FISHES OF THE DEVONIAN AGE. 69 
which constitutes the distinctive character of the genus, and which has so 
much resemblance—if we may compare small things with great—to the 
triturating surface of the crown of a molar of Elephas. The general form 
of the teeth of Ptyctodus makes it probable that this was a Chimeeroid fish, 
but the teeth of Goniodus indicate no such relationship, and the larger ones, 
both by their form and the character of the lateral surface, rather suggest 
Pecilodus. Probably Goniodus was an Elasmobranch and a Cestraciont, but 
of this we cannot be certain until more material shall have been gathered. 
The type, up to the present time the only known species, is that de- 
scribed below. 
Gontopus HERrTzERt, n. sp. 
Plate XX VII, Figs. 11-15. 
Teeth small and varied in form, triangular or oblong in outline, de- 
pressed, with more or less of the central portion raised into a simple, smooth, 
obtuse-angled ridge; other portions of the surface punctate or vermicularly 
roughened; under surface flattened, somewhat rough and bony. 
No full description of the dentition of Goniodus can yet be given, for 
only a small portion of the large number of pavement teeth, with which 
each jaw was furnished, have yet been obtained. These are, however, 
quite sufficient to show that they represent a new genus and species, inter- 
esting alike from its structure and from its geological position, which has 
hitherto furnished no other fish teeth at all like them. 
Formation and locality: Huron shale; Delaware, Ohio. Collected by 
Rev. H. Hertzer, to whom it is dedicated. 
CALLOGNATHUS, nov. gen. 
Small fishes, of which only the mandibles are known. These are from 
one to three inches in length; the posterior end of the dentary bone flat, 
thin, spatulate, smooth; the anterior half narrower, thicker, and ornamented; 
the upper edge closely set with numerous subequal, conical, obtuse, blunt- 
pointed teeth. 
But little can be said in regard to the affinities of these fishes until more 
of their structure shall be known. The form of the mandible is essentially 
