156 PALEOZOIC FISHES OF NORTH AMERICA. 
entire, but that is perhaps due to the removal of the plates, which left an 
imperfect impression upon the internal cast. 
DINICHTHYS CURTUS, 0. sp. 
Plate XLVIII, Fig. 3; Plate LILI, Figs. 1-3. 
Fishes of moderate or small size; head a nearly equilateral triangle, 
measuring about one foot on a side; cranium, maxillary, and mandible 
similar in character to those of Dinichthys intermedius, but only half to two- 
thirds as large, and the mandible bears two subordinate prominences back 
of the turned up tooth-like extremity; also the posterior end of the cutting 
edge is set with two or three unequal denticles in place of the series of even, 
lancet-like points in the same position on the mandible of D. intermedius. 
The anterior ventro-lateral plate is scimiter-shaped, eight inches long by two 
and a half inches wide, being relatively narrower than the corresponding 
bone in any other species known. 
A series of specimens recently sent to me by Prof. William Kepler 
throw new light upon the structure of this species and make it necessary 
to add a few paragraphs to the description already given. These were 
obtained from the Cleveland shale at the locality in the suburbs of Cleve- 
land from which so many fine things have been procured by Dr. Clark and 
Professor _Kepler—a locality called in my notes Linnville, Brooklyn, and 
Cleveland. They consist of the greater part of the bony structure of what 
was probably a nearly mature individual. The parts are somewhat dis- 
placed, but the entire cranium with the suborbital plates on either side, and 
the supra-scapulas articulated to the posterior angles, may all be identified. 
One mandible and one ventral plate similar to the narrow one figured on 
Pl. XLVIII, Fig. 3, are also present; and most interesting of all are the dis- 
connected and scattered, but still easily recognizable sclerotic plates. It was 
not before known that the eye in this species of Dinichthys was surrounded 
by a series of bony plates, though they had been found in connection with 
the head bones of D. Gouldii. In the present species they are trapezoidal 
in form, of about the same width as in D. Gouldii, but only half as long; 
from which we may infer that more than four were needed to form the ring 
around the visual aperture, or that the eye was much smaller. On the in- 
