618 TRANS. OF THE ACAD. OF SCIENCE. 
of thick beds of close, compact, even-textured, regularly bed- 
ded limestone. When this mass has been found in great- 
est force, the upper one hundred and ninety feet has been 
found to contain two horizons of beautiful white oolitic lime- 
together 
tinguishing fossil for about forty-five feet, with one or two 
intervals containing vast numbers of Agassizocrinus. 
and a few fragments of shells; the lower part of nh 
j A more thorough ex- 
and it is possible that this mass may be capabl ) 
subdivision upon the evidence furnished by its fossils alone. 
The mass of n is from 200 to 400 feet thick. : 
0. Middle of the sieartanefrone Limestone.—This subdi- 
vision of the subcarboniferous limestone is one of convenience 
alone, the caverns are so extensive and numerous 1 
mass of n, that running water, such as creeks and prananes 
is unknown above the surface ; the rains, being at once swal- 
lowed into the caves and “sinks,” flow under the ground, 
occasionally breaking out as an immense spring in the bottom 
some deep sink, es in the light a few feet, and oe 
again hid in darkness. The top of the mass 0! ® whic iL 
composed of alternate beds of limestone and marly yi 8 
uminous shale, appears to arrest the down of 
water, and thus ends the downwar 
