SAVI ON THE MONTI PIS ANI. 7 



but of the formation underlying it containing Diceras and Hippurites, 

 which, according to Leymerie, represents the whole of the cretaceous 

 formation, from the Neocomian up to the white chalk. If there- 

 fore the Italian nummulitic limestone underlying the macigno really 

 does represent the upper portion of the cretaceous formations of 

 the N.W. of Europe, as Prof. Pilla still considered, the macigno 

 would clearly be shown to belong to a formation subsequent to 

 that of the white chalk of the north of Europe, which has hitherto 

 always been considered as the upper member of the secondary for- 

 mations. And since the macigno, both on account of the na- 

 ture of the rocks of which it is composed and of the fossils con- 

 tained in it, and the close connexion which it offers with the 

 underlying secondary rocks, must absolutely be retained as a 

 secondary formation (and such is also the opinion of Prof. Pilla 

 and the above-quoted French geologists), even if it should be proved 

 to be posterior to the most recent secondary rocks of the north of 

 Europe, this interesting fact could only be explained on one or the 

 other of the following hypotheses : — 1. Either by admitting that the 

 macigno and its other overlying secondary rocks were formed 

 during the period between the deposition of the white chalk and 

 the eocene formations of the N.W. of Europe ; or, 2. By admit- 

 ting that these same formations were all, or at least partly, produced 

 contemporaneously with the oldest tertiary formations of Europe, 

 viz. the Eocene. The first of these hypotheses is admissible ac- 

 cording to the usual geological laws, with regard both to the suc- 

 cession of the different deposits, and to the comparison of the dif- 

 ferent living animals. But if what I have already said concerning the 

 connexion of our (Pisan) secondary beds with the tertiaries should be 

 confirmed by future observations, this hypothesis will not suffice to 

 explain the phaenomena offered by Tuscan geology, and we must 

 have recourse to the other. Speaking of our beds above the 

 macigno, I have pointed out some facts, from which it may be 

 argued, that with us a general elevation of the bottom of the sea 

 did not follow the period of the deposit of the white chalk, as in 

 the N.W. of Europe, but that instead thereof, the waters continued 

 to cover a great portion of what is now Upper Italy, the deposits 

 being continued without interruption from the cretaceous to the mio- 

 cene tertiary formation. This being the case, we ought to find in 

 the series of formations of the macigno, the alberese and the upper 

 nummulitic limestone, the beds which were formed in our seas not only 

 during the period between the deposition of the white chalk and the 

 calcaire grossier of Paris, but also the equivalents of the other 

 eocene formations of those countries. 



" This supposition is certainly contrary to the prevailing ideas 

 respecting the universality and contemporaneity of those cata- 

 strophes, which changed the state of things between the period of 

 the secondary formations and that in which were deposited the tertiary 

 strata. But, considering all things connected with the extension, 

 the configuration, and the duration of the sea, which, during the 

 cretaceous period, covered the space where are now the Alps and 



