 
verse, imperforate, but not extending from the centre to the cir¬ 
cumference. 
Vorticialis strigilatci. — The Creased Vorticialis. 
Plate LXXXIII. fig. 10. 
Somewhat depressed, transversely ribbed, and spirally striat¬ 
ed. Fossil. 
Genus 14.—P OL YSTOMELL A. — Lamarck. 
Generic Character. —Shell discoid, multilocular, with invisi¬ 
ble volutions ; with numerous transverse ribs; aperture formed 
by variously disposed holes. 
Pohjstomella crispa. — The Wrinkled Polystomella. 
Plate LXXXIII. fig. 11. 
Slightly wrinkled, and ribbed transversely. Found fossil in 
the chalk formations. 
Genus 15. — SIDEROLITE S. — Lamarck. 
Generic Character. —Shell discoid, multilocular; volutions 
contiguous, but not visible externally; the disc convex on both 
sides, and studded with tubercular dots; the circumference mar- 
