FORMING THE BAD LANDS OF JUDITH RIVER. 131 
conflicting. Mr. Meek and the writer have expressed in several papers an opinion based 
upon an inference drawn by Dr. Leidy from an examination of the vertebrate remains, that 
it might be contemporaneous with the Wealden of England. In a recent letter Dr. Leidy 
has very kindly given me the evidence upon which he based his inferences, with the per- 
mission to use it in this paper. . 7 
Ist.—“ Trachodon and Deinodon, two remarkable genera, are most closely allied with 
Iguanodon and Megalosaurus of the Wealden.” 
2d.—“In both formations remains of Lepidotus are found.” - 
3d.—* Remains of Crocodiles and Turtles are discovered in both.” 
4th.—“ The remaining two genera from the Judith, Pal@oscincus, an herbivorous lacer- 
tian, and 7roodon, another lacertian, are peculiar, and would not be unfit companions for 
the denizens of the Wealden world.” 
Again, the Molluscous fossils, though of a somewhat similar character, terrestrial, fluvia- 
tile and estuary, in most instances referrible to the same genera, do not seem to belong 
to types very closely allied to those characterizing the Wealden of England. On the con- 
trary, they appear more related to tertiary types, and two species are very nearly identi- 
cal with species common in the Lignite basin which we regard beyond a doubt as of the 
age of the Miocene Tertiary. Paludina vetula of the Judith deposit is so like P. multi- 
lineata of the Lignite basin, that it is with much hesitation we have regarded them as dis- 
tinct, the only difference observable is that the volutions of P. vetula are a little more com- 
pressed and the umbilicus a little more open. Paludina Conradi of the Judith deposit is 
so closely related to P. peculiaris of the Lignite basin that almost no well marked differences 
ean be pointed out. Indeed, had they been found associated in the same strata, we should 
have considered them identical. Fragments of a Trionyx occurring in bed E. of section, are 
undistinguishable from similar fragments found in the Lignite strata, near Square Buttes, 
below Fort Clarke. On the other hand, the only strictly marine fossil is scarcely distin- 
guishable from Ostrea subtrigonalis from the upper cretaceous beds on Moreau and Grand 
Rivers. 
Again, in no portion of the Upper Missouri have we met with any disturbance of strata 
belonging to well known Tertiary beds. The Tertiary beds of the White River deposit 
are found in the region of the Black Hills and Laramie Mountains, resting unconformably 
upon all rocks, from granite to Upper Cretaceous, and in no instance have the strata been 
disturbed. As far as my observations have extended, the same remark may be made of 
the Great Lignite Basin. We have, therefore, arrived at the conclusion, that the last great 
convulsion that uplifted the fossiliferous rocks on the Missouri, occurred after the Creta- 
ceous epoch and prior to the deposition of the Tertiary. The fresh water and estuary beds 
at the mouth of the Judith, as has already been mentioned, are tilted at every angle, from 
