6 GEOLOGICAL MEMOIRS. 



subglobose Nummulites, numerous foraminifera, and a few echino- 

 derms resembling Spatangi ; viz. that variety of nummulitic luma- 

 chella long ago observed by the author at Mosciano near Florence, 

 and at the Consuma. Above this last-described formation are other 

 deposits, which, although they have all the appearance of miocene 

 tertiaries, have nevertheless some characters which render it doubtful 

 whether they are to be considered as secondary, or intermediate be- 

 tween the two formations ; but the author considers these as beyond 

 his province, and therefore terminates his investigations with the 

 nummulitic lumachella as the most recent of the secondary forma- 

 tions of Tuscany. 



The author then proceeds to discuss the opinions of other geologists, 

 and admits that there are facts observed by them, and particularly 

 by Prof. Pilla, which make it possible that some of the formations 

 here described as cretaceous are not the equivalents of the creta- 

 ceous formations of the north, but must be considered as of a more 

 recent date (p. 58) : — 



" In the learned memoir published by my colleague Prof. Pilla 

 during the past year, he brings forward an opinion founded on many 

 ingenious arguments, that the nummulitic hippurite limestone of the 

 south, and of the north of Italy, is the equivalent of all the chalk of 

 the N.W. of Europe, and that in it we may recognize the division 

 of the white chalk and the greensand*. With these views re- 

 specting that formation which in Italy and the neighbouring coun- 

 tries contains Hippurites and large Nummulites, he naturally con- 

 cludes that the macigno must be considered as posterior to the 

 white chalk, since it is known from the observations of Paceto, 

 Sismonda, Spada, Studer, &c., that the macigno overlies the 

 nummulitic limestone ; and further deducing from his own observa- 

 tions, that the nummulitic hippurite limestone underlies the macigno 

 •with a distinct line of separation, he declares the two formations to 

 be decidedly separate and independent. All these conclusions of 

 Prof. Pilla have been fully adopted by MM. Adolphe Brongniart, 

 Beudant and Dufrenoy in their report to the Academy of Sciences 

 of Paris f on his memoir, together with that of Mons. Leymerie 

 respecting the nummulitic formation of the Pyrenees. Moreover, 

 the same geologists considering our subglobose nummulites of 

 Mosciano and those of Alberona as analogous to the nummulites of 

 the Pyrenees, and finding in the calcareous schists of Bidache 

 near Bayonne containing nummulites and other fossils peculiar to 

 those formations, an identity with those of the macigno, both in 

 respect of their external characters and of the fucoids contained in 

 them, declare the correspondence of our macigno with the for- 

 mation containing nummulites and tertiary fossils described by 

 Leymerie to be perfectly established. Hence it is evident that these 

 French geologists do not consider the Italian calcareous formation 

 with large nummulites as the equivalent of that of the Pyrenees, 



* Saggio comparativo del terreni che compongono 11 suolo d' Italia, p. 54. 

 t Comptes Rendus, torn. xxi. n. 22. p. 1201. 



