520 TRANS. OF THE ACAD. OF SCIENCE. 



the Coal Measures. And it is almost certain that the larger 

 part of them are not absolutely identical with the species" to 

 which they are referred in the Coal Measures. Even Messrs. 

 Meek and Hayden say they are "rather intermediate* in 

 their affinities." 



The true Productits Calhounianus is certainly permanently 

 different from the species (P. semi-reticulatus) to which it is 

 referred by Mr. Meek. And the same may be said of the 

 Pecten Cleavelandicus, Productus JVorwoodii, and others. 

 And it will need no argument of mine to show that perma- 

 nent varieties are of great value in determining formations. 

 In fact some contend that they should be reckoned as 

 species. f Even Mr. Meek is compelled to take this side of 

 the question in his famous review of Prof. Geinitz, and it is 

 the only view to make fossils the most useful. 



But if these arguments of Messrs. Meek and Hayden prove 

 the rocks in question not Permian, they will equally prove 

 there are no Permian Rocks in Kansas ; for all of their argu- 

 ments will apply with equal force, and some of them with 

 still stronger force, to the rocks which we all agree are Per- 

 mian, or equivalents of the Permian of Europe. 



By following their line of argument and assuming these 

 Lower Permian Rocks to be Coal Measures, as they do, and 

 that all the fossils in them are Carboniferous, and that only 

 those fossils confined to the Permian Rocks are Permian fos- 

 sils, we shall find that the rocks admitted to be Permian by 

 all, contain more Carboniferous than Permian fossils ; that is, 

 a larger proportion of the fossils in the Permian range down 

 into the Lower Permian, than from the Lower Permian down 

 into the Coal Measures. 



And if Monotis and other Permian genera do not prove 

 these rocks to be Permian, they cannot prove any other rocks 

 Permian. 



If Monotis JTalli, and speluncaria, Schizodus Possicus 

 and other Permian species do not prove these rocks Permian, 

 they certainly do not prove those above them to be Permian. 



And besides, the objectionable genera Pellerophon, Orthise- 

 ?ia, etc., are in these rocks, which all admit to be Permian. 



We also have such a change in the lithological characters 

 of the rocks at our line of separation that the rocks above 

 and below it can be distinguished at a distance of ten or fif- 

 teen miles ; but where Messrs. Meek and Hayden make the 

 line of separation they themselves say there is " no lithologi- 

 cal change." 



Now, this lithological argument is very important in con- 



* Am. Jour. No. 79, p. 35. 



t Am. Jour., No. 131, 1867, p. 170. 



