1823.] the principal Mountain Chains of Europe. 279 



fore, as conveying his matured opinion, and as 1 have, through 

 his correspondent, his sanction in extracting any observations 

 that appeared to me important, my citation may be regarded as 

 an authentic declaration of his present views. I have thought 

 this explanation necessary to remove any apparent contradiction 

 between it and the memoir alluded to. I need not add that his 

 testimony on my side derives additional weight from the circum- 

 stance, that his judgment was not hastily formed, but the result 

 of a slow conviction. 



The Series of Lias and Oolites, Muschelkulk, and Jura Kalkstein. 

 This system viewed generally consists of a series of alternat- 

 ing deposits of ciay, and of limestones of a texture considerably 

 more earthy and less compact than those of the preceding 

 epochs, and often oolitic. These are strongly contrasted also 

 with the earlier formations in the very important circumstance 

 of their zoological character, I mean the nature of the organic 

 remains which they contain, as they appear to preserve the 

 traces of a very different and more advanced state of animal 

 population in the waters beneath which they were accumulated. 

 In speaking, however, of the earlier formations, I would be 

 understood to mean those earlier than the alpine limestone ; for 

 the alpine limestone is clearly in this respect connected more 

 nearly with the subsequent than antecedent order of things; and 

 these observations should, therefore, in strict propriety, have 

 stood at the head of that formation ; but since the organic 

 remains in that series are rather of local than common occur- 

 rence ; whereas in the present they form a striking and general 

 character, this deviation from the rigour of method may be 

 excused. The vertebral class, of which rare and faint traces 

 alone occur in the older rocks, presents in these a rich and most 

 interesting addition to the lists of animals now existing ; these 

 principally belong to the order of oviparous and amphibious ani- 

 mals ; but exhibit in some instances an organisation which would 

 fit them rather for a life entirely aquatic than one divided 

 between both elements (e. g. the ichthyosaurus), and appear 

 to bear the same relation to the actual genera that the 

 cetacea do to other mammalia : others, however, are like 

 their recent antitypes fitted for moving both in the land and 

 water. In this zoology of a former world, we count several 

 species of the crocodile (England and France afford four at 

 least which may be distinguished) : these do not agree spe- 

 cifically with any of the varieties now known to exist ; but 

 the differences are very slight, often indeed less marked than 

 between the recent species ; there is no room, therefore, to 

 doubt that their general habits were similar. Were these 

 species capable of enduring the cold of high latitudes, and there 

 hatching their eggs ? or did they migrate? or was the tempera- 

 ture of our planet then higher than at present? Some varieties 



