566 The American Naturalist. [June, 
that it must have belonged to the genus Zyapa or a closely related 
form. The Point of Rocks material contained nothing but isolated 
leaves—that is to say, there were no rosettes and there were no stems 
—simply the form and nervation of the leaves. These point to the 
genus Trapa, and the probability is that they belong to that genus. 
‘“ The evidence afforded by the beds at Black Butte station, where 
the great saurian was discovered by Professor Cope, is perfectly con- 
clusive of the identity of the age of the beds from which that fossil 
was taken with that from which the leaves of that particular locality 
were taken, We haveat the National museum a specimen of the bone 
from that creature, adhering to the opposite side of which is one of 
the characteristic Laramie leaves. I have been on this spot, and col- 
lected other fossil plants from the same immediate locality. 
‘Now, with regard to the error, if error there be, in harmonizing 
or identifying the Laramie and Fort Union deposits: I suppose the 
responsibility for this must largely rest upon Dr. C. A. White, who has 
made a very thorough and exhaustive study of the entire region, as he 
defines it from the standpoint of its molluscan fauna ; and it seems to 
me that his identification of the two groups—and I have conversed 
with him very freely and very much upon this subject, and what I say 
is from memory of the oral statements made by him—was in the 
nature of a broad, geological generalization, He, in his extensive 
labors in that field, simply came upon the salient fact, that throughout 
the larger part of the region now occupied by the Rocky Mountains 
-is abundant evidence that there existed at a remote period, somewhere 
near the close of the Cretaceous or beginning of the Tertiary period, 
a great land-locked sea, originally somewhat salt, later brackish, and 
finally nearly fresh; and that the deposits which were made at the 
bottom of the sea are apparently continuous all the way up from the 
pure marine deposits of the upper Fox Hills group to the highest of 
Fort Union deposits ; and he even ventures to say he has traced it in 
some places still higher into strata which are admitted to be Tertiary. 
“I have one fact of my own observations which may be worth stat- 
ing, and which may not be known to all. About 15 miles above the 
town of Glendive, on the right bank of the lower Yellowstone river, 
there is a cliff, known as Iron bluff, which is colored very bright red 
from having the carbonaceous matter burned out, and which is full of 
fossil plants. It is also full of the characteristic Laramie shells, such 
as Dr. White has described and has daily met with throughout the 
Laramie series. These shells, he informs me, are identical all the way 
through the Laramie from bottom to top. There is nothing to indi- 
