58 Review of the New York Geological Reports. 
ring which, in England, the rocks are supposed to belong toa 
continuous group, or to be parts of one formation.” (Ha1’s re- 
port, pp. 152, 153.) 
This seems to be also the case in the Western States of North 
America; for, on comparing the eastern and western formations, 
jt is difficult to say where the geological horizon lies in the West, 
that separates the beds representing the Niagara and Onondaga 
formations. Speaking of the former of these in a previous part 
of this Review, we expressed an opinion that the coralline beds 
of the vicinity of the Falls of the Ohio might be the equivalent 
of the Niagara group, but that, until more of the corals of this 
New York formation were described and figured, the absolute 
identity could not be established. We should have said, part of 
the coralline beds, instead of coralline beds; for we shall see, on 
comparing the corals of the Onondaga Heaiatione with western 
fossils, that many of them are the same species which occur in 
these same coralline beds. The fact is, these strata probably ad- 
mit, as Dr. Cuarr has suggested, of a twofold division into upper 
and lower beds; and a minute comparison of eastern and western 
specimens, will most likely prove the lower of these to be the — 
equivalent of the Niagara group, whilst the upper represents the 
Onondaga limestone ; the intervening salt group and Manlius wa- 
ter limestone having! no western representative. The coralline 
beds of the magnesian limestones of the northwest, most proba- 
bly belong to the lower or Niagara division. 
The range of the Onondaga limestone is coéxtensive with the 
limits of the state, and is represented, together with the succeed- 
ing formation, on the chart by a light blue band, whose general 
course is nearly east and west to Schoharie, thence, with a south- 
erly curve coincident with the Helderberg range, to the Mama- 
kating Valley. 
Well defined joints in two directions, are particularly charac- 
teristic of this formation, which admits of its being got out in 
very regular blocks. A fine example of this is seen at Split-rock 
quarry, southwest of Syracuse. ; 
The large, smooth Entrochites, fig. 3, p. 59, provisionally ecall- 
ed Encrinites levis, is an exceedingly abundant fossil of the On- 
ondaga limestone. ‘The same encrinite “exists in prodigious 
..... according to Vanuxem, “ten miles north of Nashville, 
The following corals are also very common. 
