On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 473 
Genus.—Rhymodus, Agass. MSS. 
Rhymodus—L. Agassiz, 1859. MSS. Enniskillen Collection. 
Palatal teeth, transversely oblong, of medium size, the length less than half of the 
breadth. Crown, convex in centre, laterally depressed, borders prominent. Coronal 
surface, coated uniformly with enamel, slightly punctate. Anterior margin, deeply 
concave, concavity occasionally occupied by a crescent-shaped portion of the 
crown ; posterior and lateral margins convex, postero-lateral angles acuminate. 
Base, thick, smooth, longitudinally shorter than crown; transversely convex ; 
extending beyond the coronal margin, and forming an acute angle with the superior 
surface of the tooth. 
Rhymodus transversus, Ag. MSS. 
(QPAL, JENV INU, 10% IL 7) 
Rhymodus transversus—L,. Agassiz, 1859. MSS. Enniskillen Coll. 
. . Morris and Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101. 
i Enniskillen, 1869. “Cat. Type Spec.,” p. 8. 
Me 5; J. J. Bigsby, 1878. <‘Thes. Dev.-Carb.,” p. 365. 
Teeth, transversely oblong, thick, variable in size. Length of crown, 45 of an 
inch ; breadth, ‘9 of an inch, beyond which an osseous prolongation of the base 
extends 12 of an inch on each side, making the total breadth 1:14 inch. Crown 
longitudinally and transversely convex in centre ; a depression extends across the 
surface on each side, parallel to the lateral borders, which are raised and prominent. 
Surface of crown, covered with enamel; uniformly, but indistinctly punctate. 
Anterior margin of crown sinuous, central portion deeply concave ; antero-lateral 
angles, obtusely rounded. Lateral margins convex ; posterior, well rounded in 
central part, a depression on each side, corresponding to the one on the surface ; 
postero-lateral angles slightly acuminate. Laterally, beyond the coronal surface 
there is an extension of the osseous base, most largely developed at the postero- 
lateral angles. Base, conforms generally to the outline of the crown, ‘3 of an inch 
thick, transverse section, convex; thinning off laterally to an acute angle, with 
superior face, longitudinally striated, smooth. 
Figure 17 represents a specimen in which the deeply concave anterior surface 
is occupied by an enamelled, crescent-shaped portion of the tooth, the division 
being distinctly marked by the presence of a suture-like depression. The anterior 
border in this specimen is straight. 
Rhymodus oblongus, Davis. 
(Pl. LVIIL., fig. 18.) 
Teeth, oblong in contour; length less than half the breadth ; thickness 
equal to length ; crown, convex in both directions ; lateral borders shehtly 
raised. A ridge, ‘15 of an inch in breadth, extends across the coronal surface 
4D2 
