474 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 
parallel to the sinuous margin of the anterior extremity of the tooth ; surface 
thickly coated with enamel; rugose; folds extending longitudinally across the 
crown. Lateral margin, crown extended beyond the base, concave in centre, 
convex on each side, the convexity being continued to the lateral margins, 
which, towards the posterior angles, are straight ; posterior margin of tooth 
straight ; postero-lateral angles, acuminate, slightly produced posteriorly. Base, 
thick, osseous, striated; transversely convex, 95 of an inch across. Posteriorly the 
base extends beyond the crown; laterally it is produced on each side of the crown, 
forming aliform processes, widest near the postero-lateral angle, where they are “15 
of an inch in breadth. Length of crown, *65 of an inch ; breadth, °3 of an inch. 
This species differs from Rhymodus transversus in general form. The depres- 
sions on each side of the crown and parallel to the border are not present, and the 
lateral borders are much less prominent. The presence of the wide ridge parallel 
to the anterior margin is also characteristic. ‘The surface of enamel in &. trans- 
versus is punctate; in JL. oblongus it is longitudinally rugose, and the aliform 
extensions of the base parallel with coronal surface are much wider in this species 
than in the former one. The two species agree in the deeply-concave anterior 
margin, which in this species, as in 2. transversus, afforded space for the attachment 
of a secondary portion of the crown. 
Genus.—Characodus, Agass. MSS. 
Characodus—L. Agassiz, 1859. MSS. Enniskillen Coll. 
Palatal teeth, more or less inversely conical in their outline, of medium 
size ; crown, convex ; lateral borders produced, forming prominent ridges ; coronal 
surface thickly enamelled, punctate, anteriorly worn by attrition, occasionally con- 
siderably incurved over the base and crenated ; anterior and posterior margins 
parallel, straight, slightly convex or slightly concave; lateral margins straight, 
increasing in diameter backwards ; base, comparatively thin, similar in form to that 
of the crown. 
This genus comprises two species, the first of which, C. angulatus, must be taken 
as the generic type. The second, C. cuneatus, whilst agreeing in all essential cha- 
racters, is a considerably longer tooth than C. anguiatus. Characodus may be 
allied to the genera Labodus or Rhymodus. To each its transversely oblong form 
bears a general resemblance ; but a closer inspection exhibits peculiarities which 
clearly separate it from those genera. ‘The crown in Characodus is one-third less 
in diameter anteriorly than posteriorly, and the base is co-extensive with the 
crown, whilst the coronal surface of Labodus or Rhymodus is about the same 
diameter anteriorly as posteriorly ; but the osseous base extends in aliform pro- 
cesses on each side, principally towards the back, beyond the lateral margin of the 
crown, giving to those genera somewhat of the form and appearance of the crown 
of Characodus. 
