134 M. Charbaut on the 



I should observe that the argillaceous limestone forms very 

 tWn veins in the last beds, almost solely composed of small 

 shells, and in the first of gryphite limestone; its colour is 

 light or blueish grey, according to the rock that it touches. 



It results from this observation that the gryphite limestone 

 belongs to the same formation as this species of lumachella, 

 and consequently to the same formation as the immense 

 height of gypseous marls that it covers. This important 

 consequence is confirmed by the relative disposition, and the 

 uniform nature of the beds, on all the points of junction of 

 the gryphite limestone and variegated marls.* 



The ordinary texture of the gryphite limestone is com- 

 pact, but sometimes affords small crystalline grains ; in both 

 cases it possesses much tenacity, its fracture is irregular, and 

 its colour blueish grey. It takes its name from a marine 

 shell very abundantly contained in it, of which none analo- 

 gous are now found living in the present seas. 



It besides contains ammonites, belemnites,trochi, turbines, 

 nautilites, terebratulas, pectens, donaces, venus', muscles, 

 turritellae, oysters, pinnae, entrochites, baculites, orthocera- 

 tites, &C.+ 



The difficulty of separating these shells from the rock, pre-r 

 vents the determination of numerous sptecies of them, and of 

 many other genera, of which I could only give an idea by a 

 description of characters insufficient to class them. 



* ^he separation of the new red sandstone and lias is in general very 

 decided. (Trans.) 



+ Among the shells of gryphite limestone I can only determine the 

 following species : 



Ammonites Bucklandi, Sow. ; it sometimes acquires a considerable 

 size. 



I have found it at Montaines near Salins ; to the N.E. of Arau, near 

 Avalon, &c. 



The pecten equivalvis, Sow. : which I found with the preceding spe- 

 cies, is between Girole and Avalon. 



Notwithstanding the labours of M. Lamarck on the terebratulae, and M. 

 Faure Biguet on the belemnites, it is hot yet possible to determine with 

 certainty, and consequently with utility, the species of the two genera 

 found in the gryphite limestone. 



