46 coSxMos. 



terior of the globe, at a period when the earth's crust we^ 

 still furrowed and rent, and only in a state of semi-solidifica- 

 tion ; and a primordial condition is thus revealed to us, in 

 which the temperature of the atmosphere, and climates gen- 

 erally, were owing rather to a liberation of caloric and of dif- 

 ferent gaseous emanations (that is to say, rather to the ener- 

 getic reaction of the interior on the exterior) than to the posi- 

 tion of the earth with respect to the central body, the sun. 



The cold regions of the earth contain, deposited in sedi- 

 mentary strata, the products of tropical climates ; thus, in 

 the coal formations, we find the trunks of palms standing up- 

 right amid coniferee, tree ferns, goniatites, and fishes having 

 rhomboidal osseous scales ;* in the Jura limestone, colossal 

 skeletons of crocodiles, plesiosauri, planulites, and stems of the 

 cycadese ; in the chalk formations, small polythalamia and 

 bryozoa, whose species still exist in our seas ; in tripoli, or 

 polishing slate, in the semi-opal and the farina-like opal or 

 mountain meal, agglomerations of siliceous infusoria, which 

 have been brought to light by the powerful microscope of 

 Ehrenberg;t and, lastly, in transported soils, and in certain 

 caves, the bones of elephants, hyenas, and lions. An intimate 

 acquaintance with the physical phenomena of the universe 

 leads us to regard the products of warm latitudes that are 

 thus found in a fossil condition in northern regions not merely 

 as incentives to barren curiosity, but as subjects awakening 

 deep reflection, and opening new sources of study. 



The number and the variety of the objects I have alluded 

 to give rise to the question whether general considerations of 

 physical phenomena can be made sufficiently clear to persons 

 who have not acquired a detailed and special knowledge of 



* See the classical woik on the fislies of the Old World by Agassiz, 

 Reck, sur les Poissons Fossiles, 1834, vol. i., p. 38; vol. ii., p. 3, 28, 

 34, App., p. 6. The whole genus of Amblypterus, Ag., nearly allied 

 to Palaeouiscus (called also Palueothrissum), lies buried beneath the 

 Jura formations in the old carboniferous strata. Scales which, in some 

 fishes, as in the family of Lepidoides (ordei* of Ganoides), are formed 

 like teeth, and covered in certain pai'ts with enamel, belong, after the 

 Placoides, to the oldest forms of fossil fishes ; their living representa- 

 tives are still found in two genera, the Bichir of the Nile and Senegal, 

 and the Lepidosteus of the Ohio. 



\ [The polishing slate of Bilin is stated by M. Ehrenberg to form a 

 series of strata fourteen feet in thickness, entirely made up of the sili- 

 ceous shells of GaillonellcB, of such extreme minuteness that a cubic 

 inch of the stone contains forty-one thousand millions ! The Bergmehl 

 (mountain meal ov fossil farina) of San Flora, in Tuscany, is one mass 

 of auimalculites. See the interesting work of G. A Manlell, On Ik^f 

 Medals of Creation, vol. i., p. 223.]— jTr. 



