154 PALEOZOIC FISHES OF NORTH AMERICA: 
of this species are somewhat abundant, scarce any traces of D. Terrelli have 
been discovered. 
Mr. Terrell has obtained from Lorain County, Ohio, several crania, 
dorsomedian and supra-scapular plates of intermediate and small sizes which 
may have belonged to the species under consideration. Among these is a 
pair of supra-scapulas about half the size of those of D. Terrelle and with 
much rounder outlines. The dorsal plates have little to distinguish them 
from those of D. Terrelli except their smaller size. Some of these bear 
marks of the teeth of the larger species; by which it is made evident that 
the smaller ones were often attacked by them, and in one specimen we 
have proof that such attacks sometimes proved fatal The specimen referred 
to is a dorsal plate that, with the posterior process, must have been originally 
about fifteen inches in length, of which the wings are crushed quite together, 
as though by violence, and still bear deep pits and furrows, evidently made 
by the “mandibles” and “premaxillaries” of D. Terrelli, between which it 
was seized and crushed. In this specimen we have evidence that the gape 
of the mouth in D. Terrelli was wide enough to embrace a body a foot or 
more in diameter, and that the jaws were moved by muscles of such power 
as to deeply indent and even crush the armor of the smaller species of the 
genus. 
Since the above notes were written Dr. William Clark has obtained 
from the Cleveland shale in the valley of the Cuyahoga a large number of 
bones and plates of Dinichthys which we may confidently refer to this 
species. Of these several are figured on Pls. XLVII, LI, and LIL They 
include erania of which nearly complete specimens are figured on Pls. LI 
and LII, the first the outside showing the suborbital plates in position; 
second the inside with the supra-scapulas attached to the skull. The sub- 
orbital bones, though relatively and absolutely much shorter, are apparently 
the homologues of the plates which I have figured and described in the 
Paleontology of Ohio as the posterior pair of the plastron. One of these, 
which I have with some doubt referred to D. intermedius, is represented in 
views of the outside and inside on Pl. XLVI, Figs. 1, 1% These and many 
others are in the collection recently purchased of Dr. Clark, all of which 
are relatively longer than this. I was therefore at first inclined to regard 
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