IN THE MUD OF THE LEVANT. 95 



On the other hand, the Infusorial deposits of 

 Bermuda and Virginia are altogether siliceous. 

 Not one calcareous organism exists. The siliceous 

 forms comprehend the majority of those which I 

 have described from the Levant, many of them 

 being not only similar, but specifically identical, 

 and the manner in which they are grouped 

 tosrether in these distant localities indicates 

 something more than mere accident ; indeed we 

 want nothing but the calcareous structures, to 

 render these Miocene strata* perfectly analogous 

 to those now in process of formation both in the 

 Mediterranean and in the West Indian seas. 

 Are these siliceous deposits, so void of any 

 calcareous organisms, still in the condition in 

 which they were originally accumulated ? or 

 were they once of a mixed character, like 

 those of the Levant, having been subsequently 

 submitted to some chemical action, which has 

 removed all the calcareous forms, leaving only 

 the siliceous structures to constitute the permanent 

 stratum ? I am disposed to adopt the latter 

 opinion, for several reasons : 



* Dr. Bailey informs me, that the Virginian deposits belong, 

 beyond doubt, to the Miocene era. That from Bermuda is 

 more doubtful. 



