AND ANALOGIES, OF ROCKS. 219 



in the form of mud or stone, is always increasing; 

 and that as the secondary series far exceeds the pri- 

 mary in this respect, so a third series, should one 

 hereafter arise from the depths of the sea, will exceed 

 the last in the proportion of its calcareous strata. It 

 will combine the ruins of the last limestones with the 

 spoils of the present animals : animals, of which the 

 generations are also probably enlarging and extending 

 in every age, in a ratio proportioned to the increase of 

 those calcareous, or soft alluvial and submarine de- 

 posits which they affect and favour. Those who ex- 

 tend the prophetic eye of philosophy to worlds yet 

 unborn, may also thus anticipate a constant and steady 

 approach to that universal state of fertility which is 

 now the character and the pride of our calcareous soils. 

 If we now turn our views backwards to the primary 

 rocks, we find, in the disposition of their limestones, 

 a confirmation of this opinion respecting the import- 

 ant agency of living animals in the production of cal- 

 careous strata. It has always been believed, or at least 

 asserted, by geologists, that no animal remains existed 

 among the primary rocks; and to avoid a breach in 

 this hypothesis, among other reasons, the transition 

 class was invented. I shall not here discuss the truth 

 or the utility of this invention. It is sufficient to say, 

 that the schists containing shells appertain to those 

 rocks admitted to be not secondary, and that the only 

 general revolution among the strata which we know, 

 is of a later date than these. So far as the present 

 purpose is concerned therefore, the animal remains of 

 the schists are primary, in as far as they are prior to 

 the secondary strata. Nevertheless, the animal re- 

 mains of the primary strata, admitting among them 

 those now named, so as to give the most favourable 

 colour to the subject, bear a disproportion to the 



