634 J. W. DAVIS ON REMAINS OF FOSSIL FISHES 
comparatively large pustules, with the base entirely hidden by the 
matrix. It was probably the palatal tooth of some fish, and 
indeed it has some resemblance to the teeth of the genus Peltodus, 
Newb. and Worth. (Pal. Illinois, vol. iv. p. 362, pl. ii. fig. 7), but, 
unlike these, it appears to be quite round, and not to have the 
posterior portion truncated, 
There is also what appears to be part of the jaw of a fish, which 
is represented in Plate XXVII. fig. 3. The under surface only is 
exposed ; it is 0-6 inch in length; the alveolar surfaces are buried 
in the matrix. It consists apparently of the two rami of the lower 
jaw of a small fish, probably related to the genus Amphicentrum. 
The anterior portion of the jaw is consolidated into a homo- 
geneous substance for about half its length; the posterior half 
is divided. The rami are rather more than 0:1 inch in depth; 
the diameter between the outer edges of the two on the alveolar 
surface is 0:2 inch; exteriorly their sides are inbevelled, forming 
with those of the inner side of the jaw an acute angle. The 
diameter is reduced to 0-1 inch on the lower surface of the posterior 
portion of the rami. A deep channel divides the right and left rami 
of the jaw; it is deepest posteriorly, gradually becoming shallower 
as it nears the anterior portion, and disappearing before reaching 
the extremity. The surface is covered with small punctures. 
EXPLANATION OF PLATES XXVI. & XXVIL 
Puate XXVI. 
Fig. 1-5. Cladacanthus paradorus, Agass. 
1. Spine nearly complete. 2. Anterior extension. 3,4, 5. Posterior 
extensior S. 
6. Physonemus hamatus, Agass. 
7. Spine of fish, sp. nov.? 
8. Jaw of Megalichthys. 
9. Gomphacanthus acutus, Davis. 
10. Petalodus acuminatus, Agass. 10a. Vertical section. 
11,12. Astrahbodus expansus, Davis. Fig. 11 a. Underside of same. 
13. Deltoptychius plicatus, Davis. Lower jaw. 
, Davis. Upper jaw. 
15. Pristicladodus concinnus, Davis. 
16. Petalodopsis tripartitus, Davis. 
17. Sandalodus minor, Davis. 
18. Lophodus conicus, Davis. 
19. Pristodus falcatus, Agass. Upper jaw. 
, Agass. Lower jaw. 
Prats XXVII. 
1&6. Cyrtonocus gibbus, Davis. 
2. Lophodus reticulatus, Davis. 
