194 
PALAEONTOLOGY OF NEW YORK. 
corresponding in age to the formations of the Rhenish provinces of Europe, 
and, with our present knowledge, are parallelized with the Devonian. One 
species may be referred to the lower formation of the carboniferous system of 
America as at present recognized. 
It is certainly surprising that no species of Hyolithes has been noticed 
in the extensive collections made in the Niagara group of New York, Canada, 
Wisconsin, Indiana, Illinois, Kentucky and Tennessee. Very abundant col¬ 
lections have also been made in the Lower Helderberg group in New York, 
Canada, Maryland and Tennessee, in which no species of Hyolithes has 
occurred, except the one described by Dr. Barrett. 
In 1867 M. Barrande (Systems Silurien du centre de la Boheme ) enumerates 
thirty-three distinct species as occurring in the Silurian formations of Bohemia; 
and in the palaeozoic formations of all countries, including Bohemia, he enu¬ 
merates eighty-four species. Of this number, ten species occur in the first, 
forty-two in the second, and twenty in the third fauna of the Silurian system, 
as recognized by M. Barrande. Ten species occur in the Devonian and one in 
the Permian. 
The contrast in the number of species found in the different horizons in all 
other palmozoic countries, when compared with those of the United States, is 
very marked. While in the second fauna of European countries we have 
more than twice as many species as in any other horizon, we have in America, 
in the corresponding formations, but *a single known species. In the third 
fauna, which corresponds in part to our Niagara and Lower Helderberg groups, 
we have, in all other countries, twenty species, while in America we know but 
a single one. Regarding the Upper Helderberg, Hamilton and Chemung 
groups, as representing the Devonian of Europe, we have four species, while 
there are nine species in the European formations of the same age. 
The American species, so far as known, are much restricted in their geogra¬ 
phical range. Those of the Upper Helderberg are limited to two known 
localities ; while those of the Hamilton group are confined to the central part of 
the State of New York; those of the second and third Silurian faunas are 
known only in the localities from which they have been described. Our 
