196 M. Brongniart on the position 



not admit this shell in the transition rocks,* will find in this 

 fact another argument for separating the Alpine rocks of 

 Oberland from the true transition rocks. 



II. The mountain of Fis, to the N.E. of Servoz, in the 

 valley of Sallanche. 



It presents numerous and nearly horizontal strata, and 

 the following rocks may be noticed as predominant and 

 characteristic : 



1st. Schistose rocks, very numerous, very little varied, 

 mixed with mica, having the shining aspect of shining pri- 

 mordial schist, but diflfering essentially from it by the great 

 quantity of carbonate of lime they contain ; 



2dly. A compact fine limestone, of a smoke-grey colour, 

 with a scaly fracture, absolutely resembling that of Rochetta, 

 and traversed like it by veins of spathose carbonate of lime. 



Sdly. Black calcareous schists, or dull argillaceous and 

 non-calcareous schists, which resemble those of the banks 

 of the lake of Como and the northern side of the Gemmi, 

 and which contain like them ammonites, rare, certainly, but 

 which appear to be all of the same species, as far at least as 

 their state of preservation permits us to judge.t 



III. The third example that I might bring forward, will 

 be taken from the calcareous mountains of the environs of 

 Claris, from the valley of the Linth to Pantenbruck, and 

 even Mont Doedi. Not only do these mountains present the 

 same brownish and blackish limestone, the same calcareous 

 schist, the same spangled argillaceous slates as those I have 

 remarked in the preceding Alpine mountains; but these 

 rocks, which are blacker, more solid, and more sublamellar, 

 possess still more of the characters attributed to transition 



* It cannot however be denied, since M. Brochant has remarked, 

 described, and figured a shell of this kind found in the marble named 

 breche tarentaise, which forms part of the best characterised transition 

 rocks. 



+ Care must be taken not to refer the fossil shells found on the northern 

 side of the summit of the Montagne des Fis to this rock. They belong, 

 as I shall perhaps have occasion to state elsewhere, to a formation alto- 

 gether different. 



