ANNIVERSARY ADDRESS OF THE PRESIDENT. cll 
are superimposed in the same order, whatever may be the thickness 
or number of the physical groups of which they are composed, these 
systems should be considered as parallel and synchronous. 
The American series is so complete, its parts bemg conformable 
and passing into each other, that marked divisions cannot be esta- 
blished. Hence it follows that the limits corresponding with the 
different European systems are in some cases uncertain, but this is 
considered as of less consequence if the middle parts of each system 
can be established. The important point, M. de Verneuil adds, is to 
feel assured that during the paleeozoic period the animal kingdom 
upon the area occupied by the two continents has suffered simulta- 
neous transformations, so that identical species occupy the same geo- 
logical positions. 
The six lowest New York groups, from the Potsdam sandstone to 
the Hudson river group inclusive, are referred to the Lower Silurian 
rocks, the dingula sandstone of Potsdam being probably equivalent to 
the odolus sandstone of Russia and the lower sandstones of Scandi- 
navia. The siliceous limestone, with the Black River and Trenton 
groups, are referred to the bituminous slates and the orthoceratite 
limestones of Sweden and Russia, while the Utica slates and the Hud- 
son river groups, with the Graptolites at their base, are considered 
equivalent to the graptolite slates of Sweden, succeeding the red 
orthoceratite limestone, and also to those of Bain in France. Trilo- 
bites were largely developed both in Europe and America at this pe- 
riod, and the genus [sotelus represents in the latter the Asaphus of 
the former. Orthoceratites were abundant, and Bellerophon appeared 
in connection with this early life, marked also by the presence of 
Orthis, Leptena, and Terebratula. 
The New York groups, rising above those mentioned, up to the 
Oriskany sandstone exclusive, are referred to the Upper Silurian 
rocks, the Niagara limestones and shales being considered equivalent 
to those of Wenlock and Gothland. Trilobites were still abundant, 
some species being rare and limited to thin groups of rocks, such as 
Phacops Hausmanni, Spherexochus minus and Cheirurus insignis. 
Orthoceratites are less abundant than in the lower series. Spirifers 
and Tentaculites appear, and large corals are found, such as Favosites 
Gothlandica, &c., while Graptolites cease. Of forty identical species 
found in the Upper Silurian rocks of America and Europe, M. de 
Verneuil considers that thirty-two have neither lived before nor after 
this period. 
The New York groups, from the Oriskany sandstones to the sand- 
stones and slates above the Chemung group, inclusive, are all referred 
to the Devonian series. The characters common to the Devonian 
fauna of Europe and America are considered to be the appearance of 
the ganoid fishes with great plaques or scales, and the genera Gonia- 
tites, Nautilus, Pentremites and Productus. 
Above these American rocks come the limestones referred to the 
carboniferous limestones of Europe, and M. de Verneuil considers 
this division as well-characterized in both continents; and it is re- 
marked that the Trilobites, decreasing in a parallel manner in both 
