ANNIVERSART ADDEESS OF THE PRESIDENT. Iv 



a purely sedimentary and normal origin, independent of all disloca- 

 tion or disturbance of the ground. 



The process by which the author supports his views may be suc- 

 cinctly stated as follows : — He shows, in the first place, that the 

 etage G consists of three subdivisions, the lowest, g 1, being a purely 

 calcareous bed, g 2 being a band of argillaceous schists with calca- 

 reous nodules, passing, by a gradual increase of the calcareous ele- 

 ment, into the overlying bed g 3, consisting of limestone resembling 

 altogether the bed g 1, the whole forming such a complete system of 

 superposition and gradual passing of one into the other, as alto- 

 gether to preclude the possibility of the bed g 2 being an intercala- 

 tion of the overlying etage H, which consists entirely of argillaceous 

 schists. This etage is also separated into three subdivisions, Jil,h 2, 

 and h 3, in which the calcareous element appears to be altogether 

 wanting. There is no gradual passage between G and H ; the tran- 

 sition is sharp and well defined. 



The author then proceeds to describe the palaeontological contents 

 of the Stages G and H, and their subdivisions. By these means he 

 has been enabled to point out the true distinction of the diff'erent 

 beds, for which the petrographical and stratigraphical evidence alone 

 was not sufiicient. Thus the two calcareous bands g 1 and g 3, so 

 closely resembling each other in a petrographical point of view, are 

 shown, by the numerous tabular statements of their respective 

 faunas, to be entirely distinct. These tables show that, with the 

 exception of the Cephalopoda, all the classes (p. 55), including the 

 Eish, Crustacea, Pteropoda, Gasteropoda, Brachiopoda, Acephala, 

 Radiata, and Vegetables, are represented by a much larger number 

 of species in ^ 1 than in g 3. On the other hand, the Cephalopoda 

 are more numerous in g 3 than in g 1 m the proportion of 

 3 to 2 ; and, moreover, in bed g 3 the Cephalopoda alone contain 

 about four times as many forms as all the other classes together 

 in the same bed ; besides which these two beds contain very few 

 species common to both. 



With regard to the four schistose beds, g 2, h 1, h 2, and h 3, the 

 distinction is equally clear ; h 2 and li 3, being unfossiliferous, are 

 easily separated from the others ; and with regard to g 2 and h 1 , 

 although thej contain eleven species common to both, a much greater 

 number of species are peculiar to each. 



Trilobites . . . 



Peculiar to 0' 2. 

 . .. 3 



Peculiar to ^ 1. 

 



Cephalopoda . 

 Pteropoda . . . 

 Gasteropoda . 

 Brachiopoda . 

 Acephala . . . 

 Eadiata . . . 



. .. 4 



. .. 1 



2 



." ." .' 6 



...7 

 ...4 



1 





 



1 



3 







Yegetables . 



... 



2 



27 



