620 BRITISH PALAZOZOIC FOSSILS. [ Piscus. 
length of base one inch three lines, height of principal cone nine lines, its width at base four and half lines; 
width of outer secondary cone two lines, height three lines; width of semicircular base about four lines. 
This species is easily distinguished from the C. striatus by the very great thickness, convexity, and abrupt 
tapering of the principal cone; and very obviously by the far greater coarseness and separation of the longitu- 
dinal ridges; the secondary cones are also very much larger, thicker, and fewer in number. The Cladodus 
marginatus of Agassiz is founded on worn specimens of this species, as I have ascertained by examining the 
type specimens. I have little doubt that the C. acutus is a young specimen of the same species, 
Position and Locality.—Not very uncommon in the limestone of Armagh. 
CLADODUS STRIATUS (Ag.) 
Ref. and Syn.—Ag. Poiss. Foss. Vol. IIT. t. 22 4, f. 14, 17. 
Desc.—Base semicircular, large, moderately thick, and undulated at the rounded edge with a few obtuse, 
irregular, radiating furrows below, and obscurely nodose above. Average width one inch one line, from middle 
of flat side to middle of convex margin seven lines, main cusp moderately compressed, slightly sigmoid, nine 
lines long, and inclined towards the convex margin at an angle of about 70°; lateral edges smooth, sharp and 
cutting ; apex smooth for about three lines from the point, remainder of the cusp marked with very fine longitu- 
dinal slender strize, about nine in one line, irregularly alternate or nearly equal in size; lateral cusps extremely 
small, rarely visible, five or six very slender ones on each side, less than a line in length, the terminal one thicker 
(scarcely one line at base) and rather more than three lines long when perfect, and is usually the only one seen. 
The examination of a great number of specimens of this species convinces me that M. Agassiz is incorrect 
in supposing that the C. acutus is the only species with cutting edges, as they are distinctly marked in the 
present species. The very small lateral cusps and fine striation easily separate this species from C. mirabilis, 
and the others of the genus. 
Position and Locality.—Not uncommon in the carboniferous limestone of Armagh, rare in the carboni- 
ferous limestone of Lowick, very rare in the carboniferous limestone of Derbyshire, very rare in the 
carboniferous limestone of Brigsteer, Kendal. 
Genus. CLIMAXODUS (M°Coy). 
(Etym. ediuaég, a flight of steps, and ddods, a tooth). 
Ref.—Id. M'Coy, Ann. and Mag, Nat. Hist. 2nd Series, Vol. II. 
Gen. Char.—Tooth longer than wide, gradually narrowing towards the front, with nearly straight sides ; 
anterior part of the crown crossed by broad, imbricating, transverse ridges at right angles to its length; 
surface minutely punctured. 
The above generic name has reference to the remarkable step-like character of the ridges which cross the 
anterior part of the tooth at regular intervals. The broad posterior part of the tooth is without ridges, and 
resembles a Psammodus. In the fact of being as it were small, ridged, Psammodi, these teeth are allied to 
the genus Pacilodus, but all the true Pwcilodi are inequilateral mussel-shaped teeth, consequently placed in 
pairs in the mouth, and have the ridges oblique; the Climazxodi, on the contrary, are equilateral, and were 
therefore most probably mesial in position, and the ridging is transverse. 
I am aware of one species in the Armagh limestone, and the following. 
CLiMaAxopus ImBRICATUS (M°Coy.) Pl. 3. G. fig. 5. 
Ref.—Id. M°Coy, Ann. and Mag. Nat. Hist. 2nd Series, Vol. IT. 
The only specimen I have access to at present of this species is imperfect at each end, being seven lines 
long, five and half lines wide at the broad end, and three lines wide at the narrow anterior end; the anterior 
