xl PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
which, from an increased knowledge of facts, has now become so com- 
mon with respect to the paleeozoic coal deposits of Europe and 
North America; the view in this case, as we shall hereafter see, 
having reference to a coal accumulation formed at a less ancient 
geological date. ' 
Mr. Prestwich, in his communication on the London clay, inci- 
dentally mentions that at Clarendon Hill and at the Cuffell cutting 
the shells of Panopea are abundantly found in a vertical position, 
similar to that which the recent species assume in their living habi- 
tats at the present day, proving the quiescent deposition of these 
portions of the strata. He also states that Dr. Fitton had called 
his attention to the occurrence of Panopea and Pinna mm the same 
position in the lowest beds of the lower greensand. In the same 
clays with the Panopea, Mr. Prestwich observed Pholadomya and 
Pinna, the latter attaining a large size at Cuffell, also in a vertical 
position. 
It may be scarcely necessary to advert to the advantage, indeed 
necessity, of strictly observing the position in which organic remains 
are found in the rocks containing them, as also their distribution, the 
association of the different species, and the proportion of the indivi- 
duals of different kinds, if we are to have sufficient data on which 
to reason correctly on their mode of occurrence, and upon the con- 
ditions under which ancient life may have existed durimg the lapse of 
geological time. The ordinary catalogues of organic remains seldom 
furnish us with any information of the kind, some rare species of 
molluse occupying a place as important as those, the mode of oc- 
currence, distribution and abundance of which really afford us the 
information required, and on which we should reason. While on this 
subject, it may be desirable to call attention to a table by Dr. Fitton, 
in the last volume of our Journal, and dated October 1847, wherein 
symbols are employed to show when certain species first appear, 
when repeated, when disappearing, or when only discovered in one 
bed, in a series of deposits of the Lower Greensand, exhibited in a 
coast-section from Atherfield Point to Black-Gang Chine in the Isle of 
Wight. This table not only contains a list of all the organic remains 
known in the Atherfield section up to the date of publication, but also 
presents us with a lithological detail of the various groups, amount- 
ing to sixteen, into which Dr. Fitton has considered it desirable to 
divide the succession of beds. An easy system of reference having 
been adopted, and the table being surmounted by two sections of the 
coast, a valuable mass of information is at once presented to our at- 
tention respecting a succession of sedimentary accumulations and the 
distribution of organic remains in them for a thickness of 808 feet. 
Reasoning upon the equivalents of the tertiary deposits in the 
London and Hampshire districts, Mr. Prestwich observes, that he 
would not restrict the synchronism of the Bognor beds of Hampshire 
to the lower part only of the London clay of the London district, 
considering that the conditions which in the Isle of Wight area were 
favourable to the prolonged existence of the animals, the remains of 
which are characteristic of the beds of the London clay, were modified 
he a, Meg ah! 
