620 TRANS. OF THE ACAD. OF SCIENCE, 
suggest the reference of this division rather to the Subcarbo- 
niferous than to the Devonian epoch. 
r. Encrinital Limestone—This mass consists of several thin 
beds of limestone, usually about eight feet thick. The upper 
part is distinguished, in some localities, by the presence of 
small species of Productus. The middle of these beds is lite- 
rally filled with the remains of Crinoids representing a num- 
enera and species; occasionally a Pentremite of true 
subearboniferous form has been obtained from these beds, 
where it is associated with Eleutherocrinus Cassedayi (Shum. ), 
Nucleocrinus ( Olivanites) angularis, and an undetermined Pla- 
tycrinus. This an 
thin out rapidly and disappear entirely about twenty miles 
south of Louisville. It is not proposed, at this time, to refer 
this bed to any geological age. Further investigation and 
comparison of its fossils will, at some future period, fix its 
proper reference much more satisfactorily than it can be done 
at this time. | 
s. Hydraulic Limestone Beds.—This mass has a considerable 
surface extension. At the falls of the Ohio River, it consists 
of several beds, the entire thickness of the whole mass being 
about twenty feet. Three miles to the south-east, 1t has 
thinned out to four inches. 
he prominent fossils distinguishing this bed are Atrypa 
prisca, Spirifer eurelynes, Lucina pura(?) and Phan 
thalma, The fossil forms of this mass are generally silicifiec : 
t. Spirifer cultragulatus Bed.—At the outcrop on the Ohio 
River, this bed is about three feet thick; sometimes it 4 
thinner; towards the north-east it is known to be muca 
thicker. The imbedded fossils at the latter point are entire; 
the locality at the Falls occasionally affords good poms ; 
generally the valves are separated and water-worn. a 
spirifer distinguishes this bed, which is the extent of its ve : 
eal range. All other fossil forms are absent, or exceedingly 
rare 
u. Nucleocrinus ( Olivanites) Bed.—This bed is reg pe 
have a large surface extension. It is variously modified 5 
$ 
* See Report of Geological Reconnoisance of Tennessee, by Prof. Jame 
, 1856. : 
M. Safford, 1 
