Pecten Dufreynoyi, d'Orbigny, "Voyage, Part Pal." This species, which occurs here in vast numbers, according to M. D'Orbigny, resembles certain cretaceous forms. Ostrea hemispherica, d'Orbigny, "Voyage" etc. Also resembles, according to the same author, cretaceous forms. Terebratula aenigma, d'Orbigny, "Voyage" etc. Is allied, according to M. d'Orbigny, to T. concinna from the Forest Marble.

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?

I heard of a great gypseous formation in the Cordillera; and a collection of shells made there was given me. These shells are all in the same condition, and appear to have come from the same bed: they consist of: Turritella Andii, d'Orbigny, "Voyage" Part Pal. Pecten Dufreynoyi, d'Orbigny, "Voyage" Part Pal. Terebatula ignaciana, d'Orbigny, "Voyage" Part Pal.

I will reiterate the evidence on the association of these several shells in the several localities. In the same bed, Rio Claro: Pecten Dufreynoyi. Ostrea hemispherica. Terebratula aenigma. Spirifer linguiferoides. Same bed, near Arqueros: Hippurites Chilensis. Gryphaea orientalis.

Collected by M. Domeyko from the same locality, apparently near Arqueros: Terebratula aenigma and Terebratula ignaciana, in same block of limestone: Pecten Dufreynoyi. Ostrea hemispherica. Hippurites Chilensis. Turritella Andii. Nautilus Domeykus. In a collection from the Cordillera, given me: the specimens all in the same condition: Pecten Dufreynoyi. Turritella Andii. Terebratula ignaciana.

M. Domeyko has sent to France a collection of fossils, which, I presume, from the description given, must have come from the neighbourhood of Arqueros; they consist of: Pecten Dufreynoyi, d'Orbigny, "Voyage" Part Pal. Ostrea hemispherica, d'Orbigny, "Voyage" Part Pal. Turritella Andii, d'Orbigny, "Voyage" Part Pal. Hippurites Chilensis, d'Orbigny, "Voyage" Part Pal.

At the foot of the first ridge of the main Cordillera, in the ravine of Maricongo, and at an elevation which, from the extreme coldness and appearance of the vegetation, I estimated at about ten thousand feet, I found beds of white sandstone and of limestone including the Pecten Dufreynoyi, Terebratula aenigma, and some Gryphites.

The shells out of the layers of brown limestone, included in the black calcareous shale-rock, which latter, as just stated, replaces the white siliceous sandstone, consist of: Pecten Dufreynoyi, d'Orbigny, "Voyage" Part Pal. Turritella Andii, d'Orbigny, "Voyage" Part Pal. Astarte Darwinii, E. Forbes. Gryphaea Darwinii, E. Forbes. An intermediate form between G. gigantea and G. incurva.