Cakaire grossiere and Paris Gypsum. 167 



\y the same position. All these having been enumerated in our 

 Synoptical Table of Formations, published in 1828, M. Brong- 

 niart should not have omitted these deposits. Instead of admit- 

 ting with M. Brongniart only four or five deposits of lignite 

 (p. 158), we find that inflammable substance at various heights 

 in the three tertiary groups, viz. the upper tertiary sands, the 

 subapennine clay-marl, and the Paris limestone, as well as in 

 five or six secondary formations, viz. in greensand, Kimmeridge 

 clay, nummulite limestone of Istria, Oxford clay, lias marl, and 

 even in the under part of the Keuper. We are aware of the 

 fact that, in the last mentioned deposits, the coal exhibits charac- 

 ters intermediate between those of jet and slate coal (houille 

 grasse), and that it is named by M. Brongniart Stipite, but yet 

 they are also sometimes associated with true lignite. 



The comparison of the inferior molasse with the gypsum de- 

 posit at Paris appears to be theoretically true, if we conceive that 

 both deposits took place at nearly the same period of time ; but 

 the contrary if we are disposed to infer the resemblance from 

 zoological or mineralogical characters. M. Brongniart expresses 

 our opinion when he says, *' qu'il ne s'agit nullement question 

 d'etablir le moindre rapprochement entre la molasse et le gypse 

 de Montmartre.'' (Page 160.) 



On the other hand, it is astonishing that M, Brongniart should 

 say that the lignite in the molasse or the terrain proteique are 

 lacustrine deposits ; and that he further declares, that, if such 

 is the case, " la succession des generations d'animaux comme 

 le moyen le plus sur et peut-etre le seul pour determiner les 

 epoques geognostiques. (P. 159 & 290.) Yet he has well 

 stated, in another place, the characters of the various fresh- water 

 deposits. (P. 166.) He acknowledges that the foetid limestone 

 associated with the lignite of Switzerland has no sinuous tubes 

 (tubulures) (p. 165, 168), that it is a mechanical deposit which 

 ** s'il ne renforme en general que des debris de corps organises 

 terrestres ou d'eau, peut aussi avoir enveloppe quelques debris 

 d'un autre origine,'' — p. 169. In the same article he explains 

 very clearly how such deposits can be placed amongst beds 

 formed in sea-bays, or at the mouths of rivers. He speaks ex- 

 plicitly of those mixtures of marine and fresh-water shells 

 (p. 169, 186, 188) ; and he finds that some marine limestones 



