GEOLOGY. 577 



the globe, is now found in our seas; they are absolutely 

 struck out of the catalogue of created beings. ^ 



Carboniferous Period. — Later on, the first layers that 

 cooled down became covered with a luxuriant vegetation, 

 the fossilized remains of Avhich now constitute our coal- 

 beds — antediluvian forests, which the genius of man 

 extracts from the depths of the earth, to serve the Avants 

 of industry and his own dwellings.^ 



1 Tlie trilobites, marine ci-ustaceans — so called on account of their bodies 

 being composed of three lobes — were, with the exception of a verj' few shell-fish, 

 the only beings which peopled the seas of the Silurian epoch. At the present 

 time we do not find any crustaceans analogous to these extinct species. 



Although thousands, perhaps millions, of years separate us from the period at 

 which the trilobites existed, yet, by a fortunate accident, geologists have sometimes 

 met with specimens so perfect that the delicate structure of the eyes covild be 

 made out in them ; and it has been shown that these organs were constructed 

 upon exactljr the same plan as those of the crustaceans which now inhabit our seas. 



These revelations suffice to establish a parallel between the extreme points of 

 creation ; and hence Buckland, after an examination of this apparatus, daringly 

 painted the condition of the globe at the time when these strange crustaceans lent 

 life to it. " The results," he sa)'s, "arising from these facts are not confined to 

 animal physiology ; they give information also regarding the condition of the 

 ancient sea and ancient atmosphere, and the relations of both these media to 

 light, at that remote peiiod when the earliest marine animals were furnished with 

 instruments of vision, in which the minute optical adaptations were the same 

 that impart the perception of light to crustaceans now living at the liottoin of 

 the sea. 



" With respject to the waters wherein the trilobites maintained their existence 

 throughout the entire period of the transition formation, we conclude that they 

 could not have been that imaginary turbid and compound chaotic fluid from the 

 precipitate of which some geologists have supposed the materials of the surface 

 of the earth to be derived ; because the structure of the eyes of these animals is 

 such, that any kind of fluid in which they could have been efficient at the bottom 

 must have been pure and transparent enough to allow the passage of light to 

 organs of vision, the nature of which is so fully disclosed by the state of jjcrfeetion 

 in which they are preserved. 



" Regarding light itself also, we learn from the resemblance of these most 

 ancient organizations to existing eyes, that the mutual relations of light to the 

 eye, and of the eye to light, were the same at the time when crustaceans endowed 

 with the faculty of vision were first placed at the bottom of the primeval seas, as 

 at the present moment." 



2 After a careful examination of the ancient forests from which our coal- 



