and on the Geological Position of their Fossil Remains. 455 



should still be obliged to niaintain that strata (which it is on 

 all hands agreed are incumbent upon chalk) are most ancient 

 where they present the remains of Mammifera, — that the chalk 

 is hitherto found to contain absolutely none, — and that in the 

 older strata these remains still less exist ; while, nevertheless, 

 chalk and also the greatest part of those older strata, even to 

 the great coal formation, abound, in certain localities, with 

 Tortoises, Lizards, and Crocodiles, species which are, on the 

 contrary, exceedingly rare in the superficial beds. 



We ascend then, to another age of the world, — to that age 

 in which the earth was as yet traversed only by the cold- 

 blooded reptiles, — in which the sea abounded in ammonites, 

 belemnites, terebratulae, and encrinites, — and in which all 

 these genera (at this day subjects of prodigious rarity) formed 

 the mass of its population. 



This is that age which geologists have named the epoch of 

 the secondary strata. It would perhaps be appropriate to the 

 nature of our work, here to enter upon an enumeration of these 

 strata, and a description of their nature and superposition, 

 similar to that which we iiave already given of the tertiary strata 

 in our second volume, with relation to the bones in our plaster 

 quarries at Paris : but this task has been so fully accomplished, 

 (and by geologists better located than we are for effecting it,) 

 that we cannot do better than to refer our readers to the excel- 

 lent works which have recently appeared upon this subject. It 

 is not, in fact, in the canton which we inhabit, but on the other 

 side of the vast circumference of chalk which surrounds us, 

 that the secondary strata present themselves in sufficient re- 

 lief to be commodiously studied : it is between the chalk and 

 the primitive strata that they ascend into day ; and Germany 

 on the one side, and England on the other, are the two thea- 

 tres in which it has been possible to verily their succession, and 

 to form a history of them in some degree complete. 



Werner commenced by this study the great reform which 

 he has introduced in geology; and the more extended re- 

 searches of his pupils, and principally of MM. de Buch and 

 de Humboldt, have brought this work to the greatest state of 

 perfection. The results have been faithfully presented, in 

 our language, in the work of M. lionnard, entitled Apcrfu 

 Geognoslique des Tenains ; and M. de Humboldt has recently 

 presented them anew, with still further details, and an ex- 

 tended series of observations, as remarkable for their excel- 

 lence as for their novelty, in his Essni Geo<!;nostique sur le Gise- 

 meiil des Roches. A series of analogous observations has been 

 followed up with great perseverance in England by the mem- 

 bers of the Geological Society of London; and the disposition of 



those 



