372 On the Foss:} Fishes of the Carboniferous Limestone Series of Great Britain. 
Genus Cladodus, Agass. 
Cladodus—A gassiz, 1833. ‘ Poiss. Foss.,” Vol. ITI., p. 196. 
3 M‘Coy, 1855. ‘Brit. Palzoz. Foss.,” p. 619. 
“ Teeth, with a bread, horizontal, semicircular, thick, bony, coarsely-fibrous base, 
rounded behind, truncated in front ; crown divided into long, sharp, subulate, conical 
points, arranged along the straight truncated edge of the base; medial cone much 
larger than the secondary ones, of the latter the external cones are largest ; all the 
cones striated longitudinally, and either circular in section or with simple cutting 
edges, slightly compressed.” —(M‘Coy). 
In Prof. Agassiz’s definition of the genus all the characters pertaining to the 
base are omitted. He points out the great resemblance existing between the teeth 
of Cladodus and those of Hybodus of the more recent Lias formations. There is 
the same slender form of the median cone and foldings of the enamel—the same 
relations between the root and the crown. ‘The median cone in both is flanked on 
each side by secondary cones, but with this difference, that instead of decreasing 
in size from the median cone, towards the lateral extremities, they present an in- 
verse disposition, the largest secondary cones being situated at the extremity of 
the base and diminishing in size towards the median one. 
So far as known, all the species of Cladodus are confined to the Carboniferous 
rocks, so that they may be looked upon as the forerunners of the genus Hybodus, 
which makes its appearance in the rocks of Triassic age. 
Cladodus mirabilis, Agass, 
(Pl. XLIX., figs. 1-5.) 
Cladodus mirabilis— A gassiz, L. 1833. © Poissons Foss.,” Vol. III., p. 197, pl. 22 B, fig. 9-13. 
55 As Portlock, J. E. 1844. ‘Geol. Report, Fermanagh, &ec.,” p. 461. 
5 sy Giebel, C. G. 1858. ‘Fauna der Vorwelt,” Vol I., pt. 3, p. 322. 
5 5 Pictet, F. J. 1854. “'Traité de Paleont,” Vol II., p. 258. 
3 3 M‘Coy, F. 1855. ‘Brit. Paleoz. Foss.,” p. 619. 
re ns D’Eichwald, E. 1861. “Lithea Rossica,” p. 1604. 
5 _ Morris & Roberts, 1862. ‘Quart Journ. Geol. Soc.,” Vol. XVIIL., p. 100. 
es 5 towanowsky, H. 1864. “Bull. de la Soe. Imper. des Nat. de Moscou,” Vol. 
XXXVII., p. 166, pl. iv., fig. S1. - 
- Ms Young & Armstrong,1871. ‘Trans. Geol. Soc. Glasgow,” Vol. IIL, supt., p. 69. 
Teeth vary considerably in size and form. Base semicircular, very thick and 
coarsely osseous, extending more or less horizontally at right angles to the cones 
forming the crown. The under side of the base is concave in the centre, the root 
of the crown conforming to, and laying parallel above it. Crown consists of central 
cusp and an irregular number of bilateral secondary ones, usually two on each side. 
The median and secondary cones are thick, circular and strongly attached to the 
base, abruptly tapering and ending in a more or less acuminate apex slightly 
inclined backwards. The lower portion of each cone is deeply but finely striated, 
