120 Remarks on the Great Oolite of Mmchinhampton. 
one-half the entire number of bivalves can be identified in those 
works, a considerable number being from the coral rag of Ho- 
henggelsen, which seems to be the equivalent of our Great Oolite. 
Among the univalves, the general resemblance to the Mincbin- 
bampton shells is so great, that at first we feel prepared to iden- 
tify the greater number of them ; a closer scrutiny undeceives 
us, and ultimately we are surprised at the very few which we can 
call our own. It may be suspected indeed, that the meagre lists 
of univalves hitherto published relating to the formation in 
question are the result, not so much of an actual deficiency of 
those shells, as of the difficulty of separating them from the stone 
in a condition sufficiently well-preserved to admit of specific 
characters being recognized. The oolite of our district itself 
furnishes an instance in illustration ; almost the entire suite of 
univalves are procured from quarries to the north and west of 
the town, and even within those limits are certain localities from 
which the univalves can hardly be separated ; but in the upper 
and middle subdivisions, to the east of the town, we can obtain 
but few, and those only which approach the globvilar figure, as 
Natica and Bulla, usually in the form of casts ; with slender 
spiral shells the attempt is hopeless. These circumstances how- 
ever are altogether independent of the great fact forced upon 
our attention, — viz. the scarcity and almost entire disappearance 
of the Cephalopoda from the sea of this portion of the Cottes- 
wolds during a period in which deposits 200 feet in thickness 
were formed, and the simultaneous appearance of a large num- 
ber of new and more simple forms to supply their place. 
With our present very scanty knowledge of the circumstances 
which conduce to change of species on the floor of the sea, rea- 
soning would be little better than conjecture ; I have therefore 
rather preferred to state facts as they are presented to my no- 
tice, reflecting that every such contribution, however insignifi- 
cant, is something added to the general store of knowledge, and 
consequently an aid to our conceptions of the operation of that 
infinite and all-pervading wisdom which is exemplified equally 
in the lowest as in the highest beings of creation. 
Hence, though it is well known (as above-quoted from Hr. 
Buckland), that throughout the vast deposits of the secondary 
rocks those important tribes of Cephalopods, the Ammonites and 
Belemnites, reigned supreme amongst the molluscous races, and 
that they became extinct prior to the commencement of the ter- 
tiary sera, their paucity in the Great Oolite of IMinchinhampton 
would lead us to infer that some peculiar conditions of sea-bot- 
tom existed at that locality which were unfavourable to their 
increase. But so far from the carnivorous Trachelipods not 
having existed prior to the commencement of the tertiary sera,^^ 
