1847.] | LYCETT ON THE OOLITE OF MINCHINHAMPTON. 183 
peared, and have continued down to the recent period to perform the 
office of those extinct races. It will here, however, be seen that out 
of 142 species of univalves, exclusive of Cephalopoda and Radiaria, no 
less than forty-one are carnivorous, and five others belong to a genus 
(Phasianella) the recent species of which are both phytophagous and 
carnivorous, thus presenting a proportion of species in the Zoophagous 
tribes not very different from that which obtains in warm seas of the 
recent period. ‘The unusual paucity of Cephalopoda, taken in con- 
nection with this fact, is worthy of notice ;—of Belemnites there is 
only one small species, and the number of individuals is but few; so 
also with the Nautili, of which only two species occur; and an Am- 
monite is decidedly a “ara avis;’’ six species, with less than forty 
individuals, are all which have fallen under my notice. The inquiry 
naturally follows: Was this peculiar distribution of families charac- 
teristic of the great oolite generally over large areas, or was it merely 
local, and dependent upon conditions found only within certain 
limited spaces, so that it ceased when these conditions no longer 
existed? We know that both before and after this period the 
Cephalopoda reigned supreme among the molluscous tribes, a fact 
favouring the existence of a local cause to account for such an un- 
usual assemblage. Even a cursory glance at our largest sections of 
the great oolite suggests the idea that the beds were deposited from a 
shallow sea where strong currents prevailed ; where the surface and 
mineral character of the deposit were continually changing. A closer 
view confirms the first impression ; heaps of broken shells, piled in 
irregularly laminated beds, are intermixed with occasional rounded 
boulders of rock foreign to the neighbourhood, with fragments of 
abraded madrepores, dicotyledonous wood, crabs’ claws, &c. Other 
portions of the shelly beds have suffered denudation, and the re- 
moved portion has been filled with clay. These, together with false 
stratification and nonconformity of certain beds in juxtaposition, 
are conclusive upon this point ; and the effect is not lessened by the 
occurrence of other beds, barren or less fossiliferous, but of more uni- 
form character. May not these circumstances suffice to account for 
a paucity of Cephalopoda, and for the absence of species fitted for 
such conditions over large and more tranquil areas where a similar 
littoral surface could not be expected? As a contrast to these condi- 
tions, the mineral character and fossils of the same formation in the 
vicinity of Bath may be cited. The rock has there the oolitic struc- 
ture for its prevailing character ; corals are large and abundant, but 
testacea scarce, and those chiefly Brachiopoda,—denizens, it may be 
presumed, of a deep and tranquil sea. In Mr. Lonsdale’s list of 
thirty-one species of testacea from the Bradford clay, great oolite 
and Fuller’s earth of that locality, there are upwards of eight Tere- 
bratulze, and a Crania has since been discovered,—a larger number in 
proportion than will be found in the 300 species here tabulated. 
Geological features of the district. 
The beds of the great or Bath oolite within the limits of this 
sketch consist of forest marble, great oolite and Fuller’s earth; but 
