114 FLOE A OF THE LARAMIE GROUP. 



in such a way that they cannot be separated without breaking the speci- 

 mens. This fact positively indicates the cause of the distribution of some 

 remains of Cretaceous animals as merely casual, without relation to the 

 nature and the progressing development of the formation. 



As has already been remarked, the external aspect of the species of 

 different groups treated in vol. vii is an obstacle to the easy comprehension 

 of the character of each group. It is, therefore, advisable to have now, 

 separately, all the species of the Eocene flora exposed in a table, with 

 their relation indicated. This will render more clear the deductions 

 which, as said above, have been derived from the character of the flora in 

 the "U. S. Geol. Rep.," vol. vii. 1 



1 This quotation refers to vol. vii of the " U. S. Geological Survey of the Territories," by Dr. P. V. Hayden. 

 (1878). 



