ISO Intelligence and Miscellaneous Articles. 



tions, a brief view of whicii we proceed to state, nearly in his own 

 words. The following series of fossil shells are known to English 

 naturalists :— 



Simple univalves 58 genera, which comprise 401 species. 



Simple bivalves 62 583 



Complicated bivalves 3 51 



Multilocular bivalves _\2^ 230 



135 12G5 



On making three principal divisions of the formations containing 

 organic remains, and enumerating the shells they respectively con- 

 tain, we have these results : 



The first, which is also the lowest or most ancient division, may be sub- 

 divided into two series of formations. 



140 97 



The third, or most recent, divi- 

 sion, comprises all the beds above 

 the chalk, or the tertiary forma- 

 tions. 

 Simple univalves 259 species. 



Simple bivalves 141 



Complicated bivalves 

 Multilocular univalves 8 



The second, or middle, division, 

 from the lias upwards, includes the 

 entire oolite series, and the strata 

 up to the chalk, inclusive. 

 Simple univalves 106 species. 



Simple bivalves 375 



Complicated bivalves 

 Multilocular univalves 139 



620 



408 



The numbers of each of the four classes of shells which existed 

 during separate periods or geological intervals, are as follows : 



Second and Tliird Divisions. 

 First Division. Remaining strata, above the 



Ancient strata, including lias. lias, up to diluvium. 



Species 36 Simple univalves . . . 365 species. 



67 Simple bivalves .... 516 



,0^5^^ Complicated bivalves . . ^ ^ 147 



*'^'* I 83 Multilocular univalves . 147 J ' 



237 10'^8 



Here the number of complex species in the first division is nearly 

 equal to those in the immense series of succeeding strata, 134 being 

 peculiar to the lowest, and 147 to the remainder. But the individuals 

 are greatly more numerous in the older strata than in the later, and 

 give a more decided character to those formations than appears from 

 a comparison of genera or species ; and the class of complicated bi- 

 valves is wholly limited to this older division. The difference is yet 

 more striking when we compare the first with the third division ; the 

 simple univalves in the former being to those in the latter in the pro- 

 portion 



