468 * ADDRESS OF T. STERRY HUNT. 
limestone, which is the equivalent of the Trenton limestone of the 
Champlain division. Hence, as Mr. Barrande has remarked, Hall 
was justified by the authority of Hisinger’s published work in as- 
signing to the Olenus slates of Vermont a position above that lime- 
stone, and in placing them, as he then did, on the horizon of the 
Hudson River or Loraine shales. The double evidence afforded by 
these two fossil forms in the rocks of Vermont, served to confirm 
Sir William Logan in placing in the upper part of the Champlain 
division the rocks which he regarded as their stratigraphical equiv- 
alents near Quebec; and which, as we have seen, had some years 
before been by Emmons himself assigned to the same horizon. 
The remarkable compound graptolites which occur in the shales 
of Pointe Levis, opposite Quebec, were described by Professor 
James Hall in the report of the Geological Survey of Canada for 
1857, and were then referred to the Hudson River group; nor was 
it until August, 1860, that Mr. Billings described from the lime- 
stones of this same series at Pointe Levis a number of trilobites, 
among which were several species of Agnostus, Dikelocephalus, 
Bathyurus, etc., constituting a fauna whose geological horizon he 
decided to be in the lower part of the Champlain division. 
Just previous to this time, in the Report of the Regents of the 
University of New York for 1859, Professor Hall had described and 
figured by the name of Olenus, two species of trilobites from the 
slates of Georgia, Vermont, which Emmons had wrongly referred 
to the genus Paradoxides. They were at once recognized by Bar- 
rande, who called attention to their primordial character, and thus 
led to a knowledge of their true stratigraphical horizon, and to the 
detection of the singular error in Hisinger’s book, already noticed, 
by which American geologists had been misled.* They have 
since been separated from Olenus, and by Professor Hall referred 
to a new and closely related genus, which he has named Olenellus, 
and which is now regarded as belonging to the horizon of the Pots- 
dam sandstone, to which we shall presently advert. 
Farther studies of the fossiliferous rocks near Quebec showed 
the existence of a mass of sediments estimated at about 1200 
feet, holding a numerous fauna, and corresponding to a 
development of strata about the age of the Calciferous and 
formations, or more exactly to a formation occupying position 
Pe ee La a ke Sealer 
*For the correspondence on this matter between Barrande, Logan and Hall, 8°° 
Amer. Jour. Sci., Il, xxxi, 210-226. 
