of Sciences of the Insiituto of France. 335 



very great service, by iiis work on Mineral Wealth. The first 

 volume, which related to the administration of the mines, printed 

 in IS 10, has been a long time known and appreciated. The 

 second, in which he treats of the working of them, has been pre- 

 sented in n.anuscript to the Academy. The author has here 

 added to all the ttieoretical directions which science affords, a 

 great quantity of practical facts collected by him in his travels, 

 and in the exercise of his functions ; so that every precept is in a 

 manner supported by a real example. A magnificent atlas 

 which accompanies the work presents all that can be exhibited 

 of these examples to the eve. 



The discovery so important in geology, made by MM. Brong- 

 iiiart and Cuvier, of certain stony beds which contain only land 

 and fresh-water shells, and which cannot of course have been 

 formed by the sea like other shelly beds, — has led to a number of 

 researches in all parts of Europe. M. Beudant, professor at 

 Marseilles, has this year considered this matter in a new light. 

 As in some places fresh -water shells have been found mingledlwith 

 marine shells, he has endeavoured to ascertain by experiment, 

 how long the moUuscse of fresh water may be habituated to live 

 in salt water, and vice versa with respect to marine molluscae. 

 He has found that all these animals die quickly when the change 

 is sudden and entire ; but when the saltness of the water is gra- 

 dually increased for the one, and gradually diminished for the 

 other, they become for the most part habituated to live in a water 

 which is not natural to them. Some species, however, resist all 

 conciliation, and cannot suffer any variation in the water which 

 they inhabit. 



M. Marcel deSerres has communicated the sequel of his first re- 

 searches on fresh-water shells, of which an account was given in 

 the analysis of the Academy for 1813. The principal fact whieh 

 he has made known this year, is a formation of this sort, which 

 he regards as newer than any other, and which he has discovered 

 in seven different places in the neighbourhood of Montpelier. 

 His observations are somewhat similar to those of M. Beudant. 

 He distinguishes the species in the environs of Montpelier, into 

 those which do not appear to be able to live except in fresh wa- 

 ter ; those which can subsist in briny waters not exceeding a 

 maximum of 2 75; and lastly, those to which marine waters 

 appear necessary. He has by this means explained some very 

 singular mixtures of tliese organic remains. 



The stratum which he describes is in a manner composed of two 

 layers inclosing different shells. The superior one contains both 

 land and aquatic shells. The new formation appears principally 

 on the higher parts of the hills or ridges, A great many land 



shells 



