Part I. Report of progress in 1869, by J. S. Newberry, chief geologist. Part II. Report of progress in the second district, by E. B. Andrews, assist. geologist. Part III. Report on geology of Montgomery County, by Edward Orton, assist. geologist.

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remarkable fish of the Corniferous limestone, is one of the many-interesting discoveries made by Mr. Hertzer. This I have called Onychodus, from
the claw-like form of its teeth. The most striking feature in this great
fish was presented by the under jaws, which were as broad as one's arm
and from twelve to eighteen inches in length, thickly set with teeth;
while inclosed between their anterior extremities-in what anatomists
call the symphysis of the jaw-was a single crest of seven large conicalhooked teeth, so set as to act like the prow of a ram. Like most of these
ancient fishes it had a tessellated cranium, composed of plates covered
with a beautiful tuberculated and enameled surface. The Corniferous
limestone also contains some interesting fossil plants, among which are
two remarkable tree ferns, the oldest land plants yet found on this continent.
THE HAMILTON GROUP.
In New York the Corniferous limestone is overlaid by the Marcellus
shale, and a compound mass of limestones and shales of very considerable thickness, to which the name of the Hamilton group has been given.
This formation is quite largely developed in Michigan, but has never been
heretofore known to exist in Ohio. During the past summer, however,
we have discovered its representative in a band of bluish, marly limestone, never exceeding twenty feet in thickness, resting upon the Corniferous limestone where that is overlaid by more recent rocks. From this
marly limestone we have obtained many of the characteristic fossils of
the Hamilton group, such as Spirifer mucronatus, Strophodonta demissa,
Phacops bufo, etc.
THE HURON SHALE.
Above the Hamilton beds comes the great.mass of black, bituminous
shale, designated by the former Geological Board as the " Black Slate."
This is a very remarkable formation, not only from its wide distribution,
but from its peculiar lithological character. Its outcrop forms a belt
from ten to twenty miles in width, reaching from the Lake shore at the
mouth of the Huron River, almost directly south to the mouth of the
Scioto. It is everywhere a black rock, and by its resemblance to coal
has given rise to innumerable mining schemes; all of which, however,
have ended in disappointment, as, though useful for the production of oil
by distillation, it can never be successfully employed as fuel. The Huron
shale is on an average 350 feet thick, and containing at least 10 per cent.
of combustible matter, its carbon is equivalent to that of a coal seam
forty feet in thickness; a greater aggregate of combustible material than
is contained in all the coal-bearing strata of the State. Doubtless the.
time will come when this great store of power will be in some way made
available, but for the present its utilization seems for the most part be