Genus Nautilus, Linnæus. There are four well-marked species of this genus in the collection. Two of them appear to be identical with European species, and two are new. The former are cretaceous forms: of the latter, one is nearly allied to a cretaceous and the other to oolitic species. Not one of the specimens is in perfectly good condition, so that the certainty of the determinations may hereafter be questioned.

I. Nautilus lævigatus, D’Orbigny?

N. testâ subglobosâ, inflatâ, lævigatâ, subumbilicatâ; aperturâ orbiculari-lunatâ; septis obsolete undulatis; siphunculo subcentrali.

Median diameter, 6 inches. Breadth at base of aperture, 4 inches.

Shell subglobose, much-inflated, slightly umbilicated, externally smooth; the mouth suborbicular and lunate. The chambers have a slight tendency to show a sinuated outline. The siphon is a little nearer to the spire than to the back. The spaces between the chambers and the degree of inflation of the entire shell vary in different specimens. Young examples have a very smooth shell. I cannot distinguish it from the Nautilus lævigatus, except in that the chambers of the French species are usually wider. M. D’Orbigny describes his shell as from the “ couches moyennes de la craie, à 1’étage des craies tufau et au grès vert.” (D’Orb. P. F. Terrains Crétacés, vol. i. p. 84. pi. 17.)

Locality, Pondicherry.

2. Nautilus sphæricus, sp. nov.

N. testâ globosâ inflatissimâ (lævigata ?), umbilicatâ; aperturâ latissimâ, hinatâ, angustatâ; septis arcuatis; siphunculo excentrico.

Median diameter, 4 inches.

A very