112 FLORA OF THE LARAMIE GROUP. 



Tertiary, even to strata above the Eocene. The other genera, as remarked 

 by Professor Cope, are Liuosmirian of Mezozoic types, but are without any 

 representatives in Europe; hence they can only be used as hypothetically 

 implying reference of the Laramie Group to the Post-Cretaceous. For they 

 have never been found anywhere but in America, while the reference of 

 the Laramie to the Tertiary age is based on the positive evidence of species 

 or genera represented in that formation both in Europe and America. 



Professor Heer. in the Vltli volume of the ''Arctic Flora," has exam- 

 ined the question from the same point of view. After remarking that 

 the Tertiary character of the fossil plants of the Laramie Group, confirmed 

 by that of the mollusks. had rightly forced me to recognize it as Tertiary, 

 he adds that the discovery at Black Buttes of Agafhairmas s//lvesfris. a 

 Dinosaurian, had been considered by zoologists as sufficient authority for 

 the admission not only of Black Buttes but of the whole Laramie Group 

 into the Cretaceous; this from the dogma that Dinosaurians have disap- 

 peared with the Cretaceous. That a Saurian, he says, has been found 

 only at that locality, is no reason for recognizing it as a Cretaceous species,. 

 but the only conclusion which can be drawn from the fact is, that until 

 now it has been supposed that the Dinosaurian type had died in the Cre- 

 taceous, while animals of this kind have permitted some of their offspring 

 to live still in the Tertiary. And, indeed, in regard to that, other groups 

 of Saurians, like the crocodile, have lived in far different periods. There- 

 fore the Agathaumas of Black Buttes is not proof at all that at that locality 

 a Tertiary flora was existing at the same time as a Cretaceous fauna, as 

 admitted by Professor Cope; for a single animal does not constitute a fauna 

 any more than a fragment of plant could constitute a flora. Added to this, 

 it is also well to remark that at Black Buttes, in a stratum immediately 

 above the bed where the remains of Af/afJ/awnas were found, a fish, Celasies^ 

 four species of turtles, an alligator, and a mammal have been discovered, 

 and that all these animals are undoubtedly Tertiary.' 



4tli. The Laramie formation is a land or fresh-waler formation. If 

 sufficient proof of this fact was not given by the remains of plants and 

 the numerous coal deposits found at divers stages over its whole extent,. 



' O. Heer, Beitiage zur Miocene Flora von North Canada, p. 7, in Flora foBsilis Aretiea, vol. vi, part 'i. 



