DISCOVERIES OF CUVIER. 



229 



sils are those of marine animals. A bed of green marl, which may- 

 be very distinctly traced near the termination of the upper mass of 

 gypsum, separates the fresh -water from the sea shells; and in the 

 lower part of the gypsum formation, marine shells are found in the 

 gypsum itself. 



It may be useful to those strangers who visit Montmartre for the 

 first time, to state, that this thin green bed, which can be distinctly 

 seen and traced, may serve them as a key to the geology of the 

 place ; as it separates all the lower marine and fresh-water forma- 

 tions from the upper. 



The gypsum of the Paris basin was probably deposited in an ex- 

 tensive lake, on the borders of which the land animals, whose re- 

 mains are discovered in it, flourished and perished. Some of them 

 appear to be formed for swimming, or living much in the water, like 

 the otter or water rat. Whether the water in this lake was salt or 

 fresh, is by no means certain ; though M. Brongniart thinks that a 

 single fresh-water shell found in the gypsum would decide the ques- 

 tion : but this opinion, however high the authority of so distinguished 

 a naturalist and geologist may be, cannot, I conceive, be maintained; 

 for, in some of the beds, we meet with a mixture of marine and 

 freshwater shells, — and in this case who shall determine, whether 

 such beds are of marine or freshwater origin ? The intermixture of 

 shells clearly shows, that they have been transported from their native 

 situations, or if the water be brackish, that marine and freshwater 

 mollusca may live in the same estuary or lake, which is confirmed 

 by recent observations and experiments. 



The fossil bones found in the gypsum quarries near Paris are light 

 and porous, and appear to have been scarcely penetrated by gypsum : 

 this is very remarkable ; for if we suppose the gypsum to have been 

 held in solution by water, like the sulphate of lime in recent springs, 

 it seems extraordinary that it should not have penetrated into the 

 pores of the bones. I am not aware that the circumstance has be- 

 fore been noticed by geologists, but I think the state of the bones 

 proves, that they were rapidly enveloped by the gypsum, before the 

 animal matter in the pores was decomposed ; and also, that the gyp- 

 sum was speedily consolidated. The same observation would apply 

 to the bones of land animals which 1 found in the freshwater lime- 

 stone, under the volcanic mountain of Gergovia, in Auvergne ; the 

 state of these bones was similar to those in the Paris gypsum. 



Baron Cuvier was the first naturalist who successfully applied the 

 knowledge of comparative anatomy, to ascertain the forms of verte- 

 brated fossil animals. The publication of h\s Recherches sur les Os- 

 semens Fossiles may be regarded as an epoch in geology ; since that 

 time, many other important discoveries respecting fossil quadrupeds, 

 have been made. It will not, therefore, be deemed irrelevant to our 

 subject, to insert the very interesting account he has given of his own 

 feelings when he first became able to arrange the bones of each ge- 



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