Correlation of the Lower Silurian — Ulrich. 41 
talline limestone, of bluish color is present here in many courses, 
varying in thickness from three to ten inches. The intercalated 
shales are generally quite rich in fossil remains, causing the 
quarry dumps to be much frequented by collectors. The fol- 
lowing are the most characteristic species of this horizon: 
Glyptocrintis decadactylus Hall. Orthis bellula Meek. 
" ? shafferi Miller. " clla Hall. 
Heterocrinus gratidis 'biie^'k. " fssicostaViaW. 
Hetntcystties stellatus Hall. " flkatella Hall. 
Atadopordla mundida Ulrich. Platystrofhia crassa James. 
Coiistellaria forida Ulrich. Streptorhynchtis sinuatus ? Emmons- 
Bythofora frtdicosa Miller & Dyer. & Meek. 
Leptotrypa discoidea Nich. Lingtdella cincinnatiensis H. »& M. 
Discotrypa elegans Ul. Holopca paludinaformis Hall. 
Dicranofora interiiodia Miller & Cyclonema bilix Meek (.' Conrad). 
Dyer. Orthoceras dyeri Miller. 
Ptilodictya falciformis Nich. Cyrtoceras vallandinghami Miller, 
" maadata Ul. Anodontopsis? iinionoides Meek. 
•' pavonia d'Orb. Proetus parviusctdus Hall. 
Phylloporina dathrata M. & D. Anoimdoides retkulatus Ul. 
b. This sub-division embraces the upper no feet of beds 
XII. The whole is of a light blue color and consists of rapidly 
alternating layers of soft shale and limestone. The latter are 
generally in pure, very thin and irregularly bedded, (shelly) 
and charged with a profusion of animal remains, some sections 
of the beds being almost literally composed of fossils. Only a 
few of the limestones are thick and even-bedded enough to fur- 
nish desirable building rock, and, so far as I am aware, the sub- 
division is nowhere extensively quarried. Still the tops of the 
hills about Cincinnati, where much grading for streets and 
buildings has been done, furnish an abundance of excellent ex- 
posures of the lower fifty to eighty-five feet. 
The highest of the Cincinnati hills (Mt. Auburn and Price 
hill) do not contain any of the upper twenty-five feet of the 
subdivision, and only a few localities in Ohio and Indiana are 
known where they may be studied. A creek, the name of 
which does not just now come to my mind, cuts through them 
at a point about one mile northwest of Manchester, Ind. They 
are also shown in Todd's fork near Morrow, O.; and in several 
small water courses near Lebanon, O. These exposures show 
that above the well known "Orthis bed" the fossils become 
