DAVIS : FOSSIL FISH REMAINS. 
49 
Oladodiis, it is a thicker and strong-er tooth with only one lateral 
cusp on each side the large central one. The name was given 
originally by Prof. M. Co}'' to teeth from the Limestone of 
Derbyshire. Glyphanodus is a very peculiar species, the teeth 
are excessively thin and compressed, the crown consisting of a 
single median cone with a chisel-like edge, sharp and smooth. 
The base descends co-extensively with the crown and resembles 
that of the Petalodonts more than Cladodus which usually extends 
in a more or less horizontal direction backwards ; the crown of 
the tooth is however, much more closely related to Cladodus than 
the Petalodonts, possessing characters which would associate it 
with both genera it may perhaps be looked upon as a connecting 
Hnk between the two. It has been found only in Yorkshire. 
The teeth comprised in the group Orodontidce have a very 
wide distribution both in the British Islands, on the continent of 
Europe, and in America. Those found in Yorkshire comprising 
two species of Orodus are small and comparatively rare ; there is 
also one species of Lophodus and a new genus Diclitodus. The 
latter has only been found in Yorkshire, it differs from the genus 
Orodus in possessing two equal cones raised from the crown ; in 
other respects it bears a considerable likeness to the Orodonts and 
has been placed provisionally amongst them. 
The Orodonts in the Limestones of Bristol and Armagh are 
very much larger in size than the Yorkshire ones but it is 
rarely that two or more teeth are found in juxtaposition though 
two or three instances have occurred in which three or four teeth 
have been connected together in such a manner as to leave no 
doubt that they still retained a natural position. Though examples 
are rare in this country of specimens which exhibit the arrange- 
ment of the teeth on the jaws, American palasontologists have 
discovered at Osage, County Kansas in America, an extremely well 
preserved series of teeth which illustrate the whole dental 
arrangement. The teeth are from the coal measures and ai-e 
described in " Paloeontology of Illinois" Vol VI. p. oil, by 
