25 



Professor Ilecr, considering these organisms, remarks that their 

 systematic relation is very uncertain. They are, by the disposition of 

 their divisions, distantly comparable to the Characece, but that is all. As t 

 they have been found in Switzerland, only in connection with deep animal 

 marine remains and fucoids, they should have lived in the seas, if they did 

 represent vegetable, while from their association in this country with dicoty- 

 ledonous leaves the contrary assertion would be authorized. They may be, 

 after all, the marks of a peculiar kind of crystallization, and it is to be hoped 

 that somebody may procure from our Cretaceous measures specimens in such 

 a state of preservation that the true relation and nature of these fossils may 

 be ascertained. In any case their presence in the lower beds of clay of the 

 Dakota group should be recorded as an indication of their geological relation 

 with the European Cretaceous. And of course these fossils, though without 

 any relation recognized as yet, are positive evidence of the continuity of the 

 series of the Dakota group from the point of contact of the clays with the 

 Permian beds of limestone. No trace of an intermediate formation can be 

 admitted between them. This opinion has been from the first admitted by 

 Dr. Hayden, and the further the explorations are pursued the more gene- 

 rally accepted it becomes. Professor Mudge, in the Agricultural Report of 

 Kansas, already quoted, says "Observations made the past year (1871) con- 

 firm my statement read before a former meeting of the association, viz, that 

 there is in Kansas no geological representation of the formations found in 

 other countries between the upper Carboniferous or Permian, and the Creta- 

 ceous. Careful research has been made for fossils of Jurassic and Triassic 

 periods along the western borders of the Permian, and none have been found, 

 while dicotyledonous leaves and Cretaceous fossils have been procured lately 

 nearer the line of the Permian than during our first collection." In a letter 

 of October, 1873, the same geologist writes that: "Since writing the above 

 article I have become settled in the idea that the Dakota group rests directly 

 on the Permian, as I have found leaves of the Cretaceous and shells of the 

 Permian within three miles of each other, at about the same horizon and 

 without traces of any intermediate formation." 



§ 4. — The dakota group considered as a marine formation. 



Dr. F. V. Hayden, in a paper in the American Journal Sciences and 

 Arts, vol. xliii, March, 18G7, p. 178, remarks: " Both Mr. Marco u and Pro- 

 4 L 



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