2 MICROSCOPICAL OBJECTS FOUND 



careful examination of them under the microscope, 

 to offer the results of my observations to the 

 Society, believing that the subject will be inter- 

 esting to the members on two accounts. In the 

 first place, because the deposit furnishes an 

 admirable illustration of the agencies, by which 

 many of the more ancient calcareous rocks have 

 been formed ; and in the second, because the 

 microscopic organisms with which it abounds, 

 exhibit beautiful examples of some of those lower 

 tribes of plants and animals, which are now 

 attracting general attention, but many of which 

 have not yet been brought before this society. 



Various speculations have been advanced to 

 account for the origin of cretaceous and lime- 

 stone strata. Of these, time will not allow me 

 to dwell upon more than the two or three which 

 have been the most popular. 



The first is the hypothesis, which supposed, that 

 calcareous rocks have been formed by the accu- 

 mulation of the comminuted portions of shells and 

 corals, previously broken up by the mechanical 

 movements of the ocean ; a view, which was enter- 

 tained by Linnffius in 174.5, and again by Buffon 

 in 1749, and which has been more recently 



