20 Dr. Wright on the Geology of the Isle of Wight. 



In Colwell Bay the founderiug of this bed has produced three 

 great masses of oyster-shells which project from the side of the 

 cliff. At first sight they give the observer the idea that they 

 were oyster beds wedged in between the Venus bed which they 

 entirely obscure ; but it is not so ; they are in fact produced by 

 the falling of the oyster band over the inclined face of the lower 

 beds ; the sandy matrix with the oyster-shells having fallen over 

 in a semifluid state. The Ostrea bed measures from 18 inches to 

 2 feet in thickness. The shells are so closely packed together 

 that perfect specimens are obtained with much difficulty. 



Besides Ostrece of two new species in great abundance, I col- 

 lected here Mytilus affinis, Potamides margaritaceus, P. cinctus, 

 Fusus labiatus, Balanus, and Serpulee. 



No. 13. Laminated blue clay mottled with red, non-fossilife- 

 roxis : 18 inches. 



No. 14. "The Venus bed" rises on the shore 484 feet south 

 of Lynchen Chine, and runs out on the cliff at ToUands Bay near 

 the Coast-guard station. Between Weston Chine and the lower 

 flank of the north side of Headon Hill, there has been extensive 

 denudation. The Lymnsean limestone and the upper marine 

 have been entirely removed. These beds reappear in Headon, 

 and the Lymnsean limestone with its underlying beds form a fine 

 bold mural wall, which stands out from amongst the ruins of the 

 softer strata on the north side of that hill. The Venus bed re- 

 appears near the summit of the south-western escarpment of 

 Headon Hill. 



This interesting bed ought to be studied in Colwell Bay, where 

 it is best developed, and from whence the finest specimens of its 

 beautiful fossils are obtained. At the base of the Venus bed is 

 a thin band of clay, containing Psammohia compressa in great per- 

 fection. The finest specimens are obtained at low-water mark, 

 when a ground sea has removed the sand. Here likewise we find 

 Ostrea, two species undescribed, in considerable abundance. 

 Above the clay-band is the true upper marine or Venus bed ; it 

 consists of a slate-coloured siliceous sand mixed with clay. The 

 shells, which are very abundant, lie for the most part on their 

 sides, but I have found them inclined in all directions. This bed 

 appears to have been a slow and tranquil deposit from sea water 

 along a sandy shore. The shells are as perfect in all their parts 

 as recent specimens, and the peculiar nature of the matrix has 

 so preserved their colours, that one almost doubts the fact of 

 their being fossil shells. 



I collected from this bed the following shells : — 



Aetseon. Balanus reflexus. Sow. 



Ancillaria subulata. Lam. unguiformis, Sow. 



Buccinum desertum, Brand, Cancellaria muricata. Wood. 



