American Geology, by T. 8S. Hunt. 401 
the Geological Survey of Canada for 1857, and thirty-six species 
of trilobites described by Mr. Billings in the Canadian Naturalist 
for August, 1860. ese species are as yet distinct from any- 
thing found in the Potsdam below or the Birdseye and Black 
River above; although the trilobites recall by their aspect those 
found by Owen in the Lower Sandstone of the Mississippi. 
Seven species alone out of this fauna have been identified with 
those known in other formations, and of these one is aid 
while six belong to the Calciferous, to which latter horizon Mr. 
Billings considers the Quebee group to belong. The Chazy has 
not yet been identified in this region, unless indeed it be repre- 
sented in some of the upper portions of the Quebee group. The 
Calciterous sandrock is wanting along the north side of the St. 
Lawrence valley from near Lake St. Peter to the Mingan Islands, 
but at Lorette behind Quebec, at the foot of the Laurentides, the 
Birdseye limestone is found reposing conformably upon the Pots- 
dam sandstone. 
It is not easy to find the exact horizon of the Potsdam sand- 
stone among the black shales which underlie the Quebec 
group. The Scolithus of Rogers’ Primal sandstone, and of the 
summit of Safford’s 3d or Chilhowee formation is identical with 
that found in the quartz rock at the western base of the Green 
mountains, and figured by Mr. Hall in the Ist volume of the 
Paleontology. It is however distinct from what has been 
ada. The value of this 
or sea-worms. We find however in shales which underlie the 
uebee grou 
land, in which Salter has recognized trilobites of the same genus. 
These shales containing Paradoryds, like those underlying the 
Quebee group, thus appear to belong to the Primordial zone, and 
are to be regarded as the equivalents of the Potsdam sandstone 
