Geological Society. S 1 3 



author has shown neither the information nor the industry which 

 might justify him in becoming an interpreter of the labours of others, 

 or the framer of a system of his own. 



Are we then for ever to wander among the mere perplexities of 

 details, and never to hope for any system by which we may com- 

 bine them ? You must have seen, Gentlemen, that I am not the ad- 

 vocate of any such steril sentiment. It is indeed true that in the 

 very classification of our facts and of our phaenomena, there are 

 difficulties connected with all parts of natural history, which, for 

 ages yet to come, may continue to require for their solution a com- 

 bination of the greatest industry with the greatest skill. But these 

 difficulties do honour to our science: and the same great rule by 

 which the father of physical astronomy was guided, applies, at 

 every step, to us and to our conclusions. " Effectuum naturalium 

 ejusdem generis eaedem sunt causae," was the grand rule on which 

 he founded his induction. In the same way, we see the effects pro- 



the figures been well selected, they might have been of great use : as it is, 

 they can only be the means of disseminating error. 



Plate I. professes to represent the " shells of the mountain limestone." 

 Of its thirteen figures three or four are well chosen ; none of the rest ought 

 to have appeared. One of them is wrong named ; and a recent nerita, wuh 

 all its fresh markings, has unaccountably found its place among these old 

 fossils. 



Plate II. " Shells of the Lias." In this plate, of twelve species, we are 

 astonished to find a transition orthoceratite, the productus scoticus of the 

 mountain limestone, and a scaphite of the green-sand, placed, side by side, 

 with the grypha;a incurva, plagiostoma gigas, and some other true lias fossils ! 



Plate 111. "Shells of the under Oolite." Thirteen species; and a more 

 uncharacteristic assemblage was, perhaps, never before brought together. 

 A tertiary mya and a nummulite have here found their way, for the first 

 time, among the shells of the under oolite. Two or three of the other species 

 ought to have appeared, if at all, in the next plate. 



Plate IV. " Shells of the Cornbrash and upper Oolites." Here the con- 

 fusion is still greater; for of twelve species, seven are positively misplaced, 

 the others are ill selected, and one of them is wrong named. The mineral 

 conchologist is confounded at the sight of the well known turrilites and 

 hamites of the green-sand group, of the turritellae and superb rostellaria ma- 

 croptera of the London clay, jostled in among the fossils of the oolites. 

 Had the author drawn out by lot, from all the fossils in Mr. Sowerby's 

 work, the species which were to decorate this plate, chance might have 

 given him a more illustrative series. 



Plate V. "Shellsof the Chalk and Superior Strata." Among the nineteen 

 figures of this plate, no attempt is maile to separate the bhelU of the chalk 

 from those of the overlying tertiary deposits; although the two groups have 

 not perhaps one species in common. In Plate L two freshwater shells were 

 introduced which were not characteristic; here freshwater shells are cha- 

 racteristic, but are omitted altogether ; and the pecten quinquecostatus 

 is the cliariuteristic fossil of the green-sand. 



One who was even moderately acquainted with the ch.'iracteristic forms 

 of orp',anic remains, couM never have been led into such a complication of 

 errors: and they arc the more discreditable, as the greater part of them 

 might have been avoided by the mere exercise of the huniblest duty of a 

 compiler. 



N. S. Vol. 7. No. 4-0. JjJ7-il 1830. 2 S duced 



