1884.] 499 [Clay pole. 
Gypsum and salt, like iron ore, occur usually in scattered and discon- 
tinuous beds. 
No closer correspondence can reasonably be looked for than that which 
T have here established between the Onondaga rocks in New York and 
those in Perry county, which I have placed in correlation with them. 
Only the uppermost stratum, called the Magnesian limerock, is unrepre- 
sented in the Pennsylvanian section. This is of inconsiderable thickness, 
measuring only twenty-four feet. 
PALAONTOLOGICAL HVvIDENCES. 
The great barreness of these shales, which has been alreddy alluded to, 
prevents the production of very strong evidence derived from their fossils. 
Only a single species bearing on the subject has rewarded a considerable 
amount of search. This is Leperditia alta, Conrad, which has been found 
in the Red shale in a few places abundantly, near Buffalo Mill, for ex- 
ample, in Saville township. It is also found in the second division—the 
Variegated shale—in Centre township, and becomes exceedingly abund- 
ant inits upper part, whole slabs being completely covered with its casts. 
These gray shales afford few opportunities of examination, but this spe- 
cies runs up into and through the massive limestones, forming in this 
county the lowest division of the Lower Helderberg rocks or Water Lime 
of New York. Above this horizon I have not found it. 
In regard to this species Vanuxem says (l.c. p. 99) : 
‘At one place only I succeeded in finding fossils in the second deposit 
(the Varigated shales), ‘consisting of Cytherins ’ (Leperditia) about 
half the size of those in the group above.”’ 
In this respect, therefore, the correspondence is exact. 
No fossils having been reported from the Red shale in New York, the 
presence of Leperditia alta in those of Perry county is not without inter- 
est, though it supplies no additional means of identification. 
It has been mentioned that Beyrichia notata occurs in the passage bed 
below the Red shale. It may, therefore, be looked for in the Onondaga 
group, but I have not been able to find it. Its range, at present, is from 
the passage shales to the basal beds of the Lower Helderberg in Perry 
county, but it is yet known only in its extreme limits. 
Summing up the evidence now presented, it is impossible to dispute the 
inference that the rocks above described are the real equivalent in Perry 
county of the Onondaga series in New York. By adopting this view, 
order is introduced into a mass of deposits hitherto the home of much 
confusion and uncertainty. 
Below is added the correlation of these rocks with those of the First 
Survey. 
Gray calcareous shale. Scalent gray marls. 
Variegated shale. Surgent variegated marls. 
— oS o' 
Red shale. Surgent red shale. 
