INTRODUCTION. 



XXIX 



is Lower Cretaceous and not Jurassic ; >M and, in another place, he 

 adds : " With equal certainty we can assert that the Potomac, 

 the Kootanie, and the Kome groups represent perhaps distinct 

 but closely related epochs of the Neocomian or Lower Cretaceous 

 of the Old World." 2 



The following list shows the close resemblance between this 

 Great Falls flora and the Old World Wealden : 



Thyrsopteris rarinervis, Font. 



A plant near to Podozamites distanti- 

 nervis, Font. 



Cladophlebis parva, Font. 



Sequoia Eeichenbachi, Heer. 



Pecopteris Browniana, Dunk. = Clado- 

 phlebis Browniana (Dunk.) . 



Aspidium Fredericksburgense, Font. 



Sphenolepidium virginicum, Font. 



A plant allied to Thyrsopteris brevi- 

 folia, Font. 



A plant near to Cladophlebis distans, 

 Font. 



Thyrsopteris insignis, Font. 



Carpolithus virginiensis, Font. 



A plant near to Cycadiospermum rotun- 



datum, Font. 



Pecopteris microdonta, Font. 

 Thyrsopteris brevipennis, Font. 

 A plant near to Cladophlebis constricta, 



Font. 



Chiropteris Williamsii, Newb. 

 C. Spatulata, Newb. 

 Zamites apertus, Newb. 

 Baiera brevifolia, Newb. 

 Cladophlebis angusti folia, Newb. 

 Sequoia, acutifolia, Newb. 

 Podozamites nervosa, Newb. 

 Oleandra arctica, Heer. 



In a more recent paper Fontaine 3 fully endorses the opinions 

 expressed by Newberry as to the age of the Great Falls group 

 of Montana, and records the following additional species from 

 this flora : 



Equisetum Lyelli ?, Mant. 



Aspidium Montanense, Font. 



A. monocarpum, Font. 



A. angustipinnatum, Font., var. Mon- 



tanense, Font. 



Pecopteris Montanensis, Font. 

 P. Browniana, ? Dunk. 

 Cladophlebis heterophytta, Font. 

 Osmunda dicksonioides, Font. 



Thyrsopteris microloba, ? var. alata, 



Font. 



T. rarinervis, Font. 

 Sequoia ambiaua, ? Heer. 

 S. rigida, Heer. 



Sphenolepidium viramtcum, Font. 

 Taxodmm (Glyptostrobus] ramosium, 



Font. 

 Zamites Montanensis, Font. 



One of the new species in the above list, Aspidium Montanense, 

 seems to come very near to Cladophlebis Dunkeri (Schimp.). Cf. 



1 Araer. Journ. vol. xli. 1891, p. 193. 



2 Ibid. p. 195. 



3 Proc. U.S. Nat. Mus. vol. xv. 1892, p. 488. 



