INTRODUCTION. XX1X 
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 Kome 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- 
nervis, Font. 
Cladophlebis parva, Fout. 
Sequoia Reichenbachi, Heer. 
Pecopteris Browniana, Dunk. = Clado- 
phiebis Browniana (Dunk.). 
Aspidium Fredericksburgense, Font. 
Sphenolepidium virginicum, Font. 
A plant allied to Zhyrsopteris 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 angustifolia, Newb. 
Sequoia acutifolia, Newb. 
Podozamites nervosa, Newb. 
Oleandra arctica, 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. Browniana, ? Dunk. 
Cladophlebis heterophylla, Font. 
Osmunda dicksonioides, Fout. 
Thyrsopteris microloba, ? var. alata, 
Font. 
T. rarinervis, Font. 
Sequoia ambigua, ? Heer. 
S. rigida, Heer. 
Sphenolepidium virginicum, Font. 
Taxodium (Glyptostrobus) ramosium, 
Font. 
Zamites Montanensis, Font. 
One of the new species in the above list, Aspidium Montanense, 
seems to come very near to Cladophlebis Dunkert (Schimp.). Cf. 
1 Amer. Journ. vol. xli. 1891, p. 193. 
2 Ibid. p. 195. 
3 Proc. U.S. Nat. Mus. vol. xv. 1892, p. 488. 
