MrRCHISON — ON THE NEW TEEM DTAS. 
5 
I had further sustained by personal examination of the rocks of 
Permian age in various other countries of Europe.* 
It was, indeed, evident that M. Marcou's proposed union of the so- 
called Dyas and Trias in one natural group could not for a moment 
be maintained, since there is no conclusion on which geologists and 
palaeontologists are more agreed, than that the series composed of 
Koth-liegende, Kupfer-Schiefer, Zechstein, etc., forms the uppermost 
Palaeozoic group, and is entirely distinct in all its fossils, animal and 
vegetable, from the overlying Trias, which forms the true base of the 
Mesozoic or Secondary rocks. 
Owing to such a manifest confusion respecting the true palaeonto- 
logical value of the proposed " Dyas," we should probably never have 
heard more of the word, had not my distinguished friend, Dr. Geinitz, 
of Dresden, recently issued the first volume of his valuable palae- 
ontological work, entitled ' Dyas, oder die Zechstein- Formation und 
das E-othliegende.'t In borrowing the terra "Dyas" from Marcou, 
Dr. Geinitz shows, however, that that author had been entirely mis- 
taken in grouping the deposits so named with the Trias or the Lower 
Secondary rocks, and necessarily agrees with me in considering the 
group to be of Palaeozoic age. 
As there is no one of my younger contemporaries for whom I have 
a greater respect as a man of science, or more regard as a friend, 
than Dr. Geinitz, it is painful, in vindicating the propriety and use- 
fulness of the word " Permian," to be under the necessity of pointing 
out the misuse and inapplicability of the word " Dyas." 
The term " Permian" was proposed twenty years ago for the 
adoption of geologists, without any reference whatever to the litho- 
logical or mineral divisions of the group ; for I well knew that a cer- 
tain order of mineral succession of this group prevailed in one tract, 
which could not be followed out in another. After surveys, during 
the summers of 1840 and 1841, of extensive regions in Eussia in 
Europe, in which fossil shells of the age of the Zechstein of Germany, 
and the Magnesian Limestone of England, were found to occur in 
several^^ourses of limestone, interpolated in one great series of red 
sandstones, marls, pebble-beds, copper-ores, gypsum, etc., and seeing 
that these varied strata occupied an infinitely larger superficial area 
than their equivalents in Germany and other parts of Europe, I sug- 
gested to my associates, when we were at Moscow in October, 1851, 
that we should employ the term " Permian," as derived from the vast 
government of that name, over which and several adjacent govern- 
ments we had traced these deposits. 
In a letter addressed to the late venerable Dr. Fischer von Wald- 
heim, then the leading naturalist of Moscow, I therefore proposed 
the term " Permian,"^ to represent by one unambiguous geographical 
* See ' American Journal of Science and Arts,' 2nd ser, vol. xxviii. p. 256, — 
the work of M. Marcou having attracted more attention in America than in 
England. 
t Leipzig, 1861. 
X See Leonhard's * Jahrbuch ' of 1842, p. 92 ; and the 'Philosophical Magazine,' 
