CRETACEOUS REPTILES. 385 
Genus Ler1opon. 
(Tab. XXXVIL. figs. 10,11 &12; Tab. XXXVIII. figs. 8 & 9.) 
Of three teeth which, by the equality of the two sides, and consequent elliptic 
transverse section of the crown, are referable to the genus Leiodon, one, from the 
chalk of Norfolk (Pl. XX XVII. fig. 12*), presents the size of the specimens 
figured in my ‘ Odontography’ (pl. 72. figs. 1 & 2), on which the genus was 
originally founded, and belongs, therefore, to the Leiodon anceps. The other 
specimen, Pl. XX XVII. fig. 11, from the chalk of Sussex, presents only half the 
size of this; and the third specimen (fig. 10), from the same locality, is still 
smaller. 
These specimens, now in the museum of Henry Catt, Esq., may belong to 
the pterygoid bones of the larger species of Leiodon ; or possibly even to those 
bones in the Mosasaurus gracilis, since the pterygoid teeth of the Mosasaurus 
Hofmanni approach the characteristic form of the teeth of the genus Leiodon: 
but that genus of Mosasauroid Lizards is founded on specimens attached to the 
mandibular, not the pterygoid bones. 
A fine and characteristic tooth of the Leiodon anceps, found in the chalk in 
cutting the Brighton and Lewes railway, and which is also in the collection of 
Mr. Catt, is figured in Pl. XXXVIIL. figs. 8 & 9. 
Fig. 14. Pl. XX XVII. represents the crown of a conical curved tooth with a full 
elliptical base which is excavated in the middle by the apex of the pulp-cavity ; 
two principal, but not quite opposite longitudinal ridges divide the surface of 
the crown into an outer longitudinally convex, and an inner longitudinally 
concave surface: the latter, transversely, forms three-fourths of a circle, and 
the same proportion of the circumference of the tooth: the outer facet is less 
convex transversely. All the outer surface of the tooth is finely grooved or 
striated longitudinally ; but the outer surface also shows four or five longitudinal 
ridges or angles of the enamel at unequal intervals, and there is one similar ridge 
the inner side near one of the larger boundary ridges. This tooth belongs most 
probably to some member of the Mosasauroid family. It is from the chalk 
formation near Norwich. 
Tribe REPENTIA. 
Genus RapurosauRvs. 
Species. Raphiosaurus Lucius. (Tab. XXXIX. figs. 1, 2 & 3.) 
In a Memoir communicated to the Geological Society of London in 1840, and 
