Hence there cannot be any doubt, highly curious though the fact be, that these several fossils, namely, the Hippurites, Gryphaea, Ostrea, Pecten, Turritella, Nautilus, two Terebratulae, and Spirifer all belong to the same formation, which would appear to form a passage between the oolitic and cretaceous systems of Europe.

Thus, a gryphaea is stated by M. Virlet to have been met with in a lead-mine near Semur, in France, and a madrepore in a compact vein of cinnabar in Hungary. Carne mentions true pebbles of quartz and slate in a tin lode of the Relistran Mine, at the depth of 600 feet below the surface.

Hence, though both sand and mud originated simultaneously, the one near the land, the other far from it, the sands in every locality where a shore became submerged might constitute the underlying deposit. Ostrea columba. Syn. Gryphaea columba. Ostrea carinata. Chalk marl and chloritic sand. Terebrirostra lyra, Sowerby. Pecten 5-costatus. White chalk and chloritic sand.

Gryphaea nov. spec.?, E. Forbes. Perna Americana, E. Forbes. Avicula, nov. spec. Considered by Mr. G.B. Sowerby as the A. echinata, by M. d'Orbigny as certainly a new and distinct species, having a Jurassic aspect. The specimen has been unfortunately lost.

Terebratula aenigma, var. Spirifer Chilensis. Mingled together in alternating beds in the main valley of Copiapo near Las Amolanas, and likewise higher up the valley: Pecten Dufreynoyi. Turritella Andii. Terebratula aenigma, var. as at Guasco. Astarte Darwinii. Gryphaea Darwinii. Gryphaea nov. species? Perna Americana. Avicula, nov. species. Pecten Dufreynoyi. Gryphaea Darwinii?

On the other hand, taking into account the evidence derived from the cretaceous character of these three shells, and of the Hippurites, Gryphaea orientalis, and Ostrea, from Coquimbo, we are driven back to the provisional name already used of cretaceo-oolitic. From geological evidence, I believe this formation to be the equivalent of the Neocomian beds of the Cordillera of Central Chile.

Two of these shells, namely, the Gryphaea and Trigonia, appear to be identical with species collected by Meyen and myself on the Peuquenes range; and in the opinion of Von Buch and M. d'Orbigny, the two formations belong to the same age.

Some of the fragments of Ammonites were as thick as a man's arm: the Gryphaea is much the most abundant shell. These fossils M. d'Orbigny considers as belonging to the Neocomian stage of the Cretaceous system. Dr. Trigonia costata, identical with those found in the upper Jurassic beds at Hildesheim. 3. Pecten striatus, identical with those found in the upper Jurassic beds at Hildesheim. 4.

I collected sixty shells from the New Jersey deposits in 1841, five of which were identical with European species Ostrea larva, O. vesicularis, Gryphaea costata, Pecten quinque-costatus, Belemnitella mucronata. As some of these have the greatest vertical range in Europe, they might be expected more than any others to recur in distant parts of the globe.

The remarks given on the several foregoing shells, show that, in M. d'Orbigny's opinion, the Pecten, Ostrea, Turritella, and Hippurite indicate the cretaceous period; and the Gryphaea appears to Professor Forbes to be identical with a species, associated in Southern India with unquestionably cretaceous forms.