90 DESCRIPTIONS OF THE REMAINS OF FISHES. 
from the root of the tooth. The anterior side of the crown has developed from it a scroll- 
like ridge, the edge of which is nearly on a level with the triturating surface, and includes 
between it and the latter a wide sulcus. The root posteriorly forms a nearly vertical 
plane, but anteriorly is subdivided into a series of demi-cylindrical fangs, confluent at 
their back part. The bottoms of these fangs exhibit the orifices of coarse nutritive canals; 
and the crown of the tooth is a very little more dense in structure than the root. The 
transverse diameter of the specimen in its present condition is eight lines, but in its per- 
fect condition has probably been twice this extent. The antero-posterior breadth of the 
crown is one and a quarter lines, and the height one and three quarter lines. 
Locality.—The Carboniferous limestone of Warsaw, Illinois. 
The specimen upon which this species is founded appears to resemble the figure 9, 
of table 12, in volume iii., of Agassiz’ Poissons Fossiles, representing the tooth of Cho- 
matodus linearis, but the figure is so obscure that I can make nothing of its details. 
Plate V. Fig. 24. Posterior view of the tooth of Palaeobatis insignis; magnified two 
diameters. Fig. 25. Anterior view of the same tooth; magnified to the same extent. 
Fig. 26. Profile section of the same tooth; magnified four diameters. 
CTENOPTYCHIUS, AG. 
8. CrENOPTYCHIUS piciTaTUS, Leidy. 
The species is proposed on a fine specimen of a remarkable-looking tooth discovered by 
Mr. Koch, the celebrated explorer of extinct animal remains, and presented by him to Dr. 
Shumard of St. Louis. 
The crown is palmate in form, with the sides vertical, excepting that the outer one 
slopes inferiorly to the basal ridge. The summit is divided into four unequal, thick, ob- 
tuse, digitate processes, of which the median pair are confluent. The basal ridge de- 
scends much lower externally than internally, and in the former position is acute, in the 
latter thick, and presenting only the faintest trace of folding. The root slopes inwardly 
from the basal ridge on the outer side, and its inner side presents an extensive shallow 
excavation. Length of-the specimen nine lines; breadth nine lines; length of the crown 
externally six lines; internally three and a half lines; depth of the root externally three 
and a half lines; internally five lines. 
Locality—Carboniferous limestone, near St. Louis, Missouri. Plate V. Fig. 27. In- 
ternal view of the tooth. Fig. 28. External view. Fig. 29. Profile section. 
