Ch. XVI.] UPPER EOCENE FORMATIONS. 285 



on the Isle of Wight, first separated the whole into a lower fresh- 

 water, an upper marine, and an upper freshwater division. 



Among the shells which are widely distributed through the Hea- 

 don series are JVeritina concava (fig. 223), Lymnea caudata (fig. 224), 

 and Oerithium concavum (fig. 225). Helix labyrinthica, Say (fig. 

 222), a land-shell now inhabiting the United States, was discovered 

 in this series by Mr. 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, 

 havino- no local connection with the actual geoQ-raohical 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, where the organic remains have been studied by Mr. Searles 

 Wood, Dr. Wright, and the Marchioness of Hastings. To the latter 

 we are indebted for a detailed section of the beds,* as well as for the 

 discovery of a variety of new species of fossil mammalia, chelonians, 

 and fish ; also, for first calling attention to the important fact that 

 these vertebrata differ specifically from those of the Bembridge beds. 

 Among the abundant shells of Hordwell are Paludina lenta and vari- 

 ous species of Lymnsa, Planorbis, Melania, Cyclas, and Unio, Pota- 

 momya, Dreissena, &c. 



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 Le^ndosteus, or 

 bony pike of the American rivers. This same genus of freshwater 

 ganoids has also been met with in the Hempstead beds in the Isle of 

 Wight. The bones of .several birds have been obtained from Hord- 

 well, and the remains of quadrupeds. The latter belong to the genera 

 Paloplotherium of Owen, Anoplotherium, Anthracotherium, Dichodon 

 of Owen (a new genus discovered by Mr. A. H. Falconer), Dickohune, 

 Spalacodon, and Hycenodon. 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 assem- 

 blages of mammalia flourished on the earth during the Eocene period. 



* Bulletin Soc. Geol. de France, 1852, p. 191. 



