222 The American Geologist. April, i890. 
in 1871-1872, that this fault was imaginary, and that the Que- 
bec group really occupies a position «wco»/ov'waJ/?/ beneath the 
Trenton ; moreover that the series near Quebec is inverted, 
being probably the northwest side of an overturned anticlinal, 
so that the Sillery is in fact the oldest member of the series 
and was followed by the Lauzon and the fossiliferous Levis 
limestone, to which succeeded the graptolitic shales, the newest 
portion of the Quebec group." He then referred again to the 
testimony of Billings ae to the greater antiquity of the few 
organic forms (Obolella and Lingula) found in the Sillery. Af- 
ter discussing at some length,by the help of numerous sections 
and by comparisons, the relations of the Cambrian rocks of 
Great Britain and of Scandinavia to the so-called Quebec group, 
"it was urged that the name given by Logan to this group 
should be rejected as misleading, although that of Levis, as 
designating a horizon of fossiliferous strata of Tremadoc age, 
might be advantageously retained in American geology, care 
being taken to distinguish it from the Quebec graptolitic zone." 
The faunal relations of this group of strata I have discussed 
more at length in Report E of the second geological survey of 
Pennsylvania, where itissaid : (p. 112.) "The great continental 
belt of rocks originally designated Hudson River group, and 
subsequently called Upper Taconic and Quebec group, has 
already afforded us at least three distinct faunas : 1. That 
of the Red Sandrock or so-called Lower Potsdam ; 2. that of 
the Levis limestone,and 3 : that of the Phyllograptus shale of 
Quebec." Still another fauna is found in certain black slates at 
Farnham, Quebec, at first referred by Logan, from their appar- 
ent infraposition,to the Potsdam, being "atone time conceived 
to underlie the whole Levis or Orleans section, and were still 
placed near its base. From their fossils however, these slates be- 
long to a horizon above that assigned to the Quebec group, and 
correspond to the Trenton or the still higher members of the 
Champlain division." [loc. cit., pp., 116, 119.] Further south, 
in the Hudson valley, within the apparent limits of the so- 
called Hudson-River group, are other areas of similar strata of 
Ordovician age, carrying the fauna of the Loraine shales and 
thus affording a certain justification for the frequent use in 
times past of the name of Hudson River group as synon- 
omous with Loraine shales. The area of Silurian rocks at Be- 
