Dake 
Geology. : 139 
“Imay say in confirmation of the assertion that your fossil plants [species of 
i are Cretaceous, that I found near the 
w sandstone series in New —— considered hears y 7 
u,—a very similz that represen our specim species 
least being idastical wie yone sandciated with’@: pk Tacos, and Ammon- 
tes of lower Cretaceous species.” 
With such evidence, even the exact identification of the two fossil 
shells is of little importance. The Cretaceous is the lowest formation in 
which leaves of any dicotyledons have been found. 
tofessor Agassiz states that Mr. Marcou is a good Jurassic geologist. 
But this does not: affect the case in hand. For he had but two or three 
fossils about which to use his Jurassic judgment; and if this judgment 
has led him to think he can tell Permian, Triassic, or Jurassic rocks by 
their lithological characters, when he sees them in America, it has 
im badly. - 
We Tegard it therefore as still true that Mr. Marcou’s Triassic of 
i Superior, is not Triassic; and in the Rocky Mountain region, his 
oe is not proved to be Permian, his Triassic not Triassic, and his 
"rassic not Jurassic. Where are then his discoveries ? ee 
4p.—As regards the geological ma -making, there is little resem- 
blance tetinden the Sas if ‘ 
“mer do not claim to be discoverers over the Rocky Mountain region, 
and Mr. Marcou does. Mr. Marcou, while remarking that the colors to 
am sure of the limits of the formations on the line mre 
Marthe 35th parallel of latitude ;” and guided by this sure determina- ~ 
