Marcou’s Geology of North America. 331 
Marcou. This is bad luck for the Jurassic, Triassic and Permian 
of the Rocky Mountains, on which his claims to a place among 
the “discoverers” rests. His results, reduced to the simple 
facts ascertained, amount only to this—that the geology of the 
Rocky Mountain Region includes Cretaceous and Carboniferous 
rocks+~-a fact that was quite well known before. 
Whoever then may identify true Permian, true Triassic, or 
true Jurassic strata, beyond the Mississippi, will not have bor- 
_ Towed from Mr. Marcou, and can owe him no credit. 
_ But the subject is not one of mere credit to any person; for it 
1s unfortunate in its bearing on the progress of geological science 
to have false views about some 500,000 square miles of territory, 
and much more besides, spread widely abroad through reputable 
Journals, and Transactions of distinguished European Societies. 
We might here leave the author’s researches. A few other 
topics, however, may have a brief word. And while criticising 
his labors, we would say that his work contains many observa- 
tions that are better than his inferences. 
i e 
figure given by Roemer represents a small individual, but he 
The Gryphea Pitcheri of Marcou (plate 5) has well marked 
differences Hein his Gryphea dilatata (the true G. Pitcheri of 
rm - * . 
Vol. i, plate 9, fig. 2 a b) as a variety of G. Pitcheri and designa- 
ted G. Pitcheri var. navia (see d Re- 
