1884. 501 [Claypole, 
In regard to the lowest bed given in the section above, it must be ad- 
mitted that in the determination of its horizon paleontology affords 
very little aid. Still paleontology is not our only guide in the. solution 
of such problems. Indeed, she is only at best a guide whose authority is 
borrowed from stratigraphy, but nevertheless invaluable and indispensable. 
JOMPARISON OF THE Lowpr HELpERBERG Brps or New Yor«K WITH 
THOSE REFHRRED TO THAT GRouP IN Perry County, Pa.: 
New York. Perry County, Pa. 
sp ( Upper Pentamerus limestone, 
i white ¥ 4 f awe 
# O | HEncrinital limestone. Flint shales with Crinoids. 
2 
3 4 Delthyris shaly limestone. ‘ 
68 thyris shaly ime tone re cialas, 
Hs | Lower Pentamerus limestone. ! 
| Waterlime (Tentaculite bed.) Massive limestone. 
& [ ‘ 
2 | Magnesian rock. 
S , Vermicular rock. 
= | Gypseous marls. Gray calcareous shale. 
en) 
If the identifications previously made are accepted, there is no alterna- 
tive but to admit the correlation of the Massive limestone with the Water 
lime, or to deny it any equivalent in the New York series. It is so closely 
connected with the overlying lime shales that to separate these would be 
in the highest degree illogical. They graduate into one another and can 
only be distinguished by the thinness of the beds and the abounding fos- 
sils of the upper strata. Their physical resemblance to the water lime is 
exceedingly great, but nowhere in Perry county have I been able to find 
any hydraulic beds, All slake equally when burnt. 
PALMONTOLOGICAL EVIDENCE. 
In a case when stratigraphical evidence is so conflicting, the slight aid 
which palwontology can afford becomes exceedingly valuable. The Mas- 
sive limestone being almost barren of fossils, the argument must rest on 
one or two species. 
The Water lime is characterized in New York by abundance of Leper- 
ditia alta. As already mentioned, this fossil occurs for the last time, so far 
as yet observed in Perry county, in the massive limestone, where it is very 
abundant and often very large. 
Occasionally, also, corals have been seen in this limestone, resembling 
species occurring in the lime shales above it, thus forming a link between 
the two. Below this limestone no fossils of this kind have been found in 
the shales. 
Considering the high probability that this class of evidence would be 
increased by closer and wider search, especially in other counties, there can 
be no doubt that this Massive limestone should be included in the Lower 
Helderberg group of which it must then form the base, (See note, p. 502.) 
