196 Miscellanies. 



22 oz. of nickel, 18 oz. of copper, 5 oz. of zinc, and the same quan- 

 tity as before mentioned. If the zinc contains the least quantity of 

 arsenic, the alloy will be yellow. — Jour, de Connois. Usuelles, tome 

 12,^.89. 



GEOLOGY. 



CuviER AND Brongniart's report on M. Deshayes' " Tableau 

 comparatif des coqiiilles vivantes avec les fossihs des terrains ter- 

 tiaires de FEurope." — Among the organized bodies preserved in the 

 strata of the earth, none are more abundant, more diffused, or more 

 interesting to science, than shells. Their rapid multiplication and 

 their stony nature have contributed, at once, to their preservation in 

 great numbers ; so that they furnish the most positive proofs of the 

 condition of the ambient fluid at the period v,'hen each bed was de- 

 posited on its bottom. 



M. Deshayes has undertaken to examine the shells of each stra- 

 tum, and to compare them with those of the superior and inferior 

 layers, as well as with those now living in the ocean in different lati- 

 tudes, with a view thereby, to ascertain whether there have been a 

 succession and extinction of races, and to discover how those of the 

 races which have escaped the changes of the surface of the earth 

 have been distributed throughout the various regions of the sea. He 

 was well convinced that he could not arrive at any conclusions on 

 this point that would be free from objections, until he had observed 

 and compared the greatest possible number of species ; — that it was 

 not genera but species which must be taken into account, — that ge- 

 nera, which are only creations of the mind, would supply no import- 

 ant information, when they passed from one series of layers to anoth- 

 er, while they did not pass in the same identical species. 



He has thus been able, by unexampled assiduity, to bring togeth- 

 er more than three thousand species of shells, of certain origin, and 

 to arrange them in a tabular form, compared with the known order 

 of the superposition of the beds ; to show at what epoch each spe- 

 cies commenced and finished ; while, from the comparison of them 

 with more than four thousand living species, he shows which of them 

 have been preserved to the present time, and what kind of beds have 

 been deposited upon them since their appearance. 



M. Deshayes has thus become convinced that the shell formations 

 may be very distinctly divided into two grand series which corres- 



