Lower Miocene of England—Hempstead Beds.—We have already stated that the Upper Miocene formation is nowhere represented in the British Isles; but strata referable to the Lower Miocene period are found both in England, Scotland, and Ireland. In the Hampshire basin these occupy a very small superficial area, having been discovered by the late Edward Forbes at Hempstead near Yarmouth, in the northern part of the Isle of Wight, where they are 170 feet thick, and rich in characteristic marine shells. They overlie the uppermost of an extensive series of Eocene deposits of marine, brackish, and fresh-water formations, which rest on the Chalk and terminate upward in strata corresponding in age to the Paris gypsum, and containing the same extinct genera of quadrupeds, _Palæotherium, Anoplotherium,_ and others which Cuvier first described. The following is the succession of these Lower Miocene strata, most of them exposed in a cliff east of Yarmouth: 1. The uppermost or Corbula beds, consisting of marine sands and clays, contain _Voluta Rathieri,_ a characteristic Lower Miocene shell; _Corbula pisum_ (Fig. 158), a species common to the Upper Eocene clay of Barton; Cyrena semistriata (Fig. 159), several Cerithia, and other shells peculiar to this series. Fig. 158: Corbula pisum. Fig. 159: Cyrena semistriata. Fig. 160: Cerithium plicatum. Fig. 161: Cerithium elegans. Fig. 162: Rissoa Chastelii. Fig. 163: Paludina lenta. 2. Next are fresh-water and estuary marls and carbonaceous clays in the brackish-water portion of which are found abundantly _ Cerithium plicatum,_ Lam. (Fig. 160), _Cerithium elegans_ (Fig. 161), and _Cerithium tricinctum_; also _Rissoa Chastelii_ (Fig. 162), a very common Kleyn Spawen shell, and which occurs in each of the four subdivisions of the Hempstead series down to its base, where it passes into the Bembridge beds. In the fresh-water portion of the same beds _Paludina lenta_ (Fig. 163) occurs; a shell identified by some conchologists with a species now living, _P. unicolor_; also several species of _ Lymneus, Planorbis,_ and _Unio._ 3. The next series, or middle fresh-water and estuary marls, are distinguished by the presence of _Melania fasciata, Paludina lenta,_ and clays with _Cypris_; the lowest bed contains _Cyrena semistriata_ (Fig. 159), mingled with Cerithia and a _panopæa._