426 0. Meyer — Genealogy and Age of the Species 



em Old-tertiary. All localities which are mapped by Professor 

 Hilgard as Jacksonian, based upon the presence of nothing 

 but Zeuglodon, are in ray opinion mapped without sufficient 

 reason. 



The second case concerns such strata as are determined as 

 Vicksburgian by nothing except Orbiioides. Orbitoides has 

 been found in Louisiana in a fauna determined by Hilgard as 

 Jacksonian. I found moreover a specimen of Orbitoides in 

 stratum e and one in stratum b in Claiborne.* Orbitoides is a 

 /? fossil from Vicksburg to Claiborne, and this Yicksburgian 

 determination is therefore without any foundation. 



The third case refers to the strata north of Enterprise, mapped 

 by Hilgard as "siliceous Claiborne." From this whole large 

 formation he cites altogether only two species, Venericardia 

 planicosta and " Cardium NicolletiV (I, p. 124). The first spe- 

 cies is known from Claiborne and Jackson, the second from 

 Jackson. Therefore I am of the opinion that this formation 

 north of Enterprise is determined as Claibornian without a 

 shadow of reason. 



Statement B. 



Hilgard condenses his proof of the succession in the sentence' 

 printed in italics :f " Going down streams flowing to the south- 

 ward, the strata successively sink below the water's edge as the 

 observer progresses, in the order Claiborne, Jackson, Vicksburg, 

 Grand Gulf, as identified by their leading fossils." This is 

 based mainly upon two profiles in two different meridians, the 

 first through Jackson along the Pearl river, the second along 

 the Chickasaw hay. 



The proof rests on two criteria. The first is that all the strata 

 are determined as Claibornian, Jacksonian and Vicksburgian 

 in a reliable way ; the second is, that they have the stratigraph- 

 ical relation which Hilgard here claims, that is, that the dip in 

 his two profiles is not only south, but nothing else than south. 

 Now we might stop and say : the first criterion is not correct, we 

 cannot rely upon his determination of the beds, consequently 

 his deductions from their stratigraphical relation have no value. 

 This is a fact ; but I wish to show, besides, that the second cri- 

 terion is even worse than unreliable, that it contradicts Hilgard's 

 own observations. 



In I, Hilgard states that the dip of the strata in Mississippi is 

 south, with one exception. This exception, however, refers 

 just to one of our profiles. In I, pp. 128, 129, he explains, 

 that the dip from Jackson to Canton is north. He calls this 



* Part II, of this essay, pp. 69, 70 ; see also the remark below, 

 f His article, p. 268. . 



