FISHES OF THE CARBONIFEROUS SYSTEM. 173 
Of the ridges the anterior is strongest, the others diminish gradually until 
the last is barely discernible. The interior and middle portions of the ridges 
are smooth and moderately acute; the outer third, which is much broader 
and strongly curved downward, is marked by a series of transverse furrows, 
which produce first rounded tubercles, and then, as the ridge becomes 
broader, a series of transverse, flattened, elevated bands. 
The splenial bone on which the tooth is set projects posteriorly two 
inches three lines, is comparatively thin and flat, one inch six lines broad at 
its widest part, and excavated posteriorly on the outside by a broad shallow 
notch, which forms with the interior curved edge an acute terminal point. 
This fine tooth, the largest species yet known of the genus, resembles 
in the number and relative size of its ridges Ctenodus obliquus and Ct. mono- 
ceros, from the Northumberland coal field of England, but is at once dis- 
tinguishable from them by its greater size and the broad, transversely 
banded ridges. 
No portion of this fish has been found except a single inferior dental 
plate attached to the splenial bone. This was-obtained by Mr. Frank 
Wagner from the Cleveland shale, in the eastern suburbs of Cleveland, 
Ohio, and the species is dedicated to him. 
PHGBODUS POLITUS, Nn. sp. 
Plate XXVII, Figs. 27-282. 
Teeth small, robust, breadth between tips of lateral cusps six to twelve 
millimeters, height from four to eight millimeters, base broadly elliptical, 
thick, with a strong bi-lobed, pad-like prominence in the middle of the upper 
surface, concave below, with a narrow arch beneath the cusps; cusps three, 
of nearly equal size, with minute rudimentary ones in the angles between 
them, all strongly recurved, flattened in front with salient, acute angles, 
rounded behind; surface smooth and polished, or bearing a few short, coarse 
striations. 
We have in these little teeth an important addition to the catalogue of 
fossil fishes found in Ohio, as they represent a generic group extremely rare 
elsewhere, and now for the first time met with there. It is one also which 
