Zoological Characters in Geology. 255 



sandstone, so as to form very singular striped rocks (Nos. 11, 

 12, 13, & 14.) 



Sthly. Lastly, these sandstones are covered by a mica- 

 ceous argillaceous slate in thin laminas and very splintery, 

 (No. 15), and apparently yellowish, but this colour is only 

 superficial. It is blackish in the interior of the smallest 

 pieces, and so fissile, so easily broken, and with such a want 

 of cohesion, that notwithstanding the great mass it presents, 

 a good sized specimen cannot be obtained. 



This slate forms the sharp and steep crest AB of that part 

 of the Montague des Fis which we reached ; but it is not 

 the most elevated portion, the beds dipping towards th« 

 N.W. and their southern section presenting an inclination 

 towards the W : this slate does not rise to the summit of ihe 

 Pointe des Fis. This point, as well as that named Le 

 Marteau (m. fig. 1.) is, as we have been assured, composed. 

 of limestone mixed with sandstone, and appears to be the 

 prolongation of the beds No. 9 to 14. 



It is on the back of the Montagne des Fis, and nearly at 

 the point marked F, that the bed, containing the fossil shells 

 I shall enumerate, occurs on a rapid and elevated slope, 

 almost always covered with snow. The snow which covered 

 it prevented me from visiting if, but M. Beudant, who 

 reached this part of the mountain by the valley of Sales 

 (Lo), in 1818, saw a portion of it in situ. He observed 

 the shelly black rock nearly in the position given in the 

 section. It is, according to him, in nearly parallel stratifi- 

 cation with the transition rocks on which it rests. This 

 compact limestone, which is hard, coarse, blackish, leaving 

 on the surface of a solution of it in nitric acid, a quantity of 

 carbonaceous matter, is full of a multitude of grains of such 

 a deep green colour that they appear black ; but they 

 afford a green colour when crushed, and are, like those of 

 the chalk, insoluble in nitric acid ; above is a rock which is 

 calcareous, granular, micaceous, sandy, of a whitish grey 

 colour, and altogether resembling the craie tufau. It con- 

 tains the remains of undeterminable shells. 



These shells generally occur as casts, or rather as r«Heva 



