1 34 Correspondence . 
the Dominion, from Nova Scotia to British Coknnbia, and northward to 
the Arctic ocean. A unique and important portion of this report is that 
of Dr. G. M. Dawson embracing a compend of all geological information 
relating to the northern portion of the Dominion east of the Rocky 
mountains, reaching to the Arctic shores and including Greenland, ac- 
companied by a colored geological inap. This is, so far as we are aware, 
the first attempt to make a general geological map of these regions. 
CORRESPONDENCE. 
In vol. iv, March 1888, of the Mctnoirs of the Boston Natural History 
Society is a paper by Mons. Jules Marcou entitled "The Taconic of 
Georgia and the Report on the Geology of Vermont." 
In chapter IV, Mr. Marcou describes " The Section at Charlesbourg 
near Quebec," and what he calls the " Landslides at Montmorency, and 
in the plate which accompanies the memoir he gives a section (Fig. 8) of 
the structure from Quebec to Charlesbourg, in which he sliows the 
Trenton limestone resting in horizontal attitude on what he calls the 
"Swanton and Quebec City slates." These, as I understand, he con- 
siders to be a part of the Taconic of Emmons. 
On page 130 Mr. Marcou writes "Professor Lapworth says: 'The so- 
called Quebec rocks of the town of Quebec are not of Quebec age at all.' " 
This fact was first intimated by me on purely stratigraphical considera- 
tions in 1879,' and when in 1885 I sent a series of fossils that had then 
been found in the Citadel Hill rocks to professor Lapworth, he, on purely 
palsontological considerations, fully confirmed my views, the only dif- 
ference between us being that while I held the true position of all these 
shales to be above the Trenton, he is inclined to place them below it. 
This conclusion, however, rests entirely on the supposition that certain 
forms of graptolites must occupy the same horizon on both sides of the 
Atlantic, — an instance of what I have elsewhere deprecated as palaeon- 
tological stratigraphy. 
In the present instance the stratigraphy, which Prof. Lapworth has no 
knowledge of, has been carefully worked out by Logan and myself, and 
by other members of the Canadian survey, and I cannot learn that any 
one ever saw the shales beneath the Trenton limestone, as shown in Mr. 
Marcou's section, fig. 8. 
As regards Mr. Marcou's not very complimentary remarks, page 118, 
in reference to Logan and myself, I would like to refer him to an article 
1 Montreal Nat. Hist. Society, 24, Feb., 1879. 
