in the Vicinity of Reading. 45 



and in which the greatest number of teeth and shells has 

 been discovered, for description. The layers are all hori- 

 zojital, and the section is vertical. The first layer, and 

 which is the foundation, is chalk. In this formation no 

 organic remains have been discovered ; ii contains nodules 

 of flints, which are usually in beds and adhering to the 

 chalk. Immediatclv above is the stratum of sand, con- 

 taining the remains of marine animals. Its thickness varies 

 from two feet and a half to less than a foot. The bed con- 

 taining these remains is not entirely of sand, as some clay 

 may be distinguished among it. The oysters are commonly 

 entire ; one valve being coimected with another, although 

 the adhesion has become so sliiiht that they may wiihout 

 difficulty be separated, and the laminae of each valve may 

 likewise be very easily divided. On separating the valves, 

 I found that the place which had been occupied by the 

 oyster was filled bv an unctuous earth exactly of the same 

 shape with the ovsier. 



The external appearance of these shells is in some in- 

 stances entire ; but they generally have the appearance of 

 those oyster shells which have been exposed to heat, and 

 when placed in -a fire they do not crepitate. The outer sur- 

 faces are rough : the inner smooth. They differ very 

 much in size. The largest which I have observed is six 

 inches in length and four in breadth. That they exist in 

 very con>iderable quantity is proved from the circumstance 

 of their having been discovered for upwards of a century, 

 since which time the workmen have been in the daily 

 custom of finding them. Dr. Brewer, in the Philosophical 

 Transactions for 1700, mentions them without adverting 

 to the teeth which are found in the same formation. These 

 teeth are of a triangular shape, a little bent, of a dark- 

 leaden colour, and having their surfaces polished. They 

 are very small, the longesTnol much exceeding an inch in 

 length, with the interior surface in some longitudinally sul- 

 cated. They are found in considerable quantities, but no 

 vertebrae or any other remains of marine animals have been 

 discovered along with them. The land in which tbev are 

 imbedded is coarser and of a darker colour than that which is 

 superincumbent, containing a little clay and gravel ; which 

 I remark, because, in order to obtain any useful knowledge 

 on these subjects, it is necessary that the examination of 

 these bodies should be connected with that of the strata in 

 which they are found. The next stratum is a thin one of 

 blue-coloured earth, above which is a layer of sand with- 

 out aiiv adhesion of extraneous substances, and extending 



to 



