GENERAL RESULTS. 
401 
*^oinplex organ the eye, selected from each ex- 
treme, and from a midway place in the progressive 
®6ries of animal creations. We find in Trilo- 
^ites of the Transition rocks, which were among 
the most ancient fonns of animal life, the same 
Modifications of this organ which are at the 
present time adapted to similar functions in the 
hving Serolis. The same kind of instrument 
also employed in those middle periods of 
geological chronology when the Secondary strata 
""ore deposited at the bottom of a warm sea, in- 
habited by Limuli, in the regions of Europe 
""hich now form the elevated plains of central 
^ormany. 
The results arising from these facts are not 
Confined to animal Physiology ; they give infor- 
Mation also regarding the condition of the an- 
^Mnt Sea and ancient Atmosphere, and the 
Mlations of both these media to Light, at that 
remote period when the earliest mai’ine animals 
""Ore furnished with instruments of vision, in 
""hich the minute optical adaptations were the 
^ame that impart the perception of light to Crus- 
^^oeans now living at the bottom of the sea. 
^ith respect to the waters wherein the Trilo- 
bites 
maintained their existence throughout the 
Entire period of the Transition formation, we 
ponclude that they could not have been that 
Imaginary turbid and compound Chaotic fluid, 
the precipitates of which some Geologists 
G. 
D D 
