26 RELICS FROM THE WRECK 



layers of gypsum (sulphate of lime) ; it is in this series of 

 rocks where the saurian or crocodile tribe are first found. 

 The shells in it are all of marine origin. 



The Lias* formation is superimposed upon the new red sand- 

 stone : it consists principally of limestone and shale, abound- 

 ing with a vast profusion of organic remains, differing in 

 species from any found in the older rocks. 



A small slab of marl from Aix, in Provence, in the col- 

 lection of R. J. Murchison, Esq., contains scores of small 

 fishes, as perfect as if recently imbedded in soft mud. In the 

 chalk formation, many of the fishes are uncompressed, the 

 hody being as perfect in form as if the original had heen 

 surrounded by soft plaster of Paris while floating in the 

 water. But in coarse limestones and conglomerates, in oth- 

 er words, in materials that have heen subjected to the action 

 of the waves, and torrents, detached teeth, scales, bones, (fee., 

 constitute the principal vestiges of this class of beings. 



* Lias, a provincial word, meaning layers. 





