CHAPTER a 



Summary of Chapter ^, %oitli some conclusions to he drawn 

 from the same. 



We come now to the important inquiry as to the rekitive 

 age of that class of rocks which figure, in the present Amer- 

 ican nomenclature, under the name of " Upper Barren Coal 

 Measures," since all the plants that have been described 

 in Chapter 2 occur in this series. 



In order to have the evidence all before us, we shall ar- 

 range these plants in three columns, putting in the first all 

 the plants which we have found in the Upper Barrens ; 

 in the second, all of their number which have been rejDor ted 

 from the Upper or Lower Coal Measures of the U. S. ; and 

 in the third, those which are common to our Upper Bar- 

 rens and the Permian of Earope. 



Arranging the plants in the manner indicated, we get the 

 following : 



Table of Distribution of Species. 



Equisetides rugosus, 



" elongatus, 



" striatus, 



Calamites suckowii, 



Nematophylluni angustuni, . . 

 Sphenophyllum latifolium, . . . 



" filicuimis, . . . 



«• densifoliatum, . 



" tenuifolium, 



" longjfolium, . . 



*» obiongifolium, 

 Annularia carinata, 



" longifolia, 



U. Barrens of 



W. Va. 



and Penn. 



Coal Meas. of 

 the U. S. 



(105 PP.) 



Permian, Eu- 

 rope. 



