1888 .] 
59 
[Marcou. 
above, dividing what he calls “the Lower Silurian in America” into 
two principal groups, “ one above the break at the base of the 
Chazy and the other below. The former includes the Chazy, Black 
river, Birdseye, Trenton, Utica and Hudson formations. The lower 
comprises a series of formations, which are only now beginning to 
become known.” 
To be consistent with his own views of great breaks, Billings 
ought to have made three “principal groups” instead of two in or- 
der to use his great break between the Levis and Calciferous. But 
he was quite at a loss, in trying to harmonize what he thought was 
the succession of fauna with the stratigraphy used by the Director 
of the Canada survey, without paying any attention whatever to 
colonies and apparitions of prophetic types. Billings was not a 
sufficiently able practical geologist ; and the true relations of the 
great mass of strata in the province of Quebec escaped him entirely. 
With such confused stratigraphical notions, it was materially im- 
possible for him to make any reliable and good comparisons of the 
formations in Canada with those of England, and finally he gives 
up the attempt to correlate the English series with the Canadian, 
except that in a general way they may be compared without a per- 
fect parallelism of the minor groups. 
logan’s classification of 1866. 
In 1866, Logan “found it convenient to divide his Quebec group 
into a lower, a middle and an upper part” (“Report of Progress” 
from 1863 to 1866, p. 4, Ottawa) . The lowest division is his “Levis 
formation” comprising the “Phillipsburgh limestone,” and is the 
“equivalent to a position about the summit of the Calciferous for- 
mation.” The middle division is called the “Lauzon division.” 
According to Logan this is a local deposit, and not “met with much 
westward beyond Point Levis.” The upper division is called “Sil- 
lery.” Consequently we have the following table : 
r Sillery division. 
Quebec group < Lauzon “ 
( Levis or Phillipsburgh division. 
Upper Calciferous. 
Lower Calciferous. 
It differs from Billings’ classification, in regarding the Levis as 
the equivalent of the Phillipsburgh group, which Billings places 
