166 
Tae American Geologist. 
March, 1896 
[Palaeontological Notes from Buchtel College. No. 12.] 
A NEW TITANICHTHYS. 
By E. W. Claypole, Akron, Ohio. 
(Plate X.) 
The fragmentary condition of nearly all the specimens of 
Titanichthys and the other great placoderms of Ohio renders 
the identification of species a matter of no little difficulty. 
Without a single complete skeleton for comparison it would 
be rash to attempt the nominal description of the various 
plates that are found separated and scattered in the shale. 
Cases do occur in which the correlation of some parts is possi¬ 
ble either with absolute certainty or with a degree of confi¬ 
dence that justifies action. But to name the sundered plates 
as if they had belonged to different species would be only en¬ 
cumbering the subject with a mass of synonyms and repeating 
what has already proved a fertile cause of trouble and error 
in past experience. 
In bringing forward, therefore, the many fossils which the 
labors of Dr. Clark and others have of late years brought to 
light, I have limited the technical characters of the species 
for the most part to the mandibles. These are the parts of 
the skeleton most frequently found and the parts that occur 
usually in the best state of preservation. Other plates when 
described are referred if possible to their place in the fish, but 
only as plates of Titanichthys in general. 
Thus in bringing forward the present species the same 
principle is adopted and though several other plates are known, 
being contained on the same slab, yet the essential characters 
will be based in the first place on the mandibles. 
The fossil in question is one that was found by Dr. Clark 
about two years ago in the same region which has yielded 
him so many other treasures of a similar kind. It is consider¬ 
ably broken and consists of ten or more fragments fitting- 
together with fair accuracy. Weathering along planes of 
natural jointing prevents their close union. On this slab and 
its counterpart lie compressed and considerably disarranged 
the plates of the head of a small Titanichthys and the antero- 
dorso-laterals or supra-scapulas that were in life locked to it 
by the well known socket-joint. Few of these plates are per¬ 
fect, but fortunately the mandibles have been so well exposed 
by the careful work of the discoverer that they suffice to 
