INIEODTJCIION. XXIX 



is Lower Cretaceous and not Jurassic ; '" and, in another place, he 

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

 the Kootanie, and the Eome groups represent perhaps distinct 

 but closely related epochs of the Neocomian or Lower Cretaceous 

 of the Old "World." ^ 



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- 

 nenis, Font. 



Cladophlebis parva^ Font. 



Sequoia Reichenbaehi^ Heer. 



Pecopteris Browniana, Dunk. = Clado- 

 phlebis Srowniana (Dunk.) . 



Aspidium Frederieksburgense, Font. 



Sphenolepidizom 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 Cycadiospennum rotun- 



datum, Font. 

 Pecopteris mierodonta, Font. 

 Thyrsopteris brevipennis. Font. 

 A plant near to Cladophlebis constricta. 



Font. 

 Chiropteris WilUamsii, Newb. 

 C. Spatulata, Newb. 

 Zamites apertus, Newb. 

 Baiera brevifolia, Newb. 

 Cladophlebis angustifolia, JiTewb. 

 Sequoia acutifolia, Newb. 

 Podozamites nervosa^ Newb. 

 Oleandra arotica, Heer. 



In a more recent paper Fontaine '" 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. JSrowniana, ? Dunk. 

 Cladophlebis heterophylla. Font. 

 Osmunda dicksonioides, Font. 



Thyrsopteris microloba, ? var. alata, 



Font. 

 T. rarinervis, Font. 

 Sequoia ambigua, ? Heer. 

 S. rigida, Heer. 



Sphenolepidium virginicum. Font. 

 Taxodtum [Glyptostrobus] ramosium, 



Font. 

 Zamites Montanensis, Font. 



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

 seems to come very near to Cladophlehis Dunheri (Schimp.). Cf. 



1 Amer. Joum. vol. xK. 1891, p. 193. 



^ Ibid. p. 195. 



3 Proc. U.S. Nat. Mub. vol. xt. 1892, p. 488. 



