Mr. Jules Marcou’s Dyas and Trias, 257 
sical group. 
Although I will not answer objections in detail on the eology 
of Russia which proceed from a writer who has never been in 
outs of the vast region of Russia (larger than France) oc- 
| by the rocks to which I assigned the name of Permian, 
_Inshort, the whole geological series does not offer a more 
mian and those of the Trias, whether we refer to their respect- 
lvely imbedded reptiles, fishes and shells, or to their plants; the 
She set marking the close of Palzozoic, the others the com- 
mencement of the Mesozoic era. Yet these are the two deposits 
which M. Marcou unites in one natural group under th eee 
of New Red Sandstone. harps oes 
To conclude, let me reques' 
