618 BRITISH PALAOZOIC FOSSILS, [ Pisces. 
Cuomatopus (Hetopus) DENTIcuLATUS (M/"Coy). PI. 3. K. fig. 9. 
Ref.—M°Coy, Ann. Nat. Hist. 2nd Series, Vol. II. p. 124. 
Dese.—Transversely oval, base about three times wider than long; middle elevated into a compressed 
obtusely pointed cone, about equal in height to the short diameter (length) of base, from which a sharp, much 
compressed mesial ridge extends on each side to either end, its cutting edge being broken into numerous, obtuse, 
compressed denticles, decreasing in size towards the ends; the notches which separate the little cones on the 
edge give rise to obtuse sulci, defining them a short way down the sides; surface smooth; base surrounded 
with three or four imbricating folds of ganoine, irregularly jagged at their edges. Average length of tooth 
about nine lines, height of crown four lines, width five lines. 
This species is rather smaller, more elevated, and more compressed than the C. cinctus (Ag.), from which 
it is principally distinguished by the number of minor cones set on the mesial ridge. 
Position and Locality.—Rare in the red carboniferous limestone of Armagh. 
Explanation of Figures.—PI. 3. K. fig. 9, side view natural size (the extremities broken); fig. 9a, do. 
seen from above. 
Cuomatopus (HELoDUS) LINEARIS (A¥g.) 
Ref.—Ag. Poiss. Foss. Vol. III. t. 12. f. 5, 9. 
Dese.—Tooth very elongate, narrow, subparallel-sided ; crown flattened, or with a slight mesial gibbosity ; 
finely punctured, and bordered by two or three strong imbricating folds of ganoine. 
There is but one doubtful specimen of this species in the collection, which is not sufficient for a full 
description. 
Position and Locality.—Very rare in the carboniferous limestone of Armagh. 
Cuomatopus (HELopus) opitiquus (M/°Coy). PI. 3. K. fig. 3. 
Ref—M°Coy, Ann. Nat. Hist. 2nd Series, Vol. II. p. 124. 
Dese.—Obliquely rhomboidal, transversely elongate ; apex marginal, obtusely pointed; middle of the tooth 
obliquely tumid or convex; attenuated sides flattened or slightly concave ; ends obtusely pointed or rounded ; 
surface highly polished and perfectly smooth except at the apex, which is coarsely punctured; basal margin 
surrounded by a broad imbricating fold of ganoine*, increasing to three or four on the ends of some of the 
teeth. 
This species differs from the O. cinctus (Ag.) in its obliquely rhomboidal flattened form and marginal apex, 
as well as having but one fold of ganoine at the middle of the basal margin. In some examples the ends are 
equal, and the width three times the length ; in others the ends are unequal, and the length two-thirds of the 
width; but in all the apex is marginal, and the general form obliquely rhomboidal, the basal margin having a 
downward curve nearly opposite the apical projection of the anterior margin, and between the two extends the 
oblique mesial convexity. Length averaging four lines. 
Position and Locality—Rare in the carboniferous limestone of Armagh. 
Explanation of Figures.—P1. 3. K. fig. 3, natural size, front view. 
Cuomatopus (PETALODUS) TRUNCATUS (4g. name only). PI. 3. I. fig. 1. 
Desc.—Tooth longitudinally oblong, sides of crown and root subparallel except at the upper and lower 
ends, where they rather abruptly converge to form the subtruneate, slightly rounded, cutting edge at top, and the 
* T provisionally used (Joc. cit.) this term (from yavos, splendour), to designate that peculiar dense modification of 
dentine which forms the highly-polished surface of most fish-teeth, and which is not unfrequently confounded with the 
true enamel of the teeth of the higher animals; the latter is, however, secreted by a distinct organ, quite external to 
and independent of the dentine, while the false enamel, which I have proposed to call ganoine, is merely produced by the 
calcigerous tubes of the dentine becoming suddenly straighter, closer, and more numerous, as they approach the surface. 
