54 CANADIAN FOSSILS. 
city of Hudson; while some species have been found near Baker’s Falls 
on the Hudson River,‘and at Ballston and Saratoga, New-York. Grap- 
tolites of species identical and similar to those of the Hudson River for- 
mation have been found by Dr. Emmons in the shales of Augusta 
County, Virginia, and also in Tennessee. 
The more characteristic species of the formation, G. pristis, G. bicornis, 
G. ramosus, G. sextans, G. divaricatus, and G. gracilis, have been 
recognized among the collections of the Canada Geological Survey, from 
the Hudson River formation in the valley of the St. Lawrence. In the 
extension of this formation westward, a few species only have been found in 
central and western New-York ; among these, G. pristis is the most com- 
mon, while G. d¢cecrnis is more rarely seen. In Ohio, we have no more 
than two species from rocks of this formation ; while extensive collections 
from the same formation in Wisconsin and Iowa have afforded only three 
species (all unlike those from Cincinnati), and one of these has been 
found in beds of the same age in Illinois. In the catalogue of fossils 
appended to the Geological Report of Missouri, no mention is made of the 
occurrence of Graptolitidze in any of the formations. 
The great accumulation of materials at the epoch of the Hudson River 
formation has been in the direction from northeast to southwest ; and along 
this line the black and dark colored graptolite schists, alternating with 
coarser beds, have collected in much greater mass than in any other part 
of its extent. In the northwestern counties of New-York, Jefferson and 
Oswego, where the formation has a thickness of more than a thousand feet, 
the graptolites are comparatively few in species, and not of common occur- 
rence. The gradual attenuation of the rocks of this formation towards 
the west is marked by the extreme paucity of graptolitic forms. 
The graptolites of the Clinton strata have not, to my knowledge, been 
found beyond the limits of western New-York ; and both their horizontal 
and vertical range is very restricted. The graptolitic forms of the 
Niagara formation (Dictyonema and Inocaulis) are very limited in their 
geographical extent. 
The Dietyonema of the Upper Helderberg and Hamilton formations are 
known to occur in New-York and in Ohio; and in the northwest a species 
has been found in the Upper Helderberg limestone on Mackinac Island. 
This distribution of the Graptolitidze, as well as their general association 
with other fossils, together with the nature of the sediments, would indi- 
cate the proximity of the coast-line as their habitat, and as the zone of 
their greatest development. 
