220 On the Fossil Shells of the Paris Basin. 



an extent of forty leagues in diameter in one direction and' 

 fifty-five in another, there do not exist in any of our seas 

 any thing approaching to so many species in a space so 

 limited. 



If we now examine these species, we shall find particu- 

 larly large numbers of them to belong to those genera and 

 families, the species of which are so numerous in the warm- 

 est regions of the earth. One hundred and forty species 

 of the genus Cerithium, a great number of the genus Fussus, 

 of Pleurotoma, of Mitra, of Voluta, of Venus, of Buccinum, 

 of Area — fossils of the environs of Paris. The absence 

 in this basin of the forms proper to the northern seas, all 

 the considerations connected with Conchology, unite in at- 

 testing strongly the great period of time the Parisian strata 

 required to form, under a temperature probably more elevat- 

 ed than that of the present equator. 



In adverting to others parts of the Parisian Paleontology 

 not belonging to Conchology, we find in the great number of 

 Pachydermata, their size sometimes gigantic, a proof of the 

 high temperature of the Paris basin. Where do we find in 

 the present day analogous animals, if it be not in the tropi- 

 cal parts of Africa and South America, in the islands of 

 Sunda, and in those of Asia? In addition to these consi- 

 derations, those which are furnished by a small number of 

 plants, particularly palms, sufficiently prove the high tem- 

 perature of the period during which the first tertiary depo- 

 sits took place. We might here be able to form a contrast 

 between the ancient condition of the Paris basin compared 

 with its present state — we might find on one side a great num- 

 ber of animals of which the races have become extinct ; on the 

 other, the soil occupied by the races of recent animals, and 

 the seas in the vicinity peopled with species of which ninety- 

 nine per cent, did not exist in former times. We should see 

 in this comparison the proofs of the wonderful changes which 

 are in operation in the conditions of the existence of living 



