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52
A TREATISE ON GEOLOGY.
CHAP VI.
Helix hortensis, Ilford, Stutton, Grays; H. lucida, Stutton; H. fusca, Stutton; H. rufescens, Grays and Stutton; H. paludosa, Stutton; H. hispida, Erith, Stutton, Grays, Ilford; H. trochiformis, Stutton.
Carychium minimum, Stutton, Erith, Grays.
Pupa marginata, Stutton, Erith, Grays; P. sexdentata, Stutton, Erith, Grays.
Bulimus lubricus, Stutton.
Umax lubricus, Stutton.
Limnæa auricularia, Ilford, Stutton; L. peregra, Stutton, Copford, Ilford; L. fossaria, Stutton; L. palustris, Stutton, Grays.
Planorbis carinatus, Stutton, Erith, Grays; P. corneus, Ilford, Stutton, Erith; P. vortex, Stutton, Erith; P. contortus, Stutton; P. imbricatus. Stutton; P. nitidus, Stutton.
Paludina impura, Stutton, Grays, Erith, Ilford.
Valvata cristata, Stutton; V. piscinalis, Stutton, Copford; V. antiqua, Grays.
Ancylus lacustris, Stutton; A. fluviatilis, Stutton, Grays.
Thus, the former co-existence of extinct mammalia, and numerous mollusca not in the smallest degree different from recent species living in the same climates, which was first ascertained near Market Weighton, and confirmed by Mr. H. Strickland's researches in Worcestershire, is abundantly established by a large induction of instances.
Mr. Charlesworth, whose researches on the supracretaceous deposits of the eastern counties have led to other valuable results, presents, in the following general view of the beds which there occur above the chalk, a simple classification of the mammaliferous strata. (Reports of the British Association, for 1836, p. 85.)
| Section I. | Beds containing numerous remains of terrestrial mammalia:— |
1. Superficial gravel, containing bones of land animals, probably washed out of stratified deposits.
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2. Superficial marine deposits of clay, sand, &c., in which the shells, very few in number (10 or 15 species), may all be identified with such as are now existing. (Brick earth of the river Nar, Norfolk.)
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3. Fluviatile and lacustrine deposits, containing a considerable number of land and freshwater
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