FOSSIL INVERTEBRATED ANIMALS. 461 



be also found in the stratum of upper sandstone of the environs 

 of La Chapelle and Louvres, in the department of the Seine 

 and Oise ; but it is so much modified in the latter, that it has 

 been classed in the genus pyrula, before it was discovered that 

 this modification arose from the influence of a stratum, not the 

 same with that of Grignon. This pyrula was not found in the 

 last place, no more than the fusus in the other. This error 

 had crept into the system of Invertebrated Animals, by M. La- 

 marck ; but it was before the strata in question had been dis- 

 tinguished by the researches of MM. Cuvier and Brogniart. 

 This species is also found in England, in Hampshire, but with 

 additional variations of form. 



Taking the environs of Paris, as it were, for a centre, we 

 find, according to the remark of M. de France, that the genera 

 and species of the coarse limestone have a tendency to analogy 

 with those of Italy, as we proceed through Anjou, Touraine, 

 and the environs of Bourdeaux; and in the same manner we 

 find a growing analogy to certain EngHsh fossils in those of 

 the department of the Oise. 



A multitude of genera, found in the fossil state in Europe, 

 are not only no longer existing, in the living state, in our seas 

 and waters in general, but, for the most part, are found to 

 inhabit at present only the equatorial regions. 



The number of genera found in the fossil state, is superior 

 to that of the living genera, in the polyparia, the echinodae, 

 the annelides, the tubicolae, the bivalve, and comparted shells* 

 It is inferior in the serpulse, the cirrhipedes, the pteropodes, 

 the phyllidi, the univalve shells, and the heteropodes. 



The number of the genera of fossil Crustacea, being scarcely 

 more than a third of those now existing, we may believe that 

 the latter have increased since the revolutions which have 

 buried the remains of those now found in the fossil state. 



Notwithstanding the greater number of some families of 

 marine organic bodies found in the fossil state, we may believe 

 that that of these bodies, now existing in the living state, is 



