450 THE NATURAL HISTORY OF, &c. 



compelled us, from the beginning^ to mass our super- 

 abundant materials into groups, which, on many occa- 

 sions, may appear too much generalized, and on others 

 marked with repetitions, which sometimes we thought 

 requisite, to refresh the memory of the reader. The 

 basis of the questions chiefly investigated, was laid in 

 a series of lectures on the same subject, read to the 

 Plymouth Institution, between the years 1832 and 

 1837. The materials were exclusively sought for in 

 scientific researches and profane history ; and the suc- 

 cessive discoveries and conclusions of other writers 

 since that period, have, in general, strongly supported 

 the main points of our own convictions, to which we 

 attach no further personal importance, than what con- 

 tinued research will disprove, or in due time assent 

 to, when the basis of several conclusions offered in 

 these pages will have acquired more ample notoriety 

 and consequent solidity* 



