JYew (jlgcD^tk- Placodcriii. — CUtyjtole. 8 
roil shale, is manifest. D. tcrrelli., however, of the Cleveland 
shale, has no snch denticles. 
Sinking in front of this process to its average level, the jaw 
again rises so as to form at its extremity a strong pointed tooth, 
■closely resembling that of Blnicldhijs, roundl}' triangular in out- 
line and having a total hight of five inches. The whole hight of 
this tooth from the lower edge of the jaw is nine inches. 
Upj>er j((ir. 
Opposite to this tooth in the upper jaw is one correspon ling to 
the great "premaxillary" of Dinichtliys as described by Newberry. 
The specimen is somewhat imperfect, as its base (or upper part) 
has l)een broken off. So far as preserved it appears rather rounder 
in section and smaller than the great premaxillary of Dinic/itJif/s. 
As in that genus, however, it fitted close against the outer and 
hinder face of the great mandibular tooth, already described. 
This is proved by the groove which it has worn, and in which it 
was lying when found. 
Behind this is the remarkal)le tooth which most perfectly char- 
acterizes the genus. Homologous to the cutting upper blade of 
the shears of Diniclitlnjs, it evidently performed no similar func- 
tion in the animal. Neither on it nor on the tooth-like process in 
the lower jaw above mentioned is there the slightest sign of wear 
-or rubbing, such as is always visible on the jaws of DinicJitliys. 
This tooth, which measures nine inches from the front to the 
back l)y seven inches in a vertical direction, is totally dift'erent 
from the rounded upper blade of Dlnichthys^ and much heavier. 
It terminates d<jwnwards in two blunt processes, whereof the fore- 
most is the larger and the more prominent. Between these fitted 
the blunt projection of the lower jaw, though the signs of wear are 
not ver}' conspicuous on either. Both show the usual hard, close 
and polished bony structure that marks the teeth of these fishes. 
The mode of attachment of the upper teeth to the head is, as 
in the case of Diiilclitlnjs. not yet known, 1)ut their position and 
their evident adaptation to the lower jaw leave no doubt of their 
relationship. The whole outfit constitutes the most formidable 
dentary weapon yet known from this or perhaps from any horizon 
excepting possibly '-('arcliarodoii' of the Eocene. 
In addition to all the above there is another bone whose form, 
structure and position when found strongly indicate a close rela- 
tionship to them. This has l)een represented in the figure, not- 
