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ON THE COKALS OP THE

climate; and the pines might have been brought down byrivers from an elevated and bleak interior, as different in itstemperature and productions from the sea-coast, as the pine-covered sides of the Alps, where they rise towards the snowline, are different in their temperature and productions fromthe rich vine-bearing valleys which they overlook.

I remark, in the second place, that the occurrence in theOolite of those boring shells of which I have laid specimensbefore the Society is not without interest, as in some mea-sure illustrative of that unity of plan on which the Creatorhas wrought in all the geologic periods, and which serves sostrikingly to indicate the identity of the Worker. Thosefour master ideas embodied in the animal kingdom whichfurnished Cuvier with his principles of classification, eachforming the centre of a great division, seem to have beenequally the master ideas of all the geologic creations. Sofar as we know, animal life existed at all times, when it ex-isted at all, in its four master types, and no more ; and thesein the Oolitic ages,—life radiating round a centre, as in theIsastrea,—life lodged within a series of rings, as in the an-nelids and the Crustacea, —life combined with a duality ofcorresponding parts, as in the cuttle-fishes and the clams,—and life associated with a brain and vertebral column, as infishes and reptiles,—were not less prominently developedthan now. Had a Cuvier then existed to write the historyof animated nature, the various classes would have occupiedvery different proportional spaces in his “ Animal Kingdom”from that occupied by those of the present time; but themaster divisions,—vertebrata, mollusca, articulata, and radi-ata,—would have been the same. For of all the creations, Irepeat, in the leading idea there has been no change. Twoof these we find exemplified before us in single specimens,—those in which the lithodomi lie sepultured in cavities hol-lowed in Isastrea ; and we are enabled to trace this identity