EASTMAN: CARBONIFEROUS FISHES FROM THE CENTRAL WEST. 173 
J. bituminosa is very distinctly shown in Hancock and Howse’s figures,! and 
also in Jaekel’s.2_ There can be little doubt that the action of the jaws upon 
one another was similar to that obtaining in modern Gymnodonts and Chi- 
maeras. It has been stated in the definition of this species that the anteriwr 
face of the crown exhibits marks of contact with the next older tooth which 
it displaced. ‘These markings are of two kinds. In the first place a raised 
line extending parallel with the cutting-edge at a distance of about a centi- 
meter behind it (Pl. 3, Fig. 24) demarcates the area overlapped by the pre- 
ceding tooth; in other words, it divides the exposed cutting-edge from the 
covered portion. Secondly, the longitudinal ridges on the anterior face dis- 
play a number of parallel facettes caused by the impress of the oblique folds 
on the triturating surface of the next older tooth which this one displaced. 
Similar markings have been observed on the anterior face of teeth belonging to 
J. bituminosa, and this interpretation is given of them by Messrs. Hancock and 
Howse.® The thickness of the cutting-margin (cf. Text-fig. 5) and generally 
stout condition of the present specimen render it probable that the creature 
subsisted on hard-shelled prey. 
Formation and Locality. — Atchison shales (Missourian); Richfield, Nebraska. 
Janassa unguicula, sp. nov. 
(Plate 2, Fig. 13.) 
Type. — Imperfect tooth ; University of Nebraska. 
Teeth delicate and of moderate size ; crown much reflexed, regularly arched 
from side to side, and with a knife-edge trenchant margin. Outer coronal face 
smooth, posterior face entirely covered with fine longitudinal striae. Form of 
triturating surface and root unknown, 
) oe 
Fic:.0: 
Janassa unguicula, sp.nov. Outer face of crown, X 4. A, Vertical section. B, 
Oral aspect, viewed from above, X }. 
This species is represented by a unique specimen from the Missourian of 
Cedar Creek, Nebraska, shown of the natural size in Plate 2, Fig. 13, and Text- 
fig. 6. Only the cutting portion of the crown is preserved, the crushing sur- 
face (if one was indeed present) and root having been broken away. The size 
1 Ann. Mag. Nat. Hist. (4), Vol. V., 1870, Pl. II., Fig. 2. 
* Zeitschr. deutsch. geol. Ges., Vol. LI., 1899, Pl. XIV., Fig. 2. 
3 Loe. cit., p. 55. 
