742 
to have produced identifications from the mere difficulty of effecting 
discriminations, he would suggest that in that case, according toa 
fair calculation of chances, nine-tenths of the American miocene 
species hitherto identified ought to have been assimilated to exotic 
shells, instead of having been found to agree with some portions of 
the limited fauna at present known on the American shores. The 
same argument, le adds, is clearly applicable to the identifications 
which have been made of fossil and recent shells.in the European 
tertiary formations. 
May 18.—Joseph Coltharai Ksq., Parliament Street, was elected 
a Fellow of this Society. 
A memoir “ On the Geological Structure of the Ural Mountains,” 
by Roderick Impey Murchison, F.R.S., Pres. G.S., M. E..de Ver- 
ab and Count A. von Keyserling, was read. 
A short introduction explains, that although the true geological 
relations of the rocks which constitute these mountains were pre- 
viously little known, the Russians had become well acquainted with 
their mineral wealth and lithological structure. The skill and energy 
with which the mines have been worked having been adverted to, 
the authors dwell with pleasure upon the facilities which the Impe- 
rial Government afforded them by the instructions conveyed to 
all the mining establishments by the orders of Count Cancrine and 
the arrangements of Gen. Tcheftkine. They also acknowledge the 
advantages they derived from the co-operation of many officers at 
the different stations or zavods, several of whom prepared maps for 
their use*. They further express their obligations to maiy indi- 
vidual proprietors, and notably to M. Anatole Demidof, and the 
Prince Butera, for their very hospitable reception at the zavods of 
Nijny Tagilsk and Bissersk. They then proceed to state, that without 
the small general map recently published by Baron A. von Humboldt 
and his associates, the objects of the journey could not have been 
so well attained. These objects were, to reunite the various frag- 
ments of the Ural chain, to show of what sedimentary masses it 
was originally composed, and to explain by what agency the strata 
have been dislocated and altered. In the latter respect they are 
aware that tneir labours have to a great extent been anticipated by 
the researches of Baron Humboldt, and his companions M. G, Rose 
and M. Ehrenberg, as well as by their predecessors Colonel Hel- 
mersen and M, Hoffmann ¢, and various officers of the Imperial School 
of Mines f. 
Moving in two parties and upon separate but parallel lines of re- 
* Among these officers allusion in this brief notice can only be made to 
those in command, viz. Gen. Glinka, Commander-in-chief at Ekaterinburg ; 
Col. Vélkner, formerly at Perm; Col. Protassof at Bogoslofsk, who first ex- 
plored the distaats north of that age ; Col. Tchaikofski of Ekaterinburg, 
and Col. Galahofski of Turinsk. 
¢ See various works on given districts of the Ural mountains by officers 
of ie Imperial School of Mines. 
{ These works are referred to and ably condensed in a Russian work by 
Prof Stshurofski of Moscow. 
