FISHES OF THE CARBONIFEROUS SYSTEM. 99 
to Coccosteus, the near relative of Dinichthys, and it is therefore not out of 
place in the latter genus. 
In size this fish was comparatively small; the supra-scapular -plates 
are about three inches in length and breadth and nearly half an inch in 
thickness at the center. Two specimens from the same side, and therefore 
belonging to different individuals, are of about equal size. The dorsome- 
dian is also very small; it was not more than three inches in breadth and 
length, judging from the portion preserved. The tuberculation of the sur- 
face is relatively coarse, and the tubercles vary much in size and are irreg- 
ularly scattered. Most of them seem to be hemispherical and plain, but 
others are more or less pitted and a few are stellate. The great thickness 
of the plates compared with their area is a striking feature in this fish. In 
this respect it is quite different from the smaller species of Dinichthys from 
the Cleveland shale—D. minor, D. corrugatus, and D. Gouldiv. 
This species also occurs in the Psammite de Condroz, near Liege, Bel- 
gium. 
Onycuopus Hopkinsi, Newb. 
In the Chemung rocks at Franklin, Delaware County, N. Y., Mr. 
Andrew Way collected many detached teeth of a species of Onychodus, 
to which I have given the above name. These teeth are generally about 
one inch in length, conical, acute, and simply curved. Occasionally, how- 
ever, the point is slightly turned forward, giving a hint of the sigmoidal 
curve which is so conspicuous a feature in the great species of the Cornif- 
erous limestone (0. sigmoides). The bases of these teeth are expanded, and 
it is evident that they rested upon and embraced the arch of bone which 
supported them; in this respect resembling the denticles of O. sigmoides, and 
differing from those of 0. Ortoni, in which they are sunk in the substance 
of the bone as posts are planted in the ground. As in the other species of 
Onychodus, the teeth above described formed a series of six to eight in num- 
ber, set on a short arched bone, which was embraced in the symphysis of 
the mandible, constituting a piercing, tearing instrument, such as has no 
known counterpart in the animal kingdom. 
The genus, as far as yet known, is represented only by the three 
species enumerated above, viz: O. sigmoides, from the Corniferous lime- 
