BEMBEIDGK MAELS. 



173 



Fig. 59. 



Cyrena semistriata, 

 Desh. 



shaly strata follow, including a thick band composed almost 



entirely of" Melania muricata, asso- 

 ciated witli Cyrena semistriata, which 

 latter shell forms also a band of its 

 own. The specimens of all these shells 

 are beautifully preserved. In the clays 

 and mottled marls that follow, shells 

 are scarce or wanting, but fragments 

 of turtle occur, and Forbes had the 

 good fortune to find in situ the greater 

 part of the carapace of a Trionyx 

 incrassatus. 



North of Foreland Point the cliff becomes low and the Bern- 

 bridge Marls are almost entirely hidden by slipjjed gravel. 

 Crossing Brading Harbour these Marls re-appear in the cliffs near 

 St. Helen's Church. Owing to the destruction of the sea-wall 

 good sections of the lower parts of the group are now visible 

 between here and Horestone Point. 



The greater portion of the Marls is exactly similar to the corre- 

 sponding part of the Wliitecliff Bay section : but with some 

 slight though interesting differences in the region of the oyster 

 beds, worthy of detailed notice. 



The top of the Bembridge limestone in this locality, as men- 

 tioned in the account of that rock, presents a surface somewhat 

 irregular, and including oysters, Cyrenoe, and casts of Cerithium. 

 This is immediately succeeded by half a foot of greenish clay 

 containing oysters. Then come !-ix inches of brown clay charo-ed 

 with Cyrena ; a coarse greenish clay, 1 foot thick, succeeds, 

 having a crumbly and angular fracture, and including Melanopsis 

 fusiformis, Cyrena, and a small Melania. The next overiyino- dark 

 shaly clay, 1 foot thick, contains Cyrena, and is surmounted by 

 some four or five inches of pale-lilap, compact, septarian stone, 

 weathering white. Nearly two feet of dark laminated clays and 

 marls succeed, containing in their upper part a band filled with 

 Cyrena semistriata, accompanied by Cyrena obovata and Cerithium 

 Tnutahile. Then come greenish and variegated marls. 



A peculiarity in this section is the presence, in the brown clay- 

 above the oyster clay, of some shells of marine origin not noticed 

 Fig. 60. elsewhere ; these are a pretty little 



Area Wehsteri, Forbes. ^''^\ (^- f^^ehstcri), and a Modiola. 



ihe above is the account given 

 by Edward Forbes of this section, but 

 it may be interesting to add a fuller 

 list of the mollusca, from specimens col- 

 lected in 1888 by Mr. Henry Keepiiio- 

 and Clement Pieid. 



Mollusca of the Lower Bembridge Marls at St. Helen's. 



Area Websteri, Mya minor. 



Cyrena obovata. --...— 



obtusa. 



Mytilus affinis. 

 Ostrea vectensis. 



