A. E. Verrill on the Mollusca of Europe and N. America. 465 
tudes of erosion. The most remarkable of these are such as 
have been protected by sheets of eruptive rocks. In the 
Minkaret Mountains we find a group of basaltic tables and 
cones standing far out on the Carboniferous rocks. Twenty- 
between the mountains and the cliffs is seen to be Upper 
Carboniferous; but here, in the mountains, from 1,200 to 1,500 
feet of Triassic rocks can be studied, and it is found that all the 
beds that formerly extended over the intervening region. 
The contemplation of this vast extent of erosion will not 
Stagger us, when we reflect that the sedimentary beds are 
evidences of an amount of erosion co-extensive with the magni- 
tude of these formations, and anterior to that which we are now 
existed when these rocks were formed, and which were buried 
in their accumulating sands; then the folding and faulting of 
the whole series, and. pari passu with this, the excavation of a 
wonderful system of gorges, and the carving of a vast net-work 
of valleys, leaving behind towering cliffs stretching across the 
country in every direction, and still, pari passu, with the fold- 
Ing, and faulting, and denudation, great oods of lava were 
poured out from the interior to fill valleys, and form mesas, 
and tables, and mountain cones. And in the present period 
we have an ensemble of topographical features embossed on the 
face of the country, wild, grand, and desolate. 
Art. LL—Remarks on certain Errors in Mr. Jeffreys's Article 
on “ The Mollusca of Europe compared with those of Eastern 
North America ;” by A. E. VERRILL.* 
In the October number of the Annals and Magazine of Natu- 
ral History, Mr. Jeffreys published an article upon this interest- 
ing subject, in which many important errors occur, due, no 
doubt, to the fact that the distinguished author is much less 
the Annals and Magazine of Nat. Hist., IV, vol. xi, p. 206. 
