OF FOSSILS. 277 



lofe the whole of the firft genus and the 

 ;fame formuke are repeated four times in each of 

 the remaining genera, and constitute one fpecies 

 only; fo that V = 6 fpecies is of each genus and 

 4x6=24 the number of all the quadruple fpe- 

 rics. 



Let -us take another example, and remove al- 

 together a, the formuLe of that genus are imme- 

 diately annihilated, and the eighteen in the 

 three other genera arc reduced to 2X3=^6. 



In the fame manner, that the corrections are 

 made in the formula of -the lait order, can they 

 be applied to thofe preceding. For it is evident 

 that in reducing quadruple to triple fpecies, it 

 is impoflihle when p is deilroyed, that the re- 

 maining feries fliould be quadruple, and arc 

 therefore to be removed entirely. 



Let n reprefent the number of primitive earths, 

 and the number of the double fpecies beexpref- 

 fed by n. n. i. of triple fpecies by n. n i. 

 n 2, of quadruple fpecies by /;. n i. n 2. 

 n 3, and that, of the lad order by n. ni. 

 rt2. // n 2. 



{ CXLV. Species of Metals. 



HAVING determined thefe points, we now 

 proceed to the third clafs, in which, on account 

 of the greater number of genera, we fliall find 

 .the fpecies alfo to be far more numerous. 



S 3 Metalo 



