THE 
AMERICAN GEOLOGIST 
Vol. X. JULY, 1892. No. 1 
[Pal/EOntological Notes fkom the Laboratory of Buchtei. Col- 
lege. — No 1.] 
A NEW GIGANTIC PLACODERM FROM OHIO. 
E. W. Ci.AYPOLE, Akron, (). 
To the two genera and species of gigantic placoderms from the 
Cleveland shale described some years ago by Dr. Newberry in the 
Palaeontology of Ohio, and in the Monograph on the fossil fishes 
of North America, published by the U. S. Greological Survey, has 
recently been added a third, equally formidal>le in its armour and 
scarcely less in size. This creature has been brought to light by 
the labors of Dr. Wm. CMark, of Berea, 0., to whom geologists 
are also indebted for the material of great additions to our knowl- 
edge of some of the older forms of this remarkable ichthyic fauna. 
The new fish was found during the autumn of 1801, on the hori- 
zon and near the place which had yielded DinleJtflnjs and Tifun- 
ichtJii/s. 
Though resembling these, and especially the former, in general 
character, it yet exhil)its at least one peculiar feature, in so far as 
yet known, which is sufficient at once to difl'erentiate it from both 
its enormous contemporaries. 
It is not at present possible to give an}- adequate account of the 
whole animal, as only a portion of it has yet been found. Tliis 
preliminary note will therefore be limited to a description of the 
lower jaw and the; teetli, wliich have lieen completely extricated 
