SCIENCES 

 LIBRARY 



THE following pages first appeared in a series of papers pub- 

 lished in the ' Annals and Magazine of Natural History,' to the 

 courtesy of the proprietors of which Journal I am indebted for 

 the opportunity of reprinting them. The first of those papers 

 was published in August 1847, the last in May 1848. 



The investigations carefully continued from the time of the 

 publication of the first of those papers have served only to con- 

 firm, and greatly to strengthen the evidence of the truth of, the 

 conclusions therein expressed. Should these investigations have 

 served to open up the true reading of one page in an obscure, 

 but most interesting, chapter of the great Book of Nature, the 

 time and labour given to them will not have been mis-spent. 



I have had much pleasure in acknowledging, at pages 10, 42, 

 &c., my obligations to various gentlemen for their kind assist- 

 ance. 



An explanation of the Plates, fulfilling also the purpose of an 

 INDEX, will be found at the end of the volume. 



J. T. S. 



Highgatc, 20th May, 1848. 



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