SAVI ON THE MONTI PISANI. 3 



intersiratified beds of schist, good impressions of Fucoides targioni 



occur. 



The author thence deduces the following conclusions : — 



First, That the marls and schistose clay, often altered into 



galestro, certainly belong to the macigno formation, because — 



1. They are always found in the lower portion of the bed. 



2. There is a geological passage between them and the beds 

 interstratified with the macigno. 



3. They are always conformable to that rock. 



4. The Fucoides targioni occurs amongst the beds of the va- 

 riegated limestone, which is in the midst of them. 



Secondly, That the variegated limestone is a partial and not an 

 universal deposit, being in some places replaced by compact lime- 

 stone ; and 



Thirdly, That by means of these calcareous beds, the macigno 

 formation is in many places connected with the underlying forma- 

 tion of dark grey limestone with Hints. 



In the succeeding chapter (II.) we have a minute description of 

 the calcareous rocks underlying the schistose marls ; the upper por- 

 tion of these beds can only be satisfactorily studied in the moun- 

 tains beyond the Serchio, and they consist of numerous thin beds, 

 varying considerably in colour. No organic remains, whether ani- 

 mal or vegetable, have been found in this portion of the forma- 

 tion. It is succeeded in descending order by dark grey limestones, 

 divided into two groups, and below these again are many conform- 

 able beds, consisting of marly limestone, compact schists, and a 

 rock closely resembling sandstone, alternating with each other. 

 The schistose beds contain many fine impressions of Fuci of creta- 

 ceous character, viz. F. targioni, F, cequalis, and F. recursus. In 

 the dark grey limestone fossils are very rare, but near the gorge of 

 Baraglia the author found an Ammonite resembling A, Bucklandi. 



The red limestone is the lowest member of this formation ; it is 

 identical with that of Gerfalco and Donoratico (known to lapidaries 

 by the name of Broccatello della Gherardesca) and with that of 

 Massa di Sasso rosso in Garfagnana ; this is proved by the fossils 

 which the author found, viz. many Entrochi and Ammonites, and a 

 fine specimen, probably the alveolus of a Belemnite ; below this is a 

 considerable mass of limestone, divided by the author into upper and 

 lower groups. 



The following are the results arrived at respecting the formations 

 beyond the Serchio :— 



"In the first place, that the stratified formations underlying the 

 macigno, and the argillaceous marly schists of which the lower por- 

 tion of it is composed, consist of — 



" 1. A thick series of strata of dark grey limestone with flint, which 

 in some places assumes a white colour. 



"2. A group of beds, some calcareous, others marly siliceous 

 (cherty ?), others of pure flint, variegated, generally thin and undu- 

 lating. This bed does not occur everywhere. 



'^3. A second series of beds of dark grey limestone with flint. 



b2 



