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The next subdivision of the Upper Ludlow consists of grey calcareous sandstone, or very commonly a micaceous stone, decomposing into soft mud, and contains, besides the shells mentioned above, Lingula cornea, Orthis orbicularis, a round variety of O. elegantula, Modiolopsis platyphylla, Grammysia cingulata, all characteristic of the Upper Ludlow.
Its surface was there formed of gravel, cemented together by calcareous matter; and out of it I extracted the following recent shells, which are in a more perfect condition than those from the upper plain: Calyptraea radians. 2. Turritella cingulata. 3. Oliva Peruviana. 4. Murex labiosus, var. 5. Solen Dombeiana. 7. Pecten purpuratus. 8. Venus Chilensis. 9. Amphidesma rugulosum.
The shells embedded in the calcareous beds forming the surface of this fringe-like plain, at the height of from 200 to 250 feet above the sea, consist of: Venus opaca. 2. Mulinia Byronensis. 3. Pecten purpuratus. 4. Mesodesma donaciforme. 5. Turritella cingulata. 6. Monoceros costatum. 7. Concholepas Peruviana. 8. Calyptraea Byronensis.
Testa profunde umbilicata, depresso-globosa, solida, striata, sub epidermide fulvo-alba, fasciis castaneis cingulata; spira sub-depressa, obtusa; anfractus 6 convexiusculi; apertura subcircularis; peristoma nigrum, expansum, margine basali reflexo, columellari dilatato, umbilicum subtegente. Diam. maj. 37, min. 27, alt. 25, mill.
The common Turritella cingulata was dredged up living at even from ten to fifteen fathoms; but this is a species which I did not find here amongst the upraised shells.
Only the Turritella Chilensis from Huafo and Mocha, the T. Patagonica and Venus meridionalis from Navidad, come very near to recent South American shells, namely, the two Turritellas to T. cingulata, and the Venus to V. exalbida: some few other species come rather less near; and some few resemble forms in the older European tertiary deposits: none of the species resemble secondary forms.
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