Ch. XV.] 



UPPER EOCEjSTE, ISLE OF WIGHT. 



19a 



SUBDIVISIONS OF THE HEMPSTEAD SERIES. 



1. The uppermost or Corbula beds, consisting of marine sands and clays, contain 

 Corbula pisum, fig. 170, a species common to the Middle Eocene clay of 

 Barton; Cyrena semistriata, fig. 171, "which is also a Middle Eocene fossil; 

 several Cerithia, and other shells peculiar to this series. 



Fig. 170. 



Fig. 171. 



Corbula pisum. Hempstead Beds, 

 Isle of "Wight 



Cyrena semistriata. 

 Hempstead Beds. 



Kext below are freshwater and estuary marls and carbonaceous clays, in the 

 brackish-water portion of which are found abundantly Cerithium plicatum, 

 Lam., fig. 172, 0. elegans, fig. 173, and C. tricinctum ; also Eissoa Chastelii, 

 fig. 174, a very common Limburg shell, and which occurs in each of the four 

 subdivisiona of the Hempstead series down to its base, where it passes into 

 the Bembridge beds. In the freshwater portion of the same beds Paludina 



Fig. 172. 



Fig. 173. 



Fig. 174. 



Fig. 175. 



Cerithium plicatum, 

 T.am Hempstead. 



Cerithium elegans, 

 Hempsteai 



Bissoa Chastelii, Nyst, 

 8p. Hempstead, Isle 

 of Wight. 



Paludina lenta. 

 Hempstead Beds. 



lenta, fig. 175, occurs a shell identified by some conchologists with a species 

 now living, P. unicolor ; also several species of Zymneus, Planorbis, and Unio. 



3. The next series, or middle freshwater and estuary marls, are distinguished by 

 the presence of Melania fasciata, Paludina lenta, and clays with Oypris ; the 

 lowest bed contains Cyrena semistriata, fig. 171, mingled with Cerithia and a 

 Panopcea. 



4. The lower freshwater and estuary marls contain Melania costata, Sow., Me- 

 lanosis, &c. The bottom bed is carbonaceous, and called the " Black band," 

 in which Eissoa Chastelii, fig. 173, before alluded to, is common. This bed 

 contains a mixture of Hempstead shells with those of the underlying Middle 

 Eocene or Bembridge series. The seed-vessels of Char a medicaginula, Brong, 

 and C. helecteras are characteristic of the Hempstead beds generally. The 

 mammalia, among which is a species of Hyotherium, differ, so far as they are 

 known, from those of the Bembridge beds immediately underlying. 



13 



