328 Marcou’s Geology of the United States. 
other Permian regions of Britain, nor in a great part of the Per- 
mian region on the Rhine and in Russia; although Murchison 
says, “In the exploration of Russia, geologists were taught by 
the diversified Permian group not to dwell on the local mineral 
singular number], and perhaps a Belemnite.” Now ‘a Nautilus 
proves nothing as to its being the magnesian limestone; “‘ a Ptero- 
ceras” is direct testimony against it;. and “a Belemnite”? accord- 
ing to all authors, affords the idea no more encouragement. “A 
Nautilus, a Gasteropod, and a Belemnite?” prove this magnesian 
limestone to be Cretaceous, or Jurassic, aid not older than Ju- 
rassic, if the evidence may be used at all. The cautious geologist 
would have certainly doubted his “ New Red” or Triassic, if he 
found it overlying beds containing what was probably a Belem- 
nite. The evidence, if worth anything, abolishes both the Tri- 
assic and Permian together.* ; 
We conclude, therefore, that credit cannot be claimed by oF 
for the author, with regard to the discovery of the Permian 0 
the Rocky Mountains. 
3. Triassic Formation in the Rocky Mountains. 
_ Mr. Marcou observes that “this formation, which I was the 
first to notice and recognize in the West, (see A Geological Map 
of the United and the British Provinces of North Ameria; 
_ * This attempt at the identification of Permian beds in the Rocky Mountains, is 
0 : 
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