286 GEOLOGY OF OHIO. 
occur near the base, at Delaware, Monroeville, etc., fossils of great scientific interest. 
These concretions are often spherical, are sometimes twelve feet in diameter, and 
very frequently contain organic nuclei, around which they are formed. These nuclei 
are either portions of the trunks of large coniferous trees allied to our pines, replaced, 
particle by particle, by silica, so that their structure can be studied almost as well as 
that of the recent wood, or large bones. With the exception of some trunks of tree 
ferns which we have found in the Corniferous limestone of Delaware and Sandusky, 
these masses of silicified wood are the oldest remains of a land vegetation yet found 
in the State. The Silurian rocks every where abound with impressions of sea weeds, 
but not until now had we found proof that there were, in the Devonian age, conti- 
nental surfaces covered with forests of trees similar in character to and rivaling in 
magnitude the pines of the present day. 
‘““The bones contained in these concretions are those of gigantic fishes, larger, more 
powerful, and more singular in their organization than any of those immortalized by 
Hugh Miller: These fishes we owe to the industry and acuteness of Mr. Hertzer, and 
in recognition of that fact I have named the most remarkable one Dinichthys Hert- 
zert, or Hlertzer’s terrible fish. This name’will not seem ill-chosen, when I say that 
the fish that now bears it had a head three feet long by two feet broad, and that his 
under jaws were more than two feet in.length and five inches deep. They are com- 
posed of dense bony tissue, and are turned up anteriorly like sled-runners; the ex- 
tremities of both jaws meeting to form one great triangular tooth, which interlocked 
with two in the upper jaw seven inches.in length and more than three inches wide. 
It is apparent, irom the structure of these jaws, that they could easily embrace in 
their grasp the body of a man—perhaps a horse—and as they were doubtless moved 
by muscles of corresponding power, they could crush such a body as we would crack 
an egg-shell.” 
One mile north-west from Delaware, Mr. Nathan Miller struck the 
black slate, on the west side of the Olentangy, at the depth of twenty-one 
feet, in digging a well. It may also be seen along a little ravine tribu- 
tary to the Delaware Run, near Mr. Miller’s farm, on the land of C. O. 
and G. W. Little. Limestone only is seen in the bed of the run a few 
rods further west. It is blue and fossiliferous. A short distance still 
higher up the run the black member (No. 11 of the section taken in the 
Olentangy at Delaware) is seen in the bed of the same run. 
About a mile and a half below Stratford a little stream comes into the 
Olentangy from the east, bringing along in freshet time a good many 
pieces of black slate. About a hundred rods up this little stream the 
beds of the black slate appear in stu in the tops of the bluffs, the Olen- 
tangy shale, with its full thickness of about thirty feet, being plainly 
exposed near its junction with the slate, while in the river the limestone 
beds of the Upper Corniferous are spread out over a wide surface ex- 
posure. 
In Liberty township, two and a half miles south of Stratford, the 
black slate may be seen on the farm of Mr. J. Moorhead, on the west side 
