DOSSIL ARACHNIDANS. 305 



r SECTION III. 



Third Class of Articulated Animals. 



FOSSIL ARACHNIDANS. 



Under the relations that now subsist between the animal 

 and vegetable kingdoms, the connexion of terrestrial Plants 

 with Insects is so direct and universal, that each species of 

 plant is considered to afford nutriment to three or four 

 species of insects. The General principle which we have 

 traced throughout the Secondary and Tertiary formations, 

 ever operating to maintain on the surface of the earth the 

 greatest possible amount of life, affords a strong antecedent 

 probability that so large a mass of terrestrial vegetables as 

 that which is preserved in the Carboniferous strata of the 

 Transition series, held the same relation, as the basis of 

 nutriment to Insect families of this early date, that modern 

 vegetables do to this most numerous class of existing ter- 

 restrial animals. 



Still farther, the actual provisions for restraining this In~ 

 sect class within due bounds, by the controlling agency of 

 the carnivorous Arachnidans would lead us to expect that 

 Spiders and Scorpions were employed in similar service 

 during the successive geological epochs, in which M-e have 

 evidence of the abundant growth of terrestrial vegetables. 



Some recent discoveries confirm the argument from these 

 analogies, by the test of actual observation. The two great 

 families in the higher order of Uving Arachnidans (Pulmo- 

 narias) are Spiders and Scorpions ; and we have evidence 

 to show that fossil remains of both these families exist ia 

 strata of very high antiquity. 



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