94 Dr. Wright on the Geology of the 



Cancelluria elongata, Wood. Nucula, new species. 



Cerithium . Oliva, new species. 



Corbula cuspidata, Sow. Ostrea, two new species. 



Cyrena cycladiformis, Desk. Panopaea covrugata, Edwards. 



obovata, Sow. Pleurotoma semicolon, Sow. 



Cytherea incrassata, Desh. , two new species. 



obliqua, Desh. Psammobia conipressa, Sow. 



Fusns labiatus, Sow. solida. 



Lncina . Serpula corrugata, Sow. 



Mactra, new species. , new species. 



Melania fasciata. Rostellaria rimosa, Brand. 



rauricata. Voluta spinosa? Sow. 



Melanopsis ancillaroides. , new species, like V. haqja, 



fusiformis. Desh. 



Mya angustata, Sow. p 



Natica depressa, Sow. Pisces. 



epiglottina, Lam. Teeth of Squalus. 



labellata, Lam. Teeth of Myliobatis. 



Nucula similis, Sow. 



The Venus bed measures from 7 to 8 feet in thickness : the 

 lower half is a slate-coloured sand ; the upper half in some parts 

 of its course is ferruginous. It is from the lower zone that all 

 the fine shells are obtained ; those found in the upper zone are 

 brittle and colourless. 



The term " upper marine formation w is only strictly applicable 

 to the oyster and Venus beds with the intercalated band of non- 

 fossil iferous clay. 



No. 15. The next series of beds are of estuary origin. They 

 consist of alternations of sand and clay, with seams of Potamides, 

 Neritina, Melanopsis, Natica, Cyrena, Mrjtilus and Ostrea. The 

 following section gives the order of these deposits, which are well 

 exposed in a break in the cliff beyond Long's Cottage: — Pea-green 

 coloured sands with a thin band of Cyrena obovata, about 3 ft. 

 Shelly band in a dark clayey matrix, containing Cyrena obovata, 

 Potamides margaritaceus, Melania muricata, and M. fasciata, 

 4 inches. Gray, green, and yellow sands, no shells, 2 feet 4 inches. 

 Shelly band in a dark clay containing Cyrena obovata, Potamides 

 and Ostrea, 4 inches. Sandy clay striped gray, green and ochre, 

 no shells, 2 feet 9 inches. Shelly band with a seam of lignite at 

 the base and Cyrena obovata piled upon each other, 6 inches. 



The origin of these beds on the shore is seen south of Bramble 

 Chine, but it is much concealed by the ruin which has fallen upon 

 them. The upper marine in Colwell Bay forms an underclifF, 

 the wall of which is the Venus and oyster bed and upper estuary 

 series, and its terrace, the ledge of Lymnsean limestone hereafter 

 to be described. These fossiliferous bands have foundered much 

 at Warden Cliff, where they run out. They reappear in situ in 

 Hcadon Hill, and pass round into Alum Bay. I traced them 

 into the western escarpment of Headon; the beds here are 



