Association of American Geologists and Naturalists. 117 



the formation in which they occur was described, it being that 

 extensive calcareous bed which underhes a large portion of South 

 Carolina and sonrie of the neighboring states. 



A discussion arose upon the geological age of the formation 

 furnishing the specimens exhibited by Dr. Smith. 



Prof. Bailey remarked that the Polythalamia attached to Os- 

 trea selliceformis from South Carolina are not similar to those in 

 decided eocene marls from Virginia, but appear to belong to an 

 older period, and agree better with those of the numalite lime- 

 stone of Alabama. 



Prof H. D. Rogers thought it possible that while the forma- 

 tion is obviously of eocene date, as proved by its larger organic 

 remains, the Polythalamian forms may have been derived from 

 the waste of adjacent cretaceous strata. 



Mr. Tuomey said he was glad that Dr. Smith had directed 

 attention to the tertiary strata of South Carolina. If Mr. Lyell's 

 classification be adopted, which admits no fossil as common to 

 the secondary and tertiary, then must the formation in question 

 be referred to the tertiary, while the fossils enumerated by Dr. 

 Smith are those most characteristic of the eocene division of that 

 formation. The geologists who formerly held the opinion that 

 the formation was secondary, have all given up that opinion. 

 He thought, however, that the South Carolina formation will 

 prove to be much older than the eocene of Maryland and Virginia. 



Prof. Bailey stated that he had examined microscopically 

 some specimens of marls put into his hands by Mr. Silliman, 

 from Columbus, Mississippi, obtained in boring an Artesian well, 

 and taken from various depths above two hundred and sixty feet 

 from the surface. He remarked, notwithstanding the little prom- 

 ise which their appearance gave of their containing fossils, that 

 they were nevertheless mostly made up of Polythalamia, some of 

 which were the more common forms of the English chalk. 



Mr. Jas. Flail then read a paper on the geographical distribu- 

 tion of fossils, in continuation of views presented by him at the 

 Albany meeting last year. 



The object of this paper was to present a few additional facts, upon 

 the geographical distribution of fossils in the paleeozoic strata of the Uni- 

 ted States, being a continuation of the paper of last year. In that 

 paper the comparative conditions of the bed of the ocean on the east 

 and west, during the period of these depositions, had been pointed out, 



