On the Fossil Fishes of the Carboniferous Limestone Series of Great Brita. 377 
beyond the surface covered by the crown; base inclined with slight obliquity back- 
wards. Crown divided into three large cones equal in size, and equidistant. 
Central cone, circular in section, slightly constricted at the base 4 inch high, 3 inch 
in diameter, conical, tapering, acuminate, upper portion of cone sigmoidally curved 
backwards. Surface finely striated, ridges coated with shining enamel are 
bifurcated repeatedly from the point to the base. ach lateral cone is about the 
same size as the central one and in all respects appear its counterpart. The 
structure of the coronal portion of the tooth is close, hard and dense, it is thickly 
coated with enamel : the basal part is a porous somewhat fibrous bony structure. 
The peculiar and somewhat abnormal form of this unique specimen is sufficiently 
characteristic to distinguish it from any other species hitherto described. It 
possesses the broadly expanded base characteristic of the genus Cladodus. Its 
central and two lateral cones of nearly equal size differ very much from the ordinary 
form with comparatively large central cone, and lateral series of small ones, but 
there does not appear to be any sufficient generic distinction necessitating the institu- 
tion of a new genus. 
Its nearest ally is the species Cladodus curvus, previously described from the 
same formation at Armagh. The two are, however, quite distinct, the irregular and 
unsymmetrical arrangement of the cones in the latter render it easy to distinguish 
from this species. 
Formation and locality : Mountain Limestone, Armagh. 
Ex coll, Earl of Enniskillen. 
Cladodus acutus, Agass. 
(Pl. XLIX,, fic. 17.) 
Clododus acutus—A gassiz, L. 1838. “ Poissons Fossiles,” Vol. IIL, p. 199, pl. 220, fig. 21. 
Portlock, J. EK, 1844. “Geol. Report, Londonderry, &c.,” p. 461. 
Giebel, C. G. 1848. ‘“ Fauna der Vorwelt,” Vol. I., pt. 3, p. 323. 
% Pictet, EB. J. 1854. “ Traité de Paléont.,” Vol. II., p. 258. 
3 5 MCoy, F. 1855. “ Brit. Palzeoz. Foss.,” p. 620. 
% 5 Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIII., p. 100. 
This species was described from a unique specimen by Prof. Agassiz, and, so far, 
the specimen remains the only one known. 
_ “The principal cone is sharp and subulate, more conical than cylindrical, and 
slightly inclined backwards; its base is large and the point sharp. The secon- 
dary cones are of medium height, two on each side, striated similarly to the median 
one. The edge of the principal and lateral cones is produced so as to form a sharp- 
cutting surface. The base of the crown is hollowed out in the middle. Root short, 
and parallel with the base of the erown.”—(Agass). 
Prof. M‘Coy considered that thisspecies might have been young specimens of Clado- 
dus mirablis, Ag., but afteracareful examination of a large number of specimens of the 
latter, there appears to be a sufficiently well marked specific difference in the sharp 
3 P2 
