432 O. Meyer — Genealogy and Age of the Species 



contained too much salt for the fresh-water species to live in it, 

 and too little for the marine, and must have been subject to 

 great fluctuations in freshness by the influx of water in wet 

 seasons, and its evaporation in dry, to exclude species that can 

 live in brackish water." From the advanced state of erosion 

 of the Grand Gulf group under its cover of drift (pp. 20, 21) 

 Hopkins concludes that at least during the Pliocene time this 

 group must have been dry land. On p. 18 Professor Hopkins 

 says : " A rather sharp series of escarpments marks the northern 

 boundary of the Grand Gulf." These are perhaps old shore- 

 lines. 



Professor Hilgard determined a certain portion of Louisiana 

 territory in Landry parish within 70 miles of the Gulf coast at 

 first as Grand Gulf then as Cretaceous* In another article f 

 he says: "While the Vicksburg rocks show at all long expo- 

 sures a distinct southward dip of some three to five degrees, 

 the position of the Grand Gulf strata can rarely be shown to be 

 otherwise than nearly or quite horizontal on the average; 

 although in many cases faults or subsidences have caused them 

 to dip, sometimes quite steeply, in almost any direction."' 1 Why 

 have these " Miocene or Post-miocene " disturbances left the 

 Eocene strata undisturbed ? 



Interesting as it would be to discuss more fully the Grand 

 Gulf and Eolignitic, brevity again obliges me to turn to Pro- 

 fessor Smith and Mr. Aidrich. I myself described limestone 

 in the profile of Claiborne above the proper Claibornian, stratum 

 "e." Therefore Professor Smith might have omitted every- 

 thing by which he attemps to show the same thing, that is, that 

 this stratum is sometimes overlaid by limestone. His article 

 and the corresponding part in that of Mr. Aidrich, however, 

 attempt to show, moreover, that Orbitoides and Spondylus 

 dumosus occur above "e." Professor Smith as well as Mr. 

 Aidrich believe that they have proved this beyond doubt. 

 While still questioning it, I will here not dispute it. It follows 

 that no conclusion can be. made either from Orbitoides or from 

 Spondylus dumosus, as they occur above as well as below 

 stratum "e." I fail, however, to find anything in Professor 

 Smith's article that proves the fauna in Jackson or Vicksburg 

 in Mississippi to be more recent than that in the stratum " e " 

 in Claiborne in Alabama, and hence say nothing further on this 

 point. 



As to three charges made against me I add a few words: 

 I indicated some words in a quotation from Lyell by .... , 

 by dots. Professor Smith says that I thus carefully omitted 

 the proof of Lyell. I carefully scrutinized these words before 



* See this Journal, Nov., 1869, p. 343. f This Journal, July, 1881, p. 58. 



