Ch. XV.] 



UPPEK EOCENE, ISLE OF WIGHT. 



195 



SUBDIVISIONS O? THE HEMPSTEAD SEPaES, 



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. 171. 



Corbula pUnm. Hempstead Beds, 

 Isle of WiKht. 



Oyrena semhtriata. 

 Hempstead Beds. 



2. IS'ext below are freshwater and estuary marls and carbonaceous clays, in the 

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

 Lam., fig. 172, 0. elegans, fig. 173, and C. tricmctum ; also Eissoa ChasteW, 

 fig. 174, a very common Limburg 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 freshwater portion of the same beds Faludina 



Fig. 172, 



Fig. 173. 



Fis. 174. 



Fig. 175. 



Cerithium pllcatum. 

 Lam. Hempstead. 



CeritJiiiim elegans, 

 Hempstead. 



Jii.'iwa ChasteUi, Nyst, 

 Sp. Hempstead, Isle 

 of Wiffht. 



Paludina lenta. 

 Hempstead Beds. 



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

 now living, P. nnicolor ; also several species of Lymneics, Planorhis, and JJnio. 

 The next series, or middle freshwater and estuary marls, are distinguislied by 

 the presence of Melania fasciata, Faludina lenta, and clays with Oi/pris ; the 

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

 Panopcea. 



The lower freshwater and estuary maids contain Melania eostata. Sow., Jfe- 

 lanopsis, (fee. The bottom bed is carbonaceous, and called the "Black band," 

 in which Rissoa Chastelii, fig. i73, 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 Chara medicagimda, Brong., 

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

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

 known, from those of the Bembridge beds immediately underlying. 



13 



