AGE OF TOE LIGNITIO DETERMINED BY ITS FLORA. 339 



would 1)0 more lliaii sufficient to authorize the conchisiou that Ihe llora of 

 tlie Lower Liiiuitic is positively Tertiar\' in its cliaraclers. But, as com- 

 parisons made from an ex])osition like that of the table have generally more 

 or less of andjiguity, and can but leave some doubt or distrust on the value 

 of the conclusions, it is advisable to look somewhat deeper into the subject, 

 and to see on wliat kind and degree of relation is based the assertion that 

 the flora of the Lower Lignitic is of Tertiary age. 



The marine plants might perhaps be omitted, as have been the Lidicnes 

 and the Fungi, in a comparison like the one we have to make; for their distri- 

 bution is too wide and their characters too uncertain. The relation of Hali- 

 menites major, for example, which is so profusely fnund in connection witi) 

 the Lower Lignitic sandstone of Colorado and Wyoming, seems to be quite 

 as distinctly marked with the Cretaceous as with the Tertiary; for Count 

 Saporta has a closely allied form described from the Jurassic, and Prof Meek 

 has found the identical species at Bear River in strata wliich he considers 

 positively Cretaceous from the determination of their invertebrate remains. 

 We have, however, to admit a degree of evidence from the predominance of 

 Fucoidal remains in the Lower Lignitic, as equally remarked in (lie Eocene 

 of Europe, especially of Switzerland. Indeed, it was from the profusion of 

 the so-called Fucoids in the Lower Lignitic sandstone of the Eaton Mountains 

 tliat I received the first indication of the Eocene relation of this formation. 

 The presence of Delesserla species in the lower sandstone at Golden was a 

 confirmation of the first impression; for, of the eight species of Delesserla 

 described by European authors, seven are Eocene. 



Leaving out of count the Fucoids, we have the Ltjcopodiacece, a family 

 whose presence is already recorded in the oldest chronicles of the fossil floras 

 of the world, those of the Silurian, and which is especially predominant in the 

 Carboniferous epoch, where its species, mostly large trees, have contributed, 

 with the Ferns and the Cfl/flmfl?7<s, the essential part of tiie compounds of (he 

 coal. But from the base of the Permian, the Lycopodlaccoe. seem to disap])ear 

 completely; for nothing referable to them has been found in the subsequent for- 

 mations, buttwo uncertain forms in thcOolite of England, Z?/co;wrf//ra uncifoUus 

 and L. fakatus, LI. & IIu(t., plants whose relation has always been con- 

 sidered as doubtful; as, until now, no species of (his order has been 

 described (Vom (lie Cretaceous and tin' Tertiary. This disappearance has 

 been a fact (he more inexplicable, (hat the Tjycopodiaaci are mostly of hard, 



