A New Dinichthys. — Clay pole. 328 
H. Hertzer of Columbus. The characters which have thus 
far distinguished this latter species from all others are its 
large size and its serrate mandible. />. terrelli of the upper 
or Cleveland shale — which was suppossed by Dr. Newberry to 
belong to the same species until its dentition or rather its lack 
of dentition was proved by Prof. A. A. Wright from a mandi- 
ble which he discovered on the lake shore at Sheffield, in Hu- 
ron county (Pal. of Ohio, vol. 1, p. 322) — is distinguished by 
a sharp cutting edge on- the mandible without teeth or den- 
ticles. 
Every other species yet known in the Cleveland shale is bar- 
red from comparison by its small size, except possibly Dinich- 
thys clarki of which only a single premaxillary tooth has yet 
been found and this is so different in form from the type that 
only provisionally can it be included in the genus. Leaving 
this probability aside Dr. Kepler's specimen stands alone and 
is of especial interest as proving the survival of the older type 
to the higher horizon through, the barren interval of the Erie 
shale. 
The teeth on the upper edge of the mandible are therefore 
one of the chief points in the essential character of the species. 
But another may be found in the sudden downward curve of 
the lower edge of the mandible itself just in front of the place 
where in all species of the genus the bone is suddenly rein- 
forced by an external layer which begins between thedentar}" 
and spatular portions on the upper edge and sweeping down 
carries the lower edge with it and so strengthens the forepart 
of the jaw. In other species this line curves and runs for- 
ward rising again into the great mandibular tooth in front. 
But here it curves in the opposite direction indicating an ex- 
traordinary depth of the mandible toward the front and prob- 
ably great power in the teeth. 
Only three of the teeth remain, but they are of very large 
size, all measuring half an inch in hight and the foremost of 
the three reaching nine-sixteenths of an inch. 
The mandible is unusually massive. At the fracture and in 
front of the teeth it is half an inch thick and rapidly increas- 
es until for some distance near the middle it measures seven- 
teen-sixteenths which dimension is maintained almost to its 
lower edge. A crack which exists across the specimen near 
