150 PALEOZOIC FISHES OF NORTH AMERICA. 
thin and relatively short and broad; the anterior portion, composed of very 
dense tissue, is thick, polished without, and terminates above in a sharp cut- 
ting edge; the extremity is broken away. 
The outside of this jaw is shown on PI. VIII, Fig. 5. It will be seen 
that all the anterior portion is gone, and it is only interesting as showing the 
peculiar broad and short outline of the posterior extremity. Recently 
another small jaw has been found by Mr. Terrell, which is represented in 
Fig 6 of the same plate. This apparently belongs to the same species, 
though to a somewhat smaller individual. In this specimen the posterior 
extremity is wanting, but the anterior is nearly complete, and it therefore 
supplements the one before mentioned. In the figure given the inside of 
this jaw is shown; the second denticle is unfortunately broken away, but 
its position is plainly shown by the fracture and the ridge which runs up 
to it. These prove that it is situated at an unusual distance from the 
anterior point. 
In Figs. 7, 8 are given views of a premaxillary of a small species of 
Dinichthys which is quite different from any other we have met with. In 
Fig. 8 it is seen in profile, and in Fig. 7 from above. It will be noticed 
that it is flatter and more obtuse than the corresponding organ in the other 
species of Dinichthys, and that it bears a row of tubercles along its anterior 
angle; a character which is also present in the very different premaxillary 
of Dinichthys Hertzeri. 
DinicuTuys GOULDI, n. sp. 
Plate IX, Fig.1; Plate X, Figs. 1, 2. 
Fishes of relatively small size; cranium about twelve inches in length 
and breadth; dorsomedian plate circular or transversely elliptical in outline; 
external surface marked by concentric lines and roughened as though coy- 
ered by integument; inferior crest and neck relatively thin and small; 
suprascapular bones trapezoidal in form, five inches wide by three inches 
long; mandibles seven to eight inches long, relatively narrow; posterior 
and buried portion spatulate, blunt pointed, narrow, and thick; cutting edge 
ong, nearly uniform throughout, bluntly beveled; premaxillaries triangular 
in outline, two inches broad above, one and a quarter inches in vertical 
