43 !• Reviews, and Notices respecting Neio Books. 



and exposed to observation,) be found to exhibit in the organic bodies 

 thus imbedded, differences to the full as marked as those which, in 

 the same continent, characterize formations of the most distant ages. 

 Now with regard to the secondary rocks of distant countries, our in- 

 formation is as yet far too limited to enable us to return, to the above 

 questions, answers on which we can rely with any degree of confi- 

 dence : but the evidence, as far as it goes, does undoubtedly again 

 seem to indicate a greater degree of resemblance than we could have 

 reasonably anticipated : this may particularly be instanced with re- 

 gard to the older rocks containing organic remains, e. g. the transition 

 limestone. We are extensively acquainted with this rock in Russia, in 

 the islands of the Baltic, in Scandinavia, and in North America ; and 

 its fossils everywhere exhibit so near a generic resemblance, that it 

 would often puzzle even a practised eye, if two groups of specimens, 

 one from Dudley and another from Melville Island, were placed be- 

 fore him, to say which specimen came from which locality, the same 

 Catenipora:, Caryophyllise, and Encrinites, being present in both. 

 The fossil vegetables of the coal-fields of Europe and America also 

 appear very similar; but we shall probably often, on a more accurate 

 investigation, observe specific differences combined with generic re- 

 semblances : still, undoubtedly, the impression on my own mind, 

 from a tolerably careful examination of all the specimens I have 

 hitherto seen, is, that a much nearer approximation may be observed 

 between the fossil animals and vegetables of the old and new conti- 

 nents than between those occupying them at the actual period. And, 

 what is peculiarly important, we find, as I have already observed, 

 even in the highest latitudes of the arctic ocean, types which appear 

 characteristic of a tropical temperature; and the general diffusion of 

 those types in the rocks of the transition and carboniferous periods, 

 in whatever latitude they are found, appears to imply a much greater 

 equality of temperature to have then prevailed than in the present 

 state of things. It seems also inconsistent with the existence of these 

 beings that such wide variations of temperature between the different 

 seasons should then have occurred, as must necessarily accompany, 

 in high latitudes, any temperature derived entirely from the sun, — 

 a consideration which renders inapplicable to this case the hypothesis, 

 that the higher temperature required by geological inferences may be 

 accounted for by the diminution of the eccentricity of the earth's 

 orbit, since this would still leave the inequality of the seasons in the 

 higher latitudes as great as at present. For this more equable tem- 

 perature, then, it seems difficult to account, without having recourse 

 to the hypothesis, which so many other geological arguments render 

 probable, of an internal source of heat proper to the globe itself. 



" Of more recent secondary strata than the carboniferous series, 

 there appear few traces in the parts of America yet explored, except- 

 ing, as I have already observed, the marls of New Jersey, of which 

 the fossils exhibit a close generic agreement with those of our sub- 

 cretaceous formations, such as the gault, although they are certainly 

 often specifically distinct. In Virginia we have also extensive tracts 

 r.i" shells, approximating to recent species, as in our own tertiary dc- 



