0. Meyer — Species in the Southern Old-tertiary. 61 



1883. When Conrad was in Claiborne he found in a stratum 

 lower than the " Claibornian " a specimen of Spondylus dumosus 

 {Plagiostoma dumosum). See " Fossil shells of the Tertiary 1 

 formation," second edition, p. 34. 



1834. "Observations on the Tertiary and more recent forma- 

 tions of a portion of the Southern States," by Conrad, Jour. 

 Acad. Philad., vol. vii, pp. 116-157, read April 15, 1831. 



Here Conrad mentions the limestone with Nummulites Man- 

 telli Morton in the vicinity of Claiborne. As this limestone 

 contains Plagiostoma dumosum, in abundance, he considers the 

 stratum at the base of the Claiborne bluff as the upper part of 

 this nummulitic limestone. Thus, he concludes, that the num- 

 mulitic limestone underlies the Tertiary formation of Claiborne 

 and is Cretaceous. 



March, 1846. The second number of vol. i, 2d series of this 

 Journal (1846), contains the following two essays : 



1. Conrad, "Observations on the Eocene formation of the 

 United States, etc.," pp. 209-221. Here Conrad says that he 

 no longer considered the nummulitic limestone of Alabama 

 and Mississippi as a connecting link between the Secondary 

 and Tertiary strata, but as Eocene. "Between Claiborne and 

 St. Stephens it forms hills of considerable elevation and abounds 

 in that fine fossil, Plagiostoma dumosum. At. St. Stephens this 

 limestone constitutes an elevated bluff and abounds in Num- 

 mulites Mantellij Plagiostoma dumosum, Ostrea cretacea, etc. At 

 Vicksburg the Pecten Poulsoni is common to this rock and to 

 the Eocene sand." These words are important. Here the 

 Yicksburg is mentioned the first time, and at the same time 

 parallelized with the nummulitic limestone of Alabama. 



2. As postscript to this number of the Journal, pp. 313-315, 

 there is a letter from Charles Lyell, dated Claiborne, Ala., Feb. 

 4th. In this letter Lyell speaks on several subjects and says, 

 of the nummulitic limestone, that it had been referred to a pre- 

 Tertiary age, but he considered it even younger than the Clai- 

 bornian, for it occurs on higher places than the Claiborne bluff, 

 "a circumstance which, in a region where the stratification is 

 horizontal, would imply a newer deposit. ... I did not meet 

 with the limestone in question in the bluff at Claiborne, which, 

 I have no doubt, is owing to the fact that the calcareous strata 

 are cut off at the top before they extend upward into the num- 

 mulitic beds." 



We see, that Lyell does not show, why Conrad's opinion, 

 based upon Spondylus dumosus, is wrong, but he states, in a 

 few words, that the nummulitic limestone overlies the Claiborne 

 strata. His reasons are : that the stratification is horizontal, 

 and the nummulitic limestone occurs higher than the Claiborne 



