280 On the occurrence of Fossiliferous Strata in the (Mad, 
If, therefore, we assume these fish-beds as the life base, and the 
commencement of the red shale as the mineral base of the Cats- 
kill, the two are only about 200 feet from one another, and in the 
immense thickness of the group in Perry county—about 600 
feet—this difference is quite insignificant. We are then supplied 
with a clear horizon to which we can refer all that is found abort 
these limits. ' 
About 200 feet above the fish-beds occurs a thin bed filled witi 
Spirifers of a species as yet undetermined but very much reset- 
bling the Sf. mesastrialis of Hall. The specimens are as is usta 
in the shale beds, much distorted, and consequently difficult ot 
recognition. This bed is only a few inches in thickness, and the 
200 feet intervening between it and the fish-beds is made up of 
red shale with a few layers of yellow sandy shale. 
About 300 feet of red and yellow shales and brown sandstone 
follow, somewhere in which interval, though not yet detected along 
the line of section, is a bed of red sandstone containing remains 
of Brachiopods. This bed is indicated by abundant loose blocks 
lying about on the surface of the ground. 2 
The most remarkable bed in the whole section comes nes, 
lying about 500 feet above the fish-beds. It is a bed of light y 
low sandstone not more than ten or twelve feet thick where 
posed. Most of it is unfossiliferous, but it contains one or 
irregular lenticular layers which were once crammed with shel 
and other organic remains. These have been entirely remo 
solution, and there now remains a honeycombed mass 9 
stone containing excellent casts of the relics formerly em? 
there. The most abundant of these—and it occurs in i 
is a lamellibranch shell closely resembling, if not identical 
one described by Professor Hall in the Geol. of New t“ 
Cypricardia rhombea (Cypricardites rhombeus). ‘Another 
abundant species in the same bed as closely resembles Cypr 
contracta ( Cypricardites contractus) of the same author. 
these occur in less abundance remains of other lamellibr 
crinoids and gasteropods which have not yet been worked ot 
extent of country, and forms wherever it occurs a very © 
secondary horizon to which other beds can be referred. 
The ground is in part concealed for a short distance abo | 
point but where visible shows the same succession of 1® 
