Marcou.] 
64 
[Nov. 7, 
On the evidence of fossils claimed by Logan to place the Citadel 
hill and city of Quebec into his Quebec group, Mr. Selwyn de- 
clares that there is an “ entire absence of characteristic Levis fos- 
sils in the citadelle rocks.” This fact was well known to me and 
recorded sixteen years before, when in 1862 I classified the Citadel 
hill and city' of Quebec rocks as resting above the Pointe Levis 
group (Letter to M. Joachim Barrande on the Taconic Rocks of 
Vermont and Canada, pp. 12-13, Cambridge, 1862). But the great 
difference between Mr. Selwyn and myself is, that he considers the 
Citadel hill strata as resting above the Trenton and belonging to 
the Utica-Lorraine group, when I put them far below the Trenton, 
just above the Levis group and without any fault or overlap in the 
middle of the bed of the River St. Lawrence, between Quebec and 
Pointe Levis. 
Mr. Selw}m considers the Lauzon division of Logan as identical 
with the Levis and Sillery divisions and the so-called Potsdam for- 
mations of St. Jean, St. Rock, St. Denis, Bic harbor, etc., as be- 
longing to the Pointe-Levis group, retaining all that portion of the 
Potsdam formation of Logan, Richardson and Billings, which con- 
tains the Georgia formation fauna in his Lower Silurian (Cham- 
plain) system. Although he deprecates “ palaeontological strati- 
graphy,” Mr. Selwyn is a little embarrassed with the fauna at Bic 
harbor, Trois pistoles and St. Denis ( Olenellus Thompsoni , Cono- 
ceplialites , etc.) ; and in order to dispose of the difficulty he has re- 
course to boulders ! some, according to him, contain Georgia fossils, 
others Potsdam fossils, and still others calciferous fossils ; and the 
whole set of boulders kept together by a matrix almost contem- 
poraneous with, but a little above , the Calciferous. Thus in Mr. 
Selwyn’s opinion the Levis group is the equivalent of the Upper 
Calciferous and Chazy, called by him first Lower Silurian, after- 
ward Cambro-Silurian, and colored on his great geological map of 
1883 as true Cambrian, a series of blunders seldom seen. 
That the Lauzon and Sillery divisions of Logan “have no defi- 
nite or definable existence apart from the Levis group” is true ; and 
I have never admitted those unnatural divisions. But that “the 
trilobites of primitive types” of the southern shores of the St. Law- 
rence from Pointe Levis, island of Orleans, St. Denis, Bic harbor, 
Trois pistoles, Metis and Matanne are” in the pebbles or slabs of 
the conglomerates,” and that Mr. Selwyn can almost point out what 
part of the northern coast of the St. Lawrence and Labrador they 
came from as boulders, is an imaginative supposition, added to the 
