0. Meyer — Species in the Southern Old-tertiary. 63 



one species that closely resembles a Miocene fossil. The lime- 

 stone of Clark County, Ala., and of St. Stephens contains 

 Nuramuliies cruslcdoides and Feci en Poulsoni Morton, two 

 fossils which abound* in the Vicksburg deposits, and this lime- 

 stone is, therefore, probably of the same age as the Tertiary beds 

 of Vicksburg. This formation marks a distinct era in the 

 American Tertiary system, intermediate between the Eocene 

 and Miocene formations, but more nearly allied to the former, 

 etc." 



In this way the age of the Vicksburg fossils was determined, 

 and what Conrad says afterward about it is only the following 

 out in detail of this once accepted supposition. 



Sept., 1846. Conrad, "Eocene formation of the "Walnut Hills, 

 Miss." (this Journal, ii, 2d series, pp. 210-215). Conrad, 

 speaking of the Vicksburg locality, says, p. 210: "One of the 

 most abundant bivalves is Pecten Poulsoni Morton, a species 

 occurring in the white limestone near Claiborne, Ala. A very 

 thin wafer-shaped nummulite, described by Dr. Morton, is 

 common in the limestone as well as in the strata above, and 

 connects the formation of Vicksburg with the Eocene white 

 limestone of St. Stephens." Here Conrad omits the word 

 "probably," which he used in the preceding essay, and from 

 this time the identity of the Vicksburg beds and the nummu- 

 lite limestone in Alabama is an accepted fact in American 

 literature. Though I consider this identity probable, it cannot 

 be said to be proved. 



June. 1847. Lyell, "On the relative age and position of 

 the so-called limestone of Alabama" (Quart. Jour. Geol. Soc. 

 London, iv, pp. 10-16, read June 9, 1847. Published also 

 with a few alterations in this Journal, iv, 2d series, pp. 186-191, 

 Sept., 1847. 



Lyell says about this limestone, referring to his letter of the 

 preceding year: "It was stated to be newer than all the beds 

 of the well known Claiborne Bluff." Then he tries to prove 

 this stated opinion by claiming that the Claibornian bed occurs 

 also at the base of the St. Stephens bluff below the nummulitic 

 limestone. The fossils which he cites from this bed, p. 15, are: 

 "Terebra coslata Con., Cardila parva, Dentalium thalloides. Fid- 

 helium cuneiforme luorisd., Scutella LyelliConr., and several more." 

 From the few species which Lyell selects to prove the Clai- 

 bornian character of the beds, he cites, on the same page, Den- 

 talium thalloides and Tertbra costata as occurring in the Vicks- 

 burg bed, and Flabellum cuneiforme in the Jackson. So he 



* As this is of some importance, and as it is repeated afterward, I have to object 

 here to the word " abound " in relation to Orbitoides Mantelli in the sand of Vicks- 

 burg. It may be said to be "common," but is not at all "abundant," and is rarer 

 than several other species. 



