Among the shells which are widely distributed through the Headon series are _Neritina concava_ (Fig. 177), _Lymnea caudata_ (Fig. 178), and _ Cerithium concavum_ (Fig. 179). _Helix labyrinthica,_ Say (Fig. 176), a land-shell now inhabiting the United States, was discovered in this series by Mr. Searles Wood in Hordwell Cliff. It is also met with in Headon Hill, in the same beds. At Sconce, in the Isle of Wight, it occurs in the Bembridge series, and affords a rare example of an Eocene fossil of a species still living, though, as usual in such cases, having no local connection with the actual geographical range of the species. The lower and middle portion of the Headon series is also met with in Hordwell Cliff (or Hordle, as it is often spelt), near Lymington, Hants. Among the shells which abound in this cliff are _Paludina lenta_ and various species of _Lymnea, Planorbis, Melania, Cyclas, Unio, Potamomya, Dreissena,_ etc. Fig. 178: Lymnea caudata, Fig. 179: Cerithium concavum. Among the chelonians we find a species of _Emys,_ and no less than six species of _Trionyx_; among the saurians an alligator and a crocodile; among the ophidians two species of land-snakes (_Paleryx,_ Owen); and among the fish Sir P. Egerton and Mr. Wood have found the jaws, teeth, and hard shining scales of the genus _Lepidosteus,_ or bony pike of the American rivers. This same genus of fresh-water ganoids has also been met with in the Hempstead beds in the Isle of Wight. The bones of several birds have been obtained from Hordwell, and the remains of quadrupeds of the genera _Palæotherium (P. minus), Anoplotherium, Anthracotherium, Dichodon, Dichobune, Spalacodon,_ and _Hyænodon._ The latter offers, I believe, the oldest known example of a true carnivorous animal in the series of British fossils, although I attach very little theoretical importance to the fact, because herbivorous species are those most easily met with in a fossil state in all save cavern deposits. In another point of view, however, this fauna deserves notice. Its geological position is considerably lower than that of the Bembridge or Montmartre beds, from which it differs almost as much in species as it does from the still more ancient fauna of the Lower Eocene beds to be mentioned in the sequel. It therefore teaches us what a grand succession of distinct assemblages of mammalia flourished on the earth during the Eocene period.