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Geology. , ^^^ 



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Calaniltes areriaceus, p. 334 ; "good." 



Calamites diyunctus,^ Era., p. 334, "does not seem to be other than 

 the 0, arenaceus." The future will decide. 



"In conclusion " says Prof. Heer, "such species as Pierozamitcs longi- 

 folius^ Equisetum columnare^ and Pecopteris Siuttyariiensis^ are charac- 

 teristic of the Keuper or Marnes Irisees of Germany, of France, and of 

 Switzerland ; some others are lite species that are found in Europe in the 

 Keuper and the inferior Lias, but are specifically different. There is no 

 species really Oolitic in Virginia and North Carolina." 



Besides the evidence from the fossil Flora, which shows the age of the 

 Richmond and N. Carolina coal fields, there is other proof from the fossil 

 Fauna. These are the Thecodonts, found in Europe in the Bunter Sand- 

 stein, or in the Permian, and some others. 



Messrs. Rlley and Stutchbnry first named a Palceosaurus and Theco- 

 dontosQurus from the Bristol conglomerate, England. (See LyelPs El. 

 GeoL, 6th ed., p. 358.) Analogous remains w^ere detected by Mr, Lea of 

 Phihidelphia in the sandstone of Milford, Penn., which he named Clepsi- 

 saurus Pennsylvanicus, In the Deep River and Dan Hiver Coal field, 

 Dr. Emmons found analogous remains, which he named Clepsisaurus 

 Carol incus IS ^ being somewhat diffei'ent from that described by Mr. Lea. 

 Another was named (Z Xeai^ Em., in honor of L Lea, the discoverer of 

 the first "Thecodont saurians in our country." To this was added 

 Eutiodon Carolinensis, Urn., and one or two species of Pala^osaurns, related 

 to the Thecodonts of the Permian in Europe. 



Still more remarkable is the discovery of a mammal in the coal series 

 of Chathnm, N. C, which is named Droinatherium sylvestre^ Em,, a new 

 genus and species of a placental insectivore associated with the Theco- 

 dont saurians. 



Another letter has been recently received from Zurich, in which it is 

 stated by Mr. Marcou that Sir Charles Lyell, after a visit of some weeks 

 at Zurich, and a full examination of the specimens of fossils, figures, and 

 desci-iptlons from the Richmond and North Carolina coal series, has come 

 to the conclusion that this group is "Permian, or else is the Bunter sand- 

 stein ;" that the "Dromatherium is the most ancient mammal yet dis- 

 covered;" and that he has "changed the age of the red sandstone in his 

 German edition of the Manual of Elementary Geology^ now in the course 

 of publication at Frciburgh," and that he will "make the same change 

 in his next English and French editions of his Manual " c. d. 



Oct. 6, 1857. 



Addllmial BemarJcs by */. I). Dana. — In the determination of the exact 

 age of this sandstone, tlie only rock in this country east of the Mississippi 

 occurring between the Carboniferous and the Cretaceous, we cannot be 

 too cautious in the use of evidence. One or two considerations are there- 

 fore here suggested. Li the first place, the Fauna and Flora of America of 

 this moderu'epoch, is represented in Europe, and quite strikingly, as has 

 been shown, by the Fauna and Flora of the later tertiary of Europe. The 

 life of corresponding a^^es in the two continents has thus been older in 

 America than in Europe! This is one point to be well weighed. Again, in 

 determining the age of a rock from its fossils, we should rather look to 

 those which indicate the more recent period, than those which bear the 



w. 



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