474 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 19, 



In this list it is very probable, or even certain, that there exist 

 many incorrect identifications, but we may also assume that as they 

 were not arrived at with reference to any such views as those of the 

 present communication, such errors would only partially affect the 

 value of the list as a whole, with reference to the general considera- 

 tions it seems to suggest. 



What cannot fail to strike every geologist is, that so many com- 

 petent observers should have recorded so many species as common to 

 the upper portion of the oolites, and the lower of the cretaceous series. 



Prof. Edward Forbes informs me that Sir Philip Egerton identi- 

 fied the remains of the fishes he collected at Farringdon to be, with 

 one exception, oolitic forms. 



In addition to the Farringdon beds, we have also in this country 

 another group of strata, at Speeton, resting on the Kimmeridge clay, 

 not continuous or co-extensive with the gault, and which also seems 

 to present a like admixture of oolitic and cretaceous forms ; and 

 we shall also see that a like association is presented in the marine 

 formation of Hils, and in the upper oolite of Boulogne. 



Guided by the considerations set forth in the local description 

 of the several deposits, but more particularly hy the unconformity 

 which exists between the Fai^ringdon beds and the great mass of 

 the cretaceous series ; as well as, secondarily, by that intermediate 

 character in the general aspect of its fauna, I would venture to sug- 

 gest that we should abandon the present abrupt limits we have 

 hitherto assigned to the oolitic and cretaceous series respectively, and 

 that we should see in the beds in question traces of the deposits, 

 and a record of the conditions, which may partially serve to connect 

 them. In proposing such an arrangement, it fortunately will not be 

 necessary to introduce any new name or system into the already 

 overburdened nomenclature of geological classification; the condi- 

 tions which the Farringdon deposits seem to establish come as proof 

 and confirmation of the value of a division already introduced by 

 continental geologists, on considerations of the distribution and range 

 of fossil forms, and to which they have given the name of " Neoco- 

 mian," but which has hardly been accepted in this country, partly 

 from deference to the term "lower greensand," and partly from a 

 restricted view, that the scale of British deposits is to serve as the 

 type and measure of the geological changes of all time and all places. 

 I shall therefore show as briefly as possible, that such a view is not 

 only inconsistent with what we know of the subcretaceous group gene- 

 rally in its range across the European continent, but that the Far- 

 ringdon deposits explain the nature and extent of the physical change 

 which separates this group from the true consecutive cretaceous 

 series, on the one hand, and how, on the other, it presents here the 

 like order of connection with the oolitic series below, which it does 

 elsewhere. 



Physical changes, whether of elevation or depression of an oceanic 

 area, produce different geological effects, according to the conditions 

 of the several portions of such area in respect of depth : the depres- 

 sion of a portion of the deep sea deposits of a given period, so that 



