i6S * .//. H. Winchell on the Taconic 
*briari^ and zvas so admitted by Dr. Emvwns. Hence Canibriajz 
should bejiscd instead. It is true that Dr. Emmons cmjoloyed 
the following words in his first publication of the Taconic sys- 
tem : " The Taconic rocks appear to be equivalent to the Lower 
Cambrian of Prof. Sedgwick, and are alone entitled to the 
consideration of belonging to this system, the upper portion 
being the lower part of the Silurian system."' Prof. Dana has 
interpreted this to mean^ that Emmons would divide his system 
between the Cambrian and the Silurian. By "upper portion" 
Prof. Dana would have Dr. Emmons imply the upper portion 
of the Taconic, at a time when he had not yet introduced any 
division into upper and lower Taconic. But that is not what 
Mr. Emmons intended to say. He intended to express his sym- 
]-»athv \\'\Xh Mr. Murchison by saying that the upper portion of 
the Cambrian was the saine as the lower part of the Silurian, 
and that the Lower Cambrian rocks of Wales were the only 
(jues entitled to the consideration of belonging to the Taconic 
system. The expression is ambiguous, but its true meaning 
would l:>e made evident if instead of "and" Dr. Emmons had 
used the relative word zc/tic/i, so that the clause would read 
ivhich are alone entitled to the consideration of belonging to this 
system. This statement of Dr. Emmons has been taken to 
mean that he recognized, and intended to express, the priority 
of the term Cambrian. But this is a forced, and not a legitimate 
inference. Two collaborators on a subject may refer back and 
forch to each other's work without involving the question of 
priority. Mr. Sedgwick in 1855 could have referred in the same 
terms to the Taconic without implicating himself in the ques- 
tion of priority. He could have said with perfect propriety 
"The Lower Cambrian rocks appear to be equivalent to the 
Taconic of Dr. Emmons," and he would not thereby necessarily 
have given assent to the priority of the Taconic. On the con- 
trary, Dr. Emmons simply desired to exemplify by a compari- 
son with a formation which Prof. Sedgwick was working on, 
his own Taconic system. He had known the Taconic rocks 
for twenty years. He had read the treatises of Dewey, Hitch- 
cock and Eaton in the American Journal of Science since 1819, 
' Geol. of New York, .ind distinct. ]■>. 163. 
2 Am. Journ. Sci. (3) iii, 469. 
